Performance Boats Forum banner

1 - 20 of 45 Posts

·
Registered
Joined
·
307 Posts
Discussion Starter #1 (Edited)
My brother is putting together a pair of 572 cui BBCs for his 30’ Scarab. The long block specs are:
572 cui
4.375 Stroke
4.560 Bore
Cam ≈.632 lift, 112 LSA, Roller (edit:I/E @.050 256/264)
Planned Max RPM 5800
1050 Dominator, (2 circuit)
WP Merlin Marine single plane intake
CMI exhaust headers
Planned Compression Ratio 9.25:1 (based on stock Gen V 118cc heads) (He wants to run on Premium from the pumps.)
30’ Scarab, twin TRS outdrives

He runs in the James River, Hopewell, VA so he is in brackish water and but will likely run down to salt water in the Chesapeake Bay occasionally. The boat needs to stay family friendly. So considering the corrosion issue and all the performance tradeoffs, offer your opinions on the following:

Should he run Cast Iron or Aluminum heads?
What runner size?
What Valve size?
What brand has the best head for this application?

There is a budget for the project, but his wife is not looking too close. ;)

Other cool engine info:
Dart Big M block
Bryant Crankshaft
Callies Rods
Diamond custom pistons, ceramic coated

If ya want/need more info, let me know and I will ask my brother.
Thanks
Doug​
 

·
Banned
Joined
·
1,263 Posts
I'd look to cast iron since:

1) Weight vs aluminum is not going to slow that boat down at all. It's very heavy, and does not ride up on top of the water like the newer performance boats do.

2) Corrosion issues. Sure, you can get hard anodized aluminum heads but they are much more costly and the main thing is that many heads are milled after anodizing, therefore the deck faces where the water flows thru can still do a number on them.

That said, I'd look into the RHS 320 cyl heads.

================================

Optimum for performance without custom porting and going aluminum Probably 315 AFR's if you can swing it or AFR325's if not. Of course Pro 1 's are good to.

Note: head size mentioned above is going by your engine info and what I believe him to have for a cam.
 

·
Premium Member
Joined
·
2,129 Posts
My brother is putting together a pair of 572 cui BBCs for his 30’ Scarab. The long block specs are:
572 cui
4.375 Stroke
4.560 Bore
Cam ≈.632 lift, 112 LSA, Roller (I don’t have duration in my notes)
Planned Max RPM 5800
1050 Dominator, (2 circuit)
WP Merlin Marine single plane intake
CMI exhaust headers
Planned Compression Ratio 9.25:1 (based on stock Gen V 118cc heads) (He wants to run on Premium from the pumps.)
30’ Scarab, twin TRS outdrives

He runs in the James River, Hopewell, VA so he is in brackish water and but will likely run down to salt water in the Chesapeake Bay occasionally. The boat needs to stay family friendly. So considering the corrosion issue and all the performance tradeoffs, offer your opinions on the following:

Should he run Cast Iron or Aluminum heads?
What runner size?
What Valve size?
What brand has the best head for this application?

There is a budget for the project, but his wife is not looking too close. ;)

Other cool engine info:
Dart Big M block
Bryant Crankshaft
Callies Rods
Diamond custom pistons, ceramic coated

If ya want/need more info, let me know and I will ask my brother.
Thanks
Doug​
I'm gonna run about the same combo but a little more compression..I got STEELCOMP working on my CANFIELD HEADS..hopefully will be done by next month..Plans are to start assembly of the motor right after the NHRA finals..I'll get Scott to post some numbers when he gets a chance..(I bet he's in the garage right now massaging some ports right now..)
 

·
Just another Wannabe
Joined
·
1,198 Posts
When the desired rpm max is that low, don't jump on the trick heads with the huge numbers that you read in the National Dragster. A good solid deal with smaller runners that have good flow and velocity are going to be better in the long run.
I like the RHS Iron idea myself. I prefer doing a touch of work to some of the older Merlin's, but those are hard to tell if they have not been abused. So just get a good RHS or similar and get durability.
 

