PA.WOODCHUCK

Currently has MEFI-1 ECU. Is it possible to build to 500-525HP without going wild and keeping civil? I looked into Procharger's bolt on kit stating 600+ but requires premium fuel but would like t run 87 octane. Anyone have a rundown of what's all needed?

thanks

AllDodge

iTrader: (1)

I doubt you can build that much HP and run it on 87, should be able to do it with 89/90, mine is 530 and runs on 90.

articfriends

iTrader: (1)

I made 563 on.my dynonwith modded 502 on 89 octane (j607, dry dyno headers, no accesorys). We made MORE hp on 89 than 93 fwiw with flat top pistons at 8.6 to 1 or so, should have tested it on 87, had zero hint of kr on 89, even after adding a couple more degrees of timing that didnt yield any gain, Smitty

PA.WOODCHUCK

What is the OEM cam specs?
What are the limitations of the OEM intake system, injectors, and MEFI-1 for doing mods
What changes did Mercury to get 525 which I presumes is a NA engine and 8.2L

Anyone willing to share your build please PM info

thanks again from a rookie BBC owner

Crude Intentions

iTrader: (1)

Griff

502 MPI upgrade results

articfriends

iTrader: (1)

Ive built several mpi intake based motors in past couple years. Cut down intake runners to match plenum floor, cut out divider in intake snd blend it, port match intake to heads. Port the iron heads, go after the ridges in chambers around exhaust valve or even better, sell them and buy at least EQ iron heads. Send your stock throttle body to TPIS and have them bore it to twin 68mm from twin 60mm, blend intake plenum to match throttle body,use a cam that is similar to 500efi or slightly bigger. Upgrade exhaust. Your keihan injectors flow plenty of fuel to support well over 600 hp, they are the same ones the 525 efi uses, just be sure to have them flowed and cleaned. The 502 i did this to made 563 hp at 5700, i also did this to a pair of 454s that made 570 hp BUT it was at 5900 and they had more head work than the 502 and were built to add whipple sidemounts to. The power band on them might have been a little "peaky" if they were ran in boat NA. Dont buy the crappy aftermarket flame arrestors that neck down to a round element, its a hp killer. All three of these were mefi3s, not sure how tune would be above 5000 with mefi1s since you have to do all the top end tuning where the tables end. I can help lead you in right direction on some of these mods if you do it, you can pm me if you have more questions, Smitty