whats a safe psi on stock internals?
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This is a discussion on whats a safe psi on stock internals? within the STi Technical Forum forums, part of the Tech & Modifying & General Repairs category; This will probobly be a quick question for everyone, but I really need to know... COBB stage 2 makes the ...

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    Question whats a safe psi on stock internals?

    This will probobly be a quick question for everyone, but I really need to know... COBB stage 2 makes the sti run at 17.5 psi... The typhoon intake creates an extra .5-1.5 pounds... Stage 2 + typhoon = 18-19 psi... is this too much to be running on the stock sti motor with 93 octane gas? The stock psi is 14.5. 4.5-5 psi more than stock sounds like a lot... Anyone have any advice or input?

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    Where can I get a cobb stage 2 ?

    Where can I buy these and are they easy to install? Thanks.

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    Be sure and do plenty of research before you buy any old thing for your car, I can already tell that you asking where you can find a cobb stage two, you probably dont even know whats in it and what all it mods on your car. The cobb stage two is a downpipe/catback/cobb accessport. The accessport is an ECU reprogrammer that will make your car go from 240whp stock to around 295, or 370 at the flywheel. Cobbtuning.com is the website that explains it all for you, or you cans earch around for it using the search tool on these forums. Gas mileage will lgo down with this mod, and depending on how you drive you can beat on the stock clutch with this modification. Do not try and install it yourself, have a pro tune it for you and install it. Rallysportdirect.com has all the parts you need to make the sobb stage two package work, with decent pricing for it. Its a very good mod for the sti and thats where most people stop, 295-305 wheel horsepower depending on the gas used is an awful fast car.

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    To answer your question Suby, you can just get an HKS boost controller or that ApexI AVCR. THen just make it run any boost you want. But 18 psi on the stock motor from what Ive seen is easy on the sti's motor.

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    make sure the AP is throwing in extra fuel for that extra boost your getting from the intake, otherwise you would cause a lean running condition and KABOOM! a stock sti motor should be able to withstand 20+ psi of bost, but as with any motor built or not, the a/f ratios and the tune needs to be right on or there could be problems
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    I thought that boost controllers can only increase boost...not decrease boost. They act as a bleed valve to let it boost more...Unless this HKS is a standalone boost controller and not just a mechanical one... The Apexi A/F sounds like a safe bet regardless of boost... The Accessport will be pushing the car harder and its a good safety net. Im going to flash the ECU with the AP myself but eventually get a protune so incorperate my mods to get maximun safety and perfromance...

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    Best bet is to go with the Cobb AP and get it protuned or just use at least a base map on the unit for the sti. Boost controllers run into a lot of problems on the sti's so disregard what I said earlier...you should only get a boost controller after you get a utec or a accessport. The HKS one is a full unit and replaces the factory solenoid....a lot of people like it better because it reacts faster is is computer controlled within the unit. But only get one after some type of EM.

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    Registered User madmanx's Avatar
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    Quote Originally Posted by SubysEatV8s
    I thought that boost controllers can only increase boost...not decrease boost. They act as a bleed valve to let it boost more...Unless this HKS is a standalone boost controller and not just a mechanical one... The Apexi A/F sounds like a safe bet regardless of boost... The Accessport will be pushing the car harder and its a good safety net. Im going to flash the ECU with the AP myself but eventually get a protune so incorperate my mods to get maximun safety and perfromance...
    I blew my FPGreen. As soon as it went I turned the AVC-R down to zeros so I could get home w/o spinning a bad turbo. It let me accelerate fairly normal with out asking the turbo to kick in. Maybe turning the solenoid duty to zero's is what did it????
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    its not just a matter of PSI, its also a matter of fueling.

    if you're just going to crank up the boost, than ANY increase isn't really safe, if you're going to increase fueling as well, then you're limited by the flow rate of the fuel injectors. I'd say anything over 17 PSI (with additional fueling) is asking for trouble. with larger injectors, the stock block is "safe" to about 375 HP at the crank.
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    Good point. i am aware of the fueling issue at hand when the boost goes up. The aceessport handles that, but to what extent? How much can the stock fuel system be able to support before Injectors, fuel lines and rails, as well as pump and regulator are required. I dont plan to do much after the DP and Stage 2... well, at least for the time being... I saw that some sti's are running Nismo side feed injectors.... anyone have any thoughts?

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    Registered User blarg's Avatar
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    the stock fuel injectors are probably ok to about 280 crank HP. they are 480cc's

    the pink sti injectors are 565cc...they're ok to 375-400 crank HP

    the fuel rails should be fine to about 400 HP as well.

    the stock fuel pump (according to Cobb) can handle about 315 crank hp.

    i wouldn't run 17 PSI on stock parts.
    1) the turbo will poop out at the top
    2) the stock injectors/pump won't give you enough fuel

    16 PSI with proper fueling is about the limit...but you'll have to get a bellmouth downpipe to make sure you can move the exhaust fast enough.
    ScoobyDMC #009 - making dirty jokes since before you were making dirty diapers.
    Quote Originally Posted by Blarg
    go f*** yourself

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