Realistic HP

[babybeze]

Okay given that most on here are Chevy people I am going to open myself to possible ridicule. I have both a 396hi perf chevy short block with big oval port heads and also a Ford 351 Cleveland that I could use for the aquacraft motor. I have most of the marine hardware for both engines as well. I have been building Clevelands since I could drive so I am fairly familiar with power potential and the weak points of that engine. My question is how much realistic HP can I build with a stock forged chevy 396 crank and rods with oval port heads ? On both engines I will have to purchase valvetrain, pistons, machine work on block and heads, ignition, oiling and induction .. so I'm kind of at a wash as far as price goes. I just would like to know where I can take the 396 and will it handle those levels and still be "family friendly" (this is supposed to be a family ski boat). Cost is always a factor so I'm not looking to do aftermarket heads or exotic t&d valvetrains. Need to work with what I have and make the most of it. You guys are always honest on here and I appreciate that. Once again thanks in advance for your help.

[pwderman]

Okay given that most on here are Chevy people I am going to open myself to possible ridicule. I have both a 396hi perf chevy short block with big oval port heads and also a Ford 351 Cleveland that I could use for the aquacraft motor. I have most of the marine hardware for both engines as well. I have been building Clevelands since I could drive so I am fairly familiar with power potential and the weak points of that engine. My question is how much realistic HP can I build with a stock forged chevy 396 crank and rods with oval port heads ? On both engines I will have to purchase valvetrain, pistons, machine work on block and heads, ignition, oiling and induction .. so I'm kind of at a wash as far as price goes. I just would like to know where I can take the 396 and will it handle those levels and still be "family friendly" (this is supposed to be a family ski boat). Cost is always a factor so I'm not looking to do aftermarket heads or exotic t&d valvetrains. Need to work with what I have and make the most of it. You guys are always honest on here and I appreciate that. Once again thanks in advance for your help.

396-427 cranks are the same hi po's were tuff trided. As far as durability of the stock crank a friend of mine is running a stock crank in a blown application down in the mid sevens with a 427ci. He replaces the crank every 150-200 runs. How hard are you going to run it? The power levels I'm sure Paul and Buzz can give you an up to date idea on what to expect. It's hard to beat cubic inches,but it doesn't mean it can't be done. I don't have a clue on the Fords but I'm sure you could wring out some good power numbers and given your familarity with them I'd think that would be your first choice, as Chevy would be mine...

[Campbell Dude]

One of the best running “ Family ski boats” I have seen was a friend of mine’s 19" Miller V-Drive who ran a Cleveland, good power and fuel economy.
That being said I think if all else was equal I would go with the BBC, you will get more torque do to a heaver reciprocating assembly. Should be easer to make more HP with less $$$.
You could swap the Cleveland and get a 427 or 454 block, cubic inches are usually the easiest way to get HP.
Another thing to consider is the balance of the boat, If it was originally rigged with a BBC changing to a Cleveland could upset the balance of the boat, there are others here who are much more qualified than me to comment about engine placement and balance.

[Wannabe]

Well, Paul does not like to state too much about this, but he drove my car and ran a stock Forged chevy 3.76 stroke crank to 9600 rpm's in a 1000 horsepower naturally aspirated deal. No problems.
A 396 is a good deal, but getting a larger bore helps the airflow, and cubic inches. Also, if you are keeping the rpm's down, there is nothing wrong with oval port heads. They make great torque and power down low. Instant power at the step of the throttle. They just don't run the big rpms. A pump gas deal in a 396 with the parts that you have could make 500 horse without straining and definitely would not hurt parts. If you wanted to step up the bore to a 427 deal, figure another 30-40. Keep the rpms below 6400 or so and set the engine up for that. It will fly and last for ages. Possibly a decade without touching it.
And that would be more horsepower and much more torque than our 88 mph wonder. So, how much faster would you really want to go?

[Terrible toy]

Like Wannabe mentioned it would be nice to round up a 427 block. I concur that your oval port heads are the way to go. With a 427 block you could add 2.30 and 1.88 valves to the heads and bore the block to 440 inches. If you did some port matching, short side radius and maybe a little bowl work along with a cam say made for a heavy automatic car you would be surprised what an animal it would be from off idle to 6 grand. Don't need a lot of carburation either. A 750 vacuum secondary carb on an Edlebrock RPM air gap manifold would kick butt. Even with out the port work you could embarrass an over carburated, over cammed, "race" boat over the length of most lake races.

I'm in the planning stages of a new engine for my 21 foot cruiser. One option I'm thinking about is a 496 (4.250 stroke) inch engine with the oval port heads. Up to that size engine those heads work really well. The 2.30 intake valve picks up a lot of torque with the high velocity oval ports.

[RiverRacer]

My 402(.030 396)from back in the day, 2 bolt block, cast crank, 3/8 bolt rods, TRW pistons, 049 heads with the small valves, Isky Z-45 cam, Edelbrock TR2X intake with a pair of 390 vacuum secondary carbs!. Don't know how much power it had, but in my Lavey it ran 88 and change in the 1/4!..

[boatpoor]

Not to shabby Art.

[Terrible toy]

Yeah, not too shabby Art. Reminds me of the Jr. fuelers who ran two bolt main small blocks to ungodly rpms with 90% in the tank. Makes you wonder why we have splayed 4 stud billet caps and crankshafts that cost a small fortune.

[FC-Pilot]

Matt, I tend to be a little more conservative on my predictions that others. I would say a TRUE 425-450 HP is within reason with the 396. That is with a setup that would last for many seasons. If you are like me you don't want to build an engine that has to be fixed and rebuilt every year. I would rather stick in something reliable and forget about it and just feed it fuel. Like Bill (TT) said, a little work on the heads (which is something you could reasonably do yourself) could go a long way. With a small amount of home brewed port work (which really is just more of port cleaning), a good valve job and a well picked cam I think you could have a real winner. The thing that will really make it top notch will be the little things. Proper ring gap, a tight squish, a well planned valve-train and good valve-train geometry, a well fitted intake topped with a well tuned carb will run great with years of dependability. I would top off the ignition with a fresh HEI for dependability. I would not try to spin it over six grand as that will quickly reduce its life span and the stock HEI's don't like going that high anyway.

Oh, one thing that just came to mind, try to get the compression ratio over nine to one. I have seen big blocks get very sluggish under that. The little extra compression will really help it to have more snap to it. I would not try to run over ten to one as it might mean higher octane fuel than pump stuff.

Now I don't know a dang thing about Ford stuff so I will not try to say which one you should go with. If you decided to go Chevy I could share some insight and experiences and info. Hopefully there will be some Ford guys come in and share some info.

Paul

[babybeze]

Well if 450 hp is possible then its hands down the Chevy. I can get that out of the ford but have to turn it higher and I don't want to tear it down every winter. How far can you bore a 396 ? Crrently its .030 over but it needs a clean up. I have heard .100 over is possible but that seems rather large to me. I would love to go with a 427 crank but most of the cranks I have looked at are 1k or better and I woul rather spend that money on a good valvetrain or some other goodies seeing as I already have a good crank. As for heads these are actual 396 truck heads but not the 049. Don't have the numbers in front of me to say exactly what they are. Haven;t cc'd them yet either. I was looking at 10:1 compression if I stick with pump gas. Is alcohol and injection even worth the effort on something like this or should I save that for a future endevour ?