jeffgusto

i want to put out around 500HP, this means i'll have to run 8psi does anyone know if this level is safe for a completely stock 99 z28, the only other change will be my intake into a ls6

tt383lt1

yes you can run 8 psi stock on alot of cars with realiable results. i ran 10 psi on a lt1 for 3 years until i wanted more power. and i seen alot of people running more than that on bone stock ls camaro and firebirds

raulz28

I wouldn't worry too much about the engine but I would worry about the rear end grenading with that much power.

jeffgusto

do you mean the drive shaft or the rear diff? i know the stock aluminum drive shaft is pretty sturdy and that year they introduced the torsen rear diff which isnt too shabby, im not quite sure though how much torque/HP that diff can handle does anyone know the specs on the stock 99 z28 rear diff?

raulz28

I mean rear diff. The number I have seen thrown out a lot is 400hp but I've heard of people breaking them with stock hp. Do you have an A4 or M6? It is a lot easier to break it with the M6.

jeffgusto

well sweet deals i called the mechanic who upgraded my tranny on my car 2 years ago because i lost the invoice and asked what he did and he said the shift kit, tranny, rear diff and driveshaft were all upgraded and could easily handle 500+ horse, musta been why it was 4 grand, anyways raulz thanks for the heads up and tt383 thank you too, i'll be going ahead with this project and turning my car into a beast.

Orr89rocz

I have gone 9.73 at 142mph on stock 10 bolt rear from a 4th gen. Should be fine in an auto car with no trans brake and mild converter launches.

8psi will get you around 475-500whp possibly with supporting bolt ons. My friend's LS1 with LS6 intake and LS6 cam made 505 on 8psi on a stingy mustang dyno. Likely 550-575 on dynojet. They will live with good tune. Keep it intercooled if you can.

jeffgusto

thanks orr, ya the kit im getting comes equipped with an intercooler, i will be changing out my intake for a ls6, now that mechanic called back though and said the tranny wont be able to handle it i should come in and talk about upgrading it, maybe he justs wants my money i dont know i guess i'll turbocharge it and see how it goes from there and maybe it wont blow my tranny out.

jeffgusto

well from the research ive done ive summed it up that the stock tranny is good for 375 HP, so im tranny shopping unless anyone here can tell me otherwise like if a stall kit or something would work, but i doubt it.

raulz28

I've heard of a few 10 bolts that take a beaten but it is definitely not the norm. A significantly modded car with the 10 bolt with any kind of abuse is on borrowed time.

Orr89rocz

I got alot of runs on my 10 bolt so far at 750-850hp and so far it has stayed together. I've been impressed. Its only a 2.73 rear gear which makes it abit stronger in the pinion and ring gear than say a 3.73 gear. Its also a zexel torsen diff which uses worm gears instead of friction clutches so i think that helps alittle. Either way its not optimal and may be on borrowed time but i got a dozen hard 1/4 mile passes on it, a few dyno runs and alot of street abuse

So your tranny was no rebuilt?? Chances are it will handle the power for a short time, but will eventually wear out and start slipping. Need a good bit of work to make a 4l60E/65E live behind 500whp but it is possible.

My friends car just put in a stock low mileage 4L80E.

jeffgusto

i thought he swapped out my stock tranny for an upgrade built he just rebuilt it, ive been looking at 700R4 4L60 gm transmission good for 600+ HP and 1100 buckeroos, not a bad deal.

JeeperSC

As soon as I put a 150 nos dry shot and nitto d/r my 1998 the rear end fell apart soon after.... If you want to put a power adder on an LS1 its just a matter of time before the 10 bolt goes. I would invest in a 12 bolt or ford 9.