Pat McPherson

Gen VI 454.
GM rectangular intake port heads with 2.25 and 1.88 valves.
9:1 compression.
Merc 500EFI cam shaft and associated roller valve train components.
AZ Speed and Marine EFI intake and plenum.
Merc 500EFI throttle body and injectors.
Stainless Marine aluminum exhaust manifolds.

Smitty

iTrader: (1)

I'm gonna guess 450 hp as the lowest number.

LAKESIDE RESTORATIONS

I would guess about the same.. Depending on the cam & actual heads you are running you may be able to get close to the 5's.. Some carbed 454's stroked to 496 & done right can get there. You have the added bonus & luxury of EFI.. Jamie / Lakeside

Smitty

iTrader: (1)

I think he needs more compression to get to 500.

LAKESIDE RESTORATIONS

My bad.. I didnt pay attention to the comp.. He could still raise the comp a bit if he can run 91/92 octane and he hasn't bought the pistons yet.. He will have to remap the PCM though to keep everything happy..

Pat, What type of fuel system & pump will you be running?? Are you planning to do any other head work? Or just bolt on & go??

I am a bit burned out after a long day, so please pardon me if I am statring to sound silly or a bit off of my game tonight.. The ol' ass is starting to drag Jamie / Lakeside

handfulz28

Hey Pat, can I tag along on this thread? I'm probably headed down the same path.
Only 450hp from bolting on the most important 500EFI pieces? How different are those heads & comp ratio from the HP500 pieces? I guess the 48 ci are worth a lot of power?
I actually have in mind that 450hp goal for my project; wonder if I could save some $ by sticking with just the MPI system, and painting it blue
Thanks,
Michael

Donzi502

My guess is that if you loose the Stainless Marine and put some E Tops on and cut 30 thou off the base circle of the cam to crank the lift up some and add 7-8 degree of duration then you may almost make 500. You will have to set the cam up bang on and port match everything and turn to 5500 rpm as well. You will have to remap the computer and play with fuel preasure as well. Of course a nice air gap manifold and a stage 5 Bigs 750 carbon maker will give the same with a lot less agveration, oh and a lot less cash, you can use the saved cash to pick up a real nice MSD ignition. Now you can set the RPM and tune without giving Jim from AZ speed 500 a time. Just my thoughts. Jason

Griff

You're giving up 10% of the ci's and probably 10% of the hp as well.

PatriYacht

Because Pat's using most of the parts that are used in HP500's but with smaller cubes, I would say about 500 hp but at a higher rpm than a HP500. Raise the rev limiter.

Pat McPherson

Hi Guys,
I have been collecting alot of parts over the last two years.

The base engine I will use started life as a 310HP/7.4MPI.

From this engine I plan use the following:
block
crank
flywheel
balancer
sheet metal
accessories ie. starter, alternator, water pumps, brackets...
EFI harness, sensors, and computer

Goodies in my stock pile:
GM rec port heads
500EFI cam and valve-train
500EFI injectors
500EFI throttle body
AZ Speed intake, plenum, and othe EFI parts from a Volvo Penta 7.4GSi
double fuel pump from Carter/Volvo Penta
Stainless Marine exhaust.

Items I still need to acquire:
piston (probably Keith Black)
rods (probably Scat)
gaskets

Then, of course, some machine work, balance the rotating assembly, assemble the engine, and have the ECU programmed.

I was messing around with Desk-Top-Dyno last night to see what numbers it would come up with.
I started by inputting everything I know about a Merc 500EFI and the puter spit out 500HP at 5000rpm.
Then I dropped the displacement from 502 to 454, raised the compression from 8.7 to 9, and went from open small tube header to small tube headers with mufflers.
The numbers I got were 465HP @ 5000rpm and 467HP @ 5500rpm. If I raise the compression to 9.5, the power goes up 10HP, but I'd like to be able to run 89 octane.
I would plan to run the engine at a max of 5200rpm with the rev limiter set at 5300 do to the cast steel crank.

Thanks for the input; we need something to BS about during the Winter months...