Still Expierenceing Boost Creep .63 To .82

[Jaydenk92]

Hi everyone.

So my r34 gtt has had a gt3076 56trim with a .63 internal housing for some time now. I never can flog it due to the horrible boost creep. not to mention the kinda shit power from that turbo at that psi.

So to fix the issue i got a .82 housing with a ported 37mm internal gate. Drove it today and it still creeps to about 1.3bar. but holds there where before it would keep going until it started to lean out (fart, crack ect.)

this turbo is from gcg and the housing, i use a apexi avc-r controller, standard manifold (mild port), split dump from gcg, 3inch front pipe (i Think) to apexi hi silent back exhaust, no cat.

So basically can someone explain or possibly rectify this issue (which seems to be common).

if they are selling these things for rb25 they must have some form of boost control.

I'm to far gone for a external gate as it defeats my original intention.

thanks

[zebra]

split dump pipe is your prime suspect

[steve200b]

I had a gtx3076 with internal .82 on a 25 running 20psi. That's as low as it would go before it would creep. Now on a 2530 and needed to go external gate to keep it under control

[Jaydenk92]

do educate me on the issue with the split dump? thanks zebra

[zebra]

Basically

The wastegate part of the dump is what, 38mm maybe? just isnt big enough to flow...not to mention its trying to merge into a pipe with pressure, backs up and wont flow anymore.

[Jaydenk92]

Does make sense though seems unlikely, What's your thoughts on the gt3076 was originally for external gate only, but they sell IW for more bolt on options but no one is aware of the boost creep issue, made to fail?

something someone just told me?

Edited May 12, 2015 by Jaydenk92

[AngryRB]

Zebra is correct!!!

change your dump pipe to an open mouthed one and problem solved... nothing wrong with gt3076's...the 0.82 internal gate has zero problems with boost creep, 0.63 can have some issues

Edited May 12, 2015 by AngryRB

[Blackkers]

Those split dump pipes are known to have these issues man.

Although if you feel like a power upgrade too you should send your rear housing to Scotty on here to get an external gate welded on. Atmo from the wastegate + big external gate = more smiles

[discopotato03]

I looked very hard at their GT30 integral dump and opted to have an open mouthed dump/front pipe made .

If you look at the inlet of the waste gates bypass its round where the turbine housing isn't , maybe convenient to make with a hole saw but questionable functionality . Hard to believe there wouldn't be a pressure rise here and anything that does this downstream of any waste gate can effect its performance .

I bought an XR6T turbo side GT30 IW flange plate from Carlton Mufflers because theirs is thick and thick is good when you have to weld to it .

Kirawee Mufflers made the front pipe in I think 3.5 inch tube and formed a gusset for the gate outlet section . I never have creep issues and with the same housing as yours . 1 bar large can actuator and the brain box does boost control .

IMO except for big budget race apps where everything is flow tested split dumps are more trouble than they are worth . If you really want to separate the two exhaust streams and the turbine housing casting doesn't have a short divider build one into the flange plate .

If you are really concerned about pressure build up behind the T housing then use larger bore tube here and neck it down at or behind the cat . My system is 3.5 inc the cat and its conical outlet was made the reducer to 3" . My exhaust is higher flowing and noticeably quieter than the Japanese name brand POS it replaced .

A .

[Dose Pipe Sutututu]

dw man, 1.3bar is perfect

also throw that split dump into the bin.. it's more of a headache than anything else.. the wastegate flapper probably isn't able to fully open and causing all the issues, but if it's creeping and staying steady at 1.3bar then that's good...

[Jaydenk92]

so are you guys saying that the flapper fouls out onto the dump pipe?? I also notice that i have a split dump, yet i don't have a split dump gasket fitted AND the housing has a gap about 4mm deep in the middle which would allow gases between the wastegate and turbine thus DEFEATING THE FREAKING PURPOSE of a split dump being used. which i believe will cause a pressure yes????

also, disconnected my ECB (12psi spring) found it would hold 1.05 bar in second, then creep to 1.25bar in 3rd. so its not as bad but still creeps no questions about that. So my ebc isn't the issue. i believe its better as the ebc ramps boost up higher before allowing the gate to open.

[Blackkers]

you can test whether the flapper is fouling on the dump by disconnecting the actuator and seeing for yourself. Might be worth a try but it sounds like you have to change the dump out

[Jaydenk92]

you can test whether the flapper is fouling on the dump by disconnecting the actuator and seeing for yourself. Might be worth a try but it sounds like you have to change the dump out

Would you know, i tried that a sure shit it hits, the flapper travels like 35deg before hitting, FOUND THE PROBLEM :). even though i bought a whole new housing at least it what be as restrictive

[STATUS]

bellmouth dump is the go and make sure flapper doesn't foul flange... its quite common

[Jaydenk92]

I spoke to gcg and he said it might be a case where my engine flows a bit healthy at which the IW isnt large enough to control boost. Becuase he said most application the flap only opens about 30-40deg. Which i think sure maybe for 12psi with standard exhaust lift. But not tomei type b cams and 18psi i think not.I checked what 30-40deg looks like and the flapper is still directly in front of the flow direction which would cause some turbulence. So does anyone know if a open bell for a 6 bolt rear is available???? anywhere??

[Ben C34]

Make one.

Ford turbo rear flanges are very easy to come by.

[Gts-t]

my boost drops off with my ces split dump pipe 20psi dow to 18.5

[scotty nm35]

Make one.

Ford turbo rear flanges are very easy to come by.

This. Or just go external gate and never worry about it again.

[75coupe]

I had a bell mouth front pipe off the std turbo sold it off when i got my new setup, so yes ypu can get bell mouth front pipes

[Ben C34]

I had a bell mouth front pipe off the std turbo sold it off when i got my new setup, so yes ypu can get bell mouth front pipes

They aren't really available for the gt30 turbos.