I have read various comments on how much gas autocrossers have in their tank but have not read anything as a consensus. I am just curious as to the pros & cons of the amount of gas that should be in the tank. I have driven with 1/4 tank and it felt light. I have also driven with a full tank of gas. Although it felt heavy, my rear wheels felt more planted on the course.

What is the ideal amount of gas that should be in the tank for auto-x and your reason why?

 

I go with the smallest amount possible. Basically, when the heads-up indicator starts blinking the ----- after it's damn near empty, that's the perfect level. I did 18 runs at that fuel level with no starvation. So I didn't vote on the poll.

 

I would like to know as well, considering I will be there sunday with you. I was thinking about 1/4 but I have never ran either.

 

1/4 tank... full tank will be slightly heavier on the turns i think.... ive only ran with 1/4 cuz my friend told me to soo ive been doing it ever since

 

I usually leave home with less than 1/4 so most of the autoX is run at 1/8th of a tank. That means stopping for gas when I lhead home.

 

I meant to say 1/4 but i voted 1/2.

 

You can run much less than 1/4 and be fine.

 

I run 1/4 tank and have had no fuel starvation problems...but from the other replies, I might try running with less.

 

I like at least 1/2 tank or more , i dont know about the Z but with my old car if my gas was to low it would slosh and casue the chassis to be unstable in some corners.

 

As far as the wheels feeling planted, I tend to do better with a copilot, esp. on asphalt. I run half a tank because I haven't made up my mind whether more weight is better or worse for tight courses and a torquey motor.

 

I was debating on running a full tank vs. runnning empty as I currently do.... if I want more weight in the back I think I would run with the spare in, as there is no slosh.....keep in mind that the vehicle I autox is a base model with no lsd..... so you would think that I would need weight back there more than anyone.....

 

depending on what class your running, get the car as light as possible and then adjust your suspension to get the correct weight balance.

 

<------ stock (class)

 

Mine is *very* balanced at 3/8 of a tank, less than that and the rear is too light, more and there's a bit of extra weight. I'd rather have closer to 1/2 than 1/4 tank.

 

We ran a full tank and so did Chris Hammond.Based on our testing rear wheelspin out of corners was nearly eliminated with a full tank plus a big front bar plus 285/30 Kumhos plus proper shock tuning.The Z's advantage is at corner exit(torque and lot's of it) and you must do everything you can to reduce wheelspin.
Jim and Carter

 

Hey, everyone! Great responses so far, and appreciate everyone who have voted. It really helps all of us who participate in autocross to understand the dynamics of how the amount of gas affects our Zs behavior on the course. Keep it coming and we certainly are continuing to learn from each other's vast experiences in this great forum.

 

One difference between Thompsons', Hammond's and my Z is that I still have the 60 lb "boat anchor" of a muffler. Hence less fuel required to keep wheelspin down.

 

PDX makes a good point.We did use a delete tube(5 lbs) in place of the 35 lb muffler.Therefore a 3/4 tank would be the equivalent with a muffler.In either case you have approx an additional 90 lbs to help load those rear tires on corner exit.

 

Would you recommend using something other than a fluid dynamic that can slosh to weight the car down? Fixed ballast, perhaps? Something you can use in conjunction with the spare tie-down?
Damnit, now I'm going to have to try a full tank
<----------9.5 pound JIC full Ti catback exhaust

 

We preferred using the fuel load to find the right weight to keep rear wheelspin to a minimum.All our testing kept telling us that a full or near full tank was best,even on the high grip concrete at Peru Ind,so we never let it get below 3/4.
Ballast per se not allowed in stock class.