Better fuel efficiency through vapor carburators?

[Cliff_J]

Depending on the type of racer, fuel economy is very important. For drag racing, its of little concern as the track is a fraction of a mile. For any kind of endurance race, now it plays into how much fuel is needed on-board (typically limited by regulations) plus how long it will take to make a pit stop (since fuel delivery is usually the longest item) and so on. Racing officials have put rules into place to give the teams with the best economy an advantage.

So racing is about best compromise in terms of use maximum extraction of fuel's energy potential. Its THE area of development with billions of dollars dedicated to that cause. Just like how general aviation benefits from ever increasing military aircraft development, the general automobile consumer benefits from racing.

Freddie, you didn't answer me about my question regarding the validity of the idea of steam playing any part in the process of 'increasing efficiency' after I brought up the idea that the combustion chamber temperature exceeds the boiling point of water and creates the super-heated steam well before the point of combustion, that the steam creation on the compression stroke could only HURT the efficiency since there is not a process that can extract that energy back out of the steam by general laws of conservation.

Also, by adding alcohol you're adding another combustible. So while the MPG might go up because it ignores all the inputs (2 fuels instead of one) the overall system efficiency has likely gone down.

The SAE holds a high-mileage competition where high-school and college level teams build competition cars as engineering projects. The high-school level teams routinely get MPG in the 400s and up and the college level teams get over 1000 MPG running highly optimized cars. This has been going on for a while now, nothing new...

Science is about more than fancy equations, its about understanding how to correctly analyze data and combine it with your understanding of how that data works. Looking at any facet of the current automobile we could address areas that could lead to further enhancements in efficiency, no doubt. But that water injection as discovered in the 1920s as some sort of revolutionary idea that has been completely missed by the entire engineering society? An idea that far outside the range of common sense deserves scrutiny in its scientific mechanisms and properties that allow it to work and some anecdotal evidence doesn't provide information in this regard.

Freddie, I think the idea is that Russ and I believe that you are close to actually understanding the issue at hand better once you re-examine your assumptions.

And assuming something works everywhere and has benefits to all circumstances because it was used in a specific application doesn't seem very well engineered to me. You haven't even provided the ratios in terms of lbs/hr for the 'water' to the fuel and air flow rates in lbs/hr and the suppossed increase in efficiency as a result. Without a scientific test, all we have is a guess.

Cliff

 

[Freddie]

Freddie, you didn't answer me about my question regarding the validity of the idea of steam playing any part in the process of 'increasing efficiency' after I brought up the idea that the combustion chamber temperature exceeds the boiling point of water and creates the super-heated steam well before the point of combustion, that the steam creation on the compression stroke could only HURT the efficiency since there is not a process that can extract that energy back out of the steam by general laws of conservation.

Very good observation - that the generation of steam occurs early in the cycle. And yes, it does take energy to do it. After combustion, this same steam, gets heated some more which raises its pressure. But it does not just disappear. The pressure is carried farther out in the cycle and the energy is delivered back as work on the piston. The only energy that gets wasted is the heat of the exhaust gases.
I only claimed that alcohol-water injection has been used to increase mileage. I didn't say it was a universal remedy for everything. The Air Force used it successfully on fighter planes during WWII. People who are into racing are paying $1000 and up for commercial alcohol-water injection kits. This is outside of my budget so I have not bought one.
I am still having trouble with using this site, using quotes, etc. so I need to limit my remarks. Re the racing use of water - alcohol injection, the website reference is www.rallycars.com/Cars/waterinjection.htm[/URL] and if this site doesn't mangle it, like it did the previous one, this will work.
Freddie

 

[russ_watters]

The SAE holds a high-mileage competition where high-school and college level teams build competition cars as engineering projects. The high-school level teams routinely get MPG in the 400s and up and the college level teams get over 1000 MPG running highly optimized cars. This has been going on for a while now, nothing new...

Any links to that? I've never heard of it.

 

[faust9]

I only claimed that alcohol-water injection has been used to increase mileage. I didn't say it was a universal remedy for everything. The Air Force used it successfully on fighter planes during WWII. People who are into racing are paying $1000 and up for commercial alcohol-water injection kits. This is outside of my budget so I have not bought one.

I disagree with this. I race quite a bit. I have a 94 Mustang with a welll build 302, a 79 T/A with a 455, and a 91 R6 which puts a little over 125Hp to the ground--tough to do on a 600cc Bike. Water injection has limited use in racing today for amny reasons one of which, the biggest in my opinion, is the introduction of cheap CNC machined Al heads. These heads allow a builder to make a 1000+ Hp running a turbo or blower without having to rely on water injection to lower the peak combustion temps.

