aggiehobbie

I have been autocrossing my C5 in our local SCCA Solo events in SS Class and except for Hoosier's it is stock. I have been running with a full fuel load to keep some weight on the back tires for more grip. But after racing yesterday, I am wondering if that is the right tactic or should I be running a minimum fuel load or something in between.

What fuel loads are others using and why? And what do you recommend?

Thanks for your expert guidance ,
D

Bill Dearborn

Although cornering is easier with less weight I usually run with the gauge reading half full. The C5/C6 isn't as bad as earlier model Corvettes that had a horizontal gas tank mounted behind the rear wheels. I would have never run the C3 or C4 I used to autocross with a half full tank. They would have been set to just above the point where fuel starvation occurred or completely full to reduce fuel slosh reaction.

From running HPDEs I know that with a low tank my 97 and 03Z both get loose in the rear and I have to be careful using the throttle when exiting a turn. Getting the fuel level above half full on the gauge tends to make the car feel better and I can use more throttle when exiting turns.

Bill

mikahb

I always shoot for right around 1/2 tank when I'm running. With 1/2 tank and me in the seat, my car is almost exactly 50/50 side-to-side and front-to-back weight-wise.

0ATI Performance

On a C5, the left tank fills before the right tank. After the left tank is full the fuel spills over to the right tank. So that means if you run half a tank, all the fuel weight is behind the driver (~50lbs fuel). On a mostly stock C5 this hurts L/R weight balance, unless you have a big passenger...

Bob

TXCatalyst

Aggie ehh ? For a lot of the larger, faster BMWCCA or PCA autocrosses here in N. Texas, I'm in the minority and I've been running a full tank - for better stability and the rear seems more planted and predictable - key word being predictable for these 'high-speed' autocrosses.

Some of the 'autocrosses' are 1 to 1.8 miles long up here.

TommyBoy72

I run with minimum amount possible. This is calculated roughly by the number of runs expected, the size of the course, and how far it is to the gas station after the event and then of course some safety margin. Usually this is 1/4 to 3/8 of a tank.

LehmanZ06

Run with 1/8th-----------

Bring a couple of gallons in a small plastic gas can.

2 gallons will last like 5 runs on a 1 mile autox course-----showing 1/8 th you could probably take like 6-8 runs before totally dry.

Even if you hit Reserve no real worries----just add a couple of gallons.

If you hit "low range"-----you have maybe 1.5 gallons left at most.(guess)

TedDBere

Weight is the enemy!

Good Luck.

froggy47

I agree,

use other means to adjust rear grip. Gas weighs about 6 lbs a gallon, 18 gal eq 108 lbs. You want to give up 108 lbs to your competition?

aggiehobbie

Thanks for the input, I will try a much lower tank level next time and maybe I can get closer to that puke green Lotus Elise that is in my class and always has very fast times...

D.

JVetthead

Also, The right tank continuously pumps fuel to the left tank which is the main tank the engine draws from.. So, at half tank on the guage the left tank is mostly full, the right tank mostly empty...

wtknght1

As has been said, I think it's best to run minimal fuel. But be careful how far down you go. My car reaches fuel starvation at 2 ticks (1/8th tank); when turning right. For Auto-xing, even a slight hiccup is worth time...so I'd start around 3 ticks...and keep a gas can nearby and add when necessary.

7-10 lbs of extra fuel is OK, but you sure don't want to give up 40-100 lbs to your competition. And, it's easier (and cheaper) to reduce the weight on your car rather than to try to find more power!