Small blocks
 

I'm looking for info on how to bump my small blocks up to 550 hp or so. I don't know the specs of the motors now other than when I bought the boat I was told port motor dynoed @ 420 and starboard @ 423.
I have pulled the valve cover and intake. There are roller rockers on studs and the heads are ported. They have stainless marine trough hull exhaust edlebrock 750cfm carbs and performer intakes. Any proven motor packages,thoughts or help? Thanks

P.s. I want to run them n.a.

neat o projects. Tell us what is inside if you can find out. depending on what you have it will be interesting what combos some will suggest to make your desired hp. post some pics

P.s. I want to run them n.a.[/QUOTE]

You said it without saying it.

Hard to do 550 with anything under a 434 and have it idle and be drive friendly.

I would not focus on HP if I were you but Id focus on torque.

Like the prior poster asks- whats it got in it. You may not be able to "get there" from here without a lot of new stuff.


Uncle Dave

I will as soon as I get them out of the boat. I bought a project!!! Is a 83 Wellcraft nova II 26' it's rigged with small blocks and asd #6s. It needs a lot of work. Paint,dash,controls,aluminum swim platform,stero,ect,ect.
I'll be looking for a lot of parts and help ;-)

It ran 67 mph with 5 people,coolers and about half a tank in it (70 gal)
When I was checking the motors I found that the port motor had no intake lobe on the number 5 cylinder. That explains the little miss in it. Dam!! They are supposed to be 50-70 hr motors.

So I figure if I'm in one lets do both and upgrade. I thought about forced induction but there is just more moving parts to fix that's why I want to run n.a.

I'm with UD on this one, 550 N/A is not impossible, but it's going to be difficult without sacrificing drivability and spending a ton of money. Plus, like he mentioned, torque is likely going to suffer as well.

If you are willing to spend more than 10K per engine, and use aftermarket blocks with at least 434 cubes and some top of the line heads with a solid roller, you can probably get there, though it's going to be tough on pump gas, and you're going to have to spin some decent RPM. You're not going to get 550+ spinning to 5500 or 6000.

On the other hand, some 350's or 383's with hydraulic rollers, decent heads, and some small blowers will get you there easier, for probably less money, and allow you to adjust boost and power levels to the octane of fuel available.

Ig got a "recipe" of parts for a 500 hp 500 lb ft 406 that pretty cheap to build and absolutely thumps.

A quick run around the lake with a few blast here and there up to 90 MPH blast and cruising.

http://www.youtube.com/watch?v=yiYbs97NSyI

Lots of fun - in a light boat it will scare the panties off the chicks, impress you friends and not kill your wallet.


UD

This is why I'm asking. I don't know enough about boat motors to put a package together my self. This is my first "speed" boat per say.

I have a buddy running a small block in a car that put down just under 650 on 93oct. He is spinning Into the 7000 rpm range. (I think it's a Wagner motor)

I'll know more when I open them up. I guess I didn't think 550 was outside the dependable pump gas range. Hp is not the main goal here,just going faster on what I have while I have them open!!

I get it.

I was there about 20 years ago going from car to boat engines.

VEry different set ups. But nothing magical for sure.

You have a much tighter set of variables on engine manners due to a variety of factors that restrict marine setup.

In a car you can run whatever duration and lift and overlap you'd like without worry of idle or water reversion, and you can run a super long header exhaust - Boats have a much different cost structure and efficiency factor with a fully wet exhaust system.

Exhaust ranges from junk - to artwork that costs a fortune for a small block marine engine.
Unfortunately performance matches these ranges 1-1 with dollars.

If you shift your drive at more than 8-900 RPM you'll have drive problems and start spending large dollars.

Like all other things you can get there but the first thing you do is come up with a realistic budget.

The lie-o-meter

https://www.youtube.com/watch?v=yYK78rm-KPI

Uncle Dave

Find out exactly what you've got, first. Then, let us know what your budget is, and we can recommend some stuff.

Budget is the main consideration, here.

I would guess that UD's build with a little less cam should work pretty well for you. Forget about chasing peak HP, lots of torque is what you are looking for.