Can a High RPM Gas Engine Move a Heavy Load Like a Low RPM Diesel?

[Ketch22]

Another piece of this that you may need to consider. Stayed rather simplfied so to allow you to explain in similar fashion. Hp is a measure of work performed over time, torque is a measure of potential work.
In the case of the truck. The diesel engine involved has a very limited rpm range all being in the low end. The gas engine has a very wise range. If one counts only the potential (with no allowance for time) the truck engine is far stronger. Also the low speeds involved give tremendous life cycle.
At the same rpm the gas engine will have no comparison to the diesel. However, when the gas engine is turning more than 5 times the rpm it can actually be producing more Hp (near consistant torque at radically greater cycles per second ). The downside is that the high rpm give limited duty cycle.
Concider if you would your mack truck alongside a formulae Atlantic engine the 255 ft/lb 1.4 L is no comparison to the (probably) 10L or so diesel at the bottom end. However by the time the mack is wound tight at approx 2000 rpm and the car is at 12,000 up tight the truck looses. But, what happens to the drive components when you clutch and shift at that rpm against an 80,000 lb load?
The truck is a much better choice for starting, stopping, and everyday life. The high rpm has engine is more effective at high speed and controllable application of power to the ground.

 

[Moretorque]

Thanks for all the help you all, How bout the Mack with a 5 speed stick and 238 HP being able to move 60 or 70 grand to 67 MPH effectively. I talked to Reher Morrison who build engines about this and they said the people who think you can gear around the lack of torque do not understand HP . They said there is no way a 500 HP spinner car motor could move a load like the Semi engine no matter how you gear.

My assumption was the more torque you have the more gear you can feed it and get better acceleration but peak MPH would be the same because peak power is the same.

This can be confusing a little because I get different stories on this.

 

[jack action]

They said there is no way a 500 HP spinner car motor could move a load like the Semi engine no matter how you gear.

The 500 hp spinner will not move a load like the semi because it doesn't have as much low-end power as a 500 hp semi engine. I underlined power because it is a keyword.

Usually, people compare 2 identical engines with different set ups and compare the maximum torque figures which happens to be in the same lower rpm range. They can easily see that the one with the highest maximum torque is usually better for moving a large load. But, because the maximum torque is measured at the same rpm, it means the power is also equally higher. If you take 2 engines with 2 very different rpm ranges (like one in the 1000s rpm and the other in the 10000s rpm), you won't be able to compare the maximum torque numbers so easily; but you will still be able to compare the power.

What counts is the average power in the rpm range that you use. A race car can use a very narrow rpm range and engine builders maximize the power only in that narrow band, which happens to be very close to the peak power. For a semi, a much wider rpm range is necessary and the average power throughout that range is more important than peak power alone.

Performance-wise, torque is a useless quantity to know, because an appropriate gearbox can give whatever torque output you desire. It can also gives you whatever rpm you want. But it cannot give you both. And «both» is the concept of power. Power cannot be altered in any way: what comes in, will come out.

 

[cjl]

Thanks for all the help you all, How bout the Mack with a 5 speed stick and 238 HP being able to move 60 or 70 grand to 67 MPH effectively. I talked to Reher Morrison who build engines about this and they said the people who think you can gear around the lack of torque do not understand HP . They said there is no way a 500 HP spinner car motor could move a load like the Semi engine no matter how you gear.

My assumption was the more torque you have the more gear you can feed it and get better acceleration but peak MPH would be the same because peak power is the same.

This can be confusing a little because I get different stories on this.

Unfortunately, this is an area where the intuition of a lot of car and truck people leads them astray. Power tells you the rate at which you can add energy to a system, so for the same horsepower, on a vehicle with the same losses, weight, and aero, you will get the same acceleration. Let's look at an example. Let's compare a high performance car engine to a truck engine. First, we'll look at the Porsche 991 (current generation 911) GT3 engine, which makes 475 horsepower at a fairly outrageous 8250rpm, redlines at 9000rpm, and only makes 325 pound feet of torque at about 6250rpm. Second, we'll look at the Detroit Diesel DD15. Specifically, we'll look at one rated for 455 horsepower at 1800RPM, and 1550 pound feet of torque at 1100rpm. Now, if you plot both of these on the same axes, it looks rather silly, and the Detroit is way, way better at making a ton of power and torque at low RPM, which is what we want for hauling a load, right?

However, let's keep going with this analysis, just for fun. Suppose we keep everything the same except we put a 4.5:1 reduction gear on the GT3 engine, so that when the engine is spinning 9000RPM, the output shaft of this reduction gear is spinning 2000RPM. This will also multiply our torque by a factor of 4.5. Now, if we compare the output of this gear reduction to the output of the detroit diesel, this is what we get...

With this gear reduction, we suddenly have a small (3.8 liter), high performance gas engine that is spinning an output shaft with a thousand pound feet of torque at 500RPM, and over 1400lb-ft at 1500RPM. This is very comparable to our truck engine, and you would likely get similar acceleration from 1200-2000RPM (output shaft speed) with both of these engines hooked to the same transmission and drivetrain (aside from the gear reduction), despite the fact that one of them is a high-strung, titanium and aluminum 3.8L flat 6, and the other is a large, turbocharged, 14.8L diesel inline 6. The diesel will likely last much longer of course, and get significantly better fuel mileage, but purely from a performance standpoint, horsepower really is all that matters.

 

[Moretorque]

I understand all that but this is the thing, the ability to spin up and build power under such a heavy load. Torque seems to me the ability for a motor to build HP under a load and the drag car engine builder verified this.

You have two motors both make 500 HP one does it at 5000 RPM the other at 10000, you gear both with one gear that tops out at 75 MPH at HP red line peak for each engine. You have a clutch in both vehicles of same type cars and the lower rpm engine will beat the other one to 75 MPH because it is able to build power under that load better to reach top speed for that scenario. No matter how you gear the 10000 RPM motor you can do the same gearing change to the 5000 RPM so it will reach top speed faster because it is able to build power under load better.

This is why a Semi of 240 HP can pull a 70000 pound load with just a 5 speed, it literally has the pulling power of a mild Pro Mod drag car. Not the HP MPH at all but the ability to build and maintain power under a load of pulling 35 tons.

This was a debate we had on another forum and people said you could take a spinner gas motor with proper gearing and get it to pull like a semi and others who own diesels said they were high on dope, I went around with this and it made me realize how bad my math skills are but I am tying to learn. The people who build the drag motors straightened me out and said people who think you can gear around a lack of torque to do a job do not understand HP and how to read a dyno.

Torque gives you the ability to feed a motor more load and it can maintain RPM better to accelerate to speed, Max MPH speed is the same but the torquer motor geared correctly will get their faster or move more weight there.

 

[cjl]

I understand all that but this is the thing, the ability to spin up and build power under such a heavy load. Torque seems to me the ability for a motor to build HP under a load and the drag car engine builder verified this.

