aero-offshore

I agree, but he hinted about a blower for the future and being the penny pinching SOB that I am, I suggested saving for all the parts now for a blower motor ,it would be way cheaper than to do a little here and spend 800.00 on a set of heads now that would'nt be the best choice for a blower down the road.

Liberator21

Pay Attention!! GEEEZZZ
I said I was only kidding about the blower.
That will be for my next boat.
Right now, I just want to get a bit more out of what I have.
Like I said before, When conditions are just right (one person, 1/2 tank or less of fuel, cool weather), I can just touch 60. I want to be able to comfortably make 60 with 2 people on board (me and one passenger).

robyw1

If your engine runs out of steam at 4600 then the 180cc would still be considered too large according to my brain. If however you ARE going to do a whipple with a different cam, intake then the 200cc will be great. Don't get crazy with the 220s. stick to 200 or less. Now what pistons are you running because you're thinking 64cc chambers but this could put your compression a little high for forced induction.

Roby

robyw1

After reading further about your current engine just get the 180cc heads. Use a Performer RPM dual plane intake. You will no doubt be told that a single plane intake will work better but take it from me. I'm right they're wrong.

Roby

robyw1

I hate to tell you but with his duraton of 262 the extra 20cc per port will kill off the bottom-end and would probably never match the power of the 180cc until 4000 RPM. There is no reason to do this.

Roby

Liberator21

The bottom end is using a Scat forged stroker crank, with the scat forged 6" rods, and SRP forged dished pistons. Compression calculated out to 9.6:1 with 64cc heads (thats what's on it now). The intake manifold is the GM performance parts cast iron Z28 dual plane intake.
The boat pulls like crazy in the 3000- 3500 rpm range., it just seems to lose a bit of that when you get up around 4500- 4600 rpm. When I drop the prop pitch by 2", it winds up to about 4900- 5000 rpm, but it just feels like something is missing. I figured the larger intake runners would help the top end. As far as the single plane intake is concerned, they have their place, I just don't think it's here. Most of my driving is in the mid range with the occasional top end blast. I have so much pull at the lower end, I think I can afford to give up a little to get some top end improvement.

cstraub69@comcast

With a 383 and the bottom end you have I would go with a 200 cc head with a 2.055 intake valve. Althought the 180's would work, the 200 will have good velocity at low lifts and I feel the 383CID would benefit from a larger valve area. Also the small cam being used now I don't think would have to be changed. . .I prefer small cams with good flowing heads. I would sell the cast iron manifold and for the extra $200 bucks get an Edelbrock airgap.

Chris

robyw1

But you see he is running out of top-end; all a 200cc intake port head will do is make him run out of bottom-end. he won't gain any top-end with this cam. Trust me I have experience with 383s and 400 AND the 377 (400-block with welded up 350-main) They all respond better with smaller ports if the max RPM is 5500 or lower. In order to take advantage of a 200cc port head he would have to increase his cam duration to 280 or more plus add a victor style intake. In his current configuration the 200cc port head would drop his BSFC numbers which would rob him of power up till about 4500 RPM. He would be in essence paying big bucks for less power. He can use the 180cc head in future mods to make solid power to 6000-RPM.

In fact as it is now I bet if he used the 200cc head he may never see 4500-RPM unless he drops the prop pitch. It wouldn't make enough power to carry it.

Roby

Liberator21

I'm raw water cooled, and run Exclusively in salt water (LI Sound). I would love to run an Aluminum manifold, but the boat is left in the water all season, so I think that's out of the question. Also, when changing the heads, would it pay to go to a 1.6 rocker? I'd have to get new ones anyway.

robyw1

You can get a way with running an aluminum manifold in salt water because they're so cheap. Just replace it every 2 years. This would be a great way to experience the difference in intakes.

Roby