·
steelcomp was here
Joined
·
26,512 Posts
Ditto what wannabe said. I think there's a set of Merlin iron ovals in the spam section. Believe it or not, they'd probably work fine. With a little grinder work, they'd be killer even with a 2.25 valve. If they have a 2.300, even better.
 

·
Banned
Joined
·
1,263 Posts
Ditto what wannabe said. I think there's a set of Merlin iron ovals in the spam section. Believe it or not, they'd probably work fine. With a little grinder work, they'd be killer even with a 2.25 valve. If they have a 2.300, even better.
Merlin iron ovals on a 572 ? confused:

572 cui
4.375 Stroke
4.560 Bore
Dart Big M block
Bryant Crankshaft
Callies Rods
Diamond custom pistons, ceramic coated
Cam ≈.632 lift, 112 LSA, Roller (I don’t have duration in my notes)
Planned Max RPM 5800
1050 Dominator, (2 circuit)
WP Merlin Marine single plane intake
CMI exhaust headers
Planned Compression Ratio 9.25:1 (based on stock Gen V 118cc heads) (He wants to run on Premium from the pumps.
All this money on big cid's and good equipment edit in: twin engines edit end: and Merlin Oval Port's ?

Never seen it done before. Have you seen any dyno sheets or even performance reports of someone else ever doing this ?

Steel, IMHO it makes no sense to me.
 

·
Premium Member
Joined
·
1,681 Posts
I'd recommend a set of Dart 320's to 345's. Got a customer with a set of old Bull Dogs punched out to 4.600" bore with ported 990's and hyd roller cams. Engines have about 300 hours on them with hyd rollers. They made 680HP and pushed his Active Thunder in the 90's.
 

·
steelcomp was here
Joined
·
26,512 Posts
Merlin iron ovals on a 572 ? confused:



All this money on big cid's and good equipment edit in: twin engines edit end: and Merlin Oval Port's ?

Never seen it done before. Have you seen any dyno sheets or even performance reports of someone else ever doing this ?

Steel, IMHO it makes no sense to me.
I'm not surprised. Same reason VP can make 700hp with iron GM ovals on a 496. Port area and valve size.
What do you come up with for a port area and valve size for that engine? You're an airflow expert...surely you can figure that out.
 

·
Premium Member
Joined
·
1,681 Posts
Steel,
How many sets of RHS did it take to get 1 good set of heads that could be used?
 

·
Premium Member
Joined
·
5,115 Posts
Break time is over, Now get back to work Steel :|err
 

·
Premium Member
Joined
·
5,115 Posts
So the 540 is going to the dyno with Steels Heads and my camshaft. I better get out my good set of darts to "pick" the cam.

We was shootin for 800 and said the hell with that we goin for 850:)devil ...
 

·
steelcomp was here
Joined
·
26,512 Posts
So the 540 is going to the dyno with Steels Heads and my camshaft. I better get out my good set of darts to "pick" the cam.
Yeah, and give that dart board a good spin...

Hey Mike, give me a call when you get a chance.
 

·
Premium Member
Joined
·
25,975 Posts
.I got STEELCOMP working on my CANFIELD HEADS..hopefully will be done by next month.(I bet he's in the garage right now massaging some ports right now..)
hil:)hil:) Wow! You must know somebody, that knows somebody.

What do you come up with for a port area and valve size for that engine? You're an airflow expert...surely you can figure that out.

Haven't learned a damn thing have you. How many sites do you plan to get banned for life from for arguing with CFM. Going for 2 in 1 month?



100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3
 

·
Premium Member
Joined
·
5,115 Posts
hil:)hil:) Wow! You must know somebody, that knows somebody.




Haven't learned a damn thing have you. How many sites do you plan to get banned for life from for arguing with CFM. Going for 2 in 1 month?


I was thinkin the same thing:D
 

·
Registered
Joined
·
34 Posts
A 572 with max rpm of 5800 will need airflow of 370-375 cfm, at the valve lift of the selected camshaft, ie. .632". That's quite a cyl. head.
 
1 - 20 of 45 Posts
Top