Iron headed engines can benefit from this OLD idea, but I haven't seen it used since the mid 80's outside of Rally car classes because of the limitations of the class itself. http://www.rallycars.com/Cars/WaterInjection.html

Water injection does not produce more Hp. Any time you lower peak combustion temps you lower peak combustion pressure (the thing that that eventually does the work) which lowers the total power output of the engine. You've mentioned adding alcohol mixtures into the frey; however, these mixtures produce LESS power than a pure gasoline mixture. You are essentially displacing a fuel that releases more energy per volume with a lesser fuel.

Water injection should not be used in automobile racing to improve performance because that's not what it was designed for. Water injection is a tool to save the builder $10,000+ because it limits detonation. WWII aircraft usage many be different because of lower O2 levers and what not. Automobile applications don't suffer from that problem though.

Take a clue from builders--water injection doesn't improve power. If it did every dragster, 1/4 mile racer, race bike, or any other race vehicle would be using it. You can produce more Hp running Al heads and an electronic ignition with a knock sensor(carb'ed or FI) than by running water.

If you want to improve fuel effeciency go for it. It's actually easy to do. I have a T/A that I can milk 25-30MPG out of if I wanted to. I've done it. I've done it using a Q-Jet. Did I get the power levels I wanted? No. Where my NOx emissions through the roof? Yes. Fuel effeciency is easy ti come by by iteslf; however when you toss in emissions and power requirements then you're playing with a whole different deck of cards. Water injection will lower emissions but at the same time it will not increase power.

I't boils down to the fact that water injection and pump gas will have a detremental effect. Water/alcohol mixture on a turbo 4 and pump gas will increase the octane rating of the fuel allowing more aggressive timing curves but running a higher octane gasoline fuel to begin with will yield even more power.

NASA did a study of Water injection for aircraft use--not increase power but to lower NOx emissions. http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?2004/CR-2004-212957.html

 

[Cliff_J]

Russ, best link I could come up with quickly but I've read a few other sites about it before and a friend in college built one at his high school in the early 90s so I'm sure there's more info out there. With theirs they took many liberties including using the B&S bottom end but with a 125cc Honda 4V head from a motorcycle. They started with a fuel injector from Artic Cat but it was tough to get good atomization with the low duty-cycle and low fuel pressure they used for their RPMs. They used bicycle sprockets, chains, and tires at over 100psi to minimize rolling resistance, aerodynamic shape that had no room for operator and make them sweat like mad, etc. They shaved the head too to maximize the CR and so on which caused them to need to overcome plenty of other obstacles as well. But in the end it still mustered like 250MPG at nearly 20MPH which was faster than the other teams. Of course, this is how I'm remembering a story told to me that I've never verfied.

http://www.sae.org/students/supermw.htm

Cliff

 

[Cliff_J]

faust - you left out one area where alcohol injection is handy and that's for the turbo applications with extremely high boost. Forgetting the absurd ECR calculations intended for the calculus-challenged, a slow burning fuel that complements the longer pressure curve that boost generally adds (so the peak pressure increases say 20% but the BMEP increases 30% type thing) we get more of the curve closer to the 90 deg past TDC point where we can maximize torque. Especially if the rod/stroke ratio isn't great and we can take more advantage of pressure at a point of less side-loading. Oh the compromises...

Plus having a second fuel to absorb some of the heat of compression is handy if the intercooler isn't doing a good job, and lots of cheap fuel to run by the exhaust valve on the way out isn't a bad idea either. How else some of these guys are running 45psi boost is beyond me and I'm sure you've seen a engine grenade after it leaned out so shoving in some cheap insurance makes sense to protect the pocketbook.

But running 8sec quarters has nothing in the world to do with efficiency unless you need to get there in a hurry.

Cliff

P.S. And WWII was a time of frenzy, how else did it take so long for the P51D to arrive to escort the bombers? And arrive as some rushed airframe design with a limited-range low-power motor that almost doomed it until the airplane came on strong with the RR Merlin that could make the power and go the distance. As another example, I think I'd rather take any tire manufactured today instead of the synthetic tires during WWII. Have we beaten this horse long enough?

 

[racprops]

I have also been looking in how to get higher mileage.

I got this answer about using propane:

"Check this out:

http://www.welshtec.com/

A couple of board members use this kit with great results on their daily drivers. Basically 10 to 15 mpg depending on the driving conditions. I bought a kit and plan to install it on my 99 Regal GS when I have time. It basically puts small amounts of propane gas (does not spray liquid) into the manifold which creates a more complete combustion. It uses about 2.5 gallons on propane per 400 miles on the average passenger car and should take care of the need for high octane fuel."

I found this because they were talking about propane as a power booster in their TurboBuicks and how it was letting them run much more boost and get much more power, so what is good for racing can also help low speed power...

Seems that it can.

And the following questions lead me to seach for more answers and thus led me here:

"This has been such a learning adventure.

