Boost Spike - Dump Pipe Design For Gt3076r Iw

[limpus]

Good day guys,

I remember reading a thread some time ago about someone wanting to modify their dump pipe for a GT3076R and there were some very useful photos included there...i can't seem to find the thread after 2 hours of searching...can someone point me to that post if possible? I'm having boost spiking issues with me 3076 on a 2JZ and i suspect it could be due to my dump pipe design...

Cheers.

[JonnoHR31]

got a pic of your dump? i have a bellmouth style dump on my iw3076 and boost control is fine, altho i think its creating way too much turbulence, considering making a split dump for it.

[limpus]

Unfortunately i don't...but i'll try to get one if i can get a clear shot of it...could you try to get me a shot of yours? Cheers...

[SLAPS]

Boost spike?

Are you sure its not boost dropping off?

A spike is a really quick spike of boost not where it peaks up through mid range and drops off at top end. Typically related to preload being way too high or a cheap bleed valve.

If your running IW don't expect spectacular boost control if your trying to push more than 2-3psi more than the actuator is rated at. The same goes for the GT35 IW's.

Best bet for the GT30.. Throw an actuator on it that is rated for the boost level you intend to run of which with cams on pump fuel is around 18-20psi. E85 up to 25psi.

If you dont boost WILL peak up then tail off really quick to a couple of psi (if that) above what the actuator is rated to.

Edited October 3, 2009 by SLAPS

[limpus]

Yeah...it is spiking or should i say climbing uncontrollably...i'm trying to keep at at 15-16psi but it just shoots up to 20+ regardless...i even disconnected the actuator arm to see if it was actuator related but its not...boost still shoots way up so that rules out the wastegate...the flap also opens fully so its not that...therefore its pointing to the custom CES style split dump somehow not scavenging the wastegate gases fast enough...it seems that most people running 3076s are running a bell mouth type dump too which might be my next step...

[JonnoHR31]

what size is your wastegate port? turbine housing a/r?

[limpus]

what size is your wastegate port? turbine housing a/r?

Genuine garrett 0.82 exhaust housing...and the wastegate pipe on the spint dump is 1 1/4" in diameter...