Gearing for autocross

[Cobra #3170]

Originally Posted by RET_COP

I went to an autocross at Thompson Motorspeedway this weekend and had a blast. It was a tight course that you had to go through twice. It was confusing at first but by the end of the day I felt comfortable and always improved my time. I started in 1st,went through a slalom and hit 2nd for the remainder of the course, probably no faster than 35 mph I think. After thinking about my day and what I learned and how I can improve I thought about gearing. It seemed to me that I may have been better off just leaving it in 1st and use the engine for braking and the rpms for accelerating faster. The problem is most competitors used 2nd and probable had better range. So here are my thoughts. By the way I drove the car to the autocross at a comfortable 74mph at 2600rpms
I have a tko600 .82 5th, 3.27 rear, 26.5” tire a 351w about 488fwhp and a very nice broad torque curve from3000 rpms to 5000rpms 435 to 455. And 28lb. flywheel
Currently with 3.27 1st and 2nd mph looks like this at 2500 to 5000 rpms 21.0-42.0 mph-------31.89-63.78 mph
With 3.55 it’s 19.34-38.69 mph---------29.38-58.75 mph
My question is am I better off with the 3.55 rear and getting into 2nd and staying there with a better mph range?
I realize my highway cruising will be compromised but there is always a trade off.
By the way street tires and 15 inch wheels is not the way to race, and I realize seat time is 1st on the list.

Your thoughts please


I posted on ffcars also because the two guys that helped me throughout the day use that site. and I wanted to thank them.
Lou

Generally speaking when you start autoxing you are better off with a lower numerical ratio because it will avoid wheel spin and make your run smoother.
You are on the money about seat time run every event you can and sign up for fun runs too if they are available. Check out the Evolution autox schools they have them all over the country and they are a very good place to start.
Most of the time will be gained through driving experience if you decide that you like it then you can begin to change the car to improve performance but I would not do anything until you have some seat time and decide you want to go on and upgrade the car. Tires are the most important change you can make to gain time but the car has to be balanced to take full advantage of autox tires. Starting in first and shifting quickly to second is a good strategy and lots of very fast Corvettes do just that so I would leave the car as is for now. An experienced autox driver could drive your car and give you an idea of what adjustments might help to make it easier to drive fast, might just be air pressure settings but could be spring or bar change too.