We have a Volvo C30 car that we race in the ChampCar Endurance Series. Or should I say that we are rebuilding it after I stuffed it in the wall.
Since we are in rebuild mode, I am thinking (or overthinking) the placement of the fuel cell. Like many FWD cars, the rear tires are close to the rear bumper so it doesn't leave much room to put a cell behind the read axel. That being said, we had a wedge shaped 18 gal. Cell fitted over and behind the axel. Now for the rebuild, I'm thinking over and in front of the axel (more in stock position).
My question is this .... is the advantage of rear weight percentage with a possibility of a pendulum effect of the fuel behind the axel a better choice than giving up some rear percentage but having all of the fuel rearward, but still between the axel?
It wasn't too bad behind the axel, but just wondering about what is "the best" place.
Also, if by some strange reason that ypu can get a 50/50 front to rear weight in a FWD, is that really a good thing?
Thanks
Personally, for an endurance car, where it's more about pounding-out lap after lap consistently, as opposed to an outright blistering lap, i would want the fuel as centrally located as possible. To me, this would maintain a closer balance as you burn fuel through a stint. Let's say you have a 22 gallon cell, in a 2600 car. With a cell closer to the rear of the car, that's roughly 20% of your weight behind the rear axle at the start of the stint. Much less so as the fuel burns-off.
In reply to grafmiata :
Yeah that's kind of where my thoughts were going.
I'll add another vote for positioning the fuel cell ahead of the rear axle both for lower polar moment of inertia and more consistent weight distribution.
Side note: I wouldn't get too hung up on achieving 50/50 weight distribution (not likely achievable on a front drive car anyway). Plenty of fast front drive cars at 60/40 or even 65/35 front/rear weight distribution.
In front of the rear axle for sure.
Getting weight to the middle of the chassis is very helpful. You can always tune the balance with suspension.
A big difference in fuel load will make a bigger difference the further away from the middle of the car that it's located.
As other have said get it as between the wheelbase as possible.
Our crx endurance car was a handfull with a full 22 gallons on board,the EG hatch that came next much better and the 9th gen civic couple that followed it better still.
The longer wheelbases offered more space to get it ahead of the rear wheels.
