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a set of AL BBC heads for a Blown Gas Flat drag boat which would you buy? currently I run a set of iron merlin 345`s open chamber heads..
I`m thinking about the AFR 357 but I`m no expert by no means!!!!! I thought Edelbrock had some new Badass heads that were suppose to be out by now but havent seen them in a summit/jet cat.... As usual thank you guys! Tom
 

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a set of AL BBC heads for a Blown Gas Flat drag boat which would you buy? currently I run a set of iron merlin 345`s open chamber heads..
I`m thinking about the AFR 357 but I`m no expert by no means!!!!! I thought Edelbrock had some new Badass heads that were suppose to be out by now but havent seen them in a summit/jet cat.... As usual thank you guys! Tom
Tom, the AFR CNC 357's or the Dart CNC 355's would work well for your deal. If you want to step up a bit more, I'd give Curtis Boggs a call and have him prep a set for you're specific combo. That said, there's other options and a bit more to it than just heads. Give me a call later this week and let's discuss....
 

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What is the problem with the Merlins?
I personally don't think the edelbrocks are up to the quality of "real" race heads.
Wags
 

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I would stay away from the dart 355 in a blown application. They just aren't that strong of casting.The AFR would be a better choice. Its a stronger casting.
 

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I would stay away from the dart 355 in a blown application. They just aren't that strong of casting.The AFR would be a better choice. Its a stronger casting.
X2. Even one step better, I'd go (without knowing anything about the engine, but just for comparison sake)
the Brodix BB3 Extra 380CNC.
 

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Does an alcohol motor have different needs than a gasoline motor cylinder head wise? Assuming they have the same displacement and same blower?
 

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Does an alcohol motor have different needs than a gasoline motor cylinder head wise? Assuming they have the same displacement and same blower?
Not necessarily. Same boost, same rpm, then no. More boost, more rpm (which is typical for alky) then yes.
 

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Discussion Starter #10
Thanks guys
The merlins are great and have never let me down but by the end of this season I want to be in the 7`s so whatever it takes! The problems with the merlins are their Iron and heavy...
As I get older I`m trying to plan things out better instead of just running out andbuying something cause its shiney and the latest and greatest...I might just make the switch to Alky and say screw it....
 

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steelcomp was here
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The biggest baddest head Edelbrock sells that will work on your deal is the Musi CNC 377CC head part # 61419
Its a little big and they aren't all that.
LINK: Edelbrock/Musi 24* head
If the head your thinking of is the Edelbrock/Curtis Boggs Victor III, forget it. Wrong valve angle, wrong bore spacing. Not even close to anything you can use.
The Musi head has some rolled valve angles. You can use their studs and guide plates, but if you want a shaft system, you have to use a dedicated intake stand. I was looking at a set tonight that a friend is working on. They have some pretty serious potential.
 

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The Musi head has some rolled valve angles. You can use their studs and guide plates, but if you want a shaft system, you have to use a dedicated intake stand. I was looking at a set tonight that a friend is working on. They have some pretty serious potential.
Of the conventional port Edelbrocks they are head and shoulders above the old Victor/GMPP head. Much better. The shifted valve layout may have it potential too. Not a head guy, but I know when they do the same thing to the SBC they see some gains. I imagine Edelbrock and Musi knew what they were doing. Like you said, if you run a shaft system, it is a unique dedicated system. But then really, most of them are anyway.
That head seems to take more advantage of the large bore than many conventional 24* heads with the valve shift.



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Are the old gmpp/Edelbrock Victor heads you are talking about the 7760's??? If so I'd like to know more about them. I have a set that were originally cnc ported by West Coast Cylinder Heads and I just had some additional hand port work done (also by WCCH) along with a valve job and increased int intake valve to a 2.350. The intake ports are now about 410cc's.
 

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Are the old gmpp/Edelbrock Victor heads you are talking about the 7760's??? If so I'd like to know more about them. I have a set that were originally cnc ported by West Coast Cylinder Heads and I just had some additional hand port work done (also by WCCH) along with a valve job and increased int intake valve to a 2.350. The intake ports are now about 410cc's.
Just out of curiosity, any flow numbers? That's an awfully big port.
 

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Unfortunately not, I was in a rush to get the engine back together so I skipped the flow bench to try and get back on the water by last labor day (which didn't work out anyway). They are the original heads on my motor from 2001 when HTM (Ken Lane) built it as their 850hp blown 565. Last year I took it apart for a freshening/upgrade and had the additional hand porting an upgraded from 2.300/1.88 valves to 2.350/1.90 as well as swapping the tbs intake/super chiller for a Hogan's sheet metal intake with a lee I/C core, swapped the tbs 1071 for a billet 1471, swapped the 950 hp Holley carbs for Dominators, went to a solid roller cam and dry exhaust.

Next time it's apart I'll flow them to find out exactly what they are, but as I kick around ideas for my next build I'd like to have an idea if I should reuse these heads or start fresh. I'm thinking 600 cubes+\- 1471 or psi gasoline motor attached to an scx outdrive.
 

