yeah, when im boosting, it will push 8psi at like 3600 until 4800 or 5000 and then it will go down to about 4psi as i go to redline - whats up with that? should i try to hook the wastegate up to something other than the compressor housing? is it just a shitty wastegate?

 

ah, i see, it must just be a shitty turbo... ihi rhb5 off a ford probe gt. but don't you think that since it can make 8psi at mid rpms it should be able to keep making 8psi? i mean, its not like the exhaust is slowing down...

 

I had the same problem a long time ago. I replaced the hose for the wastegate from the compressorhousing some inches in front of the throttle bodey. After that everything was fine.

Greetings from Germany
Kevin

 

a dirty filter or running a restrictive screen can cause this..

 

what engine are you running? i know with my vj-14 (one size smaller than the vj-11, your probe turbo) i can run 14 psi until about 5500 rpms and then it falls to around 10 psi at redline.
It could also be something else though.

 

Sounds kinda like an exhaust restriction to me. Whats you dp/exhaust setup?

 

Not to steal your thread. But Im having the same problem. Could it be from to long of hose from the wastegate to the soleniod?

 

move the pressure source from the compressor to somewhere after the intercooler. There is a small pressure drop of 1-2psi across your intercooler and this will cause it to open up early because its not reading the actual pressure your motor is seeing, but the pressure at the turbo.

 

Believe it or not the turbo has to work a lot harder to make 8 PSI at 7000 RPM than at 3500 RPM. If you find that boost is decreasing, that is probably due to the fact that the turbo is not properly sized for your engine.

BTW, most would consider the RHB5 (similar in dimension to a Garrett T25) to be much too small for a high-winding Honda.

 

well i moved the vacuum line to the wastegate from the compressor housing to the intake manifold - that fixed it :D wheee. and now i push 10psi instead of 8 all the time. eh, whatever, its tuned up to 14...