Final Drive & Turbo Setup

[hondasingapore]

hi, Techies

Can someone HELP me on the following question?

Will a 4.929 Final Drive degrade the performance of my HKS Light Pressure Turbo Honda B16A? I am BOOSTING at 0.62 bar.

My BIG 4.929 Final Drive is inherited from my NA time, whereby it really helps in the pick up time of my car across all gear ratios despite some loss of TOP SPEED, around 10-20KM. I was TOLD that such a BIG Final Drive is UNABLE to spool up my turbo-charger efficiently as compared to a 4.4 Final Drive, for example.

Which is the BEST L.S.D. to REDUCE the torque steer resulting from the gain in power and torque? I am thinking about Quaife. Remember, I want something that will not afftect my driveability.

Thanks.
Hondasingapore

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[hondaguy72]

With that turbo setup, your gearing is fine. It will hamper the vehicles top speed, like when N/A. Turbos like an engine load to spool the turbo, but higher (numerically) gearing will give the same or better results. Quaife is the tried and true LSD. Why mess with anything else? Sounds like a nice, safe, quick setup.

 

[posol]

gearing is designed to use your engines torque, and mulitply it.

the FASTEST time your car will go in a 1/4 mile, is when you cross the traps at the very top of 4th gear... 7900 rpms on an 8200 redline is good

now, if you have to hit 5th before the end of your quarter... you should move down.

it really depends HOW fast you go. since you are running a small turbo, your times aren't going to be in the 11s, if even the low 12s. a mid 12 sec car traps around 105 give or take. if you want do 105 (or whatever your trap happens to be) in 4th gear, and must hit 5th, THEN and only then is it time to swap gearing.

 

[posol]

i also forgot to mention--

tire size plays a BIG role. if you are finding your self just hitting 5th in the top of the 1/4 mile, try stepping up to a bigger tire. for example, instead of 205/50/15s, try 205/55/15's. the tire is slightly bigger, and it will give you a couple more MPH per gear, effectively making your FD gear smaller (or is it longer? )

check out this- https://hondaswap.com/threads/gear-speed-calculator.59344/
its a neat little spread sheet.

plug in your tire size, and your gear box, and it will calculate your trap speed in each gear.

 

[posol]

i just ran it for a b16a JDM sir2 tranny, with your final drive, and 205/50/15 wheel size...
4th gear tops out at 8000 at 100.6mph

if you are going to trap more than that in the 1/4 mile, lets first try a bigger tire size... 205/55/15
that bumps it to 104
on a 24.5" slick, you are up to 106.8

doing all that, personally, i think you need to get the car running... and get it down the track a couple times. on your low boost setup, i think you are actually PERFECT with that gear box.

if you have an questions, feel free to post