Jimmy P

iTrader: (177)

He has a lot of other issues to fix before he should be even thinking about the backpressure.

Pat-Man

iTrader: (3)

Yeah, and by the time I throw the 88 on there, most of the original kit will be gone. I know there are a lot of parts currently on the car that are not the best match for the motor. The heads, turbo setup, etc. For the time being I just want to get it running good with some good supporting mods (transmission, rear, etc.) before going with a turbo that is matched for the engine. I don't think 10 PSI from the current setup is much to ask for as long as I upgrade the valve train and transmission.

So by looking at the graph, is it safe to say that would show a drive line problem?

Jimmy P

iTrader: (177)

Mismatched or not, if you get it running right with this combo it will still be a fun car. I know someone local that put down 550rwhp through a TH400 and loose stall on 8 psi on a 408 and 76mm turbo. I think his compression ratio was around 11.5:1. I think they tried to up the boost and then it blew..

You still haven't told us what the compression ratio is on this motor..

And yes it can very possibly be a trans/converter issue, but like I said before its hard for anyone on here to try to guess because of all the other things going on with the car.
You mentioned that he blew the 4L60e, and used the converter from the blown trans into the new trans. That converter could have been contaminated. Have you checked the trans fluid?

Pat-Man

iTrader: (3)

I wish I knew the compression ratio myself. As I said before, the shop that built the car is long gone, so I haven't been able to locate a lot of information on the motor. Not even sure my friend would know. I'll see if I can get in touch with him and see if he remembers.

I have not checked the transmission fluid. Maybe I'll check that this week and see what it looks like. Thanks again for all of your help.

- Patrick

lifeisgood

iTrader: (4)

once you get this thing figured out it seems to be a nice car...but i hope you got a good deal on it. it looks like you may be spending a lil extra dough

Denali08

Before you go and through parts, get good springs 1st thing then go from there. Next will be to check your transmission.

I don't thing you should have big issues with backpressure at that low boost or transmission issues. But, it's good to check your transmission and through good springs at the same time.

Pat-Man

iTrader: (3)

I actually got the car for next to nothing.

You all think 918s would be enough, or should I go with some dual valve springs?

Denali08

My advice is to stay away from 918s. I had two sets broken on two different engines.

cablebandit

iTrader: (37)

this car didnt come from Eric did it? If so it has made much more power than u have so far

Pat-Man

iTrader: (3)

No, came from a friend of mine and he was the original owner.

Jimmy P

iTrader: (177)

Get some Patriot or PRC Duals and shim them for a little extra pressure and you should be ok.

Docrocket1967

iTrader: (1)

very nice ride

2Tightwads

3xx HP? Lol This is embarassing even for a stock cammed LS1. Start over...

Pat-Man

iTrader: (3)

tell me about it...

Louis

iTrader: (7)

At 2 psi, the poor thing hasnt even made it back to NA power level. See my sig It took 2 psi Just to get back to what my motor made NA. Thats all, it needs more boost

You guys really think that a turbine housing flows REALLY well? LOL! It doesnt! It works GREAT when it actually puts a positive pressure in the intake Thats the point.

Pat-Man

iTrader: (3)

I see your point...one thing that still baffles me is that I normally see ~5psi on the street in 2nd gear. I have verified this with my tuner who looked at my logs and said my MAP would peak at 140kPa in second gear. We never really took it into 3rd because by that time I'm going a little fast for anything on the street. Got to be something with the drive line (as well as the other things mentioned) that is causing the strange HP/Torque curves.

I should of had him do some data logging while it was on the dyno. That would of really helped to see what was going on.

BlwnLs1GTO

iTrader: (12)

[QUOTE=Pat-Man;11942612]

I should of had him do some data logging while it was on the dyno. That would of really helped to see what was going on.[/QUOTE]

jamesSS

Wow man hope this gets worked out for you. Are you still running the stock fuel system?

Pat-Man

iTrader: (3)

No. It has a Racetronixs system with 60# injectors.

bigturboz28

1. Check for fouled spark plugs.
2. Set gap low (try 0.025") then move up until it starts blowing out under boost.
3. Replace valve springs with Patroit Dual Xtreme.
4. Monitor Backpressure or Get Turbo Specs (eg.A/R).
5. Look at drive line.