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Discussion Starter #1
The end of October I started the thread “What Cylinder Heads?”
http://www.performanceboats.com/showthread.php?76654-What-Cylinder-Heads/page2

I just thought I would follow up and post what my brother purchased for his build. He stated that all your discussion and pointers were helpful in making his selection. In his own words:

“AFR Heads won the battle and got my business. I was getting pretty
comfortable with the idea of using RHS cast iron heads, but unfortunately RHS's tech support fell very short, matter of fact missed the bar entirely. I wanted detailed tech info about exhaust valve seats and port options, and the rep just didn't seem interested in providing it.

Conversely, at AFR I hooked up with a guy named Jeremy (ext. 111) and he seemed to be design level knowledgeable about his product. They pretty much were able to build my heads to the spec I was looking for including the hard anodizing for the marine application. This was all it took to know I was in the right place, and I bought them. Part of the reason the AFR's seem to be on top of th power game in the tests is that the valves are rolled another 2degrees from the standard 24deg. I never knew this before.

Don’t ever ask how much I paid for them, because I'll never tell... :)"

Detail info:
Bought 2 sets of AFR 2001 335cc full CNC ported alum heads through Flatlander Racing.

- Hard Anodized
- Inconnel exhaust valves
- Flat Mill to get 114 chambers
- 2 deg rolled valves
- Springs for .632 Lift

http://www.performanceboats.com/album.php?albumid=1357&attachmentid=100641
http://www.performanceboats.com/album.php?albumid=1357&attachmentid=100639
http://www.performanceboats.com/album.php?albumid=1357&attachmentid=100640

Doug
 

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steelcomp was here
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The end of October I started the thread “What Cylinder Heads?”
http://www.performanceboats.com/showthread.php?76654-What-Cylinder-Heads/page2

I just thought I would follow up and post what my brother purchased for his build. He stated that all your discussion and pointers were helpful in making his selection. In his own words:

“AFR Heads won the battle and got my business. I was getting pretty
comfortable with the idea of using RHS cast iron heads, but unfortunately RHS's tech support fell very short, matter of fact missed the bar entirely. I wanted detailed tech info about exhaust valve seats and port options, and the rep just didn't seem interested in providing it.

Conversely, at AFR I hooked up with a guy named Jeremy (ext. 111) and he seemed to be design level knowledgeable about his product. They pretty much were able to build my heads to the spec I was looking for including the hard anodizing for the marine application. This was all it took to know I was in the right place, and I bought them. Part of the reason the AFR's seem to be on top of th power game in the tests is that the valves are rolled another 2degrees from the standard 24deg. I never knew this before.

Don’t ever ask how much I paid for them, because I'll never tell... :)"

Detail info:
Bought 2 sets of AFR 2001 335cc full CNC ported alum heads through Flatlander Racing.

- Hard Anodized
- Inconnel exhaust valves
- Flat Mill to get 114 chambers
- 2 deg rolled valves
- Springs for .632 Lift

http://www.performanceboats.com/album.php?albumid=1357&attachmentid=100641
http://www.performanceboats.com/album.php?albumid=1357&attachmentid=100639
http://www.performanceboats.com/album.php?albumid=1357&attachmentid=100640

Doug
Almost all aftermarket BB Chev heads these days are rolled 2*. I would not have picked that head for that combination. Great head for a 572 turning 7000rpm with a big solid roller.
JMO
 

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Your brother did the right thing in talking direct to the various mfg's (as I mentioned in the original thread). FWIW, I think he made a good choice on both mfg and head for his build. In fact, I chose the same head for a very similar build I'm doing right now. Best of luck and let us know how the motors turn out. Oh, and tell your bro not to worry about how much it cost, 'cause you can't put a price tag on a good time!!:)devil
 

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I would have bought different pistons before flatmilling from 122cc down to 114cc-
AFR also states that milling the heads also has an effect on flow-and it's not for the
better! I know I'm not touchin' the cnc chambers on my 305's:D they're 122cc for a reason!:)bulbalthough I am running a blower:)sphss
 

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It almost excty the same engine as a ZZ572/620hp. And they come with
GMPP/Edelbrock 315s And they used the same head for the 720 hp deal as well, and it redlines at 6750, and a .714 lift cam.
Ever look at the price of Edelbrock marine heads. They give them a away. Hard coated, iconel exhaust.

