2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

how much boost

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Old Feb 9, 2004 | 09:15 PM
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TII
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From: Florida
how much boost

just orderd a greddy profec b so i can turn down my boost have a bad boost creep hits 14 then starts to gain again 14 is too much going to go about 10 currently using stock injectors that were high flowed by venom but dont think im getting any more fuel than stock what is everyone running for boost on stock fuel system? am going to upgrade my injectors again what is eveyone running with better fuel systems?
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Old Feb 9, 2004 | 09:17 PM
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Husemoller's Avatar
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Your going to need to port the wastegate to get the boost down
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Old Feb 9, 2004 | 09:18 PM
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hey sorry to change the subject but you wouldn't happen to have a pic of it installed and where you put the vacuum hose huh? THanks.
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Old Feb 9, 2004 | 09:18 PM
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Re: how much boost

Originally posted by TII
just orderd a greddy profec b so i can turn down my boost have a bad boost creep hits 14 then starts to gain again...
A boost controller of any sort will not fix your boost creep issue at all.

You need to port your wastegate, or buy an external one and fit that (much more work).
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Old Feb 9, 2004 | 09:50 PM
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TII
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where can i get my wastegate ported.

was told i could turn down the boost lower than what i wanted to compensate for the creep would this help also what about a pop off valve to protect for over boost
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Old Feb 9, 2004 | 09:52 PM
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Well you can't turn down boost...like if the wastegate snaps shut (or open??? and all exhaust gases bypass the turbo) at 9PSi (just a random number) then the lowest boost you can run is 9...you can only raise it from there.
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Old Feb 9, 2004 | 09:55 PM
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Pop off valves are fail-safe devices. If the wastgate somehow fails, the pop-off valve will activate. However, it should not be used to control boost.
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Old Feb 9, 2004 | 09:58 PM
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Can we get a sticky for things like this? These are the same questions that we've all heard a million times.

To port your wastegate you'll need to:
1. take turbo off
2. remove the 2 bolts holding the backplate on the hotside of the turbo
3. remove c-clip holding the wastegate swing arm to the wastegate rod
4. with the flap now open go at it with a die grinder/dremel with carbide bits.

A pop off valve isn't used to regulate boost, it's more of an emergency measure to protect your engine. If a wastegate hose pops off, instead of spiking to 1.5bar, it will relase all the air. This action overspins the turbo, and isnt' very helpful to the turbocharges longevity. It's always better to be safe than sorry, so a pop off valve is always a good addition but not if it will be regulating boost.
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Old Feb 9, 2004 | 10:03 PM
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TII
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how wide do i make it

am going to add the pop off because i blew my last motor when i lost a vac and spiked at 15 but need to fix this creep will try porting the nabifold
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Old Feb 9, 2004 | 10:05 PM
  #10  
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also your bigger injectors won't be doing anything unless you have a bigger fuel pump as well. the stock pump maxes out before the injectors do.
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Old Feb 9, 2004 | 10:10 PM
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Originally posted by TII
how wide do i make it

am going to add the pop off because i blew my last motor when i lost a vac and spiked at 15 but need to fix this creep will try porting the nabifold
Go as wide as the stock flap will let you. If you can afford to have the car down for a day, take the turbo to a machinist or turboshop and have a bigger flap welded on. This will help the smaller s4 wastegates majorly. You can also upgrade to a s5 turbo to help with the boost creep, you'd need a s5 manifold as well. They have dual wastegate passages, and a better designed twin scroll manifold.

that's exactly the situation pop off valves are used in, they can save a lot of money
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Old Feb 10, 2004 | 12:01 AM
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I made a thread on a pop off valve as a temporary solution to waste gate porting and it has some good info on it. Here is the link https://www.rx7club.com/showthread.p...=pop+off+valve

I second the sticky also.
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