NEED MORE POWER 351 W aka volvo penta

[Alex V]

I have a 97 Chris craft concept cuddi 21' with a volvo penta aka ford 351 w. The engine was recently rebuilt, (less than 20 hrs) and the waterpump belt broke... turned off engine due to high temp, later boat would not start and ground teeth on flywheel... bumped engine and it wasn't frozen, although one week later it was and water poured from spark plug holes when plugs were removed....

SO when the engine is out getting redone I want to also add more tq/hp...

I have been looking at aluminum heads, intakes, cams, stroking ect...and serpintine conversion of the belts...

There is a plethora of info here and sorting through it all is tricky...

I don't want to make any more costly mistakes as I was overcharged by the first "big boat" shop and don't mind learning how to do the work myself. Any help will be greatly appreciated. I am finding the "trick flow" package will bump up hp to ~420 from the ~280 it has...fact? fiction? do's? don'ts?

OH another concern is HP/TQ the outdrive will handle... cobra SX single prop.

Thanks

[FAST FRED]

Go to your favorite Ford dealer and get his catalog of "crate" engines.

Cheaper and better to use a factory NEW engine than a rebuild and hot rod parts.

Just be sure your exhaust manifolds will fit.

FAST FRED

[stonebreaker]

Where did the water in the cylinders come from?

[Alex V]

I think I blew a head gasket when the engine overheated??

Buying a new motor is not the way I want to go... heads intake ect is more of what I am after... crate motors are too exensive, and bolt-ons sound better

[Jango]

More Torque is alot more important than HP. Go to a ROLLER CAM - 2001 Ford Explorer High Torque 302 HO will give you 50+ additional lb/ft (at low RPM) as well as additional HP. High HP Packages will NOT provide the required low end torque. If you want still more, open your 351 to 427.
John

[Alex V]

Thanks John.. I will check into that. So do you think aluminum heads intake and cam pkg will make much of a diff, or is it a waste?http://www.trickflow.com/product/eng...ekits_ford.asp
This is for the 302, but they make similar packages for the 351. If I stroked the 351, could I use the same electronics computer injectors ect? or would I have to change all that?

[Jango]

You should be able to keep the existing Comp. etc, since computer changes are usually required with "wild cams" . The Explorer cam duration is only 256/266 w. a lift of 422/448 - hardly wild. You might check this further.
Aluminum heads are a plus, with additional flow as well as the ability to increase comp. ratio and still burn Gas. Just don't go too Big, since torque could be adversely affected.

[Alex V]

Thanks, I will check with you when I begin the project...

[Alex V]

OK... next


will a cobra SX outdrive handle the 450tq-500hp power range???

What are the specs for thart outdrive and where can I find them??

[gonzo]

A new marine base engine is about $3850.00

[Pevito2]

I have a 351W that was recently overhauled. it has iron heads, with large intakes, and also low profile stainless steel valves, regular springs, and working with a 9,6 compression rate. Hipereutetic pistons and plasma rings. It works flawlessly , Very good low RPM torque, and also top end speed. it pushes my 20feet boat at 29mph with 2800 RPM with 6 adults and a consumption of only 6GPH, and it is carburated.

What you need is not HPs , but torque, unless it is a competition boat. So you should focus on increasing compression rate and also a CAM with more lifting, not duration. Take alook on this thread , specially on the "quench" issue: Higher compression rate on a ford 351W
Good Luck!!
Pevito2

[Alex V]

My stock 351 was taking my deep v Chris craft 58 on GPS with 6 adults... thanks for the info I will check out the link... for now I am thinking racing heads intake and 0 to 5500 rpm cam to match.

[gonzo]

For more lift, aftermarket rocker arms are a cheap solution. Going from a 1.5 to a 1.65 or so gives you a moderate increase.

[Jango]

Stock rocker arm ratio on Sm Block Fords is 1.6. Going to avaiable 1.7 ratio, In my opinion, is not worth the cost for the very small gain, maybe 10 hp. In most cases you will also need taller valve covers.

[tuantom]

I just ordered a cam for my 24' 351w powered boat from Delta cams in Washington. They came highly recomended from someone who has over the past 20 years built lots of marine 351's. I initially was going to get a retrofit roller cam for my older block; but Scott over there talked me out of it by saying the power increase would be so-so for an engine turning 4500 rpms. The mild performance gains (even with my GT-40p heads and thru-transom exhaust) wouldn't justify the additional machining costs you pay to have the tops of your lifter bores ground flat . He talked me into a much cheaper (around $100 for cam and lifters) hydraulic flat tappet cam. @ 0.50 in/ex 212/218 - Duration 260/268 - lift w/1.6 rockers .450/.460 and 112 separation. He says it will be a good all round recreational marine cam and still allow me to troll @ 650 Rpm. We'll see this summer.
- Just what I've learned recently,
Tom