Why rev limit at 5050 for 502 Mag?
07-08-2002, 08:06 PM
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Why rev limit at 5050 for 502 Mag?
I see from some upgrade packages like whipple and B&M that they are taking the 502 Mag above the 5050 rev limiter and going to 5400 or so. If the 502 Mag can safely go to 5400 what's wrong with just changing the ecu for a higher limit? seems like easy HP to me. I was talking to Hydromotive and he said I should re-program my rev limiter to go to 5400 to reduce the prop loading.
Why is the standard merc setup set for 5050. I think the HP500 is set for 5400. What's the difference?
Why is the standard merc setup set for 5050. I think the HP500 is set for 5400. What's the difference?
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Ray
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07-08-2002, 10:05 PM
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I may be wrong but I was told on this site sometime ago that the HP500 and HP500EFI were the only engines from Mercury Racing that were not hand built. They buy the longblock from GM. The bottom end is the same as a 502 from GM or Mercruiser.
As to the queston of why the rev limit I suspect that it is for warranty issues and the fact that the cam and EFI manifold on the 502 Mag peaks at or near 5000 rpm. The bottom end is the same as the ZZ502 for GM Performance and its redline is listed at 5800 rpm.
Ron
As to the queston of why the rev limit I suspect that it is for warranty issues and the fact that the cam and EFI manifold on the 502 Mag peaks at or near 5000 rpm. The bottom end is the same as the ZZ502 for GM Performance and its redline is listed at 5800 rpm.
Ron
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07-08-2002, 11:24 PM
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The cam won't let it make any more power at those higher RPM's. The HP 500 has a much hotter cam and only spins 5-5200. You are relying purely in rpm for any speed gains by doing this. More than likely the engine will not be able to pull your current prop from 5050 to 5400. So why re-pitch to a smaller prop only to spin it higher?
07-09-2002, 12:27 AM
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My 502mags turned 5150 with 21's on 1.36:1. turn 4950 with 23's. Picked up a couple of mph turning them slower but in the power curve (1991 carb motors - no rev limiters)
07-09-2002, 01:16 AM
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Rev limits on Merc engines are set at about 150 rpms over the max recommended WOT range. If you're bumping it at 5050rpms, then your tach could be slightly off at higher rpms and you could already be at 5150rpms.
07-09-2002, 02:00 AM
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so guys, basically on a 502 mag efi the rev limiter is set at 5150 rpms. what if i add exhaust
and the vortec max flow kit(msd ignit.,air cleaner, adj. fuel reg. and recalib. ecu) and ecu is set at 5300
rpms , do i still want to run 5000rpms max to stay at the top of the hp/torque curve ? currently i run a 23p mirage plus labbed at 5000rpms on a stock engine.should i try running a 24p bravo 1 ?
and the vortec max flow kit(msd ignit.,air cleaner, adj. fuel reg. and recalib. ecu) and ecu is set at 5300
rpms , do i still want to run 5000rpms max to stay at the top of the hp/torque curve ? currently i run a 23p mirage plus labbed at 5000rpms on a stock engine.should i try running a 24p bravo 1 ?
