454 MAG w/Whipple EFI ?

[KC]

I'm leaving the pistons as is, though I might drop the compression by softening the bowls in the heads.... easier than dismantling the block.
Still waiting for my motor to arive, then I will be evaluating the stock heads vs. aluminum heads.
I wish I had specs for these Mercruiser cams, it would be interesting to see the difference between the following motors:
- 7.1 MPI 310hp
- 454 Mag MPI 385hp
- 502 Mag MPI 410hp
- HP500 EFI
Spoken to Whipple a few times now, Dustin has been great help. I'm still working on the budget for this project, so far things are looking good.
- motor
- gasket kit
- roller rockers (a nice to have)
- Whipple system
- new prop
- engine swap
Having fun! KC

[Mach1Shorty]

Here's what I've gathered so far...
The 454mag mpi & 502 mpi both use the same cam:
Merc Part# 431-850478
224/224 .483/.483 115.5
The old 525sc (454 w/174 blower) uses:
Crane #132561
228/236 .530/.551 114
The 500 efi uses:
Crane #169621
230/236 .598/.610 114
The 525sc & 500efi cams are similiar, just more lift. So since the whipple is bigger than the 174 that the 525sc uses I think the 500efi cam will work pretty good. Have to talk to the whipple people, but I'd bet the 500efi whipple kit would work and the fuel mapping might not be too far off. Just have to have it recalibrated. Dustin may have a better cam recommendation, have to check.

[KC]

Thanks for the detailed cam information...
My 454 Mag arrives this Friday.... Ordering head gaskets today. The motor will be bone stock except for the Whipple EFI System, though it will be running AmsOil.
Talked to everyone about a prop, so far the 26P is getting the most votes.
The next two months will be an adventure!
KC

[502procharger]

keep in mind a 26 bravo 1 is just 1/2 deg more pitch than any other prop manufacturers 24p. for some reason bravo 1 4 blades are 1 1/2 pitch lower than there stated pitch numbers. so i run a 28 bravo 1 and it is actualy just a little more pitch than 26. ask anyone who knows props. good luck with the new setup.

[KC]

502procharger....
Your the second person to tell me that... The math says one thing but the performance of the prop tells another story...
First I'm going to test with a 28P, if I can hit the rev limiter then I'm leaving it on. The guy that I am buying my motor from had a 26P Bravo One on his boat, with the bone stock 385hp 454 Mag - he said it was slow out of the hole but it would hit the rev limiter. So tacking on an additional 180hp with the Whipple system the motor should turn the 28P Bravo One with no problem.
Let me know if you decide to unload yours.... I'll be needing one in the first week of October.
KC

[KC]

oops... I mean an additional 220hp with the Whipple System. KC

[502procharger]

kc,
i run about the same hp as you with my carbed/procharged 502. i spin the 28 bravo 1 all day long at 5100-5200 on my 25'v bottom switzer. do not buy a prop until you try every one you can get a hold of. every boat responds diff. to every diff pitch, rake, and cup. my good buddy ownes a prop shop and that is all he does is sell, fixes, blueprints ss props of all brands. i spend a lot of time at his shop just learning about what diff. manufactures do diff. with there props and what the effect is on your boat. what it reaaly comes down to after you add hp is what works, not what others tell you should work fine. good luck. let me know if you have any questions.

[Mach1Shorty]

KC,
Got off the phone w/whipple today. Sounds like you've got the best plan. The top mount kit they have for the stock 454mag is supposed to hit 615, maybe a little more with headers. The old kit was 590hp which was quite a bit less than the 650 I was shooting for. That's why I was thinking cam change. But if I can end up around 625hp with the headers and no cam or piston mods, I'm in spittin' distance. I think I'll take the easy way out. Plus the programming is done, so I can just mail in my ECU and won't have to tow it out west (although I was kinda lookin forward to that).
We whittled the mods down to adding the inconel exhaust valves, new valve springs, a felpro head gasket, and headers. My winter project just turned into a few weekends of work. Now what I am gonna do all winter!

[KC]

Mach....
My system should be here next week, it will take me a few weeks to build my motor and deliver the boat to them for the calibration - once that is done you won't need to deliver your boat to Whipple - but you can still come out to the river!
I going to drop in roller rocker arms and I allready have the Stainless Marine Header, with that the motor might be something close to 650.
Can not wait! It certainly looks clean! KC

[KC]

My budget got blown out of the water this weekend, so no Whiple System at this time. Bummer, maybe another time. KC