I had talk with a person that was saying that the modern injector is able to vaporize about 95 to 100% of the gas as it sprays the fuel into the engine, and that during compression some of this vapor gas will recondense!

If that is true than getting 100% of the gas converted to vapor will still cause pollution as some of it recondences and fails to burn and will still flow out the tail pipe.

So if true a hot/cold vapor carb system will do no good. Wish I were a combustion engineer. (Hope there is one here.)

I also read that gas back in the 30s was much more easly vaporized, true or not?

As for the report I read about how a computer would get in the way of a clean burn, I was told that this is true with Ford, as they are set to keep the catalytic converter burning to burn off gas, but that GM computers will run clean up to a set point that pollution starts to load up and then tip over and add fuel to fire the cat.

True of false??

I am also informed that the GM computers “learn” and to shock them with switching chips will only defeat this learning and cause it to switch back to its base defaults.

So if I switch out the chip I will lose the better settings for messed up ones of a performance chip, or worst if I try my “getting both worlds” of a stock chip and them a hot setting of a over riding controller the system will not return to it best settings until something like 45 starts??

I thought the computer had a set bunch of commands, that each is a programmed response to certain sensor readings, change a sensor reading and the computer will always respond with the very same response, every time, no change and no learning.

I have not heard of these things learning and fine-tuning themselves.

Any one knows for sure?

As in many things, I know enough to ask the questions but do not know the answers, these are such fine and specialized knowledge."

I am also building a add on system of a old Borg Warner 3 speed over
drive transmission behind the 700r4, so that I can down shift to 2nd
and have low gears for town driving that will rev the motor fast and
use less power moving out, and can still engage the 2nd over drive
for higher town speeds and on the high way upshift to third and then
even add in the 2nd overdrive for a double over drive. The motor with
a MAF controlled system and low 2000 torque cam should be able to
maintain speed as low as say 1200 rpm.(I think and hope)

And last:

Next is to find out how I can improve the Van’s wind resistance... Ground effects kit, with air dam and a rear wing?? Upsweep or downsweep like the rear window cleaner on old station wagons, to push the air back in behind the van to kill the vacuum?

To freddy, hope you still here and finds this interesting as I do.

I hope this is the right place to talk and learn.

Thanks.

Rich

 

[Cliff_J]

Rich, this is a good place to talk and learn but science and facts mean more than wives tales.

How could fuel condense during compression when the mixture will heat up according to the ideal gas law? It might cross the point where the vapor pressure is insufficient (haven't seen a phase diagram for gas) but the temps seem like they would be simply too high. The combustion is not 100% because of many factors including the shape of combustion chamber, mixture ratio, and time allotted to the burn. An engine could be run lean for a more complete combustion but that generally hikes up the NOx emissions from higher combustion temps. The EGR and catalytic converter make much more sense for the system to work properly and meet power and emission requirements.

The GM computers do have a set program but then can adjust to varying conditions and sensors when in closed loop. So if the MAF/IAT/MAP tell it to fire the injector for 5msec but the O2 tells it the mixture is rich it'll adjust the timing. For WOT conditions its straight from the stored injector maps until you get to the LS6 in the Z06 where it stays in closed loop. After 96 when OBD-II took hold the whole thing gets more complex when you have O2 sensors upstream and downstream of the cat. And when GM went to the metric LS1 V8 they have a different firing order to help clean up the intial startup emissions, the GenII 3.8 motors seem to have gotten more complex as well. Make sure you check for coolant around your EGR port in the plastic lower intake manifold, there's water passages around it and when the plastic melts it leaks...

As far as learning, the GM computers seem quite adept at it, especially once they stepped up the processing power to go SFI instead of batch fire. They can compensate for sensors getting old and even batches of gas - makes a ton of sense to keep the emissions as low as possible under an even greater set of conditions. Haven't been able to swap chips for years now...

A second transmission makes only mild sense, even manual cars show a roughly 18% power loss to the tires on the dyno and that 700R4 is already sapping plenty of power. If you can decrease the revs down the road it could help but you've added a lot of losses with that extra transmission so a gain might be tough to come by. Drive even a 3200lb Camaro around at only 1500rpm in 6th and it becomes apparent how difficult it would be to run much slower in RPM.

A rear wing designed to help minimize the turbulence of the air tranistioning from the top to the back could help, the rest would likely fall into very small improvements. Look at a new Corvette, a Lexus LS430, and a S-Class Mercedes-Benz. The first two have a Cd of .29 and the MB has a Cd of .27! Vastly different shapes, the last two have been carefully designed top and bottom to achieve such a low number. Oh and the Corvette has a larger engine and makes more power but gets better fuel economy at a lower price. So much for a rule-of-thumb!

