anyone thought about or got !!!

[74TC]

the 4.1.1 diff upgrade? see those of you that have diff done have 391 why not 411 or is it to much ?

[Island boy hsv]

I have a 3.91's, they are a good compromise between acceleration and speed. I believe that drag racers go for 4.11 as they give ultimate acceleration.

[Ferb]

I have 3:9 as well and agree with island boy. Drag racers in WA use 4:1, but they have very strict speed limits, max 110kph/68mph

[74TC]

Ferb said:

I have 3:9 as well and agree with island boy. Drag racers in WA use 4:1, but they have very strict speed limits, max 110kph/68mph

take it you were referring to road speed and not diff. speed ?

[Ferb]

Yes

[74TC]

Ferb said:

Yes

do you know what you would see out a 411 diff top end ?

[Ferb]

Sorry I d'not, I just found out my ute has a speed limiter on it, 220kph/136mph [end of hanger straight]

[ringram]

Ive heard you need to be in 5th to get top speed normally so Id imagine top speed with either was much the same given that 6th becomes more useable.
You can up the stock RPM limit from 6200 to 6800 (as per hsv limit) without too much drama giving back some of what gearing loses you. Suffice to say you can still lose you license in 3rd with any of the gears!

[stevieturbo]

The last thing I'd be reccomending for a car that makes some decent power and torque, is shorter gearing.

All that does, is end up with more wheelspin and useless lower gears, and often makes the car slower.

[madazrx7]

But surely it's accepted that with the tyre size and gear ratios, the HSV is geared higher than ideal. Probably to achieve better fuel economy rating? Therefore it's performance WILL benefit from a shorter diff ratio.

[caspy]

I think the 3.9 complements it perfectly. never tried a 4.1 but i would imagine it would be a tad too short for real world driving, swapping cogs to often.

[ringram]

Stock tyres are easy enough to lose traction. If you go crazy with drag radials etc you will either blow your diff or your clutch up. Just take a look at what the Ozzies and yanks do.. First port of call is a new clutch, then beefier diff...
Best to keep to stock sizes and gear it to match power I guess.

[stevieturbo]

madazrx7 said:

But surely it's accepted that with the tyre size and gear ratios, the HSV is geared higher than ideal. Probably to achieve better fuel economy rating? Therefore it's performance WILL benefit from a shorter diff ratio.

quite often you find, that with shorter gearing in a high powered car, you end up either losing traction, or wasint time changing gear too often, when tall gears will just keep on accelerating.

obviously there is a balance to achieve though.

[monkfish1]

There is a table of engine speeds versus road speed for the different gear ratios on our website www.monkfishperformance.com

Personally i think 4.1 gears will be too low for a high(er) power car.