What's keeping the numbers down is the boost falling off at the high end to around 6psi. If we could hold 10psi to redline the numbers would easily be over 300. The culprit hasn't been positively identified yet. It may be the turbo, or the excessive backpressure from the exhaust manifold.

 

But how is it the E-01 users are able to hold their boost through redline? I'd like to know what is different about that specific model than all the rest.

 

The culprit has definitely been identified. The compressor section is too small as you stated. Excessive exhaust backpressure also doesn't help and power could be had everywhere if this was improved. The turbo itself is the limiting factor. You might ultimately get it up to around 300 but that's it. New turbo is needed to go higher.

 

Thanks again rotarygod.

 

Here is my dyno from a few days ago.

 

To be honest.. I've been reading for months about boost falling off at high rpms and I'm highly suspect of the wastegate personally. I have been having some overboost problems and have consistently hit and held 8-9+ pounds near redline.

I'm going to be installing an external wastegate over the winter to attempt to resolve the overboosting issue but I know for a fact that this turbo has been able to hold high boost at high rpm instead of the standard fall off alot of people have been seeing. I DID encounter boost falling off before at HIGH RPM but discovered it was a result of bad catalytic converter.

I don't have the interceptor X personally guys. Just my own feedback reading the thread though.

 

^I wouldn't be surprised if that's the case. RX8PR was the first person I know of to really push the GReddy. I had it above 10psi (can't recall exactly how far) and was dynoing at 273HP with the emanage. Doesn't sound like his boost was falling off. I know for a fact that he welded the internal wastegate shut and went with an external one. I had to have it cut open when I bought the kit from him!

 

Easy way to verify if its the wastegate. Watch the wastegate rod when you're under boost, see if its opening. Best way to do this would be on the dyno of course, but there's more creative ideas. - One idea is put the car on jackstands and use the brakes to load it. Or even a usb camera run inside to a laptop. If it stays closed then its the turbo running out of oommph, if it opens it is excessive backpressure forcing open the wastegate.

Option 2 is to tie the wastegate shut and see if you can hold more boost. Just be careful with the throttle to make sure you don't push too much.

 

is there even room down there for an external wg? seems to tight down there, and those manifold runners are so short.

 

There are 2 possibilities with boost falling off up high. The first is with too small of an exhaust housing. The Turbo II second generation RX-7 suffered from this. To fix this, you actually have to open the wastegate a little at higher rpm's to get the exhaust flow up high enough. Sounds weird but true. This was easily accomplished on that car with a simple electroic boost controller. The other thing that could be holding boost back at higher rpm's is too small of a compresor wheel. The more likely scenario is some small combination of both of these issues. The Greddy compressor wheel is too small to hold high boost at high rpm's. It might be able to hold 10 psi or thereabouts but that doesn't mean that it couldn't do 14 psi at lower rpm's. This is still boost falling off due to a small turbo. The turbo is just limited ultimately to the 300 hp region on this engine. It's a physics issue.

 

Mad Dog... why did you have it cut open? You went BACK to the internal wastegate??


I wonder if the weather and elevation affected his dyno #'s... i've tuned for 8 psi..and hit 267 whp with the emanage...

 

Yeah, ***-backwards. I know. But, I just wanted to take things one step at a time. The internal wastegate was a slightly more simple solution, so that's where I elected to start. Besides, Manuel had the external wastegate vented to atmosphere which would be slightly illegal here! I might go back with that setup, but only when I reach the limits of the setup I have right now.

 

Why is it a more simple solution? I'm not quite sure what you mean by that..

I would've opted for an external wastegate in ANY turbo setup....the only reason ppl go with internal typically is because of costs.

 

We finally finished up the tuning, and I must say the Interceptor-X works very well. Good power and drivability. Here are the final numbers

-Ray@PFS

 

Wow, 295 and 247! This is with the Interceptor, Stock Greddy Kit (sans emanage, of course) and a Cat Back exhaust only?

 

This is excellent! I can't think of better advertising! I want one now.

 

Ray, I give you permission to post whose car this is..... ooops. guess I blew that one! props to Scott at Mazsport and of course, to Ray and his team at PF Supercars.

dd sends...

 

Just caught the end of this thresd -Is this NA- 295 and 247 with the Interceptor, Stock Greddy Kit (sans emanage, of course) and a Cat Back exhaust only? Please pardon my ignorance-Newbie. Thanks!

 

No, this is turbo (Stock Greddy means the Greddy turbo kit).

 

Excellent job Ray. Glad to hear your feedback and see the results from a experienced Rotary tuner. Scott