No, torque is purely the turning force available at a given RPM. The "ability to build HP under a load" doesn't even mean anything - HP is a mathematical function of torque and RPM.

You have two motors both make 500 HP one does it at 5000 RPM the other at 10000, you gear both with one gear that tops out at 75 MPH at HP red line peak for each engine. You have a clutch in both vehicles of same type cars and the lower rpm engine will beat the other one to 75 MPH because it is able to build power under that load better to reach top speed for that scenario. No matter how you gear the 10000 RPM motor you can do the same gearing change to the 5000 RPM so it will reach top speed faster because it is able to build power under load better.

Nope, given similarly wide powerbands (as a percentage of peak RPM), and appropriate gearing, they will both reach top speed in about the same amount of time. If both are geared for ideal performance, the gearing on the 10krpm motor will be a factor of 2 different than the gearing of the 5krpm motor.

This is why a Semi of 240 HP can pull a 70000 pound load with just a 5 speed, it literally has the pulling power of a mild Pro Mod drag car. Not the HP MPH at all but the ability to build and maintain power under a load of pulling 35 tons.

A 240hp semi with a 5 speed will be fairly underpowered pulling 70klb, first of all. Most semis have 400+hp and a 10+ speed gearbox. Second of all, the pulling power at a given speed is purely a function of horsepower, as long as you have appropriate gearing. A pro mod drag engine, with appropriate gearing, will way, way outaccelerate a semi pulling the same load, since it has immensely more power.

This was a debate we had on another forum and people said you could take a spinner gas motor with proper gearing and get it to pull like a semi and others who own diesels said they were high on dope, I went around with this and it made me realize how bad my math skills are but I am tying to learn. The people who build the drag motors straightened me out and said people who think you can gear around a lack of torque to do a job do not understand HP and how to read a dyno.

Torque gives you the ability to feed a motor more load and it can maintain RPM better to accelerate to speed, Max MPH speed is the same but the torquer motor geared correctly will get their faster or move more weight there.

Just because the people who build drag motors have a misconception doesn't make them right. Did you even read my last post?

While googling torque curves and such to use for the example in my last post, I came across a great analogy for this argument. This is like a bunch of people arguing about water tanks, where one group says that the volume of the tank determines how much water it can hold, while another group says the height of the tank is most important. Yes, all other factors being equal, the taller tank holds more water, but at the end of the day, the volume is a direct measure of how much it can hold, and you can achieve that with a tall skinny tank or a short squat tank. Similarly, you do need some torque to make horsepower, and all else equal, more torque equals more power, but at the end of the day, the acceleration, the work the engine can do, or the weight you can tow is determined by the horsepower, and you can achieve that with a high revving low torque engine or a high torque low revving engine.

 

[Moretorque]

I read your post above and thanks for posting it, and I forgot to say with similar power curves for their respective HP RPM ranges. First off these guys build some of the fastest engines on Earth and second off they have been doing it since the 50's and 33rd off they have rigs pull their race stuff so ?

I am just looking for the right answers and here we go again, what about roll on acceleration with each motor being equal gearing everything, that would be about the same ?

The Mack will move a load with just a 5 speed and 238 HP, I looked at buying one. I am not sure but something tells me you guy's " it's a big crowd " my step father is a astrophysicist and he says the same thing you do but are missing something in this. I am just looking to understand this so thanks.

So what you are saying is they do the same work.

Here is something else, the guy's on the PU truck forums who bought a 300 HP diesel to replace their 300 HP gas motor say the diesel pulls night and day better way more powerful at building speed under load.

 

[Moretorque]

I need to talk to a electric motor builder to straighten this out, I know the right ? to ask. Since there torque curve is much more linear it should make it easier for me to understand.

Here is the ? I will ask him and it will answer it all, maybe you can save me the trouble ?

You gear the spinner electric motor to where the output is turning the same RPM as another of same HP but it turns much slower to make same HP and then ask if the spinner stopped can build RPM under the same load as the other one stopped when you let go and let them rev up together to make power and also is it easier to stop it with a brake maxed out spinning both being same HP value but one has more torque.

Again thankyou.

 

[Moretorque]

h

Unfortunately, this is an area where the intuition of a lot of car and truck people leads them astray. Power tells you the rate at which you can add energy to a system, so for the same horsepower, on a vehicle with the same losses, weight, and aero, you will get the same acceleration. Let's look at an example. Let's compare a high performance car engine to a truck engine. First, we'll look at the Porsche 991 (current generation 911) GT3 engine, which makes 475 horsepower at a fairly outrageous 8250rpm, redlines at 9000rpm, and only makes 325 pound feet of torque at about 6250rpm. Second, we'll look at the Detroit Diesel DD15. Specifically, we'll look at one rated for 455 horsepower at 1800RPM, and 1550 pound feet of torque at 1100rpm. Now, if you plot both of these on the same axes, it looks rather silly, and the Detroit is way, way better at making a ton of power and torque at low RPM, which is what we want for hauling a load, right?

View attachment 84240

However, let's keep going with this analysis, just for fun. Suppose we keep everything the same except we put a 4.5:1 reduction gear on the GT3 engine, so that when the engine is spinning 9000RPM, the output shaft of this reduction gear is spinning 2000RPM. This will also multiply our torque by a factor of 4.5. Now, if we compare the output of this gear reduction to the output of the detroit diesel, this is what we get...
View attachment 84241

With this gear reduction, we suddenly have a small (3.8 liter), high performance gas engine that is spinning an output shaft with a thousand pound feet of torque at 500RPM, and over 1400lb-ft at 1500RPM. This is very comparable to our truck engine, and you would likely get similar acceleration from 1200-2000RPM (output shaft speed) with both of these engines hooked to the same transmission and drivetrain (aside from the gear reduction), despite the fact that one of them is a high-strung, titanium and aluminum 3.8L flat 6, and the other is a large, turbocharged, 14.8L diesel inline 6. The diesel will likely last much longer of course, and get significantly better fuel mileage, but purely from a performance standpoint, horsepower really is all that matters.

The problem is you can't keep your motor peaked at 9000 RPM, peak output Torque MPH is the same but only peak. It is your ability to maintain it and build it when you shift and when your RPM drop you do not have the torque coming out of the engine shaft to maintain the power when the revs go down shifting and pulling 40 tons you cannot build them back up under that load.

Paper says one thing but real world loads say another and I am not saying you are wrong, If all else fails I have a test I can do using electric motors that will answer the ? I am pretty sure if you are wrong this is what you are missing, the torque values you are looking at on paper you are not considering the torque it takes coming out of the motor shaft to build to the next level of power and you do not have that no matter how you gear a 400 HP gas car engine to pull 40 tons.

You would need a chase truck to push you to each extra MPH once there you could stay there but on your own the engine does not have the torque to build revs under such a load. I am pretty sure this is what your camp is not seeing

The Mack has the ability to build it's puny 67 MPH 238 HP under 30 ton load with a 5 speed like a Pro Mod why because it has Pro Mod torque.

