https://www.evolutionm.net/forums/sh...d.php?t=195467

Holds 1.9 bar

 

A few worthwhile notes:

- The more air an engine can flow mechanically, the less boost pressure a given turbo will be able to maintain at the power peak. Holding more pressure at the power peak does not automatically equate to greater power. I've seen more power on 19psi than most folks who manage to eek 22 psi or so with the same turbo.

- Where pushing a turbo to the limit is concerned, there is a point called 'choke flow', whereby despite the possibility of increasing the boost pressure another 1-2 psi, there will be no further power increase - just more heat for the IC to dissipate. The greater the airflow potential of one's engine, the lower the boost pressure where choke flow is reached.

- Cramming a larger compressor wheel (20G) inside a 16G cover doesn't automatically make it more capable or otherwise better. Some ideas that seem good on paper just don't please the gods of physics when they're put to real world testing.

- Regarding the 6-blade vs. 5-blade debate, I'm aware of two sets of data, mine and Buschur's, which are entirely independent of each other. Unfortunately (for me), they arrive at the same conclusion. Unless or until someone, anyone, posts data that demonstrates otherwise, there is no counter argument. I have yet to see any individual (including myself), vendor, manufacturer or otherwise with a 6-blade 20G demonstrate anything impressive. . . or pretty much anything at all for that matter. This is just a stark observation, so make of it what you will.


Disclaimer: These concepts and conclusions were sponsored by no one.

 

Back to the boost taper question. After a year of trying to reduce boost taper to a negligble level, I think that I got it. Using the utec and the Perring BCS I can progressively ramp up the duty cycle of the BCS to offset the effects of boost taper. So far I have only done it with my pump map, but I can hold 22.5 PSI to redline from a 23 PSI max. This is with a 6 blade 20G turbo and stock actuator. BTW I do not have dyno results yet as I rely on road tuning, but it is a world of difference from the 9.8 03 turbo. I hope to have track times next week. The but dyno says 11.9 with OK driving. We will see what the timing lights say. I will keep you posted. And Yes Warrtalon this will be with methanol at higher boost (26 PSI)!

 

FWIW, the problem I observed with the 20G9-6 was performance below 5000rpm (a loss of 50ft/lb torque), which isn't revealed on the drag strip. Above 5000rpm it was ok, although it made no more peak power than the TME it replaced.

 

On my stock buscher mbc and stock turbo, i can hole 27psi to red line. I took my guage it to work jsut to have it checked and yep, perfect. I have 280 cams not sure if this helps any. My car would spike 27-28psi and then drop to 22 then i changed all my clamps to tbolts and did a boost check at 50psi. No leaks and now it holds boost fine. Was funny, when big Al tuned my stuff he asked if it was a diffrent turbo. But the but dyno tells no diffrence from 26-29 psi so i keep it at 27

 

I find it particularly interesting that the cars that report holding abnormally high boost to redline do not show any increase in performance, whether at the track or at the dyno. I have no choice but to discount these cases as ****ed in some way.

 

Mine was road tuned, but yeah I cant notice any power diffrence, seems as if its tops out at 26psi. Maybe my but dyno is off, hahah. When my wife gets home ill go get a video. Had to vid and drive but ill give it a shot.

 

I value your input very much, but I do not think you've tested the 5 blade turbo, correct?

 

I have not tested the 5-blade wheel and can make no first hand claims therewith.

 

I see in your sig. that you got a GT35R. How is that working for you? Which kit did you go with?

 

My new GT35R setup is entirely custom fabricated. I'll post a writeup soon . . .

 

no one of those is already spoken for

 

While this may appear to work, this is far from an ideal solution and is why we are in the process of prototyping a 9 turbo specific actuator which is very different from the 7/8 actuator.

I cannot recommend to anyone else to modify our Evo 7/8 actuators in this manner to be fitted to a 9 turbo.

The 9 actuator has a longer rod, and a different bracket.

With the 7/8 actuator modified as shown in the link above, the actuator rod is not moving/travelling in a straight line. You can clearly see that the direction of movement of the wastegate flapper is not parallel to the movement of the actuator rod as it protrudes from the actuator body. This "arc" of movement will put unnecessary stress on both the actuator and the wastegate flapper obviously affecting how much exhaust gas is bypassed.



We are currently working on an Evo 9 specific actuator (available with your choice of base spring pressures just like our 7/8 actuators), and hopefully they will be available soon.

 

You may want to change your boost controller. I had a Profec and when it was turned all the way up, I could spike to 25-26 psi then fall to about 21-22. I doubt you will be able to hold the amount of boost that you could possibly spike to with that bc. I think that if you want to be around 26 psi at redline, then you may need to have to boost spike to 28-29 psi (then you will probably need a new bc). I don't think that your turbo and especially the stock turbo can hit a desired boost level then hold it to redline. Cough cough.

 

Well i guess i busted myself. Took the video cam out and sure enough at 6grand my boost drops and holds at 24psi. not the 27 i thought, I guess my eyes were never quick enough to catch it. I can still post the video if your interested, ahh well my exhaust still sounds cool. right guys, right?.........