Congratulations...now correct your fuel/boost issues BEFORE you replace the engine please.

 

So how is it people are able to spike so high? I've done that on my old WRX and GTI turbos...is it just absolutely no exhaust and intake restriction and no wastegate porting?

This has me worried about my wastegate being inadequately ported (still hit fuel cut with factory intake on).

 

S4 wastegates are TINY. Hogging it out huge is absolutely necessary if you have modified the exhaust and don't want to blow up the engine(unless of course...you have enough fuel for the added boost, which you won't know unless you have a wideband)

 

Not only is a tiny 13mm hole, but it also only goes into one runner. Exhaust gas velocity in the 2nd runner is unregulated. The S5 turbine housing's wastegate has 5x the area and there is a port for each runner.

 

I'm S5

 

10K mile motor, runs great. Shortblock $1500...
https://www.rx7club.com/nw-sale-wanted-classifieds-209/1987-rebuilt-tii-engine-10k-miles-shortblock-%241700-obo-963546/

Could do a package deal w/ some goodies...

 

That statement wasnt ditected toward you.

 

I found a motor. Thanks though.

 

Yeah prob the most common misunderstanding about turbochargers. The pressure they can produce is fairly independent of their sizing. Nearly any turbo can produce 30psi.

Its the volumetric airflow that is a direct result of sizing. Pressure is dependent on the volume of air being pushed. If a turbo is above its design CFM range it cant produce very much boost where as at a low flow it can produce all kinds of boost.

A stock turbo on a healthy ported engine can barely make 6-7 psi at redline. But at lower RPM could easily make 20psi exceed the fuel flow capability and and blow apex seal shards out the tail pipe and to the moon.

 

My unmodified stock turbo with a streetported motor and RB exhaust still pushes up to 12psi in 4th and 5th at redline on cooler days*. Cold days it's simply ridiculous. I suppose if I still had a cat it wouldn't.

*Don't ask me how I know this.

 

Sorry, I'm gonna have to issue a retraction. It's more like 9psi at redline.

 

That just means the VE of your engine is lower than the ones im talking about. Could be lots of factors, but besides porting its usually intake and exhaust as well as how worn the seals are in the motor...