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Drives 2003 COBRA 435rwhp
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Hey guys just wondering what all your opinions are on this I hit 22 PSI last night and bam instant cut off! I have hit 22 before with no problems that was the first cutoff problem so far. Yes, it is still a stock fuel system.





OK OK I know it is not too safe I need to turn it down to about 18 PSI but have not had the time not to mention I do not boost to 22 all the time maybe 3 times since the boost control was put on. I really just wanted to see what some pple had to say.
 

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Aghhhh
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Are you nuts? The stock fuel system is maxed out at 14.5 The turbos are blowing hot, useless air past 17. Unless you've got some fuel upgrades you're not listing, your engine is not long for this world.
 

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Mod O' Day Pron
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I run 18 psi on a stock fuel system with stock injectors. Plus, VR4's run rich stock. My gauges tell me I'm running rich under boost. It peaks at 18 psi, then drops off to about 12 psi before shifting.
But, yeah, Derek, we need to turn that MBC down :D

Sean
 

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What does your EGT gauge read or are you relying on just an A/F ratio gauge? (analog or digital?) Even though your 18psi only lasts for a few seconds as the stock turbo's start running out of steam past 4500rpm, you are most likely still damaging your engine. Plan on a rebuild soon. At the very least, get a pocketlogger or datalogger to see how much knock you are creating. If you're getting a lot of knock, your car will make more power by turning the boost down. (will also keep the pistons from desintegrating). It's too easy to go to "bam 18-22psi boost". Never know when "bam" turns into "boom", no compression until it's too late.
 

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air/fuel is not your only concern. i'd look into egt guages. http://www.3sxperts.com/ makes a really sweet dual egt guage (so u can monitor both banks in one guage). good luck man - some guy destroyed his engine the other day running 16psi on stock fuel system. If i were you, i'd consider myself really lucky.

.jon
 

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22psi! :eek: after people upgrade fuel systems, upgrade turbos and get a good airflow they shoot for 22psi... turn her down a bit.
-Greg
 

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You break em, we fix em
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You people are all nuts!

Do you have a datalogger!!!!!? EGT gauge!!?

An Air/fuel gauge and its meaurement are not your only concern.

At 18, 22, anything over 15psi on the factory fuel system and turbos I ASSURE YOU you are getting a TON of knock and are killing your lower end and bearings. Not to mention the damage, your ECU is probably retarding the hell out of your timing, and the factory turbos are way out of their efficiency range which means the air you ar pushing in is HOT. Anything your gaining with the extra boost you are losing that and more due to the timing retard, knock, heat of air the turbos are pushing. You are most likely killing your factory turbos pushing them this hard. I am AMAZED that you are not getting spark blowout, fuel cut, etc as well.

Your car will be faster and last longer running 14-15 psi!

I will watch for your "I ruined my expensive engine now what do I do" posts. This is EXACTLY the type of irresponsible, uninformed modification that gets our cars a reputation for being "unreliable".
 

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You break em, we fix em
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BTW my last words of wisdom are:

"More is not always better"
 

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That Others May Live
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One more thing, you aren't supposed to boost past 18psi w/o alky injection or race gas! (or so i'm told).
 

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just some guy.
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Italianstealth said:






OK OK I know it is not too safe I need to turn it down to about 18 PSI but have not had the time not to mention I do not boost to 22 all the time maybe 3 times since the boost control was put on. I really just wanted to see what some pple had to say.
Well buddy, I hope you have enough time to do an engine rebuild, because that is what's going to happen.
 

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ItalianStealth, check this pic out...is that one of your pistons on the left? turn the boost down paisan.
 

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Sean Johnson said:
I run 18 psi on a stock fuel system with stock injectors. Plus, VR4's run rich stock. My gauges tell me I'm running rich under boost. It peaks at 18 psi, then drops off to about 12 psi before shifting.
But, yeah, Derek, we need to turn that MBC down :D

Sean
Do I see a rebuild soon here ! Your engine will break if you contignously drive in this boost area. 1 bar is simply the max on stock fuel system !

Hitting 22psi on an occasion (fallen off wastegate hose) then this shouldn't result in immediate failure. The problems start after doign that several times or for a longer period than 7-8 seconds. Even then, the damge may not yet big but it is already there ! Here's what I've seen :
http://www.rtec.ch/engine_problems.html
 

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That Others May Live
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Toxic-
Do you actually have a sticker like that(the turbocharger warning)!? Where can I get one??? Thats hilarious.
 
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Lets also remember that the Rich condition that shows on an A/F gauge during WOT is INCORRECT! the gauge is really only good for part throttle. What is rich at part throttle is not so rich at WOT.

Yes, or stock fuel syst is good for 14.6 psi. And there is no way you are holding 22psi on stock 9b's to redline?! past 4500 they should drop of considerably...

PLEASE DO NOT rely on a non WOT adjusted A/F gauge and don't boost past 14.6 (using aftermarket gauge of course) with factory fuel syst...
 

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Drives 2003 COBRA 435rwhp
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Discussion Starter #16
Roger you never amaze me

Roger,
As always you have facts to back up anything you say which puts you light years ahead of so many other ppl. Not to mention you have a nack for explaining information in a non-derogatory way. In regards to the rebuild it was actually just completed then the manual boost was put on. The 22 is def. not constant as someone eluded to it is peak and I know I need to turn the wik down hence my last sentence in my original post. It will actually be turned down within this week-Not only do I make sure the car does not boost over 15psi I do not even drive it everyday(For I am not really at a shortage of alt. transportation).

Roger-I can honestly say (and we have corresponded before)
that anytime you have any info or advice I am
always willing to listen to you fully.

I can however say this to the rest of you My car and 3 other ppl on this board Since there rebuilds have been running at 18psi problem free for over 30,000 miles. Seeing as how they rebuilt my engine I feel very confident in there ablities seeing as how they have some of the fastest 3S's on here.

F27 corsair = Very nice SIG pic.
 

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Roger, thanks for the info, vs. the "Here Say" I'm turning my boost down to 14.5 / 15 psi tonight. I rebuilt my engine 2 yrs ago, and don't really feel like doing it again. When I ran 18 psi, I did run 110 octane fuel. Thanks again to everyone for your concerns :)

Sean
 

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Turbo-Less
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I agree that you might as well not bother with anything over 15psi anyway.

now this was just MY test but when I did my 1/4 mile runs, there was NO DIFFERENCE in my times/speed from 12psi to 15psi. It's correct that you are just pushing HOT, THIN air after 15psi anyway.

If I didn't see any gains moving from 12 to 15psi, I can't see any benefits going any higher.
 

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Jeremy

Thanks for the test info. Very soon, I plan to upgrade my fuel pump & injectors. Then would running 18 psi be ok? Or is the 15 psi all that stock turbos can handle? Thanks!

Sean
 

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It is not recommended. Even with the fuel upgrades, you will get a ton of knock at boost levels that high. When the knock skyrockets, the timing is retarded and you lose power. Lots of it.
If you want to run higher boost pressures, you should really consider some larger, more efficient turbo's, a fuel controller to control the larger injectors and an alcohol injection kit. I would recommend getting a logger and running the car at different pressures to see the effect it has on the engine. When I first started upgrading, I found some sites, (I think GTPro or AAM), that did some dyno testing with different pressures and found that on the stock 9b's that the car lost power at higher pressures. One of my first upgrades was a Stillen down pipe. I couldn't believe the added power felt in the butt dyno. (Not to mention the sound). I'll try to find the site with the dyno testing and post it.
 
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