Yup yup, right here:

http://www.scheides.com/gallery/evo8/CHRIS2

Running a tad more boost now so it holds 20psi solid.

Your tapering from a hair below 25 psi to a hair below 20 psi. The issue here is to eliminate 90% of the taper. Your MBC does not do that. You are loosing 4 psi between peak boost and redline. With an MBC you more than likely need to spike the boost inorder to get it to hold to 20 psi. That is what happened in your dyno log.

If you look @ my chart in the first one I hold boost from 21.xx @ peak to 21.xx @ redline. There is virtually no taper. You cannot do that with an MBC on a stock turbo. In the second chart I PURPOSEFULLY taper boost from 21.5 to 19.25 psi. If I wanted to, I would have held the boost to 21.5, but there was no power to be had with all this extra boost on the stock turbo.

Yea, I totally get that, just I think we took each other's posts out of context. You're trying to boost 22psi peak to 22psi at redline, I'm trying to boost 25psi peak to 23-24psi at redline....which TTP is claiming as possible, but won't seem to find the time to post some hard data to back it up!

Ryan Tech is able to hold 23-25 at redline with a large spike. There are plenty of datalogs here.

Specifically with this red spring you are talking about? How high is the spike? We're talking about spiking to 24-25 and holding 23-24 to redline and people from TTP keep saying this is possible with this forge wga w/ red spring, but we still see no evidence! If you see something specific posted here already, please link to it. Otherwise post up some dyno graphs plotting boost as well as power, or some datalogs.....

I have a FORGE actuator with the highest spring going in soon on my evo.

I will have data then, hopefully for the better.

Any update on this subject. I am looking to eliminate some of the taper from my MBC setup (wanting to maintain 18-19psi up top).

Also TTP, what configurations (spring-psi correlation) can be had with the Forge WGA??? Also how large of a spike is need would be needed to achieve my goal???

Any information would be greatly appreciated.

I had a evo 9 hold 22.5 psi at 7,000 rpm with a FP actuator and GM solenoid yesterday. Stock turbo.

Bryan, any idea how much preload was setup on the FP actuator??? My goal is to keep my same boost spike but be able to maintain 1-2 more psi to redline. If you want to take a look at my boost log to see if there would be any benefit, let me know and I will send it your way.

Standard 3 turn preload as per FP site. Not sure how the FP actuator works with MBC's as all the ones I have tuned have been with ecu-boost.

I'll take a look at your log no problem. Send me a PM.

You got PM!!!

I use a perrin EBCS and a stock actuator. When you ramp up the duty cycle in the higher RPM it greatly reduces tapering. Next step would be a upgraded actuator, but for now I can handle holding 26 PSI to redline from 28

26psi at redline? Stock turbo? Got a log?

Remove the line to the WGA and you'll have a good idea of what boost your car is capable of at any RPM. I have seen about 31 psi to 22 at redline

Weld the WG shut and that will show the turbo's capability. Never tried it but my guess would be 32 psi to 24 at redline.

This also depends on the IC plumbing, the small diameter restrictive stock setup tends to show higher psi but less volume, the psi coming out of the compressor can be like 40 psi .

My point is levels of psi can be made to register much higher from the setup and efficiency of the IC, even exhaust. Hot turbulent air has much higher static psi but cooler laminar air will read lower on a guage and capable of more volume of air - power.

Boost pressures can only be compared to the system that it's with, bla bla bla, bla bla bla

Yes but with what spike? 28psi? the point is to have a 22-24psi boost and be able to keep over 20psi at 7500rpm...


i have the spring, the midrange is amazing, no spikes, but eventually it will taper... The only way to keep more boost higher is to preload the wastegate more where it boost creeps at around 4500rpm and keeps about 1-2psi more at the very top end...

Also i have a cat which kills the very top end. I will try a testpipe this coming saturday and i am positive that the car will be able to keep more boost up top... i will post the results...

i think the best combo is the Forge wastegate with a rpm based ellectonic boost controller where you increase the duty cycles as the rpm raises...