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

Weird boost fluctuation

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Old Apr 13, 2008 | 11:38 AM
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Weird boost fluctuation

Just got my car out today for my first spring drive.

So, after a half an hour drive, I decide to floor it to see if all is well and something different happened. I used to run stock boost last year, meaning -PSI, but this winter I installed a boost controller but its set to default/stock boost still since its not dyno tuned for PSI like I want it to be.

So I floor it and when I get to full boost under 4500rpm, the boost goes up to 8-9 PSI but as soon as I hit 5500RPM the boost goes down to 6PSI...

Anyone has an idea why?

Spec.
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Old Apr 13, 2008 | 09:12 PM
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****, I had Numlock off....

Originally Posted by Spectator
Just got my car out today for my first spring drive.

So, after a half an hour drive, I decide to floor it to see if all is well and something different happened. I used to run stock boost last year, meaning -PSI, but this winter I installed a boost controller but its set to default/stock boost still since its not dyno tuned for PSI like I want it to be.

So I floor it and when I get to full boost under 4500rpm, the boost goes up to 8-9 PSI but as soon as I hit 5500RPM the boost goes down to 6PSI...

Anyone has an idea why?

Spec.
So, it was supposed to be...

Just got my car out today for my first spring drive.

So, after a half an hour drive, I decide to floor it to see if all is well and something different happened. I used to run stock boost last year, meaning 5.5-6PSI, but this winter I installed a boost controller but its set to default/stock boost still since its not dyno tuned for 10PSI like I want it to be.

So I floor it and when I get to full boost under 4500rpm, the boost goes up to 8-9 PSI but as soon as I hit 5500RPM the boost goes down to 6PSI...

Anyone has an idea why?

Spec.
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Old Apr 13, 2008 | 11:37 PM
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it's called the stock wastegate. It sucks--even when you port it, unless you port it big. boost creeps up in the midrange area and then falls off because the stock turbo can't flow enough air.
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Old Apr 14, 2008 | 10:42 AM
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So what do you recommend I do?

My boost controller is still set to default. If I set it to 10 PSI, do you think it should be stable at 10PSI since it never creeps over 9?

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Old Apr 14, 2008 | 12:33 PM
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anyone?
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Old Apr 14, 2008 | 05:50 PM
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don't bump... the ***** will get you. i would be weary running anything over stock with a stock WG. if you arent tuned to run 10 psi, then what do you think if you creep up to 12 without additional fuel? POP goes the Wankel. Keep it stock until you can compensate fuel and port your wastegate. i dont know what mods you have but it isnt like you can just buy a boost controller, and crank it up. There are supporting mods, proper fuel, a way to control said fuel, correct voltage to pump etc... ask me how i know... i would hate to see another 7 blown up.
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Old Apr 14, 2008 | 08:21 PM
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Originally Posted by well uhhh
don't bump... the ***** will get you. i would be weary running anything over stock with a stock WG. if you arent tuned to run 10 psi, then what do you think if you creep up to 12 without additional fuel? POP goes the Wankel. Keep it stock until you can compensate fuel and port your wastegate. i dont know what mods you have but it isnt like you can just buy a boost controller, and crank it up. There are supporting mods, proper fuel, a way to control said fuel, correct voltage to pump etc... ask me how i know... i would hate to see another 7 blown up.

I have everything to compensate for 10PSI even more...thats why I am waiting to go on the dyno before I raise up the boost. I have a SAFC-II and 720ccs, walbro...etc....

So my question still stands. If I set my boost controller to 10PSI when I go to the dyno, since I dont creep over 9PSI, should it stay stable at 10PSI?

Thank you.

Spec.
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Old Apr 14, 2008 | 08:35 PM
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Port the wastegate and set the boost controller to 10 psi. Make sure you have an FCD if you're still on the stock ECU. You should be hitting fuel cut @ about 8.5 psi...hence the need for a FCD.

And no bumps allowed in the 2nd gen technical section...
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Old Apr 14, 2008 | 08:42 PM
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No worries, I have an FCD...or else it would have cut already.




Spec.
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Old Apr 14, 2008 | 08:44 PM
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Originally Posted by Spectator
No worries, I have an FCD...or else it would have cut already.




Spec.
cool.


Just port the wastegate. Mine boosts at a solid 11-12 psi with no drop up top.
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