Cliff

 

[hitssquad]

Drag coefficient vs drag-at-airspeed

Look at a new Corvette, a Lexus LS430, and a S-Class Mercedes-Benz. The first two have a Cd of .29 and the MB has a Cd of .27! Vastly different shapes, the last two have been carefully designed top and bottom to achieve such a low number.

Another way to get a low Cd is to design the car to be as large in frontal aspect as possible, even if this raises the drag-at-airspeed. Because of this, reducing the drag-at-airspeed can result in a higher ("worse") drag coefficient and increasing the drag-at-airspeed (as Lexus may have done with the LS430) can result in a lower ("better") drag coefficient.

Drag coefficients are useful specs to know about airplanes. This is because the drag coefficient is a ratio of drag-at-airspeed (something bad in an airplane) divided by airfoil area (something good in an airplane). The Cd number gives a concise estimate of how well the airplane's designers achieved the general goal of maximizing airfoil area while creating a minimal corresponding increase in drag-at-airspeed.

In regards to cars, drag coefficients are useful specs for marketing purposes. By simply engineering increased drag-at-airspeed by making the car larger, the drag coefficient correspondingly gets "better," and thus the car becomes more marketable (though this "better" Cd may catalyze worse freeway fuel mileage and premature drivetrain wear since more work might need to be done to push the car through the air; better Cd, since it generally corresponds to increased drag-at-speed, will also generally reduce maximum drag-limited speed, ceteris paribus).

Since Cd is actually

• drag D divided by the quantity: density r times half the velocity V squared times the reference area A.
  
  Cd = D / (A * .5 * r * V^2)

it seems that to come up with a useful drag rating for cars, one might simply take the above equation and delete the division by "reference area A". This would give us a drag number for a given car unencumbered by an otherwise accompanying frontal-area-handicap-factor. Drag specs computed this way, for comparing cars, would seem to be more useful than the traditional Cd (coefficient of drag).

 

[Cliff_J]

hitssquad - while I agree that the Cd may be influenced by the overall size of the car I would think it odd for the engineers of large luxury cars to make them arbitrarily larger to get a better number for marketing purposes. The current S-class is smaller than the model it replaces.

In addition, if we compare the straight drag force without respect to other factors a bus seems like a great waste of fuel with a large surface area, heavy-duty components, and overall large amount of mass. But factor in the number of passengers for a per person fuel usage...

So unless the "reference area" is not accurately based on an honest cross-section of a car the Cd still represents how carefully the aerodynamic drag was minimized with respect to the size of the auto. Sure my example of comparing large luxury sedans to a compact sports car has flaws but the point was about the efficiency of the design and not the raw drag produced.

Because if we assume a typical van with a shape approaching that of a large square box it has a large surface area and poor aerodynamic shape we could also assume a it to be a larger percentage of the total force necessary to move the vehicle down the road at speed. And the large mass will obviously hurt the acceleration and require a large amount of force there as well regardless of speed. So to engineer for better overall fuel economy with respect to cargo capacity we'd simply get a modern minivan.

Cliff

 

[racprops]

OK the compression pressure and heat keeps gas in a vapor state Correct?
Then a better vaporizing of gas may help the burn?

On the computer I was going with the older 87 one with the changeable chip and sadly batch firing, so it is better but not too smart, so is it a learning computer?

I am again told by local Fuel Injection tuners that the difference between a batch fires and FSI system is barely notable. And in my case, a 90s Chevy 350, not worth the cost to switch.

And again I was thinking I could run the stock chip for gas mileage and a performance add on computer system for power and higher performance. So if that will harm my mileage settings it may not be such a good idea, IE if the computer really learns and takes so long to retune its self?

As to the transmissions, I am concerned on internal drag, but an told that as automatics go, the 700r4 is one of the best in lower power usage, and I am considering using a lighter gear oil than the old 90W, more like the current performance transmission oils.

One of the extras I will be getting is a lower gear ratio with the use of second, this should give me a great city gearing, winding up the motor faster and using less power to get it moving in stop and go driving.

I am aware of the power drop in overdrive, and with two different overdrives I can use the best one for the best power range and both when I can, granted this will only be on flat ground, but as I live in AZ, and to get to the east I have to cross a lot of flat ground…

And I will running a Mileage computer so will “see” which gear will/is working best.

And I know it is a more complex system but I am willing to work with it. And lastly, truckers have run their front transmissions and with a second transmission called a “Browny” and two speed rear ends.

So gearing is very important to them, and yes I also know their power range is smaller, like 500 to 3000, but my new motor also is 800 to 4000 of real power making, so more gears are called for my setup.


I had been planning of a 403 Olds motor but when doing a little more research found out a Chevy 350 with a Tune Port Intake mades as much if not more torque that the Olds, and with the Max Air Flow sensor can run tighter and leaner at these planed lower RPMs than any other fuel deliver system, that a carb and Map system would be unable to operate correctly at these low RPM due to the low vacuum, which on these systems would cause more gas flow as they get a false reading.

