454MagEFI upgrade HELP!

[pondrunner]

Is the best (reasonable)mod for the stock 454mag EFI to add an IMCO proflow exhaust,K+Nfilter and MSD ignition? I'm told this will net approx 4-6 mph 50-60hp. Is it necessary to reprogram the stock ECU? Any pitfalls? I'm told the Imco exhaust was designed for this engine specifically, netting the biggest results?!?Any info thanks...

[playdeep]

I did the aftermarket exhaust k&n filter swap on my 502efi. motor.Reprograming the ecm I was told by several motor experts was essential.I had jim shoffner at arizona speed&marine do it.picked up about 4mph.better midrange acceleration and no more blackened transom.

[SupriseSuprise]

I am with you Pond Runner, I recently bought the imco package from Teague and also purchased a Vortech EFI package which comes with the MSD ingnition and an adjustable fuel regulator. They said I should see about 60-65 hp added to my 502EFI. Doing the math, 13hp equals 1 mph, I should get about 5mph. I am also sold on getting the prop "lab" finished to take advantage of some extra rpms. The goal was to get 7-8mph.

[Maverick]

Originally posted by playdeep:
I did the aftermarket exhaust k&n filter swap on my 502efi. motor.Reprograming the ecm I was told by several motor experts was essential.I had jim shoffner at arizona speed&marine do it.picked up about 4mph.better midrange acceleration and no more blackened transom.
What exhaust did you go with, and at what cost? You're 4 mph --- took you from what mph to what_____ mph?
Finally, who has had any success with "trueing the trailing edge of the transom" - making the edge sharp? Old Hot boat articles talk about 3 mph...

[playdeep]

Maverick,sorry I wasnt more specific.I went w/the EMI thunder manifolds.Jeff Clark in havasu showed me dyno sheets that showed they made as much h/p as the imcos about a grand less(even including S/S risers).My boat was a 25 eliminator eagle went from 75.3 gps to 79.7 labbed the prop and broke the big 80.(81.1) 1 person 1/4 tank of fuel.

[SupriseSuprise]

What size and degree prop are you running on that eliminator? After my recent changes to the motor, I want to upgrade the prop and need to consider simply a lab finish to my existing or going up 2degree with a lab finish? Any suggestions?

[Maverick]

Originally posted by playdeep:
Maverick,sorry I wasnt more specific.I went w/the EMI thunder manifolds.Jeff Clark in havasu showed me dyno sheets that showed they made as much h/p as the imcos about a grand less(even including S/S risers).My boat was a 25 eliminator eagle went from 75.3 gps to 79.7 labbed the prop and broke the big 80.(81.1) 1 person 1/4 tank of fuel.
Obviously, your eliminator is a much faster hull than my Outlaw - I'd be happy to see a real 70 mph. Thanks for the info on the EMI manifolds. Who did your "lab" prop work and at what cost?

[playdeep]

I ran a 26p bravo1 reworked by the Propeller co. in havasu just right for wakeboarding,waterskiing etc.When I did the 81.1 run I borrowed a 28p bravo1 reworked by Bronson-Hill propellers in so-cal.With the big prop it took a while to get that speed Ihad to make a long run at it.Maverick,I have a couple of friends w/bajas they use Hydromotive Intimidators.I guess bajas are a true V-bottom (no delta pad,steps etc.)Tom at hydromotive says this prop works great on that type of bottom because it lifts the transom.He really knows his stuff might be worth a phone call.