Insane Boost creep on HX40

Lurker27 · Post by **Lurker27** » Jun 09, 2012 9:52 PM

I'm at a total loss here now.

My setup:
E30 chassis, stripped
M30B35, custom cam regrind
72lb low z injectors
MS2 v3.57
14point7 NAW wideband
t3 flange HX40 with 16cm^2, internal WG welded shut
Otis' RapidSpool SS manifold
Screamer pipe dumped into wheel well behind tire (is this a high pressure area at speed?)
38MM TiAL wastegate. New vacuum lines
4" full exhaust

Tune (93oct) and data logs are attached. The first log was with a small red spring in the wastegate. Overboost cut was set at 215kpa, which is about 17psi of boost. As you can see, it boosts right through that, so we removed the spring ENTIRELY.

Builds much more slowly, but still has insane amounts of creep.

What the heck am I gonna do? My tune may still be a little rich and retarded up top, so I'm thinking about saying eff it and installing my meth kit to put a crapload more advance and less fuel in there. I'm really frustrated by this now.

www.ogrestrength.com/boostcreep.zip

T_C_D · Post by **T_C_D** » Jun 09, 2012 10:38 PM

Have you asked Otis? Is a 38mm WG big enough for his manifold?

Lurker27 · Post by **Lurker27** » Jun 09, 2012 11:09 PM

Not directly yet, though I will. He runs the exact same 38mm setup more or less. Differences:

Mine is t3 16cm^2 his is 18cm^2 T4

His is tied back in to exhaust

he runs a better tune on e85 (more timing and leaner)

Post by **Jeremy** » Jun 09, 2012 11:13 PM

How did the wastegate port on the manifold look? Is it possible it's not as large as the wastegate needs it to be?

Shadow · Post by **Shadow** » Jun 10, 2012 2:24 AM

Is your coolant temps really doing that?

IMO looks like it needs a bigger gate if no spring, open valve,
is still making 15psi.

1.5'' wastegate vs 4'' exhaust.

Good & Tight · Post by **Good & Tight** » Jun 10, 2012 7:33 AM

Lurker27 wrote:Not directly yet, though I will. He runs the exact same 38mm setup more or less. Differences:

Mine is t3 16cm^2 his is 18cm^2 T4

His is tied back in to exhaust

he runs a better tune on e85 (more timing and leaner)

Mine is not tied back into the exhaust. I run a 38mm gate but run over 15psi. Did you just get the car running? I thought you have been boosted for awhile now, did this problem just start?

Lurker27 · Post by **Lurker27** » Jun 10, 2012 2:43 PM

It's been running a while, but I thought I was chasing an EBC issue, not a physical problem. I didn't think I'd have any issues since i was basically copying your (awesome) setup.

I think my turbo is calling me a pussy and I should install meth injection and go 20+ psi and live with it. I don't really think I can redo the manifold or wastegate setup without screwing up my clearances....so that leaves the tune, the screamer pipe, and maybe the hotside of the turbo as a culprit

Lurker27 · Post by **Lurker27** » Jun 10, 2012 4:13 PM

Shadow · Post by **Shadow** » Jun 11, 2012 1:42 AM

you sure you don't have room for a bigger gate by
the firewall?

Looks like you do.

ealoken · Post by **ealoken** » Jun 11, 2012 3:32 AM

you need a bigger WG on a 3.5 liter.

50mm at least.

Lurker27 · Post by **Lurker27** » Jun 11, 2012 9:56 AM

Shadow wrote:you sure you don't have room for a bigger gate by
the firewall?

Looks like you do.

I don't think so, getting the pipe there would be a huge endeavor plus dumping 1700 degree exhaust on my electronics seems like a bad idea. the 38mm gate in the current position already dented my hood from the inside

zrossa · Post by **zrossa** » Jun 11, 2012 4:21 PM

I am not so shure about the size of the waste gate but I did notice it seems to feed from one exhooassed pipe. I am going to guess that Otis has made it so its actually feeding from the collecter where all the pipes merge but it does look as though it would have a bias towards one side. That could mean that the other 5 pipes are not able to put enough pressure on the W Gate.

I.e. Its easier to spool the turbo then exit the gate.

Otis may not have come across this ecuase he runs more boost.

Cheers,

Douglas

Lurker27 · Post by **Lurker27** » Jun 11, 2012 5:34 PM

I think you're right - in our case because the turbine has essentially NO backpressure due to actual exhaust (4"), controlling boost is going to be really hard until the compressor runs in to serious resistance from the intake side. Only way to do that is to run more boost. A rough calculation says I need to let it get to 20psi.

Shadow · Post by **Shadow** » Jun 11, 2012 5:47 PM

Take some 20psi vids.

It looks like you have room by the compressor for
a bigger gate too.

thespeedfactory · Post by **thespeedfactory** » Jun 12, 2012 11:51 PM

Before you start upping the boost, What does your exhaust contain. Are you straight pipe from turbo back? DO you have mufflers/cats/etc?

Have to ask, did you confirm the vacuum line hookups at the wastegate? Are you sure you have the lines corrected properly?

Pu the red spring back in and disconnect the vacuum lines. You should see only 5-6 psi of boost

thespeedfactory · Post by **thespeedfactory** » Jun 12, 2012 11:52 PM

ealoken wrote:you need a bigger WG on a 3.5 liter.

50mm at least.

Bullshit.

I ran a 38mm no problem to 18 psi and then upped to 40mm when I swapped manifolds and ran 29+ psi to the end.

Lurker27 · Post by **Lurker27** » Jun 13, 2012 12:14 PM

Top vacuum line totally off. Side routed a new line right to the compressor outlet. Creeps to at least 17 even with no spring in. Tried 6 and 15 lbs springs

T_C_D · Post by **T_C_D** » Jun 13, 2012 1:38 PM

Lurker27 wrote:Top vacuum line totally off. Side routed a new line right to the compressor outlet. Creeps to at least 17 even with no spring in. Tried 6 and 15 lbs springs

Check the valve guide and seat. Maybe the WG isn't functioning properly.

240sxpooter · Post by **240sxpooter** » Jun 15, 2012 12:40 PM

You need to add a little back pressure to the exhaust system. I reduced my 4" to 3.5" at the tip and it fixed my issue 100%.

MyE28.com DEV

MyE28.com DEV

Insane Boost creep on HX40

Insane Boost creep on HX40