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-   -   begi and boost creep (https://www.miataturbo.net/prefabbed-turbo-kits-3/begi-boost-creep-11559/)

reckless_abandon 07-31-2007 09:46 PM

begi and boost creep
 
so on the weekend, i installed the begi downpipe for my greddy kit.
now, i get some scary boost creep. it'll hit 6psi, then creep up from there to about 8 or 10psi.
i've only got the 1.6l injectors, so this can spell disaster.

anyone else get this?
ideas?

Snowsurfer03 07-31-2007 10:06 PM

yeh...it will be fun for a while but if you want to keep her safe you need tuning and more fuel.

trust me! just invest a little in some tuning and it will pay off in the long run!

Ben 07-31-2007 10:18 PM

that's a feature, not a problem. get yourself some injectors and/or a hp fuel pump and enjoy.

I have never heard of a boost creep problem with the greddy. It's always a boost droop. Perhaps some porting on the turbo's turbine out would get it flowing better. Where does your WG actuator reference boost signal?

reckless_abandon 08-01-2007 01:35 AM

the wastegate has a vacuum line to the turbo housing.
do you recommend just the injectors? or will i need a fuel pump to go with the injectors?
and if so, which fuel pump? i was thinking about getting the 7MGENA supra injectors to be safe. but i'm no expert.

kotomile 08-01-2007 01:44 AM

I would *think* the Begi would make the boost drop, not creep, since the WG gasses aren't nearly as choked as the "Stock" downpipe..

My Begi just arrived yesterday..

Are you sure you did nothing else to the car that might have caused this?

Ben 08-01-2007 07:50 AM

yeah you'd probably be good with the 300cc injectors only. i'm thinking by the time your boost creeps, the ecu is at 90% duty cycle. be safe, get a wideband.

check to make sure that your actuator rod can move feely and the flapper door actually opens fully. like i said, I've never heard of creep on a greddy, only droop, and usually bad droop due to their shitty wg actuator.

Braineack 08-01-2007 09:06 AM

haha, I was going to say the problem is!??!

y8s 08-01-2007 10:23 AM

you get boost creep because the WG is too small to pass that much gas. it's more apparent on low-boost setups because less exhaust is going through the turbo and more is diverted through the WG.

if you dont want to change the fuel system, port the wastegate.

reckless_abandon 08-01-2007 10:50 AM

i just checked the wastegate to see if it moves, but i cant get the wastegate flap to open manually. this may be my problem.

Joe Perez 08-01-2007 11:29 AM


Originally Posted by reckless_abandon (Post 136043)
i just checked the wastegate to see if it moves, but i cant get the wastegate flap to open manually. this may be my problem.

If it is still connected to the WG canister it is *very* difficult to operate manually. For a device that's designed to actuate on only a few PSI, the diaphragm in that canister is surprisingly stiff. This is not indicative of a problem.

reckless_abandon 08-01-2007 08:17 PM

that makes sense.
i havent tried to move it while disassembled.

wildfire0310 08-01-2007 10:44 PM


Originally Posted by kotomile (Post 135962)
I would *think* the Begi would make the boost drop, not creep, since the WG gasses aren't nearly as choked as the "Stock" downpipe..

My Begi just arrived yesterday..

Are you sure you did nothing else to the car that might have caused this?

Like Y8s said, boost creep is caused because off opening the exhaust. Its normally only a problem on small turbo on larger engines running low boost. Supra have that problem really bad with stock turbos. Running just a full exhaust 3' on a 7mgte supra without any other mods will cause a boost creep of 9 psi before setting back to stock 6psi. DSM have the same issue hence the reason for the 34mm wastegate "mods".

The only cure for boost creep is to port the wastegate.... well that or just turn up the boost...but yea

Agent935 08-01-2007 11:24 PM

I've heard of the same problem on FDs when you get a downpipe or pull out the cat. Their solution is like y8s said, porting the wastegate.

Joe Perez 08-01-2007 11:40 PM


Originally Posted by reckless_abandon (Post 136244)
that makes sense.
i havent tried to move it while disassembled.

If you have a hand-operated vacuum pump which has a port on the exhaust, you can connect the outlet of the pump to the inlet of the WG canister and make enough pressure by hand to actuate the diaphragm.

reckless_abandon 08-02-2007 08:18 PM

what is involved in porting the wastegate? and should i get a professional to do it?

Ben 08-02-2007 09:11 PM

I would say if you have to ask, let a pro do it.

I have always wanted to do this:
http://www.gpopshop.com/portpolish.html
(minus the exterior polish that is)

I'd bet the gains are as worthwhile as they claim.

kotomile 08-03-2007 02:01 AM

Is it just take off turbine housing, radius the corners, polish?

kotomile 08-08-2007 02:56 PM

Another question: I have the stock 1.6 injectors on mine now, but with a 190HP. Vortech FMU is untouched, so 12:1 disc. If I bolt on my Begi DP and get boost creep to, say, 8 psi, will I run lean?

And another: If I bite the bullet and get the AEM EBC.. will it help to control the creep?


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