5l-eater

I have an IHI RHB5 with an internal wastegate. I did the carb return spring mod to the wastegate. Instead of using the WG actuator, i just used a spring. The turbo spools fast and spikes to 10 psi at 4000rpm and then goes back down to 6-7 at 5000rpm. If I use NO spring, itll steadily build boost and hit 5-7psi at 5000rpms. it seems no matter what I do, the boost wont go past 7 psi at 5000rpms. If I try a stiffer WG spring, the spike is larger, but it still settles to 6-7 psi. Any suggestions? Is the return spring causing difeerent psi's at diferent rpms? or is my turbo hooped?

JDMs1eeper

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRXdan1.6 &raquo;</TD></TR><TR><TD CLASS="quote"> If I use NO spring, itll steadily build boost and hit 5-7psi at 5000rpms. ?</TD></TR></TABLE>

So with nothing to manage the boost level It still only goes to 5-7psi? Do you have any before the turbo exhaust leaks?

SOHC_MShue

may be a problem with your internal wastegate setup or the flapper. I have huge problems getting mine to spool fast enough on my wrx turbo. I will be going externalaly wastegated soon.

5l-eater

no, with the wastegate flapper opened. I havent tried shutting it fully closed yet, and i dont think i will lol.
But, i think that a return spring instead of a WG actuator will produce spike because a WG actuator will open the WG so far, whereas a spring will allow the wg to fullyopen, and once it hits 9psi at 4000rpm i guess the WG opens too much and it settles back down to 6psi?
Right now I am thinking the only problem is to use the original WG actautor, thast set at 8 psi, and make a homemade MBC. I dont have any exhaust leaks.
I want it to hold 10 psi