And with the Chevy I am able to use a 9:1 ratio with a much better piston, a “D” shaped dish piston that gives a much better flame travel, so it will make a little more power than the old 8.1 Olds full disk and looser fitting pistons.

And with the van I can say positively a smaller motor seems a no go, I swapped an Olds 307 in place of a 350 and lost mileage and power big time.

Now the last question, which I cannot make out your answers, what will help the box get though the air best?

I am planning on an air dam under the bumper, and side panels which are called a ground effects kit, this is suppose to lower drag by keeping air out from under the van.

So I wonder which will work best: a spoiler, or a air foil on top and perhaps on the sides to push air back in behind the back to fill up that vacuum that is created behind the box?

I am not going to a mini van. Sorry need the room.


Thanks or all of your answers and help.

Rich

 

[Cliff_J]

Funny thing is the other day I was reading a site with details on an LS1 swap into a late-model S10. My dad has a 2001 with the 4.3L V6, barely eeks out low 20s for mileage. But the guys with LT1 or LS1 swaps are getting 26-29MPG which is about the same as the Camaro/Formula/Corvette. Go figure.

No, SFI isn't much of a gain. And the learning is short-term only, think like you have a low tire and you learn to steer funny for just a few miles until you find a service station to air it up. After you air it back up you go back to driving the way you had been.

Well the L98 style TPI seemed to do well for mileage too, just not quite as good as the LT1 or the LS1 down the highway. Since the LT1 has been abandoned now with the LS1 stealing the glory the price has come down but not to the traditional SB prices. I'd at least hope you have centerbolts, I hated the leaks from the original design where some fool lost the spreader washers and overtorqued the covers... From what I've heard the SLP runners help a lot and are cheap at swap meets.

Oh, and for the 700R4 the lighter oil might be a problem depending on vintage, if it is a newer one with the better pump it might not be such a problem.

Spoilers prevent lift by spoiling the air flow, its how the stealth planes turn. This creates drag big-time. And while its a balancing act for a NASCAR guy with extra power to add some drag while getting more traction, you'd like to reduce drag instead.

So the turn-down style wing like you'd mentioned from station wagons could help. I say could because while it is potentially reducing the lower pressure area behind the van the turbulence there is going to be pretty big and the effectiveness might be kinda small. Its like some pickups where leaving the tailgate down does little besides get rock chips all over it.

An air dam helps trap the air and create a higher pressure. Good for forcing more air through the radiator, not so good for drag since you're creating more high/low pressure air to pull back on the vehicle.

I consider the ground effects on my TransAm as cosmetic. Once they're above a couple inches off the ground the effect is tiny. On a van, they make for nice steps.

Hey the box is the new style (again) with the Scion Xb and Honda Element being all trendy now. Both are small and lighweight but the Element is rated 24MPG while the Scion is 34MPG - obviously Toyota made some efforts to get that but the 100HP engine is likely a large part of it.

The engine might see the biggest gains. If you could go with aluminum Corvette heads and run 10.5:1 compression (each point worth 3-4% gain) and an appropriate cam and spark advance, you could likely help things out a lot. Not sure how much more than an L98 (which it sounds like you're piecing together) but for all that work, an LT1 swap sounds cheaper and just find one with a 95+ Optispark that's vented and you'd be set. Might be tricky to fit the accesories with f-body brackets (and corvette brackets were/are coveted by hot-rodders so very rare) but you'd have all the goodies then once you get the computer/wiring hooked up. My 96 TA with 90k on the odo got 28.5MPG on labor day weekend when I had to go 65MPH through Kentucky, better than the normal 26 when going around 80MPH - that's not too shabby!

An LS1 swap would rule, but too pricey so I won't bother. Regardless stepping up in the GM lineup over the years is a pretty easy trend to follow with increasing efficiency at affordable costs. And would probably have little trouble beating your old rocket block too.

Cliff

 

[hitssquad]

Tailgate up or down for improved aero flow

Its like some pickups where leaving the tailgate down does little besides get rock chips all over it.

Recent research has actually found increased drag with tailgates in the down position. Leaving the tailgate up reportedly creates a locked vortex flow which improves aerodynamic efficiency. Even better is to use a bed cover (AKA a "tonneau cover").

 

[racprops]

“Funny thing is the other day I was reading a site with details on an LS1 swap into a late-model S10. My dad has a 2001 with the 4.3L V6, barely eeks out low 20s for mileage. But the guys with LT1 or LS1 swaps are getting 26-29MPG which is about the same as the Camaro/Formula/Corvette. Go figure”

I think it is the power to weight thing, too small a motor and it works way too much and uses more gas than a big motor lazing about.

“An air dam helps trap the air and create a higher pressure. Good for forcing more air through the radiator, not so good for drag since you're creating more high/low pressure air to pull back on the vehicle.

