What fuel load are most of you running at autocross events? Does the car suffer from any fuel starvation? Also what rpm's are you launching at? And lastly what tire pressures are you running on kumho's. The car will be on 285 kumho's for the first event

 

hmmm... no less than 1/4 tank as our fuel pumps are at the front of the tank. Found that out the hard way

Honestly everybody launches differently. There are those who burnout, those who like to start out slowly. I launch at 3.5K; no need to lose traction and we need all the help we can get in low RPM's

Also make sure your DSC is completely off (hold button for 7 sec)

I'm not sure on pressures for 285's though...

Have fun!

 

Fuel Load - Just above the point where the fuel light comes on to be "safe", typically you can make 2-4 runs with the light on with out starvation, but it will depend on the course design and will likely vary some from car to car.

Fuel Starve - There have been several fuel pump revisions over the years, some cars suffer from starve with more than 1/2 a tank if the pump has not been updated. I changed my pump about a year ago after experiencing problems during my second season in the car. I now have zero issues with fuel starve after updating the pump. (Fuel Light off)

Launch RPM - This will vary with surface condition, tire temp and driving style. At ProSolo's, with perfect conditions, we have launched with the buzzer on ! On lower grip surfaces or cold tires you may find 4,000 RPM is too much. Test & Tune your style to the conditions.

Kumho Pressure - I only have experience with the 245 Kumho, where we used upper 30's for warm tire pressures on medium grip asphalt. Your optimum pressures with the 285's will vary with the surface conditions and car set-up, maybe Carter/Jim or others can speak to their experience with them.

Chris H

 

if you are launching on r-comps you can launch at 7500 and let the wheels grip. haha.

for drag racing i like to launch at 4500 rpms and feather the clutch out. 245/40s.

since you are running 285s, you might be able to launch at 5000rpms or higher. my advice would be to go to your local drag strip and get a few runs in, playing with your launching. if you get there 30 minutes ahead of time, and wait in the small line that forms, you'll be able to get in 5 runs almost hotlapping it, before the crowd shows up. also, on my toyo t1rs, i seem to get the best results launching at 32psi.

i've seen miatas at my drag strip outfitted for autocross. heh.

 

I always start with a 1/4 tank. We have had the car hiccup twice when starting below that. I figure its better to be 7lbs heavier, than to come up short on the run you need.

 

it's different for everyone, but i find 5k the best for a launch, hold it at 5, and feed clutch in halfway for a second maybe 2, let everything sync, and full throttle and off the clutch completely.