Stock Turbo Upgrade

[GrandNatty87]

I'm going to be upgrading my turbo and I'm wondering what a good option for it would be?
The car is an 87 GN and it's mostly stock. It has a 3" downpipe, GN1 exhaust, 42lb injectors and chip. Upgraded fuel pump and hot wire, and that's about it.
Best run with the car is a 13.3 at just shy of 100mph but the boost falls off at the top end with the stock turbo.
I had in mind a PTE5858, didn't know if that would work well with this setup, plan on doing more in the future. Just looking for something that's going to work well and give more power. Thanks

 

[TurboTdr3.8]

Maybe Bison will chime in on this one as he is the Turbo Man

 

[bison]

You should be able to get to 108-109mph before you consider spending $$$ on a turbo. More turbo will slow you down at this point.

 

[Rose]

Schooled by the turbo master

 

[scojack_2001]

Agreed with Bison. I got 111mph out of my stock turbo on my GN. Thats with a stock convertor and a bone stock IC too (no Dutt neck) on 93 octane and methanol injection. I did have a ported compressor housing with the big inlet, fully ported stock IC, and a port matched plenum. Gained about 2psi by doing just that, and I only had to buy the inlet bell. Had the same setup as you on my old T-Type and it went 12.9 at ~106 on 19lbs.

What was the short time on the 13.3 run?

 

[TurboTdr3.8]

. More turbo will slow you down at this point.

Listen to this man he will steer you right

 

[bison]

Put a 2800 ptc converter in it. That'll wake it up some.

I disagree. The quickest and fastest cars with stock turbos all ran the stock converter and locked it at WOT

 

[we4Mateo]

I agree with above. If the car is nosing over, you have other problems at that mph, ignition, not enough octane, etc. 109mph out of my stocker on a stock TC before I switched.

 

[GrandNatty87]

Thanks for all the good information and responses. I guess I'm just curious to what the best step would be for me to do. Port some things and it will help the boost hold on?

 

[scojack_2001]

Thanks for all the good information and responses. I guess I'm just curious to what the best step would be for me to do. Port some things and it will help the boost hold on?

That would be a good start. I know porting the stock stuff isnt as glamorous as having all the "cool guy" parts, but hey; it works. Easy upgrades that take nothing but your time, and are cheap/nearly free. BTW, I went 12.39 in my GN on the stock turbo with a stock DP and untouched exhaust elbow.

First thing to do is make sure everything is in good working order, especially the ignition. That and put a good tire on the car and see how it runs. I usually ran 17 pounds on my straight 93 setups. Seemed to work for me.

 

[GrandNatty87]

Thanks, yea I did put a nice set of drag radials on my car and it hooks up way better now but my 60' time actually got worse because it's a taller tire. My et's got a lot more consistent with those tires tho. I'll have to do some of the usual maintenance but everything should be in pretty good working condition. Is there anything that should be upgraded first to make everything else work together better?

 

[we4Mateo]

Thanks for all the good information and responses. I guess I'm just curious to what the best step would be for me to do. Port some things and it will help the boost hold on?

YOU HAVE A PROBLEM WITH YOUR CAR! If it feels like the boost isn't "holding on" then get that fixed first. Porting will do nothing until you get it running right first. What valve springs are in there?

 

[bison]

Maybe the ECM is seeing detonation and pulling the boost?

 

[we4Mateo]

Maybe the ECM is seeing detonation and pulling the boost?

Does the stock ECM do that? I thought timing adjustments were it with KR.

 

[bison]

Does the stock ECM do that? I thought timing adjustments were it with KR.

Yes with it written into the chip via the wastegate solenoid. Most chips disable it or the owner disables it. If you unplug the factory solenoid the boost will be about 10psi. That's the baseline. The chip bleeds the boost and uses the 3rd and 4th gear switches to adjust boost. 4th was 10psi. So the solenoid wasn't bleeding anything in 4th with the stock calibration

 

[we4Mateo]

Yes via the wastegate solenoid.

Got ya. I knew the ECM controlled boost, but didn't realize it cut timing AND boost in the stock program from KR. Do the TT and Extender chips do this too if still using the stock wastegate solenoid? I use the RJC controller, so not related to me, but I'd like to know.

 

[bison]

I'm sure it could be written into any chip but I don't know if those parameters are used in other chips. They were used in the KB high/lo chip

 

[Howling Mad]

I seem to recall a thread on the TT forum that said the solenoid was set to 100% on TT chips and boost should be controlled via wastegate or boost controller

I'm sure it could be written into any chip but I don't know if those parameters are used in other chips. They were used in the KB high/lo chip

 

[GrandNatty87]

Well the boost drops and I can literally just watch it on the gauge at higher rpm's at the end of the quarter. The valve springs are stock still which should probably be changed out soon. And it's possible that there is detonation going on, I didn't realize the ECM would pull the boost because of it. I have a tt chip with the stock solenoid and an external wastegate down pipe. What are other things that could be causing detonation? I run 93 octane and even dump a little 110 octane in sometimes.

 

[we4Mateo]

...The valve springs are stock still which should probably be changed out soon....

Bingo...