 

[jack action]

You would need a chase truck to push you to each extra MPH once there you could stay there but on your own the engine does not have the torque to build revs under such a load. I am pretty sure this is what your camp is not seeing

What you are not seeing is that you need to compare power curves and not peak power alone. Nobody here is saying that engine builders don't know how to build engines. It's just that a lot of them don't use the right terminology when they express themselves.

Here is something else, the guy's on the PU truck forums who bought a 300 HP diesel to replace their 300 HP gas motor say the diesel pulls night and day better way more powerful at building speed under load.

Yes, but you are comparing maximum horsepower only. Are both power curve alike? Meaning does the diesel engine makes more power at a lower rpm than the gas engine? Usually, diesel engines have the advantage in the lower-end:

​

If we can convince you, here's a wonderfully well written and illustrated page about the subject. I also suggest the page about comparing power curves.

I especially like the corrected version of the popular phrase:

Peak power sells cars. High average power wins races.

Again, it's not a matter of which theory gives the best results, it's a matter of looking at the right data, the one that is meaningful. Nobody argues against the results.

 

[cjl]

h The problem is you can't keep your motor peaked at 9000 RPM, peak output Torque MPH is the same but only peak. It is your ability to maintain it and build it when you shift and when your RPM drop you do not have the torque coming out of the engine shaft to maintain the power when the revs go down shifting and pulling 40 tons you cannot build them back up under that load.

That's why I showed you the torque curve comparison with the motor geared down 4.5:1. It makes about the same torque at all output shaft RPMs, and it's making over a thousand pound feet starting at 500rpm output shaft speed (2250RPM engine speed), and over 1400 pound feet at 1200RPM shaft speed. You would set it up with a transmission so that it would engage the clutch at ~1000-1200RPM shaft speed, and on each shift, you'd drop back down to about 1300 from 1800 or so. This would keep you very solidly in the power band. If you look at the torque curve again (https://www.physicsforums.com/attachments/dd-15-vs-991-gt3-2-png.84241/), you'll see that the GT3 motor makes comparable torque to the Detroit Diesel from a shaft speed of about 1200 to about 2000 RPM (5400 to 9000 RPM motor speed), and from about 1750 RPM to 2000 RPM (7875 to 9000 RPM motor speed), it's actually making more torque (and power) than the Detroit. Given both of these torque curves, why would you not expect the GT3 engine to be able to tow? Hell - even at 400RPM shaft speed, it's making 1000 pound feet of torque, which is easily more than the 238hp Mack that you keep talking about would make at any speed, and this is just at 400RPM!

Paper says one thing but real world loads say another and I am not saying you are wrong, If all else fails I have a test I can do using electric motors that will answer the ?

Real world loads? When has anyone ever put a 400+hp 8000+rpm motor in a semi and geared it like this?

I am pretty sure if you are wrong this is what you are missing, the torque values you are looking at on paper you are not considering the torque it takes coming out of the motor shaft to build to the next level of power and you do not have that no matter how you gear a 400 HP gas car engine to pull 40 tons.

What "torque to build to the next power band" are you talking about? If I set the 911 engine to idle at a shaft output speed of 1000RPM (4500RPM engine speed), and then apply gas while I engage the clutch, I have well over a thousand pound feet of torque, and if I raise the RPM to 1200 on the output shaft, I have over 1400 pound feet of torque. This is more than enough to get a fully loaded 80klb semi moving, given typical truck gearing.

You would need a chase truck to push you to each extra MPH once there you could stay there but on your own the engine does not have the torque to build revs under such a load. I am pretty sure this is what your camp is not seeing

I've already explained why this is wrong

The Mack has the ability to build it's puny 67 MPH 238 HP under 30 ton load with a 5 speed like a Pro Mod why because it has Pro Mod torque.

Not a chance. Let's ignore aerodynamic drag for a second (just to get a ballpark number) and assume 2500 horsepower from a pro-mod drag motor. Let's assume we gear it in a way to average 2000hp during a zero to 60 acceleration run on an 80klb GVW truck. The kinetic energy of an 80klb truck at 60mph is 13 megajoules. 2000 horsepower is 1.5 megawatts. This means that a pro-mod engine making 2000 horsepower on average during an acceleration run can get an 80 thousand pound truck to 60mph in less than 10 seconds. There is no way that your Mack can even come close to this level of acceleration.

 

[cjl]

Here is something else, the guy's on the PU truck forums who bought a 300 HP diesel to replace their 300 HP gas motor say the diesel pulls night and day better way more powerful at building speed under load.

Here are a few likely reasons:

1) Chances are, the pickup makes more power at low RPM than the gas. This by itself isn't enough to explain it though, since it could be made up for with gearing
2) The gas is probably not geared to make peak power at as low of a road speed as the diesel, so the diesel makes more power at low road speeds (good for getting a heavy loads started). This is largely because the manufacturers assume that if someone is buying a diesel, they're probably towing a lot, so they gear the diesel appropriately. The gas, on the other hand, is probably geared more for fuel efficiency rather than purely for towing. This advantage will start to go away as transmissions get more gears.
3) Because the diesel makes more power at low RPM, it feels like it has more power in reserve, even though it doesn't (this is a largely psychological effect). The gas engine sounds like it's working really hard at 5-6krpm while the diesel is just loping along at 3k or so, even though the power output is actually the same.

 

[Moretorque]

What got me started on this was a individual on a site who could care less was saying he had driven a tractor trailer for a while that was over 600 HP and he claimed it could accelerate a load of more than 80000 pounds up a hill and actually gain speed while going up the hill. Do you think a 600 HP car motor could do that ? not a chance.

I am going to figure out what is missing here, the pickups with the diesels just stomp the gas trucks bad bad no matter what they try , no matter where they operate the RPM. I have talked to people who build transmissions for these things special autos for the gas engines so they can try and compete but even being able to stay I in peak power RPM range they are OK but do not compete when the load is to much and we are talking same HP.

I think you all are missing something in the paper world, I am fairly sure I know what it is, I have no problem if I am wrong just trying to figure this out and thanks.

None of you all have explained how the Mack does what it does with a 5 speed and I was not talking about racing a Pro Mod motor equipped rig but it's ability to move 60 or 70 grand efficiently with a 5 speed with only 238 HP. Can a car motor spinner do that.

I know all about the math you all are laying out, again thanks will get back.

 

[insightful]

Why did the loaded Mack diesel dumper next to me today take 5 speeds just to get to 20 mph?

 

[cjl]

What got me started on this was a individual on a site who could care less was saying he had driven a tractor trailer for a while that was over 600 HP and he claimed it could accelerate a load of more than 80000 pounds up a hill and actually gain speed while going up the hill. Do you think a 600 HP car motor could do that ? not a chance.

Sure it could, geared appropriately.

I am going to figure out what is missing here, the pickups with the diesels just stomp the gas trucks bad bad no matter what they try , no matter where they operate the RPM. I have talked to people who build transmissions for these things special autos for the gas engines so they can try and compete but even being able to stay I in peak power RPM range they are OK but do not compete when the load is to much and we are talking same HP.

