I dont know why my MBC cant hold on the 21PSI. It start to drop at 5500-6000 from 21 drop to 14-15PSI. Does anyone know whats wrong with it ?

 

What MBC are you using? sometimes the Hallman stock spring is too weak. The heavy duty spring seems to be working much better on the Evos since we run 20psi plus.

You might want to inspect yopu boost lines to make sure they are free of pinching. Definately make sure non of your lines are partially cut.

Carlos

 

Im not sure wut brand is it, but i dont think is any named brand. Wut brand do you recommend for a MBC ? THanks

 

go with a tuboxs, work great!!

 

Any name brand will most likely work fine. Just go with a proven one like Hallman, turboxs, forge etc...

 

It not your MBC, it's your factory wastegate. And there is nothing wrong with it. The only way to resolve it is to upgrade the wastegate. Call FP, maybe their BigWG will work for you.

 

This solution sounds reasonable.

 

I will sell you my Forge MBC....

The issue you are having is not the wastegate.

 

Yes, it is. The stock wastegate is venting pressure. This is why for years big power required an after market wastegate. It is also why FP sells their big WG for the White Rabbit. if you don't use it you can't take advantage of the greater boost potential or hold it at peak.
Even an EBC would not be able to bypass the wastegate setting.

 

its deff, not wastegate, for stock boost pressure 20-21 PSI stock wastegate is suficient. If he was losing pressure after he hit 25psi, then you would 100% on the spot. But 21psi droping to 15psi, problem is somewhere else like Boostcotroler or boost lines or even intercooler piping that might get loose once it hits sertain pressure.

Piece

 

No, Shaker, it is not the wastegate. The turbo is SUPPOSED to taper, because it cannot flow enough CFM at higher rpms to maintain the boost. Taper is natural. I have an upgraded WGA, and it still tapers plenty. Plus, him dropping all the way to 14-15psi shows a real problem in either his boost system in general (leaks) or his crappy old style MBC.

No, do NOT get TurboXS. Whoever recommended that should stop - it's one of the worst for the Evo, because the bleed hole is too big. Get the Forge UNOS or Hallman MBC - CJ up there is selling a Forge used, so get that.

He should be able to run 21-22psi daily and taper to 19-20, which is perfectly normal. Trying to force the stock turbo not to have 0 taper is fruitless, because that will make it blow hot air at high rpms.

 

A little , But I am a newb and have a question.. How do you measure the taper? I just installed my boost gauge so I could see exactly where my boost is at.. Do I run it up to say 19 PSI stay on the throttle at the same point when I hit 19, and see where it tapers to? Thanks for any help, and sorry about hijacking this thread..

 

With measuring tape.




You just go full throttle from low rpm and watch the boost. It will spike at its highest point right at the beginning, then slowly lower itself towards redline (taper). Take note of the max and min.

 

I thought you said IX's taper more than the VIII due to the MIVEC. I have a Forge Unos MBC on my IX and I still taper down to 16psi by redline, although its very gradual. I have checked for leaks and I have none at 21-22psi and even took it to the dyno to see my power levels and it was at 300whp/310wtq which sounds reasonable for the limited amount of mods I have done to the car...

 

AWESOME.. do I measure it where the exhaust comes out? hehehe

Thanks Warrtalon for helpin me with a lot of my questions!!