My engine builder said that I should keep my cars ride height to where the axles are straight for least resistance and max acceleration. Has anyone noticed a difference? What about lower for least drag ?

 

there are several things to talk about here. Weight transfer is more of an issue with acceleration on a FWD platform then anything. I cant say that lowering your ride is a reason to go faster , as the axles are pretty straight or 'inline' from the factory. They are purposely designed that way. Granted not all applications are perfectly inline, but I doubt you can even achieve this just by lowering your ride anyway.

Best drag setup is high rate springs and higher in the rear, lower in the front. This is for transfer, not to put your axles more 'inline'.. This is not rear driveshaft car..

 

Just a point of clarification: spring rates affect the rate of weight transfer not the amount. Lots of people get that confused. It's not about lessening it, just about getting it over as soon as possible.

Lowering the car will, however, reduce weight transfer.

 

It does make sense that a severely angled driveshaft will have more internal friction in the joints than a straight one.

Whether or not it is a perceptible difference is anyone's guess. I guess someone will have to run their car on the dyno at different heights to know for sure.

 

You absolutely can change the amount of transfer from the front to the rear. You just cant ever eliminate it. Instead your changing how and where the weight is transferred. If you had a solid chassis with no rear suspension (solid rear suspension) and hard tires will little give if any, the transfer will take place how ever it can, via the front motor mounts.. the transfer case.. the engine block , axles , front suspension , front tires.. etc.. this is getting really technical fast.. but here is a start in understanding what I am talking about..
http://www.eng-tips.com/viewthread.cfm?qid=87498

 

What influences weight transfer is rate of acceleration, height of the center of mass, and wheelbase. Suspension compliance is not a factor. A car with a solid suspension still experiences very similar weight transfer during accel/decel as a car with a soft suspension. It's just that the chassis responds very quickly to the weight transfer, and the change in pitch will be much smaller. Granted, the weight transfer will be slightly less if the rigid suspension doesn't allow the c.g. to rise (compounding the weight transfer), but that effect is usually going to be pretty small.

 

true true... drag setups on FWD take a lot of work to refine. This is why everyone strays from a full on FWD drag setup. Its not easy or cheap. Its easy to build a XXXwhp b series comparably lol. True die hard FWD drag groups spend thousands on setups only to pick up a few .0xx in the 1/4. Back in the day, I remember papadakis getting **** for running wheelie bars.. and he only just broke into the 10's LOL

 

Obviously, looking at all the fast FWD setups, to aid in traction(excluding spring/shock rates) the rear ride height needs to be slightly higher than the front. The front tires expand(get taller) the faster they spin, effectively leveling the car at some point down the track. If you can tuck the front tire in the wheel well you can lower overall ride height and have a definite aero advantage. Problem is the big meats require partial tube frame or tubbed front wheel wells to lower the front down enough to tuck them. How low to the ground are the fastest dragsters?? Practically dragging belly pan.

 

Low = less drag, less aero lift, AND less weight transfer.

As far as axle friction, any wasted power would produce heat. Even a single hp lost through friction would heat up the axle quite a bit. It's backwards reasoning I know, but wouldn't people notice that? I'm not in the drag racing scene at all but I've never heard of people having that problem.

 

your right.. you wont notice it at all. Frictional losses with tire choice is more of a problem then the minor correction of your axles.