- #1
adynes
- 2
- 0
Hello, newbie here.
I am building a dual purpose (street/strip) twin-turbo 77 T/A. I plan to run a midplate between the bellhousing and the block which ties into the frame. The midplate will react the driveline torque to the frame instead of through the stock mounts, which bolt to the side of the block. I feel this will take a lot of load off of the block sides, as 800ft-lb engine torque x 3:1 first gear ratio = 2400 ft-lbs. If this torque is reacted at the stock mounts (~1ft apart), that would be an unnecessary 2400lbs-force on the sides of the block. Midplates are common on high horsepower drag cars, mainly because its an easy way to mount an engine to a tube frame chassis (and I don't think most racers realize the benefit I mentioned above, based on feedback from other forums). A common failure mode in high hp Pontiac engines is structural failure of the block near the stock mount location.
Virtually all cars built with midplates solid-mount the plate to the frame. Since my car will be a street-car 50% of the time, comfort and longevity will be important. I am a little uneasy about solid mounting the engine to the frame through the midplate. I am considering using vibration dampening grommets to reduce vibration in the rest of the car. I am also worried that If vibration is large enough, it could shake the car to pieces over time.
Now for my question:
Are the grommets necessary? What could be some pros/cons of each configuration? I know a lot depends on the specific vibrations present, materials used, and geometry of parts. Could dampening the vibration energy through grommets increase the durability of engine block/components by any appreciable amount?
I missed out on the machine-vibrations class in college, but understand some of the basic concepts, so feel free to keep the discussion technical.
All input is welcome
I am building a dual purpose (street/strip) twin-turbo 77 T/A. I plan to run a midplate between the bellhousing and the block which ties into the frame. The midplate will react the driveline torque to the frame instead of through the stock mounts, which bolt to the side of the block. I feel this will take a lot of load off of the block sides, as 800ft-lb engine torque x 3:1 first gear ratio = 2400 ft-lbs. If this torque is reacted at the stock mounts (~1ft apart), that would be an unnecessary 2400lbs-force on the sides of the block. Midplates are common on high horsepower drag cars, mainly because its an easy way to mount an engine to a tube frame chassis (and I don't think most racers realize the benefit I mentioned above, based on feedback from other forums). A common failure mode in high hp Pontiac engines is structural failure of the block near the stock mount location.
Virtually all cars built with midplates solid-mount the plate to the frame. Since my car will be a street-car 50% of the time, comfort and longevity will be important. I am a little uneasy about solid mounting the engine to the frame through the midplate. I am considering using vibration dampening grommets to reduce vibration in the rest of the car. I am also worried that If vibration is large enough, it could shake the car to pieces over time.
Now for my question:
Are the grommets necessary? What could be some pros/cons of each configuration? I know a lot depends on the specific vibrations present, materials used, and geometry of parts. Could dampening the vibration energy through grommets increase the durability of engine block/components by any appreciable amount?
I missed out on the machine-vibrations class in college, but understand some of the basic concepts, so feel free to keep the discussion technical.
All input is welcome