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Unfortunately not, I was in a rush to get the engine back together so I skipped the flow bench to try and get back on the water by last labor day (which didn't work out anyway). They are the original heads on my motor from 2001 when HTM (Ken Lane) built it as their 850hp blown 565. Last year I took it apart for a freshening/upgrade and had the additional hand porting an upgraded from 2.300/1.88 valves to 2.350/1.90 as well as swapping the tbs intake/super chiller for a Hogan's sheet metal intake with a lee I/C core, swapped the tbs 1071 for a billet 1471, swapped the 950 hp Holley carbs for Dominators, went to a solid roller cam and dry exhaust.

Next time it's apart I'll flow them to find out exactly what they are, but as I kick around ideas for my next build I'd like to have an idea if I should reuse these heads or start fresh. I'm thinking 600 cubes+\- 1471 or psi gasoline motor attached to an scx outdrive.
Your moves were probably in the right direction with the valve increase. The head is seriously valve starved. The problem is that even with the bore size of the 565, the valve is somewhat shrouded. Thats why Edelbrock/Musi shifted the valves in the new head. The Edelbrock/Musi started with the EDDY/GMPP Victor head, shifted the valve layout and finished raising the port in the head which the original head had a considerable step at the port roof at the opening to match available manifolds. Removing that drop in the roof opened the head near 390+. When they raised the roof, they raised the floor, and maintain pretty close to the original size with a much better port.

Why Ken Lane chose that head is uncertain. At the time, the Dart 360 would have been a better choice IMO, but the choices were few in a head that size. But at 850 HP, that head is HUGE! You can make waaaay more than 850 all day long with a 320 head on a 565.
My guess is, Ken either figured that with a blower there is no lack of low end, or that he could soften the low end and be easier on the drive. The man knew what he was doing so I imagine he had his reasons.



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Thanks GN7, that's good info/history on the heads. What's out there now that would be a good choice of head for a 600 inch blown gas motor with a small enough cam ([email protected] 0.50 .720 lift) to be outdrive friendly?
 

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Thanks GN7, that's good info/history on the heads. What's out there now that would be a good choice of head for a 600 inch blown gas motor with a small enough cam ([email protected] 0.50 .720 lift) to be outdrive friendly?
I doubt you would find alot of power over the ones you currently have. If it was in a race boat there may be some gain by going to a more modern head with smaller port with the same or better flow. The smallest head that can get the airflow you need for the target HP is usually the better choice. With a blower and a boat that isn't all about acceleration, the head can be a little more forgiving. The two things that make that head a little on the big side are the intended RPM and the target HP. You have enough port size to run a 565 well into 7000+ if the flow is there. But with an outdrive I doubt you're running anywhere near that.

You mention the cam, which is one reason Steelcomp asked about the flow numbers. I am guessing, but if the port work is effective on a port that size, your max flow is well passed the max lift of the cam. So you end up with a big port your not able to take full advantage of.
If it wasn't for the blower the thing would probably be a mess. But like Ed Iskendaerian likes to say, a blower is just something you use to fill the big hole made by the heads and cam.

When I look at a blower manifold with its HUGE open plenum, and short 1" runners to the heads, and positive pressure pushing on the back of a closed intake valve, with no need of the piston or exhaust to START flow, I can't get to overly excited about the size of the head runner size so long as they flow. Take off the blower and drop on a T ram, and the game changes drastically



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I doubt you would find alot of power over the ones you currently have. If it was in a race boat there may be some gain by going to a more modern head with smaller port with the same or better flow. The smallest head that can get the airflow you need for the target HP is usually the better choice. With a blower and a boat that isn't all about acceleration, the head can be a little more forgiving. The two things that make that head a little on the big side are the intended RPM and the target HP. You have enough port size to run a 565 well into 7000+ if the flow is there. But with an outdrive I doubt you're running anywhere near that.

You mention the cam, which is one reason Steelcomp asked about the flow numbers. I am guessing, but if the port work is effective on a port that size, your max flow is well passed the max lift of the cam. So you end up with a big port your not able to take full advantage of.
If it wasn't for the blower the thing would probably be a mess. But like Ed Iskendaerian likes to say, a blower is just something you use to fill the big hole made by the heads and cam.

When I look at a blower manifold with its HUGE open plenum, and short 1" runners to the heads, and positive pressure pushing on the back of a closed intake valve, with no need of the piston or exhaust to START flow, I can't get to overly excited about the size of the head runner size so long as they flow. Take off the blower and drop on a T ram, and the game changes drastically
You have to remember one thing...the air doesn't care if it's coming from a blower or from atmospheric...velocity still rules the game for VE, and VE is what fills the cylinder and makes torque (cyl pressure). The blower helps increase VE where normally, the ports and intake would be stupid lazy, but port velocity is still port velocity when that intake valve opens.
 
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