Dart Pro or Air Flow Research
 

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?

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.

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.

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.

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

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

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.

more useless information
 

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?

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?

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.

TJ- I used the Canfield 350's on my 540 from last year and saw minimal gains in power over the Brodix. I talked to Jim V and he was very decent to deal with, he certainly has a good reputation on the board for quality work. I do question with your blown application just how much power is to be gained from a motor or head change versus getting the jetting exactly right with a fuel injection setup. I am really high on that being my upgrade in the future, for these centrifugal setups. At times my motor is crisp with the right jetting, but I have never beena able to get it right, all the way thru the RPM, idle to wide open. When I do my feeling is the motor will be EVIL. I would recommend the canfield's, and I was told the 310 Canfield's had slightly better exhasut ports, which would be best for a blower. Also I think fresh outside air for your boat would be a big key, instead of sucking in that hot engine compartment stuff. I remember you mentioning you lost a lot in the summer months, if you run it in early October it will be interesting to see if the power comes back.

You might go with the Canfield 360 or the BB2-Extra they are recomended for an engine of about 570 cubes. The smaller ones fully ported will work but in the long run power might be down due to the air speed being to high. You might find boost numbers will go down from 10 to 7 or 8 with the bigger heads but this will still produce a lot more power due to reduction in intake temps less restricted air flow and fuel not coming out of suspension. Well I am out of here its the weekend and got to get the boat out changed the tabs around hoping to see some lower slip figures.

JimV- On AFR they did have a article where the same guy compared a number of the different heads & of course the AFR came out the best(???) but we all know that is not always the answer. On the head degrading after use that would be a good test. I bet some will degrade less that others.

Jspeedemon- Middle of summer when I checked the compartment air was aprox. 120 & when I would hammer the throttle the compartment would go into negitive pressure. I since have added 2 big bilge blowers to blow air into the compartment. Have corrected the negitive pressure problem & have gotten the air temp down to 110. In getting the temp down more I have looked at the vents that eddie marine sells & putting on the back side.
eddie marine vent

& I have looked at making some vents that will go on the side of boat that would force the air in the compartment. Just like the 28' daytona has. UT said when he was going to be back at eliminator he was going to discuss that with them about getting something made. Per calcuations from Tomcat looks like with the difference between the 55-85 water temp & undercover air temp of 80-110 I am losing aprox. 10%+ HP. Not including the jetting being way to rich this summer. (Stopped tring to get jetting just right when air temps got hot, but transom looks good)

As far as EFI or carbs, I am going to stay with carbs. The jetting may not be perfect but I feel the cooling efect of the carbs is a big help in keeping this motor from detonating.

The bottom line thought Jack is that the answer is not to build a bigger hammer if the one you have will do the job. everyone that builds big power will tell that a carb was not meant to have air rammed thru it at boost, and you can't effectively BandAid this. I have spent two years with Procharger setup and would not change what I have done to now, however I think we are sitting here with our fingers in our ears, not moving forward with technology. Carbs are old news, and especially with what we are attempting to do with them. You may worry about some highly technical jargon about cooling thru the carbs, but seriously hear me out. What you gain by that, you lose double or triple, because of bad tuning. I bet you, me, and everyone else running carbureted Prochargers we have left gobs of power on the table due to inability to tune. Unless you have pyrometer, air fuel meter, oxygen sensor, these motors can't be tuned all the way thru the RPM range. Why, because a carburetor doesn't have enough circuts to accomplish this, that is what the couple of hundred post thread months back ended up about, regarding the staged power valves. I wish you all the luck, and hate to be negative, but cannot live with another year of black transom, or worse leaned down for cruising (so I don't black up the transom) then it definitely will be lean on top, it's not possible both ways. I have drilled out the power valve transfer slots, epoxied them back up and redrilled, and if you haven't done that, you haven't gone as far as I have, trying to get it perfect. Again good luck with going forward, but I am definitely changing course.

Heads for N/A 572 cubes...
 

When speaking about aluminum heads for a MARINE application that are CNC PORTED, would a 335cc head be better for a 572" NATUARLLY ASPIRATED engine or would something close to a 355cc head be better?

This would probably be used in combination with a hydraulic roller cam of about 246*/254* @ .050, Dart single plane intake, 950cfm Holley, good free flowing exhaust system, and about a 8.8- 9.0 comp ratio. Looking for an honest 675-700hp at about 5500rpm. I do not need GANG BUSTING torque! I am looking for excellent idle quality, good drivability around the docks, shifting, etc, I like to try to burn the fuel as efficiently as possible before kicking it out the exhaust.

I usually like to cruise at about 3000-3500rpm in a 32' boat that weighs about 7500-8000lbs dry with max WOT RPM's to be about 5500rpm.

Taking all this into consideration, what head do you guys might think would be best for a 572 incher?

When I talked to AFR they said for a boat application the 335 cnc was the way to go. Said that head would have more torque that the 355. They said if I was to go with 700 lift & rap it tighter that the 355 would start to show there stuff. Remember I was talking to them about a blown 572, but I think the same would apply.

Thanks Turbo. Did they give you a price on the CNC 335cc's bare?

Yes but I do not remember what it was. It is on their web site. I called around to other people also & they all quote the web site price. I am going to go with complete heads. AFR said for me to give them the specs. on cam I am planing on using & they will build for me. Dave @ AFR also said that they now will install with the iconell valves for I think $150 option. Might be wrong on that price but it was the same difference between regular & iconell it I bought the valves thru someone else. In talking to my engine builder he said he thought I would be cheaper getting them complete but to let him verify all is correct before I put on engine.

Turbo, I looked on AFR's website and didn't see a price listing, but I will go back a take a second look. I DID see that they had flow bench numbers WITH and WITHOUT a pipe for any of you guys who are curious.

How quickly did they say they can have a pair at your door?

On the bare 335 CNC part # 3350 $2292.00
full assembled part # 2001 $2939.00 + 150?? for upgraded valves. I do not remember if I asked how long but I want to say 1 1 1/2 week before they ship since changing from their package valves & springs.

Turbo,

1-2 weeks eh? You know, the more I think about it the more I think that the CNC ported heads are the way to go if you're looking for a full port job. I mean these things are done by a computerized CNC machine, plus you know what the price is going to be and a reasonably short waiting period! Works for me! :)

Make sure you flow em before you bolt them on