5.7 250 HP

[FJB20]

I read at Mercmarine.Com that the difference between a 250 HP 5.7 and a 300HP 5.7 is the Multi-Port Fuel Injection and a Digital Ignition.
If One had a mind to Upgrade-- Any Idea on Cost
50 HP Sounds Niice Thanx FJB20

[Sam]

A few years back a friend of mine and I looked into converting his SeaRay into an EFI system. At that time it was going to cost him $2,000 per engine for the hardware . Needless to say the bang was not worth the buck for him. I would venture to say that the same would hold true for you. There are to many other upgrade choices that you could do that would gain you some real HP for a lot less money. I am no gear head but I would think about a cam, heads and or and intake all would gain you some real HP without breaking the bank. I just completed an upgrade of my 5.7. I basicly put in a new top half and went from 220 hp to around 325-350 hp. I would be happy to share my example with you, just let me know.

Sam
Donzi Mainia ! Catch it

[Kikwear]

Sam, I'd be interested in knowing your plan. So, my 2V 350 is only about 250hp?

[Rootsy]

Kikwear,

your 350 2V is rated at 210hp @ prop... although there is really no difference between it and the 250hp version that i can find and i've done a lot of research. btw, I have the same year/boat/engine combination as you. actually my motor is out of the boat and on the engine stand as i write this... with a new camshaft nestled in between those cylinders. cylinder heads get done this week and it should all be back together next weekend unless something "more important" distracts me (that'd just plainly tick me off though)... removing the engine is no piece of cake either, but hey i like a challenge...

[Kikwear]

Any info to stir me in the right direction for more power for this unit would be appreciated. Pulling the engine would not be that big of a deal for me. When you say the heads are getting done, do you mean P&P?

[Rootsy]

I retained the stock heads, 14096217 casting number (GM 300 hp crate motor head), they are sufficient for what i am doing, except they weigh a bit more than aluminum . I opted to do the valvetrain only. with the comp xtreme marine roller camshaft i had to step up to dual valvesprings in order to achieve the required spring pressures and they are 1.45 OD x .660 ID. They require the use of teflon valveguide seals which are 0.530 ID. In order to make all of this work on a stock chevrolet head which uses 1.25 OD springs you have to have the spring pockets enlarged. In order to have the seals fit you have to take the valveguide OD down to 0.531 and in order to accomadate anything over about .470 lift you have to have the valveguide height reduced. so that is what i was talking about. If i do any porting and polishing it'll be port matching the intake side and if i put new valves in i'll probably work the bowls over a bit and toss a valve job on em... depends on how ambitious i get. Most i'd do is probably knock the sharp edges and the casting flash off. all the machine work for the springs and seals comes to about 50 bucks and though i can do it myself, for 50 bucks it isn't worth my time and effort. if you go purchase the seat and guide cutter and arbor that is over 100 bucks alone. I have the guide cutter but not the seat so instead of buying stuff i figured i'd just get it done...

Where Sam and I will be with power is just about all you are going to want to put through an alpha anyways if you want to keep any kind of longevity. Fire me some email if you want to know all that is stuffed inside of the SBC.

as far as ease of getting the motor out.. it isn't a matter of mechanical inclination... it's a matter of too big to go through the hatch.. you have to basically remove the exhaust manifolds and the accessories off of the front of the motor... i had my cylinder heads off also so that i could get the machine work done so it was easier... removed the motor mounts @ the upright studs and had to turn the motor 90 degrees to get it through the hatch... and the motor mounts were just about the width of the hatch in that direction... i'm gonna put her back in with the cylinder heads and intake manifold on the motor.. we;ll see how it goes...