i know there are differences in final drives and what not for acceleration, but which is the more preferred for a turbo car? the slower to gain more mph with a lower rpm or the other way around?


would it be more logical to have the 4.2 and get better rpm's and have the boost push the trans and cover more mph or to have the 4.4 and have the boost take care of only half the work on the transmission?

 

Rpm for rpm and power for power, the 4.400 will generally provide the better acceleration (provided 100% traction). You'll have slightly more load for the engine/turbo with the 4.266 final drive, but it's going to be negligible.

However, gearing is, and should be, tailored to each individual setup (power band, rev limit, tire size) for each individual track. Every scenario is going to be different so no one can tell you what will be better without the exact setup or usage. It's too broad, as, just for drag racing, you can make a 4.785 work fine with large enough tires and 9500+ rpm rev limit. Gearing is the FINAL thing you change once you have everything else figured out and setup how you want it.

 

well i have 2 ideas as to what i would want to run, either: A. gsr with ls 5th. or B. ls with gsr 2nd.


both will have an lsd equipped with them.

 

LS and GSR 1-2 are the same ratio minus the synchro design on 2nd. And multi-cone synchros aren't the "be all end all". If you are looking for performance, just ditch the LS trans period. And if you want to put a 4.266 final in anything, put it in a B16/ITR trans.

 

We sell more GSR builds to people running turbo cars. Seems to be a perfect balance of gearing. We are building one now for a 600hp drag car.

As mentioned by Honda Bull..gearing is something that needs to be setup with the car...some cars work better with more aggressive gearing and vice versa. Starting with a GSR will give you decent gearing and you can play with final drive ratios from that point.

 

ya thats what im thinking about doing, im already in the market for an ls 5th and that should put me where i need to be.



have any of you ever extended the ratios a little longer than the stock gsr and make the 4th and 5th top out for a higher trap speed?

 

Well let me know what you need and I can get you taken care of. I keep LS 5th gears in stock..have both good used and new depending on your budget. I will PM you some prices.

Traction is also gonna be a big factor..if you lose traction with a smaller tire than it is gonna throw everything off. To big of a tire will also change things.

 

How much higher trap speed do you need? My car went 152mph in the 1/4 with the 4.40 ITR final and ITR gear setup. The shorter geared trans is going to accelerate the quickest, as mentioned above by Honda Bull, given traction is optimal. He really hit it on the head and the changing of the gears should be tailored around what your setup does. Most people opt for the GSR trans because of the combo of traction/MPH ability/accel rate. Post what your tire size, power/trq numbers, rpm shift, etc. so that we can help you better.