Have you actually drag raced or measured them to verify that the diesels stomp the gas, given the same horsepower and appropriate gearing?

I think you all are missing something in the paper world, I am fairly sure I know what it is, I have no problem if I am wrong just trying to figure this out and thanks.

None of you all have explained how the Mack does what it does with a 5 speed and I was not talking about racing a Pro Mod motor equipped rig but it's ability to move 60 or 70 grand efficiently with a 5 speed with only 238 HP. Can a car motor spinner do that.

Sure, given the right gearing. It'll be very different gearing than the truck would use, but it'll work just as well.

 

[rcgldr]

What got me started on this was a individual on a site who could care less was saying he had driven a tractor trailer for a while that was over 600 HP and he claimed it could accelerate a load of more than 80000 pounds up a hill and actually gain speed while going up the hill. Do you think a 600 HP car motor could do that ? not a chance.

Note that in the virtually unlimited class for tractor pull contests, high power, high rpm engines running on mostly nitro-methane and some alcohol are used, not diesel engines. These engines have to be rebuilt after nearly every run, similar to a top fuel dragster, so they aren't practical, but it does show that power and not torque matters.

In some cases, it's the torque versus rpm curve that matters. Some gasoline engines have nearly flat torque curves. I have a 2001 Suzuki Hayabusa motorcycle with a 1.3 liter engine that redlines at 11000 rpm. The engine makes peak torque at 8500 rpm, but makes 80+% of peak torque from 3500 rpm to 10500 rpm, which is a fairly flat torque curve.

 

[Ketch22]

I would have to agree with cjl here. Measured at the output shaft of the transmission whichever power unit has the higher torque will be the one accelerating quicker. I am not sure where your truck friend compared however in the real world my experience is; one of my earliest jobs was a lumber yard. We had one of the old Macks with a brownie splitter. We also had a Ford Flathead with a 4 speed high/low. Both flatbeds worked ok however, if you wound the flathead up tight it would out accelerate the Mack up hill with comparable loads. We did on the down side have to rebuild that flathead approximately once a year.

The Math is that Horsepower is what it is about. More Hp can do more work in the same time. Longevity and serviceability are where people run there rigs. With the torque an easy demonstration is to use any Manual transmission vehicle. Find a hill where you are mid to upper mid range in the power band where you can barely maintain speed when in the highest gear and the foot fully down. In this condition the motor output is relatively stable and the full throttle position prevents human factors. Now Downshift one gear, with the foot fully down you will accelerate. In the mid range of the engine the torque curve is relatively flat however the increase in RPM (regulated by being at full throttle) creates more Hp and you over come the gravity accelerating up the hill.

With very large loads the low clutch engagement torque makes it where gas engines would fail trying to get the load going. Case in point if you are looking at Large truck engines one of the selling points (and bragging rights for motorheads) with a diesel is "Clutch Engagement Torque" which is essentially saying "how much load can I get moving from a dead stop?" On a Gasoline spinner nobody even considers "Clutch Engagement Torque" as it is a forgone conclusion that Gasoline has a rough time getting loads moving.

Your observations are correct as to the race teams and rigs. After the lumber yard I became an official motorhead. I worked on Blown Nitro Funny cars and had a personal Pro Bracket car that I raced when not working. In both cases there was a large diesel rig to move stuff. This was in reality due to us always fixing our race cars and wanting to not spend time on the truck because of that.

 

[Moretorque]

Why did the loaded Mack diesel dumper next to me today take 5 speeds just to get to 20 mph?

Where not talking about racing just to let you know, I am talking about being able to maintain the HP to do the job under heavy load. The Mack Tractor I am talking about only has 5 gears a Maxidyne but can do what I said not fast but can pull it. I asked the guy's who build the engines if you can gear around a major lack of torque and asked if geared correctly can a 500 HP car engine run a loaded semi and they said no way. I agree with what you all are saying because on paper it should fly but something tells me in the real world when under that much load the spinner motor can not maintain those torque values and maintain RPM when you have to accelerate those loads to speed.

Essentially if you gear a 300 HP car motor to only go 6 MPH in first when you drop the clutch it stalls under such load and the Maxidyne 238 will pull it even taking flywheel and so forth into consideration

I have had this conversation with many engine builders and they have told me the dyno #'s mean little in the real world so I will investigate a little further. Thank you all for taking time out of your lives to try and get my brain on par here.

 

[jack action]

I asked the guy's who build the engines if you can gear around a major lack of torque and asked if geared correctly can a 500 HP car engine run a loaded semi and they said no way.

This is what people on this forum are attempting to teach you: Everybody agree with you and the engine builders you know and that sentence is 100 % correct. You wanted to know why that is and asked how you could explain it to others. Here is our answer: It is not due to a lack of torque, it is due to a lack of low-end power. An engine is define by more than its maximum power, the whole shape of the power is important, i.e. the power output is important at every rpm.

Why are we telling you this? Let's illustrate with an example. We have three engines:

engine-------max torque@rpm-----------power@max torque
----A---------400 lb.ft@3000rpm------------------228 hp
----B---------200 lb.ft@3000rpm------------------114 hp
----C---------300 lb.ft@5000rpm------------------285 hp

Just for fun, let's say that all of these engines have the same maximum power, no matter what it is, no matter at what rpm. Which engine will give the highest acceleration at wheel rpm of 500, 1000 and 2000 rpm? Let's do the calculations:

engine-------gear ratio-------engine rpm--------wheel rpm-----------wheel torque
---A---------------6:1---------------3000---------------500-----------------2400 lb.ft
---B---------------6:1---------------3000---------------500-----------------1200 lb.ft
---C-------------10:1---------------5000---------------500-----------------3000 lb.ft

---A--------------3:1---------------3000--------------1000-----------------1200 lb.ft
---B--------------3:1---------------3000--------------1000------------------600 lb.ft
---C--------------5:1---------------5000--------------1000-----------------1500 lb.ft

---A-----------1.5:1---------------3000--------------2000------------------600 lb.ft
---B-----------1.5:1---------------3000--------------2000------------------300 lb.ft
---C-----------2.5:1---------------5000--------------2000------------------750 lb.ft

With appropriate gearing, the winner is always engine C, even though it doesn't produce the maximum torque. With engine A & B, it is clearly the one with the highest torque that gives the highest output torque, but this theory doesn't hold up with engine C. But if you compare the power they produce at maximum torque, then you can see a direct relation with their maximum output torque.

