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

Recommended psi

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Old Feb 17, 2003 | 02:35 PM
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bov ftw
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From: Ft.Worth, TX
Recommended psi

What psi can safely be run in all gears with stock primaries and 720 secondaries?
Mods are in my sig.
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Old Feb 17, 2003 | 03:03 PM
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bov ftw
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Anyone have a clue?
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Old Feb 17, 2003 | 03:33 PM
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huge custom side mount dent
LOL

It looks like you've got the fuel for all the stock turbo could handle. Since you said "safely" I will say 12#. I think there are people running 14/15, but I don't think the turbo would last long. Besides that's over what the stock IC was designed for, from what I've read. Combined with the extra heat being generated by the turbo running past it's efficiency would seemingly lead to problems. Augment with H2O inj. maybe? Cheaper than a FMIC?
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Old Feb 17, 2003 | 11:47 PM
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bov ftw
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I do, in fact, have a front mount! Check out the sig one more time. Whoever you know that is running 14-15 psi on a stock intercooler with just a pump and s-afc won't be driving that car very muchm longer. Anyone know how much I can safely run with my mods + 720 secondaries?
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Old Feb 18, 2003 | 06:39 AM
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If you're on the stock turbo, my answer would be the same. The FMIC will help save the engine not the turbo.

Sorry I missed that in your sig. Just trying to help and I get attitude. Whatever, good luck bud.
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Old Feb 18, 2003 | 01:41 PM
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bov ftw
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From: Ft.Worth, TX
Just stating the obvious, Heffboost. Any input is appreciated.
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Old Feb 18, 2003 | 06:40 PM
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SUPRAMAN
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ya the turbo is efficent after like 12-14psi. or something like that like you could crank the boost up to 18-19 but you aren't going to be making anymore power than you would at say 13psi.
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Old Feb 18, 2003 | 06:48 PM
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Think about it - the stock boost controller only "reads" up to 15psi.&nbsp if you run higher, the ECU has no idea you're running any more boost.


-Ted
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Old Feb 18, 2003 | 07:04 PM
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On the same lines, whats the max boost that the Stock fuel system can handle? I heard anywhere from 8-10.


Jarrett
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Old Feb 18, 2003 | 09:59 PM
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Think about it - the stock boost controller only "reads" up to 15psi. if you run higher, the ECU has no idea you're running any more boost.
whoah whoah. I was under the impression that with the fcd the ecu reads the correct amount of boost up until it clamps the voltage so the ecu see's 8.6psi at anything at or above that level of boost. I know the boost controller is a fancy series5 gizmo, but I was unaware that the ecu would react to levels of boost over 8.6pounds by changes in the injector duty cycles/timing and what not.

On the same lines, whats the max boost that the Stock fuel system can handle? I heard anywhere from 8-10.
well with a factory fcd of 8.6 pounds I would at or below that on the stock system with a fuel pump rewire. Sure the ecu runs rich on our cars so you could run probably 10 and maybe even 11 pounds of boost, but for how long? In my experience walbro(rewire if you want) + fcd is good for up to 12 pounds on stock IC.

Last edited by gsracer; Feb 18, 2003 at 10:01 PM.
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Old Feb 18, 2003 | 10:05 PM
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Originally posted by J-Rat
On the same lines, whats the max boost that the Stock fuel system can handle? I heard anywhere from 8-10.


Jarrett
There was an article I saw, it said with stock fuel system and an fcd it can handle 11psi(I think it was an s4). And then don't go past 12psi on the stock IC, and don't go past 14psi on the stock turbo. They did a lot of testing, it was a great article. This was all on the stock ecu, and the car was brand new. But play it safe, don't push things to the limit, its not worth the risk.
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Old Feb 18, 2003 | 10:18 PM
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I was looking for 8 PSI now, on the stock pump and injectors, then I was gonna shoot for 10 with 720 secondaries and a Walbro. Which is about as far as I wanted to take it.

I am just worried that the installation of my mid and downpipe will cause me to get boost creep. The wastegte isnt ported.
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Old Feb 18, 2003 | 10:20 PM
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Originally posted by gsracer
whoah whoah. I was under the impression that with the fcd the ecu reads the correct amount of boost up until it clamps the voltage so the ecu see's 8.6psi at anything at or above that level of boost. I know the boost controller is a fancy series5 gizmo, but I was unaware that the ecu would react to levels of boost over 8.6pounds by changes in the injector duty cycles/timing and what not.



well with a factory fcd of 8.6 pounds I would at or below that on the stock system with a fuel pump rewire. Sure the ecu runs rich on our cars so you could run probably 10 and maybe even 11 pounds of boost, but for how long? In my experience walbro(rewire if you want) + fcd is good for up to 12 pounds on stock IC.
No need for 720s at 12 pounds of boost?
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Old Feb 18, 2003 | 11:10 PM
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No need for 720s at 12 pounds of boost?
From my own personal experience and what I've seen of others - not at all. Really my own personal limit is .8 bar which is 11.6 pounds. I've run just over .8 bar in third and fourth with just the walbro for 10 months now. The highest I've seen my EGT's get is 800 even with the probe being mounted just behind the o2 sensor. If you just want to run 10 pounds of boost the walbro and fcd will be absolutely fine, don't even bother with the bigger secondaries or you will run CRAZY rich.

With my thunderfab dp/mp and cone filter I was running a max of about .7bar or just a little over it. I think you could get away without a ported wastegate fine.
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