I am a little disappointed with AFR for recommenting a CNC head for a 5800 rpm marine deal, with a .632 cam. I bet there isn't 10HP diff at redline betwen them and th 325s that the 235s are cut from. If they wanted to sell a CNC'd head, I would have thought they would have gone wth the 315 CNC.



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It almost excty the same engine as a ZZ572/620hp. And they come with
GMPP/Edelbrock 315s And they used the same head for the 720 hp deal as well, and it redlines at 6750, and a .714 lift cam.
Ever look at the price of Edelbrock marine heads. They give them a away. Hard coated, iconel exhaust.

I am a little disappointed with AFR for recommenting a CNC head for a 5800 rpm marine deal, with a .632 cam. I bet there isn't 10HP diff at redline betwen them and th 325s that the 235s are cut from. If they wanted to sell a CNC'd head, I would have thought they would have gone wth the 315 CNC.

we almost bought some 335 cnc heads for our 565 build,but luckily i talked with some good people and researched were we wanted power and ended up going smaller.

thanks to Steel:)devil

never the less best of luck,nice heads,Travis
 

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I was getting pretty
comfortable with the idea of using RHS cast iron heads, but unfortunately RHS's tech support fell very short, matter of fact missed the bar entirely. I wanted detailed tech info about exhaust valve seats and port options, and the rep just didn't seem interested in providing it.
Doug
You think this may be what happens when a cam company decides to go into the head business. And to make matters worse, the cam company is Comp. Lucky he got some one on the phone at all. And when he did, surprised they knew that they even sold heads.



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Discussion Starter #8
Ya know I was reluctant to post the info because.....

Oh never mind, I will let you all know how it works when he gets the boat in the water this spring.

Doug
 

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Ya know I was reluctant to post the info because.....

Oh never mind, I will let you all know how it works when he gets the boat in the water this spring.

Doug

B/c what we didn't tell you want you wanted to Hear:)bulb

makes no difference in the end factor,they are nice heads just in most of our .02 worth to big.

Best of luck.:thumb:
 

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McCoy, the heads will work just fine. Specially considering its a 30ft'r with 2 572s. I seriously doubt he will feel any lack of low end response.
Just a little surprised that was the choice AFR made considering the cam and RPM. Allow me to explain.The cam spends waaaay more time from .100 thru .500 , than it does at the max lift of .632. Its only at max lift for the amount of time it takes for the lifter to go over the nose. The valve is almost always in a state of opening or closing. Now look at the flows of the 315 CNC and the 335 CNC. and tell me where the the 335 starts kicking the 315s ass. Add in the fact that the port velocity will be higher with the 315s and you start to see this might just be a better head for that use, at that RPM. This is why I am a little set back by AFRs choice. If you took the 335 head to a cam designer, the cam wouldn't look like the one you have. If you took the 315s to a cam guy, it would look alot closer to your cam.

315 CNC


335 CNC


Does what I said make any sense to you?

But they are a long ways from being a bad choice. Throw in the fact that AFR is able to custom build them for your use, and their quality is excellant, he made a good decision.



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Discussion Starter #11
hotbo and gn7,
I made that comment above pretty much tongue in cheek. I have read the forum enough to know that the replies won't always agree with choices me or my brother may make. The cool thing is that there is usually some great discussion and I usually end up learning something.

GN7,
Thanks for your explanation above. I see exactly what you are saying, by the graphs you posted he won't get anymore flow out of the 335s up through the max lift of his cam (.632). He would need to be in the .700 to .800 area to take advantage of the increased flow.

On the other hand it doesn't seem that it will hurt him much if any with the bigger port. Knowing my brother, though he didn't say so, he is probably thinking of the next upgrade - he never leaves anything alone. Speculation on my part but once he gets the boat squared away he may be thinking more cam and other performance enhancers.