Essentially if you gear a 300 HP car motor to only go 6 MPH in first when you drop the clutch it stalls under such load and the Maxidyne 238 will pull it even taking flywheel and so forth into consideration

Again, nobody will argue with you on that point. But this relates with the power curve shape. If you already read the previous link I presented to you earlier about rpm range, you should understand. Let's look at an example again. Let's use engines A and C again. Let's add these extra data:

engine-------rpm--------torque@rpm--------power@rpm
----A---------3000--------400 lb.ft---------------228 hp -------->max torque
----A---------4000--------374 lb.ft---------------285 hp
----A---------5000--------315 lb.ft---------------300 hp -------->max power
----A---------6000--------254 lb.ft---------------290 hp -------->max rpm

----C---------5000--------300 lb.ft---------------285 hp -------->max torque
----C---------8500--------185 lb.ft---------------300 hp -------->max power
----C--------10000-------152 lb.ft---------------290 hp -------->max rpm

Now they both have the same maximum power and engine A can produce 285 hp just like engine C can. And if we choose an appropriate gearing for engine A, it can produce the same wheel torque as engine C at maximum torque:

engine-------gear ratio-------engine rpm-------wheel rpm-----------wheel torque----------max wheel rpm
---A---------------8:1---------------4000---------------500-----------------3000 lb.ft-----------------750
---C-------------10:1---------------5000---------------500-----------------3000 lb.ft-----------------1000

---A--------------4:1---------------4000--------------1000-----------------1500 lb.ft-----------------1500
---C--------------5:1---------------5000--------------1000-----------------1500 lb.ft-----------------2000

---A-----------2.0:1---------------4000--------------2000------------------750 lb.ft------------------3000
---C-----------2.5:1---------------5000--------------2000------------------750 lb.ft------------------4000

Now we can see that they both produce the same wheel torque just like in your example. But now you can also see that the maximum wheel rpm that can be attained with their respective gear ratio is higher for engine C than engine A. What does that mean? It means that you will need an extra gear to cover the full rpm range you need with engine A. The wheel power (not torque) will look a lot like this (I took the figure from the link about the power curves comparison, so the numbers don't match with my example):

The blue line would be engine A and you can see the shift point. What you will find is that the average power available at the wheel will be lower with engine A than with engine C. Why? Because engine A doesn't have as much power in the lower rpm range than engine C does.

In my example, engine C is a high-revving engine with a strong lower power band and engine A is a low-revving engine with a weaker lower power band. In real life, by design constraints, it is usually the other way around. But it is technically possible to build two such engines.

Conclusion:

• Torque is a meaningless measure;
• Average power throughout the rpm range is important, not maximum power alone;
• Maximum torque gives an idea of the power at lower rpm (when compared engines are in the same rpm range) but it is not reliable.

So we're not saying you are wrong. You asked «how can I explain the phenomena?» We gave you the words to use. It is now up to you to accept them.

 

[cjl]

This is what people on this forum are attempting to teach you: Everybody agree with you and the engine builders you know and that sentence is 100 % correct. You wanted to know why that is and asked how you could explain it to others. Here is our answer: It is not due to a lack of torque, it is due to a lack of low-end power. An engine is define by more than its maximum power, the whole shape of the power is important, i.e. the power output is important at every rpm.

No, it really isn't 100% correct, and I already showed this a bunch of times. Diesels really don't have exceptionally wide powerbands, and if you set up a gas engine properly, it will easily tow everything the diesel will with the same horsepower. In fact, most large diesels have much narrower powerbands than gas engines do - they only work over about a factor of 2 in RPM (1000-2000), while most gas engines provide good torque over a factor of 3 or more (2000-6000 or so). If geared correctly, a 500hp gas engine will very easily pull a semi. For a really extreme example, look at the Chevrolet LS7:

This engine makes about 350 lb-ft of torque at 1000RPM, up to a 470lb-ft peak at 4800RPM, and it's still making about 350lb-ft at 7000RPM. This means it's making 75% of peak torque or more across a factor of 7 in RPM. This is much better than the GT3 engine I picked before, because I intentionally chose a very peaky engine with a narrow powerband last time to prove the point that it could still haul a load just fine. Now let's look at another Detroit Diesel, similar to the one I was talking about before (but a bit more powerful):

This engine makes 75% of peak torque or more from 1000 to about 1900RPM. This isn't even a factor of 2. This is also why modern trucks have so many gears - the diesels need them because their RPM range is much narrower than for a gas engine.

Why are we telling you this? Let's illustrate with an example. We have three engines:

engine-------max torque@rpm-----------power@max torque
----A---------400 lb.ft@3000rpm------------------228 hp
----B---------200 lb.ft@3000rpm------------------114 hp
----C---------300 lb.ft@5000rpm------------------285 hp

Just for fun, let's say that all of these engines have the same maximum power, no matter what it is, no matter at what rpm. Which engine will give the highest acceleration at wheel rpm of 500, 1000 and 2000 rpm? Let's do the calculations:

engine-------gear ratio-------engine rpm--------wheel rpm-----------wheel torque
---A---------------6:1---------------3000---------------500-----------------2400 lb.ft
---B---------------6:1---------------3000---------------500-----------------1200 lb.ft
---C-------------10:1---------------5000---------------500-----------------3000 lb.ft

---A--------------3:1---------------3000--------------1000-----------------1200 lb.ft
---B--------------3:1---------------3000--------------1000------------------600 lb.ft
---C--------------5:1---------------5000--------------1000-----------------1500 lb.ft

---A-----------1.5:1---------------3000--------------2000------------------600 lb.ft
---B-----------1.5:1---------------3000--------------2000------------------300 lb.ft
---C-----------2.5:1---------------5000--------------2000------------------750 lb.ft

With appropriate gearing, the winner is always engine C, even though it doesn't produce the maximum torque. With engine A & B, it is clearly the one with the highest torque that gives the highest output torque, but this theory doesn't hold up with engine C. But if you compare the power they produce at maximum torque, then you can see a direct relation with their maximum output torque.
Again, nobody will argue with you on that point. But this relates with the power curve shape. If you already read the previous link I presented to you earlier about rpm range, you should understand. Let's look at an example again. Let's use engines A and C again. Let's add these extra data:

engine-------rpm--------torque@rpm--------power@rpm
----A---------3000--------400 lb.ft---------------228 hp -------->max torque
----A---------4000--------374 lb.ft---------------285 hp
----A---------5000--------315 lb.ft---------------300 hp -------->max power
----A---------6000--------254 lb.ft---------------290 hp -------->max rpm

----C---------5000--------300 lb.ft---------------285 hp -------->max torque
----C---------8500--------185 lb.ft---------------300 hp -------->max power
----C--------10000-------152 lb.ft---------------290 hp -------->max rpm

Now they both have the same maximum power and engine A can produce 285 hp just like engine C can. And if we choose an appropriate gearing for engine A, it can produce the same wheel torque as engine C at maximum torque:

engine-------gear ratio-------engine rpm-------wheel rpm-----------wheel torque----------max wheel rpm
---A---------------8:1---------------4000---------------500-----------------3000 lb.ft-----------------750
---C-------------10:1---------------5000---------------500-----------------3000 lb.ft-----------------1000

---A--------------4:1---------------4000--------------1000-----------------1500 lb.ft-----------------1500
---C--------------5:1---------------5000--------------1000-----------------1500 lb.ft-----------------2000

---A-----------2.0:1---------------4000--------------2000------------------750 lb.ft------------------3000
---C-----------2.5:1---------------5000--------------2000------------------750 lb.ft------------------4000

Now we can see that they both produce the same wheel torque just like in your example. But now you can also see that the maximum wheel rpm that can be attained with their respective gear ratio is higher for engine C than engine A. What does that mean? It means that you will need an extra gear to cover the full rpm range you need with engine A. The wheel power (not torque) will look a lot like this (I took the figure from the link about the power curves comparison, so the numbers don't match with my example):

The blue line would be engine A and you can see the shift point. What you will find is that the average power available at the wheel will be lower with engine A than with engine C. Why? Because engine A doesn't have as much power in the lower rpm range than engine C does.

