LS engine tuning

[Gav]

Bobby,
Have you any experience with the hand held tuners?
I really only want to play with the shift points, and pressure on track days. Would a predator unit do what I want or are they a waste of money?

[Aussie Mike]

Paul,

My 3.9 diff is pretty civilized. I reckon 4.1 and the T56 will still be fine.

Bobby did a great tune on mine and He's a real font of knowledge on this stuff.

Cheers

[sambo]

That's interesting re 4.11 gears... on the other hand plenty of people have said it's too short. I might have to find one of those gear ratio calculators and work out top speeds in each gear.

Roughly what's RPMs does the L98 torque curve start to drop off?

[Rebel1]

The 2009 model L76 which should be the same is 521Nm at 4400RPM.

see here: http://media.gm.com/us/powertrain/en...76_G8_GT_n.pdf

[Aussie Mike]

Here are my calcs for 3.9:1

@6500 RPM

1st 2.66:1 = 77KMh
2nd 1.78:1 = 115KMh
3rd 1.3:1 = 157KMh
4th 1:1 = 204KMh
5th 0.74:1 = 276KMh
6th 0.50:1 = 410KMh

Cruising @ 100KMh in 6th = approx 1600RPM

Calcs for 4.11:1 diff gears

1st 2.66:1 = 72KMh
2nd 1.78:1 = 109KMh
3rd 1.3:1 = 149KMh
4th 1:1 = 194KMh
5th 0.74:1 = 262KMh
6th 0.50:1 = 389KMh

Cruising @ 100KMh in 6th = approx 1700RPM

These numbers are based on my 315/35/17 rear rubber.

Cheers

[ledge]

Hi Sambo

I Have mates with Skyline's and they have
over 300kw at the wheels plus there car weighs 1650kg and they have never had diff probs. As our cars are lighter the diff will take way more.
My gears are 4.1 and if you have a 6 speed this ratio is fantastic, I like you thought that first gear would be a waste but trust me it is bloody great. The fact that my eyeballs are now an inch further back in my head is testiment enough. As for traction with the nissan diff, Talk to a good wheel aligner and nothing will hook up like these things.
Even with 300kw+ i need to try to loose traction, Its all grip .
WOOO HOOO

Regards
Paul

[WKB]

Sambo/Ledge
If you are using a R32 GTST diff you will find it is 4.3 to 1 ratio. The R32 GTR has the 4.11 gears.

Warren

[sideshow]

what ratio do u want we have alot fo nissan gear at my work

anyway 99% of drag cars in japan are gtrs they run 2wheel drive off the mark then bring in the front wheels abit after u take off
this is due to the front diff which is in the sump is not as strong

but the rear diffs are pretty bloody strong

im sure we ripped a 4.11 from the race gtr at work today
swapped it for a 3.5 to suit it better for drifting

[sambo]

Mine is R33 Gts-t and I'm pretty sure its 4.11. Glad to hear they are tough units though.

Semi back on track here... I know the rear gear ratio can be programmed into the ECU. Does it also take wheel diameter?

[sideshow]

yes u can adjust diff ratio tire diameter
speed pulses in for auto changes
speedo pulses out for speedometer adjustment
theres prob a couple thousand adjustemnts if u got serious

[Plums]

Sorry Gav, I don't know anything about the predator.

I run 4.09 gears with the 4L60 Auto and I reckon it's great. It's 3:1 first gear gives great acceleration off the line, and the .70 overdrive keeps the revs down in the cruise. 100kmh = around 2200rpm in overdrive.

[sideshow]

i have used a predator twice
but was purely for removing security on a ford 4.6 quad cam

u can adjust timing slightly
like form 0 to 4000 revs is one adjustment so if u ajsut it by 10 it does everything form 0 to 4000 by 10
then u have 4 to 10000 same thing adjust all at once
same with fuel
its not every 500 revs its all below 4000 or all above 4000

u can adjust fan temps
i guess u should be able to do shift points
not sure if thats load related or speed related

last time it cost me 700 aussie landed here

there are heaps more tuners like the predator out there

sct is one

[Gav]

Thanks Bobby and Sidewhow, I will probably need to have a look at one in the flesh before I do anything. I am quite happy to leave engine tuning to someone else but would like to be able to adjust the shift points as I said earlier.
I have 3.9's in mine and have found it to be great.

[sideshow]

i doubt u will get chance to see one in the flesh
have not seen one in 3 years
and with th eprice of hp tuners efi live and others
the predetor and similar units in australia are just to expensive for whta u get
in the usa they are dirt cheap

if yr gear changes are related back to the speed sensor u might be able to slow the speed signal down
so it changes a tad later
i did this to my hilux

[stiffy]

SAMBO,

I'm running 3.9's with the 6 speed.... too tall/short (always get them mixed up) I'm going to 3.68's. I hate changing into 4th in my driveway


STIFFY

[sambo]

Thanks for adding to the confusion Stiffy! Two very different schools of thought here... might need to discuss at length over a beer tomorrow night.

[Rebel1]

Keep this in mind Sambo:

The VZSS 6Ltr used a 3.46 rear end as did the VZ Monaro and I believe the HSV's.

None of them were slouches.

Now consider the difference in weight and you get some idea why we have traction problems even at mid three gears.

[sambo]

Les, I think I'm hearing you on this one. Time to scour the wrecking yards...

[Aussie Mike]

Just try driving it with what you've got before spending the $$$ on a new diff. It's a fairly easy job to change the diff head later. I'm sure yo've got other goodies to spend the cash on.

Cheers

[Aussie Mike]

Originally Posted by Rebel1

Keep this in mind Sambo:

The VZSS 6Ltr used a 3.46 rear end as did the VZ Monaro and I believe the HSV's.

None of them were slouches.

HSV clubsports got 3.73:1 gears and the GTS got 3.9:1 Regular old SS got the same diff as every other Commondor except it had LSD.