how much boost would you run on a stock turbo off of an FC. Mine is an 87 and i was thinking about a manual boost controller to put it up to 5.
p.s. how big is the stock turbo anyway?

 

I always thought the stock boost on those were 6psi.....my friends is an 88 AE TII running six stock....but i could be wrong

 

stock boost is 6psi on a TII, however, if you are talking about doing the turbo-N/a thing, the N/A's will take 5 or 6 psi no problem.

 

I was just wondering what it was capable of running over stock. i was wanting to raise it to 10psi.

 

You can raise to 10. Your turbo wont last as long, but it can do it.

 

10 psi on a stock fuel system and stock exhaust? NOT a good idea - true, it's not as dangerous as a full exhaust and TID which will creep like mad, but you are making that turbo work SO hard to maintain that boost with a sock exhaust and that means extra heat and no turbo life...it's dangerous for the motor as well...it could blow at that boost on a fully stock car - fuel cut is 8.6 psi right?

 

Stock fueling will support 10 PSI, as will the stock exhaust, I would imagine. And I DID say it was bad for the turbo!

 

What boost level does the turbo start to get inefficient at?

 

I was planning on a fuel upgrade:walbro pump, 500ccinjectors, and ......whatever else needs to be done. I figured it would be bad for the turbo. is the stock turbo a t25? i plan on replacing it or rebuilding it eventually. that and something along the lines of completely unrestrictive exhauste system(straight pipes). No inspections in OKlahoma.

 

The stock turbo is a ht-18.

 

ht? what does that mean

 

hitachi t-18 i guess?

 

I think at 14 PSI, its 60% efficient. I could be wrong, I dont actually have a MAP here.

 

I have been running 12psi of boost for over a year now no problem.

 

500cc injectors? thats downgrading. stock is 550cc all the way across.

if you're going to run 10psi, here's what i would recommend MINIMUM.

- full exhaust
- intake
- 680cc or 720cc secondaries
- FD3S fuel pump or walbro 255
- FCD fuel cut defencer
- aftermarket boost gauge
- aftermarket air/fuel or EGT gauge
- S-AFC (optional)
- AVC-R (optional)
- aftermarket BOV (optional)
- porting the S4 turbo (optional)

good luck. dont blow the motor. like everyone said, you can run high boost, but your turbo wont last long and if you dont have more than enough fuel, neither will your engine.

- Kevin

 

An FD fuel pump barely flows better than a TII pump. If you're going to upgrade, go for the walbro.

 

I'm doing a TII conversion and will have a 2.5 DP ro a 3inch CS single catback. Stock TID for now to keep boost down but I will make a TID to go with my Cold air box.

I'm figuring I will see 10psi with the intake and exhaust.
I will be upgrading fuel pumps in like a month or 2 when I build money up.

I've heard the 550 injectors can do 10 psi OK. I might go with 720's(hehehe Jrat) later on. I have to get the car runnning first.

The S4's are known to boost creep so I am porting the **** out of the waste gate to help this.

Now in my situation what would cause the Turbo to die like you said Jrat? Just the immense spinning of the turbines? I've heard the turbos' lose efficiency after 12-14psi.

Also what about the EGT and AF gauges?
Aren't they unreliabe and just for mild gauging of where the real stats are?Unless you have a Wideband O2 and so on?

 

I dont agree... there is plenty of fuel available with the stock injectors. I ran 10 PSI all day long, stock intake, stock injectors.

Now I run 14-15 PSI with mods listed. But I am not really right in the head either.

Jarrett

 

i dont' agree either............

i wouldn't put larger fuel injectors in if you can't control them with the optional electronics.

and 4x550cc is enought for 10psi with a good pump.

 

How big is your wastegate ported? Is it just as big as the stock flapper allows?

 

Hmm - so I just got this stock S5 turbo & it's boost gauge was erratic as hell. Sometime it sort of works up to half scale, sometimes not.
Last week the pressure sensor failed all together.
I had bought an FCD from Shane (for future mods) so I installed it early just to keep the ECU from giving a check.
I remember having al old mil-spec aircraft absolute pressure gauge in a storage bin, so I dig it out & T it in.

HOLY CRAP! 8psi in 2nd, 10psi in 3rd, 10psi in 4th, with NO fuel, intake or exhaust mods.
The waste gate seems to be working at 10psi.
It gets to 10psi by 3500 & just stays at 10.

So - should I be happy or worried?

 

Yeah the flapper is still covering the hole. I drilled out as much as I could, you can barely see light coming through around the flapper door. It seems to be working out ok for me.

 

Cool, that sounds good. I ported mine as big as the stock flapper but haven't actually got the motor running yet. The turbo is still off the engine and I was considering having a turbo shop make the hole even bigger and welding on another flapper but maybe I will just try mine out. As long as I can stay under 13 psi I will be happy. I have an aftermarket fuel system so no worries there, I guess I may just shorten the life of the turbo.

Here's a before pic


and after I ported it

 

Listen to J-rat he knows what he is talking about. I only had Detonation problems at 14 psi on a stock turbo with a stock fuel system. My Apex-i AFC and Wahlbro Pump helped out a lot but I will be getting 4x720cc.
alwase go overkill on your fuel system and you can tune it down with a AFC.

I was running 12psi on stock fuel and I was fine. Try to stay at 10 for the turb's sake.

BTW, your boost controler will hardly afect the boost after 5k with a stock waste gate, I creep to 14.5psi