Thread: hp estimate.

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hello all.
I am planning on adding the following items to my 454 and was just wondering what kind of power you think i will be getting.

3931063 heads
single plane intake
lond tube headers
and the following cam specs.
278 292 234 237 .564 .566 112°

the motor all ready has
flat top pisons
hei
750 cfm carb

thanks,
Mike

What heads are on it now? the 063's are good heads, they are small chamber (about 101cc) so they might boost your compression ratio, depending on what's on there now. The cam is OK, mid range...what are you doing with the car?? Strictly street? The single plane intake is cool looking, but it will kill a little of your low end torque, but will give you a little more power up at the higher end. If you drive it on the street all the time, that's not where you will want it. Give me more info on the heads (stock or modified at all, ported, stock valves, etc) and I'll run a simulation on it for you. Also, do you know what head gasket?? (steel shim or a composite gasket?) What diameter headers? John

well the motor is actually in my jet boat. The heads came off a 396 out of a chevell.
I did notice that the heads seem to have some work done to them (I.E. valve springs, titanium retainers and some port matching. I am most likely going with a metal head gasket, as thin as possible.

Welcome to the forum Mike,

What size boat, what type hull ("V", flat, pickle, cat), what pump and impeller cut. All of these will have an input on where you want to make your horsepower.

Do you pull skiers with the boat, or just use it as a morning and early evening river racer?

Regards, Mark

its an 18' speed boat. I dont really know if its considerd a v haul, theres not much of a V, but it has one in the front. As far as the pump goes i have a berkeley jc with and a impeller.

Per Johns suggestion I'd consider using a dual plane like the Performer RPM instead of the single plane manifold. Assuming you have compression around 9.0:1 it should all work ok and be very drivable.

The "A" impeller behaves similar to a 2000-2200 RPM converter tied to a 3.0:1 rear end. Even though the boat is light weight you need good low to mid RPM performance to get the hull up on top.

By the time you get to 5000 RPM that impeller cut is requiring 415 HP to turn, By 5200 you need 450 HP and the log curve is rising quick. I don't think you'll ever see the benefits of a single plane manifold.

Cheers, Mark

thaks for the info Maw. Im hoping to get 400 out of the motor n/a. I have a NOS plate set up, running a 100shot. With this combination im hoping to max out my pump for now.

Good morning Mike,

Don't put a pile of money into the motor until you get the pump set up first. A good blueprint on the impeller and bowl works miracles and allows later horsepower gains to be transfered to the water. Figure on spending $1,000-$1,500 on the pump but you'll get more speed this way than spending the same money on the motor. This price included a new aluminum impeller.

If you haven't bought the cam yet you might look for a grind with a few more degrees of intake duration. If you're using Bassett headers (or equiv) then the motor will tolerate a bit more intake, say another 10 degrees.

p.s. We're adding a stainless "AA" impeller to our boat to load the engine harder. The motor is a blown injected 454 that I want to keep under 5500 RPM. The "AA" impeller should provide a 625 HP load at that RPM.

Regards, Mark