I consider the ground effects on my TransAm as cosmetic. Once they're above a couple inches off the ground the effect is tiny. On a van, they make for nice steps.”

First if close enough to the ground I was under the idea that it pushes the air around to the sides and with rubber siding that I plan on getting as close as I can to the ground again to help keep that air out from under the van, I read that doing so lowers drag as there is less turbulence from all the junk under the van., and short of a full belly pan the best I can do.

As for the motor, it is out of a 90 Caddy, and a true 5.7 350 with the one piece rear seal and the center line valve covers and the early Torvek heads that are tuned for low RPM power.

It was bored .030 and is fitted with Keith Black pistons and the stock cam as every other cam rises the power band and is counter point to my projected power band and gearing.

On the Rear foils, I am thing a fairly sizeable one across the top and a couple of little ones on both sides, all to catch and fold in the air.

On the trans I will use standard Transmission fluid in the 700 r4 it was the old stick shift transmission that I was talking about using a lighter oil than the old 90 Weight gear lube.

Somewhere I read that they are again trying the 4/6/8 thing, where they cut out a few cylinders, for at cruse you really do not need all of the motor.

I always said that was a great idea, but sold in the wrong car, Caddy buyers are not the kind to worry about gas mileage, now put it into a Chevy and I bet it would sell.

Both seem to let the dead cylinders run as drag, it only they could really unload them like some A/C units do, by keeping the valves open so there is no compression and drag.

Rich

 

[Cliff_J]

Sounds like that engine should be fairly decent for the job, the truck versions just seem to never get decent mileage like the car versions do.

On the new 5.3L they are doing the 8/4 thing and are calling it displacement on demand (DOD). It involves a new throttle-by-wire and a chamber in the exhaust so when it transitions the throttle opens and the exhaust closes so you don't notice it. Inside the engine half of the lifters have an extra oil passage. In DOD mode a solenoid opens and pumps up the lifters to hold the valves open. Suppossed to gain 12-15% mileage. Only in trucks because GM doesn't have a V8 car aside from the Corvette and Grand Prix,er, uh, GTO (like a person can tell them apart on the street, and yes I'm bitter about the f-body being cancelled).

New Hemi in 300C/Magnum does DOD as well, but not the truck version of the Hemi. Both covered pretty well this summer in Popular Hot Rodding, might ask friends if they have old copies if you want to read up on it.

Mercedes recently setup the S600/SL600 models to do 12/6 cylinder and I have a friend whose dad purchased one and had many engine management problems with it. It was so bad he almost got a new car under lemon law policy!

So far it seems detroit has learned from the 80-82 caddy with the 8-6-4. But if you want to see how bad they can mess things up for their name then search on the "caddy that zigs" (remember the commercials?) the Catera. They're super cheap to pick up used because they are so bad.

As far as ground effects, I'd like to see some measurements. The air is always going to be coming in from the front and pushing even half of that air aside is going to require a lot of power.

hitssquad - interesting link!

Cliff

 

[hitssquad]

Cylinder deactivation in the LS2, or a lack thereof

I understand that GM wanted to incorporate DOD into the LS2 but found that it decreased the maximum RPM and so left it out (something about the added moving parts interfering with the free running of the engine at high RPMs; I do not recall where I read that). Apparently, GM http://www.roadandtrack.com/article.asp?section_id=7&article_id=1556&page_number=4&preview= where the DOD mechanicals would attach if they were installed:

• The LS2's cylinder block is an entirely new casting with LS6-inspired openings in its main-bearing bulkheads for chamber-to-chamber airflow. There are also DOD (displacement-on-demand) bosses in its valley that did not have to be used.

Popular Hotrodding reports GM attained 35 MPG in testing of an experimental C6 equipped with DOD:

• ...an early prototype C6 Corvette with an LS2 running DOD provided equal power and acceleration to an LS2 without DOD, but produced 35 mpg instead of 30 mpg. When applied over a large volume of vehicles, GM could have the choice to pocket the improvement in economy and reduce the need to import small outside-sourced cars, or it could build a larger V-8 with more power (say a 6.5L V-8 with 430hp) and keep the same 30 mpg.

 

[racprops]

Truck vers Car motors, I have found that the truck motor came with flat lifters not the roller lifter/cams that the cars got, and normally have taller gears, like 307s and 343s where cars like my 79 Caddy has 243 gears, so that would account for a lot of it.

I am building a car motor with the roller cam and lifter system, and do not plan on ever hauling a full ¾ ton load.

Darn they are doing the DOD correctly now.
Too bad refitting one will be so hard.

I take it as good news that I am on something of the right track.

Rich

 

[racprops]

Darn has this thread run out of gas...?? Pun intended.

I hope more will jump in and fill-in the missing information.

