Engine Position?

Hey all,
In relation to a door car, is there an ideal distance between the rear of the block (engine plate) and the axle centreline?
In other words,can the engine be set back too far? To a point where it induce's
bad handling,wheels up launch's and aggresively striking the wheelie bar?
Car in question,SBC,4 speed CS1,4 link,single wheelie bar.
Jason.

 

I'm not sure this is the right forum for your answer.

If you have a car already together (I see one in your avitar) it might be a good idea to scale all four corners, determine the center of gravity and see how that compares to similar cars that handle well or get chassis builder recommendations for your wheelbase and engine combination.

.

 

Yeah I am no chassis guy but I read two books so I am an internet expert and I would think it all depends how you define a door car if you built a door car as long and low and lacking in wieght above 20 inchs as a funny then you could use the all the set back you wanted. On the other hand if you were talking about any sort of conventional car then the ideal height and set-back are already there plus lot of classes limit the set-back anyhow.

Richard Gavle

 

Randy, sorry bout being so vague in the origonal post
No that's not the car in question in the avatar,the car i'm refering to is a 115" W/B,double frame rail,left steer,pro mod style sedan.It is by no meens a new combination having previously run a Hemi and then changing to a sb.for a different class.I believe yes it has been scaled and the c.o.g is where it should be(the car was built years ago by one of the premier chassis builders in this country!) The main reason i ask is that after several passes the clutch (a 3 disc 10" crower) went from 17 grms on three fingers to "0" and yet the car still reacts violently on the launch! Like on the step it picks the wheels up a foot and steers left. Could it be more a case of the 1st ratio is too low? The car weighs 2370lb 315" psi "D around 1500Hp.
Jason.

 

try taking some static out of the clutch
i do not know any one who runs "0" on the fingers on a 10"
i am guesssing some where between 15 and 20 depending on the weight of the levers

 

i would leave the weight on the fingers and take some of the base out are put more in depending on where you have it set and why wouldnt you split the weight up over the six fingers and also leaving at to low of rpm will make wad the tires up and pick up the front end and drive on way are the other sounds like you need to get the wheel speed up leaving let the tires rotate a little more at the hit i know on my car if i leave to low of rpm by letting the rpm drop when i stage it will pack the front end and be on the bar hard and drive off one way are the other and go right into tire skake ( wheel speed )very important

 

This may or may not help, Im no expert. My door car wieghs 3200 lbs and I too have had problems with the wheels up, hard left launches, we put a bunch of preload on the left side and the problem went away. My front/rear percentage is right at 50/50 and a little heavy on the left side, but I use a tiny tire by most standards.

Oh and this is a GLIDE car, and I hit the tires very hard, lots of tire slippage for a while, and it goes straight.

I think the problem comes in when you only hit the tires with enough to turn your "weak tire" that makes you turn hard left. When you hit the car with enough to turn both tires it goes straight.

Just my thoughts

 

That is a lot of clutch for that car. 1500HP is less that what a Mountain Motor Pro Stocker sees and they run dual disk 10" or 3-disc 8" and are right about in the middle of the clutch window. You might consider running it as a dual disc to give you an actual tuning window because it doesn't sound like you have much of one at all right now. Sounds like an interesting combo you've got going there.

I also agree with Moparius, you need to get a little more preload built in since you only have a single bar out the back. It sounds like you chassis is dead nuts if you're actually getting the thing to hook enough to be dangerous.

 

Thanks for the insight guys
A new first gear ratio is on the way! See what happens once that's in.
Just a note: the clutch HAD i believe 700Lb base,the recommended amount for the clutch from crower. The reason all the weight was deducted (off only 3 fingers)was that any less base pressure would surely end in disaster?
Once all weight was removed and the maximum amount of base taken out, what then could it be put down to? And yes, some preload is probably a good idea.
Thanks so much
Jason.

 

i have to agree that does seem way over clutched, i know a guy who runs a 9" triple in a legal pro mod car and another who uses a dual 10.5 in an aussie screw blown doorslammer car

 

Arron,
The guy that owns the car,(a yellow mustang) is i believe going to a 9" clutch complete with a NEW (higher) first gear set. Guess we'll see what happens then.......
Jason.