502 MPI upgrade results
10-08-2016, 07:24 PM
#61
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I called Mark at Precision about a year ago mentioning this thread and he gave me a grind number for a custom Comp cam he recommended and had a tune for. I called Comp and they sent me specs on it which was 230/230 @.50 and .578/.578 on 114. What scares me is that this may be the one that was used in this original build which led to the reversion Haxby just spoke of...or maybe not...lol.
10-09-2016, 02:14 AM
#62
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Just to update this old thread that's been brought back up. This motor is still running but has had a couple cam swaps. The original cam had reversion issues that caused some rusting in the exhaust ports. The only cam I had laying around for a quick swap at the time was a zz502 cam. It made a little more hp 15-20 ish and had a broader torque curve, but performance in the boat wasn't much different. The idle was a fair bit rougher then the first cam and the owner didn't really like it so we swapped that out the following year for an Erson 230 - 236, similar to a 500efi cam with a bit more lift. That really woke it up, making 570hp and picked up 3mph in the boat. It's still a bit of a lumpy idle but very solid.
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10-11-2016, 10:24 AM
#64
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Haxby, I forgot to ask you if that Erson cam you posted would work for my application or if it would be too much? (provided I can get a tune for it). I can't seem to find a GEN V version of the 500EFI Crane 169621 (230/236 @ .50)
Last edited by Diamond Dave; 10-11-2016 at 03:36 PM.
10-12-2016, 07:21 AM
#65
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I have a few 502s to do this winter. Might have to give you a call
Just to update this old thread that's been brought back up. This motor is still running but has had a couple cam swaps. The original cam had reversion issues that caused some rusting in the exhaust ports. The only cam I had laying around for a quick swap at the time was a zz502 cam. It made a little more hp 15-20 ish and had a broader torque curve, but performance in the boat wasn't much different. The idle was a fair bit rougher then the first cam and the owner didn't really like it so we swapped that out the following year for an Erson 230 - 236, similar to a 500efi cam with a bit more lift. That really woke it up, making 570hp and picked up 3mph in the boat. It's still a bit of a lumpy idle but very solid.
11-16-2016, 06:58 AM
#66
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A few months back you mentioned you had a couple of modified mag mpi systems for sale. I am needing a mag mpi lower intake, would you sell one of the ones you have if you still have them? If so, is it modded like the ones I have seen on here and how much? My intake is damaged from corrosion on the back water port side. Thanks, Steve
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