I am really building this setup, I have the motor to build, all work done but final assembly, preoiler and filter on hand, modified 3 speed on hand, and I am building the coupling and adaptor to join the two transmissions.

I have the TPI injector system with wiring and computer.

I also now have two Propane bottles and will be ordering the propane injection kit.

I am building a custom dash with a ton of SW gages to monitor everything. And I have the 87 Chevy LWB Van.

I have the Cold Vapor injection unit and will try it as well.

And I have a old (their last version) Edlebrock water injector and may see if that adds anything to the mix...

I will have the rear end gearing changed if needed to match the power and gas mileage findings.

The tech questions have not been completely answered, what happens to gas vapor in the combustion chamber? What does water ad to combustion? Will the two transmissions work?

And what air control will help the boxy Van get though the air the best?

I am hoping to get more information on these questions, my building and running all of the above will only answer some, but if I can be convinced that any line of work is running up a blind alley, it will save me time and money.

And as I lack a wind tunnel I cannot test the Van.

So if you can help, please jump in.

Once done, I hope to share all these findings with everyone. After all not everyone can afford nor wants a very costly new SUV.

Rich

 

[Cliff_J]

what happens to gas vapor in the combustion chamber?

Any matter will be a solid, liquid, or gas at certain temperature AND pressure. Given that the fuel should be atomized by the injector and that its 7% of the mixture by weight there is a slight possibility that it could start to condense but (guessing) since the temperature quickly rises hundreds of degrees during compression its very unlikely.

What does water ad to combustion?

It will help absorb some of the heat of compression which should lower the chance of detonation. Most applications for water injection seem to be for boost applications. The additional heat from the boost process raises the starting temperature and the additional charge means the compression process makes more heat - both mean detonation is that much more likely to occur. Like having aluminum heads that can remove heat faster (and actually hurt efficiency a little because of it) the extra heat control to prevent detonation is better in the overall scheme of things.

Will the two transmissions work?

It will get the van down the road if you implement it properly. Whether or not you can use it to get better mileage remains to be tested I guess. In the end a 3.07:1 gear or 3.23:1 is probably going to work the best by guessing but there are plenty of factors like the loading (weight and drag) and so on.

And what air control will help the boxy Van get though the air the best?

A big cow-catcher (like old locomotives) mounted to the front would help a lot and is like an upside-down boat hull if you think about it. Seriously though, the boat example is useful since we're talking about traveling through a fluid - the front is where the most rewards are to be found, the rest is mere icing on the proverbial cake.

Just the testing equipment alone to measure the effects of aero aids would be too expensive to justify unless gas prices multiply a few times. Maybe a local college would have some students who could use some of the schools equipment to find out. The tailgate example above shows how common sense is contrary to empirical data.

Lets say the ground effects cost $500 and you drove 15,000 miles a year and gas is $2 a gallon. If it increased your mileage from 10 to 12 then it would pay for itself in a year, not bad ROI. It if increased your mileage from 10 to only 10.2 it'd take over 16 years to pay for itself since it'd save less than $30 a year - what's that, one fillup?

There's a couple other gearheads who have posted in the past but I haven't seen them here lately, must be busy with school or work. Oh well, hope at least I answered part of your questions...

Cliff

 

[Cliff_J]

Oh, and if you really wanted efficiency and if propane is available easily enough, a diesel would be a strong canidate. The old 5.7L has a bad reputation but that was mostly because of the timing problems caused by poor fuel filter care. One of those or a 6.2L would be cheap and should have little problem with the loads. Trick would be finding a good mechanic that could get it all setup for you with a propane retrofit kit and diesel ability as well.

Cliff

 

[hitssquad]

Ideas for aero testing sans wind tunnel

And as I lack a wind tunnel I cannot test the Van.

My understanding is that most companies that do wind testing of their products similarly lack wind tunnels. You don't need one in order to test your vehicle and come up with valid results. In fact, the artificial nature of the breeze produced in wind tunnels can give numbers that don't mean much in the real world.

I have read that most companies simply test their aero engineering ideas out on an open road on a calm day. Unpowered rolling tests on the flat are supposed to be popular, but I think for an automobile that rolling it unpowered down a downgrade starting at a freeway speed would provide results that are more distinct.

For your van, I would pick a favorite downgrade stretch of a nearby freeway. After selecting a starting speed that can easily be remembered (say, 60 MPH; a higher starting speed should be better in regards to the distinctiveness of the results since air resistance rises logarithmically but I wouldn't want to get pulled over, of course) so it can be used by me in future testing at that spot, I would also select begin-test and end-test points on that stretch that are next to easily recognizable and easily remembered landmarks. Then, on a calm day or night with preferably little or no traffic, I would drive the van down the highway toward the testing stretch and bring the van up to my preselected start-test speed. At the moment I was passing the begin-test landmark, I would dump the transmission into neutral. Then I would keep one eye one the speedometer and one eye on the next landmark. As soon as I passed the next landmark I would memorize the speedometer reading at that moment as that particular run's result.

