Slight boost creep.

[japmadlad]

Hi guys :wave:
Been a while since I posted on here. Been doing a few bits to the car. No longer standard like when I got it. I'll post up pics & spec soon.

I'm having a slight issue with boost creep. I say slight when really I should say major. I am running a GT2871R turbo with a full 3" straight through exhaust from the turbo back. the problem is that I can't control the boost at all. Even with the actuator arm off and the wastegate half open I am boosting off the clock when I shouldn't be getting any boost at all. I stop @ 1.5bar only because I lift my foot but if I keep it on I'm sure it will just keep rising. We reckon that the wastegate is unable to dump the gases quickly enough & just keeps spooling the turbo. Thinking of porting the wastegate a couple of mm. Some lads reckon the exhaust is too free flowing & causing the problem. I've also been told that porting the wastegate may help but not elimate the problem. Other option is a bung in the exhaust to create back pressure but kind of seems like a backwards step. Will defo port the wastegate & probably get the bung for now as i've been told both together should sort the problem but anyone got any other ideas?

cheers lads :thumbs:

 

[Nicely]

Firstly, how is your boost controller plumbed?

 

[japmadlad]

Boost controller is plumbed off the same pipe as the defi gauge. It is a Greedy Profec E01. It worked fine before I put the GT2871R on the car & has been checked by Stiv on the SXOC who does most of my work for me. He says its working fine

 

[Nicely]

Just checking, as some people make the mistake of plumbing into one of the carbon canister hoses without realising that the canister setup is completely different to the S14 and allows unrestricted boosting.

Boost creep problems I've heard of from people who have upgraded turbos have often been down to the internal wastegate. Fitting an external wastegate cured the issue.

 

[slammedmind]

instead of restricting the exhaust why not restrict one of the boost pipes with a jet? In most cases this will slow down the air passing through the pipe. Hks used to use this on alot of their starlets. Also another option would be to weld the wastegate shut and go to an external one, not the cheapest option but a permanent solution