Turbojack

I have decided to build a new 572 BBC this winter & keep my exisitng motor as a spare. I am trying to figure out what heads to go with. I am thinking of going with the AFR 335cc CNC's or AFR 357cc CNC. Some of the people that I have talked to say go with the dart pro 1. If you go by manufacture specs the AFR 357cc CNC's win. Motor is going to have my stage 4 procharger which I am currently running at 10 lbs boost w/ 8.2:1 compression. I am not planning on running motor over 5600-6000 rpms. Will be using the crane 741 cam (little over .600 lift) Exhaust is cmi elbo tops.

Which ones would you go with?

WETTE VETTE

Flip a coin. I really don't think you will see a huge advantage from either head when compared to each other. Take a look at Canfield and Brodix as well as the Darts and the AFR. I run 325 Pro 1 heads and have had very good results. They are fully ported and have 2.3 intake valves with Jesel shaft rockers. With a blower motor and a cam under .700" lift porting on the intake probably isn't required and some exhaust bowl work will be advantageous. Dean Nickerson likes Canfield and Dart and he seems to know his blower stuff pretty well. Let us know what you decide.

Turbojack

I am leaning towards AFR. I called tech supporft & was told the 335's were better then the bigger ones with the cam, RPM's I plan to turn & being in boat. Dave at AFR said they now offer them with the good valve for marine use & set up with valve springs for the cam I am going to use. A true bolt on with no rework. Just going to think about if for week or two before I order them.

jspeeddemon

Jack I would think the most important criteria for head selection with your setup would be exhaust flow from say .300-.600 without a pipe. Make sure you compare apples to apples about the pipe, a lot of times its in small print or not even mentioned. I would think that the Pro 1's would need work, from talking to Jim Valako last year about the same thing, I don't know about AFR's CNC'd heads.

Turbojack

JS- What ones did you go with last year & what did you do this year? Notice any difference?

timucin

what do you think about
brodix bb2xtra?
anybody have this?

turbo2256

Go with the Canfield second choice Brodex remember max flow at max lift dosent mean you flow the most total air. also on my bench these two manufactures heads always flow within 5 cfm of advertized flow. Most others dont.

JimV

jspeeddemon mentioned the advertised numbers are different. AFR and Canfield uses a pipe to enhance the airflow on the exhaust side. If I remember the Canfields flowed 340 cfm @ .800 lift and still climbing, very impressive. That's with a 6in. pipe. Without it around 310 cfm. The Canfields dont have the short turn radius that the Darts have consequently the Darts flow substantially more in the mid lift area. I'm not bashing the Canfields, I believe they make a great product but for relitively low lift marine cams the Pro one's (or better yet the 320's) has a better exhaust port. The pro one's may not work as well with boost, the castings are thinner including the deck surface. If you average the numbers from .2 to .650 on both ports the Darts will come out on top. Like WETTEVETTE said we are problaby splitting frog hairs.


turbo2256 What did you see on your bench?

Turbojack

JimV- When I talked to AFR they made a big deal about the casting being thicker (???) than any of the others, thus sealing better. I forgot about that until you said the dart's casting are thinner. Am I taking it if you were to build a 572 blower (8-10 lbs boost)motor you would go with cantfield & have them ported?

JimV

TurboJack

As much as I like the Pro One heads I problaby would opt for the AFR or Canfield heads. The 360 Darts would work just as good but would require full porting to equal the AFR heads. That's going by the advertised numbers from AFR. I honestly dont remember If I flowed the newer AFR heads on my bench, so I can't answer your question. I know I have flowed the Canfields and with minor port work on the intake side and valve grind, they flow very good. My bet is you will be within 20 hp using any of these heads.

One other point to confuse everyone (even myself) is all the airflow numbers are done on fresh ports meaning no carbon build up in the ports and fresh grind on the seats. I have seen exhaust ports loose 10% + airflow that have had some time on them. Now that would be a great test, dyno the heads after 20 hours of use.