custom gearing?

i have a 4 spd in my auto cavy, right now stock it runs a 15.9@86mph, im looking to eventually make my car a low 14 second car, high 13's. But i noticed when im racing it doesnt even get into 4th gear on the track, that doesnt come into play untill about 100MPH, but my car is speed limited to 105MPH. So i was wondering how much does it cost to have the gears changed to produce a faster 1/4 mile time, how will this effect engine life, and how much would this hurt gas millage?

well you would be talking about a track specified tranny, which would affect all drivability. What rpms are you reaching and speed when you hit the quarter? It should shift into fourth unless your rpms are unbelievably high. You could probably solve the problem, with some mods to the torque converter, have a talk with a few racing shops, and or tranny shops to see what they say.

Um...i think you could just swap in some taller gears maybe instead of going to the extreme's of a new tranny. And a torque converter is not going to make a difference in gear ratios buddy. An aftermarket one might help his launch but it wouldnt really be worth it either. I have no idea of what it would cost to change them. It shouldn' really hurt your engine other than that your going to be running at higher rpms in 4th gear so your mileage will not be as good. I think you could get the speed limiter taken off because if it's a Cavalier, I'm guessing my friend has one, Z24 2.4L blah blah blah. We've had it well over 105 mph before until his brother set it back to 105. You could get your car to run around 14's and keep the gearing you have now, I'd go that route. If you find out what it costs to swap gears see what you can do for engine performance for around the same price first, cuz the gear swap might not be worth that much, well yea it'll make it faster but at an expense.

what i was referring to with the torque converter applies to your overall acceleration, which is important for drag racing applications. Not only will you improve your launch, you (if you still have a stock converter) have converter lockup which loses you about 300rpm, from experience i know you can modify the torque converters, how much i dont know exactly. Obviously you cannot change gear ratios with the torque converter but you can increase acceleration exponentially, and that would produce faster 1/4 times.