Thanks for all the feed back.
Doug
 

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steelcomp was here
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McCoy, the heads will work just fine. Specially considering its a 30ft'r with 2 572s. I seriously doubt he will feel any lack of low end response.
Just a little surprised that was the choice AFR made considering the cam and RPM. Allow me to explain.The cam spends waaaay more time from .100 thru .500 , than it does at the max lift of .632. Its only at max lift for the amount of time it takes for the lifter to go over the nose. The valve is almost always in a state of opening or closing. Now look at the flows of the 315 CNC and the 335 CNC. and tell me where the the 335 starts kicking the 315s ass. Add in the fact that the port velocity will be higher with the 315s and you start to see this might just be a better head for that use, at that RPM. This is why I am a little set back by AFRs choice. If you took the 335 head to a cam designer, the cam wouldn't look like the one you have. If you took the 315s to a cam guy, it would look alot closer to your cam.

315 CNC


335 CNC


Does what I said make any sense to you?

But they are a long ways from being a bad choice. Throw in the fact that AFR is able to custom build them for your use, and their quality is excellant, he made a good decision.
While a long way from a bad choice, I'm going to disagree and say they're a long way from a good choice. You made a great point about where that 315 kicks the 335's butt, and that where it does, it's a moot point in this app. Your opening sentence I'm going to adamantly disagree with.
This application will never take advantage of those 335's, but will definitely be at a disadvantage in 99% of where these engines will operate. I'm guessing that at the rpm these engines will run, even at max, there is no performance gain to be had with the 335's even over the 295's. The average torque/hp will be down for sure. Idle quality and docking manners will suffer, as well as part throttle cruise. Efficiency and fuel consumption's going to suffer as well...all for very little, if any performance gain. The port area and valve size are just way overkill for this application.
 

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While a long way from a bad choice, I'm going to disagree and say they're a long way from a good choice. You made a great point about where that 315 kicks the 335's butt, and that where it does, it's a moot point in this app. Your opening sentence I'm going to adamantly disagree with.
This application will never take advantage of those 335's, but will definitely be at a disadvantage in 99% of where these engines will operate. I'm guessing that at the rpm these engines will run, even at max, there is no performance gain to be had with the 335's even over the 295's. The average torque/hp will be down for sure. Idle quality and docking manners will suffer, as well as part throttle cruise. Efficiency and fuel consumption's going to suffer as well...all for very little, if any performance gain. The port area and valve size are just way overkill for this application.
I saw that. You just better at telling the way it is reguardless of the pain than I am. You would be a busier oncologist than I would be. You would be "your gunna die sucka" NEXT!, and I would be trying to tell them it might possibly be OK.

Your right, but I didn't have the heart to even bring in the 295 CNC.

Hey, they could have been 357s



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The cool thing is that there is usually some great discussion and I usually end up learning something.


On the other hand it doesn't seem that it will hurt him much if any with the bigger port. Knowing my brother, though he didn't say so, he is probably thinking of the next upgrade - he never leaves anything alone.


Doug
The number one rule in choosing a head is, smaller cross sectinal area that will fullfil your flow requirements. If it weren't for this rule, there would zero reason for CNC, or ported heads. You would just make the port bigger to get flow, and not try to get the flow with the smallest possible port. Its a pretty important rule.

I thought the same thing about the upgrade thing. It was the one thing that made me think the the 335 would be OK for now. And them I remembered the TRS drives and thought MMMM. How much are they good for.



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Discussion Starter #16
.......And then I remembered the TRS drives and thought MMMM. How much are they good for.
The TRS are really pretty stout, no forward/reverse in the drive and just two 90 deg gear sets. There are upgraded shafts and gears available....

And I also heard my brother talking about Arneson drives as possible replacements after he destroys the TRSs. We'll have to see where he goes with it. :)

Doug
 

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Ya know I was reluctant to post the info because.....

Oh never mind, I will let you all know how it works when he gets the boat in the water this spring.