In my example, engine C is a high-revving engine with a strong lower power band and engine A is a low-revving engine with a weaker lower power band. In real life, by design constraints, it is usually the other way around. But it is technically possible to build two such engines.

This makes it a relatively useless comparison though, since a high revving engine will almost never have as strong of a low range as a lower revving, high torque engine. Also, you could greatly improve engine 2's performance by spacing the gears more closely, such that the 1-2 shift occurred at a shaft RPM of 1900, with the next gear low enough to match the 500 horsepower at the shift point. If you're losing something like 50% of peak power at your optimum shift point, the gearbox is very poorly designed for the engine, since the idea should be to keep it in the power band at all times.

Conclusion:

• Torque is a meaningless measure;
• Average power throughout the rpm range is important, not maximum power alone;
• Maximum torque gives an idea of the power at lower rpm (when compared engines are in the same rpm range) but it is not reliable.

So we're not saying you are wrong. You asked «how can I explain the phenomena?» We gave you the words to use. It is now up to you to accept them.

I am saying he's wrong though. He has stated that a 500hp diesel can accelerate faster and haul more than a 500hp gas (wrong), that acceleration rate depends on torque (wrong), that a 238hp Mack will pull a load as well as a 2500hp Pro-Mod motor geared for hauling (wrong), and that if you gear a 300hp car motor to go 6mph in first gear, it'll still stall when you try to release a clutch to pull a load with it (wrong).

(Sorry Moretorque - I'm not trying to pick on you here, just explaining a point).

 

[cjl]

Where not talking about racing just to let you know, I am talking about being able to maintain the HP to do the job under heavy load. The Mack Tractor I am talking about only has 5 gears a Maxidyne but can do what I said not fast but can pull it. I asked the guy's who build the engines if you can gear around a major lack of torque and asked if geared correctly can a 500 HP car engine run a loaded semi and they said no way. I agree with what you all are saying because on paper it should fly but something tells me in the real world when under that much load the spinner motor can not maintain those torque values and maintain RPM when you have to accelerate those loads to speed.

Just because someone is familiar with building engines doesn't mean they're familiar with their capabilities in a decidedly nonstandard use. A 500hp car engine could easily run a loaded semi, though it wouldn't be very reliable doing it (car engines aren't usually designed to output 200-300hp continuously for hundreds of thousands of miles). As for the "spinner" motor (I assume you mean gas?), the dyno shows the torque it is capable of as a function of RPM. If the GT3 motor is at 6000RPM, and it is at wide open throttle, it will happily maintain 320 foot pounds of torque all day long. It doesn't know or care whether it's driving a racecar, a dyno, or a semi. Similarly, the LS7 in my example above will maintain 470 foot pounds of torque all day long if the throttle is open and the motor is at 4800rpm, again, completely independent of what it is hooked to.

Essentially if you gear a 300 HP car motor to only go 6 MPH in first when you drop the clutch it stalls under such load and the Maxidyne 238 will pull it even taking flywheel and so forth into consideration

If you slip the clutch appropriately, and have everything geared correctly, it will not stall. That's the point of having a clutch that slips - you don't just instantly hook the output shaft to the drive wheels, you let the clutch slip, let the friction pull the truck up to 1mph or so, and make sure the engine doesn't stall. It's the same procedure you'd use with a normal truck, honestly, though you might give it a bit more gas due to the lower idle that most gas engines use.

I have had this conversation with many engine builders and they have told me the dyno #'s mean little in the real world so I will investigate a little further. Thank you all for taking time out of your lives to try and get my brain on par here.

Unfortunately, your engine builders are dead wrong here. Dynos tell you a huge amount, and the power an engine puts out means everything, whether it comes to hauling heavy loads or winning a race (there are a few weird exceptions, like turbos with odd spooling characteristics, but I'm ignoring those for now).

 

[jack action]

@cjl

I tried to read between the lines with @Moretorque to understand what he means and what he's referring to, rather than analyze every single word he said.

What I think he's referring to is the small highly-boosted engines vs large displacement engines. It's not really about diesel vs gas. Your Corvette engine is not a good reference in this case, as it can be considered as a truck engine fitted within a car (I mean 7.0L ! C'mon, that is huge!). Here's a dyno sheet I retrieved from the web that is claimed to be from a 1999 Honda Civic with a turbocharged 1.8 L:

​

If you look at the run with 503 hp and 334 lb.ft, the 75% of peak torque rpm range is 5200-8500 rpm (a ratio of 1.6).

So from that point of view, he is right, even with your criteria (I personally prefer qualifying useful rpm range by the power curve rather than the torque curve, since engine torque is irrelevant to acceleration as you and I stated). With two engines with the same peak power, the one with the highest power in the lower rpms should accelerate faster (Even though he used the terminology «diesel» and «gas», I considered he meant a generalization for a «wide power band» vs «narrow power band»).

When he said that acceleration rate depends on torque, I know he's «grammatically» wrong, and that's why I pointed out that when people talk about «maximum torque», they actually - indirectly - refer to «low-rpm power» (Whether they understand it or not). So from that point of view, he (and engine builders) is still technically right.

But concerning a 238 hp engine that will pull a load as well as a 2500 hp engine or a that a 300 hp engine that will stall while pulling a large load, no matter the gearing, I admit, these are wrong. But at this point, I think @Moretorque was on the defensive and this is stuff that is obviously made up and not based on actual facts. So I prefer to calm everything down and focus on what is right, assuming the best of intentions from everyone.

Sometimes we have to use baby steps to get where we want to go. Otherwise everybody is just arguing in a cacophony and we all stand still.

 

[Ketch22]

More Torque, It is great to have you visit the forum. Couple things to spread out the answer as I believe I have recognized an issue not previously addressed directly. As brought up before Hp = Hp there is not a way around that however there is some items that cloud our perceptions. Let me list several fictional or reasonably so motors and engines.

