Has anyone been able to consistently boost 12-16 psi on a stock Turbo II turbocharger?

Okay is the deal, I have a monster street ported 91 Turbo II motor with a full 3 inch straight pipe exhaust system, HKS blow off value , HKS AIC, and HKS early 90's boost controller.

At full throttle, set at maximum boost the car will boost up to 10-11 psi in first and second gear. But when I get up to fifth gear boost climbs to 15 psi. What’s really weird is that when I roll into the throttle say in first or second gear boost will jump up to 15 psi but then drop down to about 10 psi at full throttle.

Can anyone please give me any suggestions on why my car does not consistently hold boost.

 

In general you'll get more boost with more load. 11 pounds in first seems much more than normal and I would attribute this to the porting.

I would think you'd be able to hold max boost from 2nd or at least 3rd on up.

Maybe you are just over-ported for the stock turbo? The engine is pumping more air than the turbo is capable of handling efficiently? Or turbo and wastegate in combination anyway?

I dunno, just throwing that out there.

 

Ever port your wastegate?

 

I forgot to metion the I had the exhaust sleeves removed.

No I haven't had the wastegate ported.

Would porting the wastegate help me boost consistently?

 

YES! Get that thing ported and you shouldn't have any more problems like that.

here check this out.

https://www.rx7club.com/2nd-gen-archive-72/serious-s4-wastegate-porting%85-352816/

 

Have any of you guys boosted say 14-16 psi consistently on a stock turbo?

 

Will porting the wastegate help keep the boost up at around 15psi?

Is it possible that the motor is over ported for the stock turbo components?

 

No, it stop boost creep. The stock turbo simply cant flow enough to hold anything over 11-13 psi to redline. Boost should start falling from 15psi at about 4.5-5k rpms.

 

A couple people have claimed to. That is far out of the turbos range and creates alot of heat in the intake charge. In return you get little horse power. 12psi is the generally accepted safe limit with the stock turbo. You will get a load more torque at low rpms boosting up to 16psi, but as stated before it is dangerous and will drop off in the higher rpms.

 

Well if the stock turbo is simply maxed out, do any of you guys have turbo upgrade recommendations?

 

BNR hybrid works best around 15psi and makes 300+ at the wheels.
~$750, alot of members running this turbo. Straight bolt on. Tried and true. Good bang for buck

If you want more power look at a custom set up or the Greddy upgrade kit for around $3k.

 

who can I call or what site can I check out for this BNR hybrid turbo?

 

http://www.rx7store.net/index.asp?Pa...S&Category=220

 

I know this is off topic kind of but I just saw the new stage III for third gen rx7's and man is that some craftmanship put into that thing. Very cool.

 

you are running 15lbs on stock fuel and intercooling? Might check your boost guage. You might be spooling more like 10lbs. 15 would cost you a engine

 

YEa okay, All I can say is Someone might be runing a little lean.
Lean enough to cause some engine replacement

 

What sort of Fuel mods do you need to support 15+ psi?

I had a PGT running 27 psi on a .60/.63 T3 with SDS standalone, but SDS don't support rotarys so i am going to try to make some decent HP on the stock ecu and injectors...Nothing crazy but 15 psi maybe max....

I also have a walbro 255lph....

 

Fuel mods:
HKS AIC (four extra non-turbo injectors welded on intake manifold, after the butterflies)
High Flow Mercedes fuel pump

 

With stock main injectors, that's enough fuel for about 500bhp at 85%.

 

Man thats really cool, I didn't know that this was available!
At first I was like "why the hell pay that, just buy a T61 garrett or something for less" but then I remembered that you'll need a manifold and wastegate with that as well, jacking the price up to above a grand.

I wonder if they also do a rebuild for the core while they're at it? do you guys know if they charge less if your wastegate is already ported?

Overall its a great deal!