Doug
Doug, your brother did the right thing talking to a few different manufacturer's and getting their recommendations. Even though all the mfgs had different heads to offer, I bet most centered their recommendations around ports about the same volume. The better mfg's (Brodix, AFR, Dart, as well as a couple head specialists like Curtis Boggs) do this stuff every day, all day and have for many years. They know what works. If they thought a 280-310 cc port was best, they would have recommended it. I doubt any of them did and there must be a reason why.
Been some things been wanting to discuss, and the OP's post seems like a good opening. You'll hear many say you can tell squat about port characteristics based on volume. I would submit that it's not a bad scaler for evaluating one port to another between mfgs. Here's why. The port size/shape is dictated a lot by the head design; valve location/angles, where valve stems and intake surface are located pretty much dictate basic port shape. Combined this with available casting technologies, there's not much a mfg can do to get a lot of differences in say, a 320 cc port in a BBC head. Look at the "as cast" flow numbers for similar size ports between mfg's and you'll see they are all very close.
CNC porting allows you more control over the shape of the port than does casting, so you can do a bit better optimizing shape, and therefore achieve better flow characteristics. Again, there's not much difference between different mfg's CNC flow numbers either (those that post anything close to honest numbers). Bottom line IMHO, port volume numbers are not a bad way of comparing different heads/mfgs. It's not all the story, but it's a really good start.
The trick becomes knowing how much flow a particular engine needs to do a good job of filling the cylinder. In simple terms, one approach is to use a smaller port, with the increased velocity that comes with it, to better fill the cylinder. The hurdle is the energy it takes to speed the flow up is no longer available for use to fill the cylinder. Use to much energy up trying to speed the flow up, cylinder filling becomes compromised.
Chevy did a lot of work on this with their Vortec engines. The goal for them was to speed the flow up so it generated more swirl/tumble in the cylinder, resulting in more HP. They did a lot with a very cool fluid dynamic model to get the balance correct. Turns out that balance is pretty hard to achieve even for advanced engineering groups like Chevy, much less for the average guy. Too much energy used up, cylinder filling is compromised.
Others work from the idea to more or less, keep the port out of the way and allow the difference in pressure created by the piston moving down the cylinder to fill the cylinder. Those that suscribe to this approach will typically use a larger port. Personally, I believe the second approach works best for the "average" hot rod/race engine builder to use. I suspect a lot of the mfg's also use this approach based on the port volumes typically recommended. If you hang around big forums like Yellow Bullet, you'll see a LOT of racing engine builders do the same thing. The OP's/AFR's choice of head would be a lot more common among those guys.
Some qualifiers in my somewhat simplified explaination. There are some dynamic/acoustic properties involved that further complicate the intake process, but these exist in only a small part of the RPM range, typically at or near the TQ peak. This is where proper cam choice comes in. Also, a head's valve job and how the seat is installed play a big part in how similar heads perform. Lastly, and likely the savior for a lot of builders, there's a lot of "slack" in the decision process. A port that's marginally to large or to small can still be made to work pretty well if the rest of the build is decent.
OK, I'm done. I'll probably end up sorry I posted something that might go against the grain of popular opinion (at least here). I usually am, but I'm due for a break around here anyway.... Flame away, I'm out:)sphss:)hand
 

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It almost excty the same engine as a ZZ572/620hp. And they come with
GMPP/Edelbrock 315s And they used the same head for the 720 hp deal as well, and it redlines at 6750, and a .714 lift cam.
Ever look at the price of Edelbrock marine heads. They give them a away. Hard coated, iconel exhaust.....
Man, I wonder how much HP they would have got if they used the right head!! :)sphss Seriously though, 620 HP from a 572 is not even 1.1 HP/Cu", not a real barnstormer. I get Chevy is trying to build a "universal" motor, but I can't imagaine anyone around here building a "performance" motor and be happy at that HP level. The 720 HP deal is a step in the right direction, but again, 1.26 HP/Cu", again, not steller.
Here's an example of a pump gas deal done right http://sunsetracecraft.com/CRStage.cfm?&Page=View Orphan Article&Active=Public&UID=0U812&ArticleID=54
A buddy has this engine in a Cole flat other than he opted for a solid rolller of the same basic size. His engine made over 800 HP out a 565 on 91 ocatane. I've driven the boat, it's pretty bad ass for a lake deal. Notice what heads are on it and where the tq/hp peaks are... The guy that owns Sunset builds a TON of motors and has a great reputation around the asphalt drags....
You guys do what you think is right. I'm not trying to change anybody's mind here. Just putting out an alternative set of ideas so those around here that do use bigger heads know they can work very well. OK, now I'm out... gotta get out to the shop, parts are waiting!!!
 

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McCoy - you picked a great head for that combo. Those motors should charge hard.

Congrats.

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

Almost all aftermarket BB Chev heads these days are rolled 2*.
Yes, but from OEM 26 to 24. Some exceptions are Brodix Race Rites and I believe Edelbrocks are still at 26.
 
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