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Thread: IROC R/T dohc T-3

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    IROC R/T dohc T-3

    Can anyone tell me what the maximum boost should be on a stock T-3 motor? Thank you.

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: IROC R/T dohc T-3

    Stock was 11psi I think. It's not all that much relatively speaking. They threw crazy timing at the TIII cars, as they had great faith in the knock retard function. Many have reported their cars pulling a good amount of timing at stock boost levels. Be careful if you plan on turning it up. A weak fuel system from the 90s may not be up to the task...

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    Re: IROC R/T dohc T-3

    Quote Originally Posted by cordes View Post
    Stock was 11psi I think. It's not all that much relatively speaking. They threw crazy timing at the TIII cars, as they had great faith in the knock retard function. Many have reported their cars pulling a good amount of timing at stock boost levels. Be careful if you plan on turning it up. A weak fuel system from the 90s may not be up to the task...
    Thank you. I donít drive my 93 IROC R/T real hard but after some parts replacements it has jumped from a max of 6 to a max of 15 on the in dash gauge, do you think that is acceptable for short bursts?

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: IROC R/T dohc T-3

    It sounds like it wasn't giving the proper boost before the repairs, probably minimum boost. Now it seems like you are getting too much boost. I would definitely look at the vacuum line routing and go from there.

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    Re: IROC R/T dohc T-3

    Quote Originally Posted by cordes View Post
    It sounds like it wasn't giving the proper boost before the repairs, probably minimum boost. Now it seems like you are getting too much boost. I would definitely look at the vacuum line routing and go from there.
    The car only had 1k miles put on it in the last 20+ years (it now has 52k) so there are lots of minor issues. It has a new actuator and replacing the vacuum line to the actuator gave the boost increase. The car is a work in progress but it will be worth it as itís near mint, red with red leather. Thank you for the information.

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    Re: IROC R/T dohc T-3

    If memory serves me right, the stock fuel injectors are basically maxed at 13psi on the TIII engines. I would be weary about running higher than that without a wideband.

    Does the boost go to 15psi then come down on it's own? Stay there / continue to climb?

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    Re: IROC R/T dohc T-3

    Quote Originally Posted by EaZyE426 View Post
    If memory serves me right, the stock fuel injectors are basically maxed at 13psi on the TIII engines. I would be weary about running higher than that without a wideband.

    Does the boost go to 15psi then come down on it's own? Stay there / continue to climb?
    Under hard acceleration it goes to 15psi but itís shift time so I donít know if it would continue to climb. Are you saying that I could be forcing a lean condition at 15psi?

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    Re: IROC R/T dohc T-3

    Quote Originally Posted by Sael View Post
    Under hard acceleration it goes to 15psi but itís shift time so I donít know if it would continue to climb. Are you saying that I could be forcing a lean condition at 15psi?
    I can't say for sure, but I will say I would be worried if my R/T was running 15psi on a stock fuel system. If you check it during a 3rd or 4th gear pull, you should get 15 long before it's time to shift. If it hits 15 then immediately drops back to 11-12, I would not be worried too worried about it.

    If it stays at 15 or goes even higher (A stock SBEC controller won't let you stay above 14.5 for more than a second or two before hitting boost cut), there is something very wrong. You said you got a new actuator, was it a NOS piece or a used item? If you hit boost cut or the boost stays fairly high, test the wastegate. Run a vacuum line from the manifold direct to the wastegate can and plug the line from the solenoid to the actuator to see what boost you get. Should be in the 6-7 range. If you get more than that, I'd say there is an issue with the new wastegate can. If the boost stays low, it's likely a vacuum line routing issue like Cordes said above.

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    Re: IROC R/T dohc T-3

    Quote Originally Posted by EaZyE426 View Post
    I can't say for sure, but I will say I would be worried if my R/T was running 15psi on a stock fuel system. If you check it during a 3rd or 4th gear pull, you should get 15 long before it's time to shift. If it hits 15 then immediately drops back to 11-12, I would not be worried too worried about it.

    If it stays at 15 or goes even higher (A stock SBEC controller won't let you stay above 14.5 for more than a second or two before hitting boost cut), there is something very wrong. You said you got a new actuator, was it a NOS piece or a used item? If you hit boost cut or the boost stays fairly high, test the wastegate. Run a vacuum line from the manifold direct to the wastegate can and plug the line from the solenoid to the actuator to see what boost you get. Should be in the 6-7 range. If you get more than that, I'd say there is an issue with the new wastegate can. If the boost stays low, it's likely a vacuum line routing issue like Cordes said above.
    thank you for all this information. I will start checking things and refer it back to my mechanic.

    - - - Updated - - -

    Lots of useful information here, thank you all.

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    Re: IROC R/T dohc T-3

    Our bill is in the mail :P

    Gotta keep these cars around!

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