262.6 FtLb x 12,000 RPM HIgh performance racing gasoline engine = 600Hp

370.7 FtLb x 8,500 RPM High performance street gasoline engine = 600Hp

1,400.5 FtLb x 2250 RPM High power diesel engine = 600 Hp

1,750.7 FtLb x 1800 RPM Low rpm truck diesel engine = 600Hp

5,729.5 FtLb x 550 RPM Medium speed propulsion diesel engine = 600 Hp

1,800.7 FtLb x 1750 RPM Electric Motor = 600 Hp

21,008 FtLb x 150 RPM Steam turbine Marine main engine = 600 Hp

All of the above can do the same amount of work. However, in the real world the steam turbine will dominate. The Electric motor would be next in line. The diesel engines would be third in the order. Coming up the rear would be the gasoline motors. This is not due to the Hp. It is due to engineering concession and design practices. If you look at Design specs or even marketing catalogs you will notice the most significant difference when you look at industrial equipment. Anything with an electric motor is a lower rated motor than an equivalent gasoline or diesel. This is a due to how the ratings are applied and something called Duty cycle. Normally accepted correction factor is 3-5 Electric motor to Gas engine.

Electric motors and turbines are rated at a continuous rating ( the spot where they can maintain indefinitely). Internal combustion engines ( aside from gas turbine which I am intentionally not bringing into this) are rated at the peak output. Some of the motors have varying correlations to life but generally gasoline engines ( due to heat accumulation) can perform at approximately 75% for reasonable times and still see reduced life down to 25% of operation at peak. Diesels due to their better design in handling heat can operate for reasonable periods at 80% and see little change in life up to approximately 40% of operation at peak. Electric Motors can operate (as rated) at 100% of there rating full life and for short periods at above peak. Typically 115% is what they are capable of. Steam Turbines are also fully capable of running continuously at rated level. They can usually exceed this rating be 120% and sometimes more. The down side here is the parasitic losses due to all the associated equipment is high.

To accommodate these factor Design personal usually design with the companies proprietary correction factors. But the closer you get to the public the more those same companies pad the facts by reporting an inappropriate statistic.

Let's revisit those motors with more appropriate statistic;

High performance racing engine = produces 600 Hp peak, rated at 600 Hp, works as if it is approximately 540 Hp, design as big as the class allows, and dies very quickly

High performance street engine = produces 600 Hp peak, Rated at 600 Hp, works as if it is approximately 400 Hp, designed as whatever the customer wants, and requires frequent maintenance to keep it running.

High power diesel = produces 600 Hp peak, rated at 600 Hp, works as if it is approximately 480 Hp, designed as near 480 Hp and delivers long service cycles.

Low RPM truck diesel = produces 600 Hp peak, rated at 600 Hp, works as if it is approximately 500 Hp designed as near 480 Hp and delivers very long service cycles.

Medium speed propulsion Diesel = Produces close to 680 Hp peak, rated at 600 Hp, works as if it 600 Hp, designed as near 600 Hp, and delivers extremely long service cycles.

Electric motor = Produces close to 690 Hp peak, rated at 600 Hp, works as if it is 680 Hp, designed as near 600 Hp, delivers full rated life when used within rated duty cycle (even if cycle is greater then 100%)

Steam Turbine = produces close to 720 Hp peak, rated at 600 Hp, works as if it is 600 Hp, designed as near 600 Hp, delivers very long service cycles even when run occasionally at 20% above capacity.

You can see from this that there is a lot of hubris involved here. Some of it is justified and some of it is just game playing. If one could magically adjust all motors to be the same after rating/derating and just go by the numbers they all fall into Hp is all the same. but we would have to test only the momentary peak. Heck the blown nitro motors start to break in less than 1 sec. and by the end of every pass they need to be completely rebuilt. There is not an actual Dynamometer to see how much they produce. It is all just someone's best calculation.

 

[Moretorque]

Hey you all thanks for taking the time, I agree with what you all are saying from what I have read, I need to go back over it closely. You can gear to optimize a motor and HP is HP no matter how it spins up just make sure you are in the RPM groove of peak output but in the real world I have noticed on my CR 500 and I weigh 320 it stomped my CRF 450 bad in getting me going all things being pretty much equal and the CRF 450 has a way broader power curve and same HP pretty much on a dyno but the CRF 450 peaked at about 9 grand vs 5600 for the CR 500. It will kill a CRF 450 on hill climbs just google CR 500 hill climb and it has a way narrower power curve but makes like 50% more torque.

So all this over the years kinda got me wondering a little after talking to people about real world app, then I opened a can of worms and the engine builders all of them pretty much and even today a guy who I have known since 1999 and has built engines since the 60's told me what other engine builders have told me that people who think a 500 HP car motor geared correctly can pull like a 500 HP semi motor moving 80 grand do not understand HP. So I am not arguing at all just trying to figure out what I may not be seeing because I agree with you all but motor builders have told me no.

 

[Ketch22]

Moretorque, Thanks again for your honest response. If anything I would say keep on searching. As a new person myself to the forum It is great to encounter someone who is trying to work through an issue that is so deeply ingrained. I would caution with a quote of an old saying. " If you always do what you have always done, You will always get what you have always got."
In the early days of my experience I built and raced both gasoline and exotic fuel motors. I first was introduced to diesel engines in a blown nitro speed shop. I spent most of my career ( and all of my schooling) in large marine propulsion both diesel and steam. Now I work in an entirely unrelated field and dabble in gasoline engine and electric motor performance automobile. This I know makes me an oddity.
I have seen and I am sure you have as well that persons working in a field become somewhat myopic. A diesel mechanic will always tell you diesels rule. at the same time an alcohol burner will tell you they rule. It is a rare breed, you among them, that really wonder why. with an open mind.

I will move your search with a different reference entirely. Here is a link to an engine builder ( and speed shop for small displacement Toyota motors) that I found as a result of your thread. He has a very good write up dealing with the Torque-Power relationship and is also attempting to open his piers to how this works.

http://www.matrixgarage.com/content/understanding-relationship-torque-and-power

Good searching

 

[Moretorque]

No you guys got it and especially CJI and all of you all so thanks a million, no he is right the engine builders are wrong. Actually I understood it better before I got lost searching to understand it better by listening to info that was wrong. You have to have a setup for what you are doing and have the right gear set for your app.

The dyno does not lie, I have a couple more ?'s but let me go over all this so I understand it correctly before I ask. Again thank you.

If you throw enough spaghetti against the wall enough will stick for a good meal, so thanks for taking the time.

 

[jack action]

I have noticed on my CR 500 and I weigh 320 it stomped my CRF 450 bad in getting me going all things being pretty much equal and the CRF 450 has a way broader power curve and same HP pretty much on a dyno but the CRF 450 peaked at about 9 grand vs 5600 for the CR 500. It will kill a CRF 450 on hill climbs just google CR 500 hill climb and it has a way narrower power curve but makes like 50% more torque.

Not according to these power curves:

​

Not only does the CR500 can achieve 20% more power than the CRF450R, it can produce more than 44 hp from 4600 to 7250 rpm, a ratio of 1.58. The CRF450R can stay above 44 hp (without ever reaching the power of the CR500) from 7750 to 11 000 rpm, a ratio of 1.42. So the CR500 power band is not only wider, it also have a higher average power rating in its power band.

