Technical questions.

[Thessman]

I have a spare LSD from my vx ss and was going to have it rebuilt to different ratios but I didn't know what would be the best way to go. A few people have suggested 3:45 for a nice tight little diff, others have said go 3:9 and some ppl have even said 4:11. I'm not much of a diff person so I'm wondering what other people have put in their cars that worked really well. It's a 6 speed if that makes any difference.

I also heard that the supercharger from the Holden super six will fit on an LS1 motor and by changing the pulley a 10psi or larger (as well as doing a few other mods to the engine itself to counter the charger) you can make decent power for a lot less than the price of say a yella terra charger. Is this true and can anyone suggest different paths for this?

My goal is to make around 300rwkw without losing to much drivability.

[GEN3RATD]

with the diff mate

as your vx is a 6spd, it will already have a 3:45 ratio in it. If you cruise a lot of highways id recommend 3:9's, otherwise 4:11 are awesome.

with the supercharger

ive never heard of someone running a super 6 charger on an LS1, but i think around 8psi is about as far as id push it on stock internals,
an exhaust, cam, heads, and intake will get you 300kw easy, otherwise a CAPA supercharger kit will get you 300kw and then some

[Thessman]

Thanks for the help mate. The diff situation really sorted me out. I'm more of a cruiser than a bruiser. I'd rather have enough grunt to take most street cars but I don't want a quarter mile monster. Might have to research a little more on the whole supercharger path though. It's still a while away but there will be intakes, tunes, cams and probably some minor head, throttle body and manifold upgrades before hand. Just to cover all bases.

[GEN3RATD]

yeah most people search for a good medium, something streetable but can still post good times.

with an off the shelf supercharger kit (assuming you already have a full exhaust) you can make 300kw easy, it is a lot less stuffing around then cams and the like but most people dont have enough coin to lay 10k on the table straight away, so the progression takes them through exhaust, OTR, cam, etc.

[GEN3RATD]

double post

[monkeys437]

Id go 3.9's with a 6 speed since its got 2 overdrive gears, you shouldnt do too many revs at cruising speed. The factory blower would definitley not be a straight bolt on and I would think its too small to service an engine of that size

[QldKev]

I would look at the 4.11 diff.

On my website there is a spreadsheet
My World
Under LS1, Diff Gears, Speed Calc

It has the gear ratios and you can plug them in to see at given revs what your speed will be; and also at set speeds what your revs would be.

QldKev

[Thessman]

Thanks for that, Ill definitely have to check that out.

I didn't think it would bolt straight on. I'd rather an off the shelf charger anyway but it grabbed my attention when I heard people talk about it.

[Jesterarts]

I have 4.11's in my 6-speed VZ and am not a fan. I want to get 3.73's down the track.

In 6th gear @ 100kmph I sit at like 1900rpm odd.

Having a VX SS you will have a t56 box if you have the 6speed instead of the t45-m12 I have so youre RPM will probably be 1700rpm @ 100kmph in 6th.

3.9 is probably as high as you want to go. 4.11 if it's going to be a strip car.

[QldKev]

From my spreadsheet I llinked to earlier, t56 with 4.11 = 1695rpm, but 3.91 = 1612rpm, and 3.73 = 1538rpm.
less that 160rpm difference between 3.73 and 4.11.

my A4 with the stock 3.07 diff was 1772rpm at 100km/h

QldKev

[Jesterarts]

From my spreadsheet I llinked to earlier, t56 with 4.11 = 1695rpm, but 3.91 = 1612rpm, and 3.73 = 1538rpm.
less that 160rpm difference between 3.73 and 4.11.

my A4 with the stock 3.07 diff was 1772rpm at 100km/h

QldKev

160rpm difference is a 10% difference when we're talking about a 1538rpm baseline.

And as you said on your site, 4.11 makes first get rather short.

4.11's are really not all that street friendly in my opinion.