Boost Question, ST165

Ive got a few questions on this matter.

Ive got a 165, which Ive replaced the manifold and turbo to that off a 185 with the twin entry system, Ive also installed a 3inch downpipe. The manifold ive got has flange for a 38mm external wastegate.

Im also gonna be removing my stock IC and installing a 600 x 300 x 75mm front mount. Running a bov up by the throttle body.

The wastegate I have for the manifold has a 15psi spring on it, I was intending to use the potentionmetre "Pot" method to raise fcd to about 16psi.

If i did this, ran FCD at about 16psi, to have the ct-26 boosting at 15psi, through the twin entry exhaust setup, with frontmount, would I need to modify the injectors, fuel pump or anything like that, Im just wanting to know if I can run that setup with minimal risk to my engine, Only done 120,000ks.

Thanks, any help would be gladly appreciated.

Vinnie

Are you speaking of a factory twin entry CT26 from a 185 or some aftermarket turbo? The mention of an external wastegate makes me wonder, and the size of the turbo is a huge factor on what boost level you can run..

The fuel system is easily capable of supporting 15psi on a ct26. I'd be more worried about the HG or ringlands at that boost level on a gen1. 15psi is right on the limit of what's commonly considered "safe" so with a front mount you will probably be ok. However, I have blown two gen1 engines at 12-15psi. The first one was unknown condition and ended up shooting the #3 rod and half of the piston through the block @15psi. (To be fair, I don't think the boost level was the cause). The other one was an excellent condition gen1 which blew the head gasket at only 12psi. Other's have successfully run higher boost with no problems. It's a gamble but if you're confident about your engine's condition go for it.

If it's an aftermarket turbo, (depending on what turbo) I'd run a much more conservative boost level for a stock gen1. Actually, I wouldn't even put an aftermarket turbo on a gen1 with the factory bottom end.

Thanks d1alltrac

Yes its a factory 185 ct-26 twinentry setup, just with a flange for a 38mm external welded into the cast iron manifold. The condition of the turbo seems pretty good, both impellers are undamaged, and theres minimal/no play in the shaft. I could always get a rebuild kit just to make sure.

Its good to know that the fuel system is adequate for that boost, but with saying the other issues, kind of makes me scepticle, maybe I should play it safe, get a 10psi WG to run for now, and when I can get my hands on another engine, I could expirement.

Are there any stronger compound HG's I could use to minimize risk of blowing it? Or is it best to only run 10 - 12 psi with basically a stock engine? Engine is all still stock, only mods been to IC and exhaust.

Awel you've given me a good nudge to go get a 10psi WG and play it safe for now.
Cheers for the quick response.

Vinnie

It just depends on your situation and how you drive the car. If it's your only car and you're tight on cash I would play it safe, if you have a backup car and you're ok financially go for the 15psi spring and have fun. You can run 15psi stock if you drive casually and only boost once in a while, even a stock 165 with only 3" exhaust will hit 12psi on occasion. I drive my cars as sports cars are meant to be driven, which was definitely a factor in my BHG @12-13psi.

What kind of IC setup do you have? An upgrade there will make it safer, you could also consider water/meth injection.

For the HG, IMO a quality metal HG and ARP studs are worth the money and work required. Cometic and TTE are the cheapest and are both great gaskets. On a tight budget the st205 copper HG (same as TRD from what I hear) and new head bolts would still be a huge improvement.

I would suggest a manual boost controller for a little extra boost if you go with the 10psi spring, 10psi might be a little too safe...lol

Well currently I don't drive it, Ive got a st183 drive around, The st165 is my project which im doing.

The intercooler setup ive got is still factory at the mo, but am gonna remove that, and put front mount with 3inch in and out, 600 x 300 x 75mm with 2.5inch steel piping with BOV setup just up by throttle body.

Im thinking of getting the 10psi spring, and run manual/electrical boost controller, bringing it up to about 12psi, as long as I don't reach FCD.

Gonna spend abit of time on it this week as got the week off work, and access to the workshop, so will install all i can, and try to get it running.

Ill post up pics of my IC setup and engine bay once all installed, just incase i'm not explaining it to well.

Cheers
Vinnie