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how much boost before it blows up? mpi 502

Old 06-02-2014, 03:26 PM
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Default how much boost before it blows up? mpi 502

97 mag mpi 502. Stock with exhaust, fuel system and an M3SC inter cooled Pro charger kit. Running 5/7psi now on 91 octane. I've got 110 available here, if I ran the gas, what kind of boost could I push the motor to without worrying about it letting go?
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Old 06-02-2014, 07:35 PM
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Stock head bolts and gaskets, I'd say you're living on the edge at 7lbs right now. You want more boost, I'd consider some MLS gaskets, and head studs. Just my opinion. If you want more power, I'd def lose the baby 502 MPI cam for starters.
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Old 06-02-2014, 09:50 PM
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Does the stock 502 cam have a slightly rough idle? Mine does but I know stock big block pickup motors idle baby smooth with there peanut cams..... I'll leave the boost alone then but will do the better gaskets and studs if it ever let's go. Thanks!
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Old 06-02-2014, 10:11 PM
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You are right on the edge now with injector. I would bet that it is at damn near 100% duty cycle with that much boost. I'm actually surprised it hasn't let go yet.
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Old 06-02-2014, 10:21 PM
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Assuming, Modern engine management, (holley efi) bigger injectors, proper cam, better fuel, studs and mls gaskets what can the bottom end take?
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Old 06-02-2014, 10:41 PM
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Quite a bit actually. I wouldn't take it past 700 or so. You are probably playing with fire beyond that. That's my opinion, at least. I prefer to error on the safe side. It could withstand more in shorter bursts, but if you are talking about running at will, then I wouldn't go much past 700 or so.

Last edited by Young Performance; 06-02-2014 at 11:06 PM.
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Old 06-03-2014, 08:13 AM
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My 502 has built bottom end and some head work, im right around 700 hp. and mine did idle rough, i think because of no thermostat and engine not getting to operation temp. I have m1 procharger and intercooler. we tuned the low end took a little fuel away and seems to idle much better.
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Old 06-03-2014, 08:28 AM
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Originally Posted by Young Performance
You are right on the edge now with injector. I would bet that it is at damn near 100% duty cycle with that much boost. I'm actually surprised it hasn't let go yet.
Eddie
I believe he is running factory Procharged set-up that just uses the FMU and no computer programming. Which i don't like.
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Old 06-03-2014, 08:34 AM
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Thanks for the info guys. My setup is NOT factory, gues I could have mentioned that.. My ECU was calibrated by Arizona speed and marine back in 2004. I have the M3SC pro charger kit with remote mount inter cooler.

With a forged bottom end I assumed it could handle quite a bit of boost as long as it didn't detonate but I'm no Chevy guy.. Makes sense that the head bolts and gaskets would go first. Unlike my BB Fords, the Chevy head bolts protrude in to water jackets so there not as strong..
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Old 06-03-2014, 08:59 AM
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502's don't have headbolts that go into water. Another plus for the 502's. Chevy did a decent job with them.
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