 

[Moretorque]

Not according to these power curves:

​

Not only does the CR500 can achieve 20% more power than the CRF450R, it can produce more than 44 hp from 4600 to 7250 rpm, a ratio of 1.58. The CRF450R can stay above 44 hp (without ever reaching the power of the CR500) from 7750 to 11 000 rpm, a ratio of 1.42. So the CR500 power band is not only wider, it also have a higher average power rating in its power band.

I am talking modified, go look them up. Guy's are getting 60 to 75 RWHP out of them with no problem with mods and they really do work good. The one thing about a 2 stroke over a 4 stroke they build power faster. In the sand a 2 stroke hydro plains on the sand much quicker and gets going on top of it, a dyno does not show this.

There getting over 100 out of the new CR 500 big bore kits, A Cr 500 motor in a modern chassis with over 100 HP at 225 pounds tagged for getting around anywhere set up would destroy practically any other vehicle made.

Jump over curbs going 50 or 60, cut through the neighbors back yard then jump the creek to hit the road behind the house in a 9 second package.

If you have the balls.

 

[Moretorque]

Now I will talk to some builders because I understand it better and see what they say it means in the real world in apps.

I always believed the dyno did not lie and actually understood this to a pretty good degree until people starting saying no it is not like that in the real world then I got really really lost but understand it much better now. They have the engine operating out of it's zone and not set up right and do not understand this but overall now that I understand it better it makes it obvious why a good diesel not the new ones for the most part are the way to go for pulling.

Thanks.

 

[jack action]

@Moretorque:

I don't follow your argumentation. We're telling you only how much power produced counts. You come back with this CR500 vs CRF450 real life example where you state:

all things being pretty much equal and the CRF 450 has a way broader power curve and same HP pretty much on a dyno

(...)

It will kill a CRF 450 on hill climbs just google CR 500 hill climb and it has a way narrower power curve but makes like 50% more torque.

So I show you evidence that a stock CR500 has more HP (and a not-so-narrow power curve) than a stock CRF450 and you come back by telling us that the CR500 is modified, maybe up to 100 hp, i.e. twice as much power as the CR450?!? I've been doing a little search and even if you used a modified CRF450, the most powerful modified bike I've found had 60 hp.

At this point, you are just proving what we're explaining to you. You really need to understand that we are not working against what the engine builders say, we are just explaining it better than they can. Believe us, this «power theory thingy» we're talking about has been established for a few hundred years now and it's the reason why we have airplanes that can break the speed of sound, why we have turbines generating electricity for millions of people, and why men were able to walk on the moon. Believe us, it works and the combustion engine of a car/truck/motorcycle is not an exception to this concept.

 

[Moretorque]

The CRF will do better than 60, guy's use them in go karts making quite a bit more. There very expensive however. My modified CRF 450 was about the same as the stock CR 500. The CR 500 peak is around 5600 hundred or 5700 RPM like a diesel truck narrow and that usually is the way 2 smokes are. The CRF's that are built up to around 55 plus have way more over rev and pull over a longer range but not near the torque however.

When you ride a CR 500 it is odd the light guy's say the power band is way to short with no top end and the heavy guy's say the CRF 450 does not pull them right on hills. This is why you will find the CR 500 is real popular with big guy's and smaller guy's will tell you it is to narrow power for them. The CRF with mild mods make the same peak HP as a CR 500, there are a lot of them out there.

I agree with what is being said the dyno does not lie but talking how it equates to seat of the pants is all in real world.

 

[Ketch22]

I really like this statement. As we have explored already it is more about having the appropriate drivetrain as an entire package and that matching the use. On another forum a while back I was part of a thread looking at performance mods. I made the comment that unless you can actually deliver the power where the customer uses it you are not really a Tuner but just a builder. This drew tremendous distain as it was an affront to some peoples sensibilities.

The big picture is that there are large numbers of variables. Case in point you can get great performance for you on your bike. If you gave it to me and I went out with my 195 lbs riding aggressive enduro type stuff. I would possibly come back and say "your bikes OK but not great" It is all about the fit within the variables.

 

[Moretorque]

It's all in setup for what you are doing. Thanks for getting me straight on this everybody who took time. You can make anything work if HP is there for what you need to do but some power types work better for certain apps than others depending on what you are doing.

 

[Moretorque]

iT's all in setup for what you are doing. Thanks for getting me straight on this everybody who took time. you can make anything work if HP is there for what you need to do but some power types work better for certa than others depending on what you are doing.

@Moretorque:

I don't follow your argumentation. We're telling you only how much power produced counts. You come back with this CR500 vs CRF450 real life example where you state:
So I show you evidence that a stock CR500 has more HP (and a not-so-narrow power curve) than a stock CRF450 and you come back by telling us that the CR500 is modified, maybe up to 100 hp, i.e. twice as much power as the CR450?!? I've been doing a little search and even if you used a modified CRF450, the most powerful modified bike I've found had 60 hp.

At this point, you are just proving what we're explaining to you. You really need to understand that we are not working against what the engine builders say, we are just explaining it better than they can. Believe us, this «power theory thingy» we're talking about has been established for a few hundred years now and it's the reason why we have airplanes that can break the speed of sound, why we have turbines generating electricity for millions of people, and why men were able to walk on the moon. Believe us, it works and the combustion engine of a car/truck/motorcycle is not an exception to this concept.

Why are diesels so slow, I saw videos with a 1400 HP diesel funny cars only able to muster a 9 second 1/4 mile.

 

[jack action]

Why are diesels so slow, I saw videos with a 1400 HP diesel funny cars only able to muster a 9 second 1/4 mile.

It's hard to answer you because I just don't know where you take your numbers. This http://www.bankspower.com/magazines/show/599-the-worlds-quickest-diesel-pickup-breaks-new-ground. This top fuel with 1800 hp is in the 6-second.

http://www.bankspower.com/magazines/show/609-Marine-animal is even more interesting, as we have a weight (817 kg) and it has the same 1300 hp engine as the previous funny car. http://www.bankspower.com/topdieseldragster/overview2/ (The video in the previous link seems to indicate 7.17 s). If you put 1950 lb (= 817 kg + 150 lb driver) and 1300 hp into a simple ET calculator, you get 6.6187 sec. Note that these calculators don't care about torque or whether it is diesel or gas: Power and weight is all you need for an amazingly close approximation.

So I did a little search for you 9-sec, 1400 hp funny car and I found this one. We don't know the weight of the car and even if we assume the 1400 hp is exact, it is probably a standardized value. And if you look carefully at the description, the run was done at Bandimere speedway, which is in Morrison, Colorado (elevation 5764 ft) at 79°F. This means that the actual power is only 77.9% of the standardized value or 1090 hp. But I admit that even with this number, it should be faster than that ... unless it weighs 4500 lb ... unless that 1400 hp claim is exaggerated!