Gains are at top end only .

Did some sound clips .....................but not happy with the sound
. Needs the same muffler combo i have on the main pipe .

 

^+1

Err for the sound clip post, that is. You snuck in before my lol

 

just post the clip Brett! We won't judge....

 

I like the active exhaust idea. Should save cat some punishment as well. And you get sound when you want to have sound, not ALL the time.

Is it connected to VFAD or APV valves? EDIT: I guess you are using your BC in a way...

 

 

With EBC on there is no flow thru the WG exhaust till boost reaches my set psi .
Although I don't have a cat , the setup would work really well with one , as it would pass all the tests yet be able to flow extra when you need it to.

Was intrigued to find that what i have is actually legal here ...... yes, it's written into law that a wastegate can be plumbed seperate from the main exhaust so long as it exits at the rear.

 

What's a cat?

 

^This guy gets it

 

I gotta read up on this. I don't think Texas is that lenient!

 

This is what our law says FWIW

 

^living in Alabama means: No emissions, no crazy laws. #Merica

 

So ....no bueno ?

 

Is it dyno week yet?

 

Patience Igor !

 

So I took the 8 to a local dyno shop to see the effect of all the improvements I've made .
Did runs at 14,15 and 16psi . Results were actually lower than the last dyno : 405whp @ 16psi.

Disappointing

The reduction in back-pressure from the separate wastegate exhaust has been offset by having the 0.82 AR turbine housing in place . Switching back to the 1.01 AR will certainly yeild a better result but I have other changes in mind also so it's going to be a while before I can do any better than the original dyno.

 

Shame the housing made such a difference - a little surprising it made such a difference. Thanks for sharing the results. A few lessons I can see in your results:
- Gains from larger AR at high flow really highlight how much gas the rotary is capable of breathing. As a side note it really shows how much of a bottleneck the Greddy T25 housing really is.
- Gas flow out of the engine is just as critical is gas flow in, but there's a tendency for people to focus more on the cold side rather than the hot side as it's more visible and much easier to measure boost pressure than exhaust efficiency.

For comparison, what was your 14psi dyno figure? That's the max psi most of us would ever want to run.

I lose track, which of your turbine housings was twin scroll?

 

14psi was around 380 .
The 1.01 is twin scroll . I will put my new gtx3576 compressor wheel with the 1.01 hot side and see how that goes . I'm picking it will meet what my original goal was : 16psi by 3500 and 400whp .

You are right about gas flow out of the engine . I think it's actually doubly important on our engines because of our our puny exhaust ports. Decreasing backpressure is the key.
This is also why i'd like to explore the benefits of bridge-porting . If I can get backpressure very low I think having some overlap will be a major benefit in the mid range . I'll be able to get backpressure lower than boost pressure right up to about 6000rpm so that 4000-6000 range should see a dramatic VE improvement.

 

Haha, when everyone else would call it Done you go and start the next chapter.

 

The fat lady hasn't sung yet !

 

probably why the turbo 13bs have overlap,

is your .82 a twin scroll?

 

Yeah , I've been comparing dynos with the rew engines and there is a night and day torque difference through the mid range at similar boost. I can only put it down to overlap .So any we introduce into the Renesis should have quite an effect in the rev range where boost pressure is higher than turbine pressure. They talk a lot on the 7 forum about how you need a big turbo to get any benefit from a bridgeport which makes sense when you consider that.

The 0.82 is a single scroll ....effectively.

 

I think a lot of the torque difference is the ability to run more timing in the REW too. That's one issue with the Renesis that makes things a bit scary tuning more than 10lbs of boost. The effective boost is a lot higher than it seems..and with the high back pressures from the poor exhaust flow through the side ports it just adds up to issues

 

I think the bridgeport idea should improve things . Getting rid of most of the carryover exhaust gases by introducing some overlap might just be what the Renesis needs.

If I compare my dynos with rew dynos at the same boost , the mid range is where the Renesis suffers most . The top end seems fairly close which kinda suggests that the exhaust port flow isn't such a big issue . At my power levels anyway .

 

It's a bit strange...I would think that the Renesis should make more at lower RPM and boost levels and less up top. Never really compared the dynos though. I am going to tune mine today. I can pull some logs and see what I get if you want to look at it. I have a 1/2 bridge REW that I hope to get about 550whp out of at about 18lbs boost. ( although we both know the boost guage doesn't mean squat )

 

I think you are running a much bigger turbo than me though plus probably a whole lot of porting if you are getting those numbers . The dynos I've been looking at are for stockish rew engines with similar sized turbos . They seem to achieve 400whp at around the same boost mine does .... 14-15psi