I would think that if your vehicle is typical, your speed should drop significantly from 60 MPH, even if you pick a nice, steep (and the steeper the better, in my opinion) freeway downgrade.

One caviat here is that air density will affect your numbers and air density changes with air temperature. Part of your testing data should include air temperature. Wind speed and direction, I think, would also be potentially critical data to have recorded, though of course you would optimally be testing only on the calmest days/times possible.

 

[racprops]

Thanks for all info.

Gas condensing back into liquid, very unlikely, thanks I will work on the gas vapor injection system as it may work.

Water sounds like poor idea but for the hot dry air here in AZ, other wise turn it off.

Two Trannies, your gearing sound like my idea as well, thanks.

Streamline the front end first…

Well I needed more room in front of the motor anyway so that is a possibility.

I passed on diesel as being too costly to buy, too costly to run and way too costly to repair.

I CAN and am building my own gas engine. And there is so many more ways to fuel it.

Rich

 

[racprops]

Wow this has been such a trip though the rabbit hole.

Claims and counterclaims:

That you can get up to 200MPG.

That you CANNOT get any more than what the stock fuel injection gives you…!

That you can run your car on water...

One page said that the total possible power out of gas would produce is 100 MPG IF there were no friction losses, not in the engine, drive line or tires, MAX Possible.
And only IF you burned every atom of gas AND uses ever erg of power, and lost none of it to heat.

All write great pages, all seem to have science to back their claims, most seem reasonable and real.

I am hoping like a lot of things, the truth falls somewhere in-between, SO:

OK Here is what I hope and expect to get. 20 to 30 MPG, In a long wheel base 87 Chevy van, and be able to go up mountains faster than the Trucks. (More will be gladly used)

I think it is a reasonable hope and goal.

I know that there are new trucks getting this mileage, but I would then have to spend $30,000+ and that is the sale price before insurance and payments, these will add costs of thousands more…

I hope to get this out of a $1000,00 Van (bought for) with a $1500.00 motor (Rebuilt for) and about $1000.00 more in fixups (Hoses, belts, the TPI ect.) and at worst $1000.00 in extras like the propane system.

I all ready have the Vapor injector and the water injector and the modified three speed with over drive, so I guess those would add in for an extra $1000.00 all ready spent.

So for a about $4500.00 to $5500.00 I will have a custom Chevy Van that get great power and great mileage and does all the other things I need a van for, like camp outs and going on cross country road trips.

And almost all the parts are easy and cheap to get in nearly any wrecking yard any where, should I suffer a breakdown, AND I personally can make these repairs.

And last IF I want to change something, the ride, (Shocks and springs) the rear end, the transmission, the tires the wheels, I can.

I like it.

On the wind testing on the road: good idea, but I can just drive and see what happens to the mileage as well, problem is I will have to spend a few hundreds of dollars adding the ground effects sides and the rear wing air deflector and NOT know until after I road test if any thing worked, I was hoping to find out before all the money goes out…

Rich

 

[Cliff_J]

Rich - thought of one more thing you might want to try. The lockup for the torque converter is easy to control externally, all it needs is electricity supplied to a solenoid inside the tranny. You can access the wire right at the diagnostic port (GM service manuals tell which pin) and if you used a couple diodes to keep the computer output separate from your switch you could prematurely lock up the converter.

Depending on how efficient your converter is (most factory ones are like 80%, bad afermarket ones are like 60% and some good ones are 90%) and how good your lockup clutch is, this might mean significant gains in MPG for around town driving. The converter will not lock in 1st but will in every gear after that. One of my old cars with wiring problems would not lock the converter anymore automatically so I wired up a switch to lock it up manually. Pretty nice going up hills and just letting the motor work instead of slipping the converter like mad...but it was a 3200lb f-body so one can cheat a little more there too.

Just a thought.
Cliff

 

[racprops]

I am very much aware of the Lock up torque converter and I also know I will need a heavy-duty version for my Van.

That can work both ways, unlocked and the engine can rev up into the power curve and you get the toque converter’s multiplier.

Locked and you have less power loses and a cooler running transmission.


Your preaching to the choir.

I have already installed 200r4 in my older van and in a 79 Camaro that got 19-highway mileage with a Quad….

My 87 Van came with a computer controlled truck 700r4.

And I just switched out the old TH400 for a 200r4 in my 79 Seville and as it is a CA version FI that will run in closed loop, I expect even better mileage.

Once the repairs and a setoff full gauges are installed, I will drive it stock and get the base lines of its performance and then see if I can improve on it.

Any thing that works will then be put on the Van.

Rich