Problem<U></U> = Boost Spike to .91 Bar (12.75 PSI)

Description<U></U> = Below 5250 RPM 3-5 PSI on Wastegate spring. Above 5250 RPM (in VTEC) boost spikes to 12.75 PSI under hard acceleration.

Setup<U></U> = B20/B16 VTEC (stock internals on both), Tial 35mm Watesgate (5 PSI spring), Eqi-distant SS Manifold, Garrett T3/T4 Turbo (.48 x .63), 2.5" Intercooler piping, 2.5" exhaust from turbo back, Hondata S200B (tuned 8 PSI), Apexi AVC-R (set to .55 Bar/7.7 PSI). The turbo spools lightning quick. I am dumping through the gate at around 2200 RPM.

Analysis<U></U> = AVC-R set to .55 Bar and all connections are according to manufacturer instructions for external wastegate. Highest boost spikes came when AVC-R was connected. The solenoid is working properly. Vacuum lines are a bit of a mess. I am fabricating a vacuum manifold to install directly on the Brake booster line to clean up the set up. I will also replace all the soft tube (windshield washer hose) with harder tubing to prevent possible swelling / colapse during operation. Disconnected AVC-R and ran vacuum line directly from Turbo to watesgate to test the spring. Boost stayed at approximatly 5 PSI until VTEC. Spike to .75 Bar (10.5 PSI) while in VTEC. Don't know if it would have went higher through to redline because I dumped the throttle as soon as I noticed the spike. I have a dump tube firing straight at the ground. I removed it and it made no difference to the spiking in VTEC. The car originally had a different manifold and an internal wastegate. I had no problem holding at 8 PSI through to redline while using that setup. I have a friend who has the identical setup except for the block (LS/VTEC) and he has no problem controling th boost levels.

Questions<U></U> = Is there that much of a difference between LS/VTEC and B20/VTEC when it comes to flow in high RPM that I would have a problem getting rid of the boost due to the extra .2L of displacement? Is the wastegate to small? Is it possible that the head flows so well that the wastegate can't get a chance to dump the extra boost? Is the wastegate not opening all the way? (We opened it up and the range of motion seemed to be fine with no restriction. The bladder has no pin holes.)

The only thing I haven't tried is replacing the wastegate with another identical piece to see if for some reason that changes things. I will give that a go over the weekend to see if that eliminates the problem.

Any thoughts? Anyone have a similar problem?

Thanks in advance........... Ialandspeed

 

I doubt it has anything to do with your engine setup. The answer most likely is related to the vacuum hoses or wiring to the boost controller. Recheck all your wiring and get those vac hoses cleaned up like you said.

 

why don't u unhook the boost contoler and try to run it like that and see if it stays at 5 psi, that would make sure ur wastegate is working right, if so it's the boost controler witch im sure it is, alot of my firends hate the AVC-R overpriced boost controler

Greddy Prof B 1st Gen, **** the 2ed gen