AFR Heads
 

Looking to buy heads for my new 540's, naturals. Has any body used AFR 325 cc heads 119cc out of the box. I'm told they work nice. Any thought's . Wanna make the right choice. Thanks JOHN

Site member rmbuilder/Bob Madara of Marine Kinetics would be a good guy to go to for info on AFR's. His phone number is 585-654-8583.

They look to be a nice head eventhough we have not used any YET. We mostly use the Dart Pro-1 out of the box non-CNC a really good basic head. As always you must consider the application and your goals for hp & tq.

I know several reputable engine builders who use the AFR's pretty much exclusively and they are really great cylinder heads. As a cylinder head manufacturer I can tell you that these are some of the best GEN 4-6 cylinder heads produced in the good old USA today. They are a little price'ier than some of the others, but you pretty much get what you pay for in cylinder heads. You've started your choice in the right place.

Regards,
Ray @ Raylar

Kinda depends on what you're looking to do.I used the 315 cnc on my 548. tq-677 at 3900,Made 670+ ft lbs from 3000 to 4200,hp 640 at 5400 pulling all acc. and wet headers.Rather mild cam.Mark set the comp. up. Very happy with it. BOB

Congrats....We just made dam near the same numbers on a 540 with ported Iron Eagle 308's. (699 TQ at 4,100, 628 HP at 5,100) Mark at Precision did my Dyno run, seawater pump to CMI's too. What compression are you running? I'm at 9.7 with "stock" looking 500EFI's.

Great Cylinder Head, makes lots of power. Make sure you order them with Hard Anodize coating and Inconel Valves .

I'm at 9.8 with JE forges pistons. .600 intake/.610 exh. Cam Motion cam. Since then I've had the intake extruned honed(polished not enlarged,stupid me!?)and added the AS&M mono blade.Would be courious to see if that helped but not enought to R & R the engine! lol BOB

I have a set of AFR 315 cnc on my NA 540. Made good power with a mild hydraulic roller cam. 680 hp @ 5800 rpm, 660 torque @ 4500 rpm.

Do some homework before you buy. I had had at least eight sets (16 heads) go across my flowbench. NONE of them came close to flowing what their advertised numbers on the exhaust side.

are you saying that there was something wrong with the castings? or that AFR is lying, or are the numbers just different because AFR lists them using a pipe?

On my flow bench the intake numbers are very close to what is advertised by AFR, within 1%


All of the AFR castings I have seen have had ridges from the cnc process in the exhaust seats, which is a very sensitive area for airflow. Also equally important is the overall volume in the exhaust port. A 300 cc intake port will no way flow 400cfm at .650 simply because of lack of volume, same with an exhaust port. In general ports need volume/area to relive pressure.


AFR claims 330 CFM @28" with a 2 1/8 by 6" pipe using a 1.880 valve. On my bench they will flow 300CFM @28" with a 2 1/8 by 6" pipe, without the pipe there about 270 Cfm.


To make a point, I just finished a set of Pro Topline heads 1.880 valve that flowed 323CFM with no pipe. With my cool guy 2 1/4" single steped, double bell mouthed 6" pipe it increased the port to an HTG 400 CFM @28". This tells me "A" a 1.880 will flow well over 300 CFM with enough volume and "B" my pipe flows more air than their pipe which is why I don't use a pipe to flow exhaust ports.(although I have an idea for a twin steped design).

I would never accouse AFR of lying

I agree.

Now I'm confused. I don't see any AFR heads that they claim flow anywhere near 330cfm on the exhaust side. The most I see is on their 357 cnc'ed of 325 @ .800 lift

Thse are fantastic increases for these heads.(265 stock I think) Which are they? The 320's or 360's, and how well did they improve overall to porting?


Final question. What is AFR's reason for showing numbers with the pipe on the exhaust, as no one else seems to publish numbers this way? Based on what you have found it looks like the pipe increase cfm by about 10%. Is that correct?

Alot of the LSX engine shops use the pipe also to flow exhaust ports. They claim it mimics the exhaust pulse as it leaves the port as it would when you have your headers installed.

They say it's to duplicate the header pipe. The % increase depends on the size and lenth of the pipe. Thats the deal. you can change the pipe size and see more airflow . Just another shell game

I just spent 2 weeks testing heads and intakes on the 500 EFI engines. I ran a set of Dart 310 Pro 1 right out of the box No Porting as cast and made 582 HP. Then I put a full cnc ported AFR 315 on with their special ex valves and made 12 more HP. I had the divider cut out of the intake plenum and the Bigger throttlebody on both times. I then put the Holley Intake on made 25 more HP but lost a ton of torque thru the whole RPM range. So I went back to the stock intake and mounted a 2000 cfm throttlebody right on the top of the stock plenum and made 35-40 HP and pick up the same on torque thru the whole RPM range. I should have my new Plenum tops ready in about 3-4 weeks.They will bolt right on your stock intakes and will flow over 2000 cfm. The 2 throttle blades are mounted right in the top flush so you don't need any more hatch height.

What heads were on when you pick up 35 or 40 hp

I had the AFR's on at that time but the Darts would have picked up some also. We just could not get enough air thru the 1300 cfm thottlebody.

New Plenum's should be nice! Thanks

John, I am using the 315cc AFR CNC ported heads on my naturally aspirated 565cid engines, with dart single plane intakes, 950cfm Holleys, 9.5cr, 34*timing, and very mild hydraulic roller cams that will as low as 600rpm or so in neutral.

I have a friend with a pair of 556cid surpercharged engines with Dart Pro-1 heads with some port work, with dyno sheets that show the engines SUPPOSEDLY making 810hp. I seriously doubt that is what they actually make, but that's what the dyno sheets say----and he has the same conventional V, 32' boat/hull (none stepped hull Active Thunder) as I have. I have a little different set-up (extension boxes, IMCO 2" shorties), than he has, but from about 3000rpm on up side by side he cannot pull away from me----I cannot pull him either. I'm sure he was thinking he was going to wail on me with his supercharged engines. We have done this a few times and every time he said he was light on fuel and my tanks were always full. He seems to be a bit surpirsed that he cannot pull me on top or in acceleration with his supercharged Pro-1 headed engines----but he's having the engines freshened as we speak and making some changes while he's at it. So, this summer he might be anxious to show me that things won't be so close as they have been in the past---GULP!!! :o

Last fall with full tanks I also ran up against a stepped hull 36' Apache in flat water with a pair of 540cid Vortec supercharged engines with ported GM heads that make something like 815+hp---his boat runs really good, but I was right there waving hello to him side by side down the stretch. Just having fun that's all.

Anyway, just wanted to let you know how well the 315cc AFR's ran on my 565's. By the way, I was one of the guys who took my AFR's to JimV's shop for some exhaust port work as he has described. Have fun.

Couldn't get enought air thru a 1300 cfm T/B on a 500efi with 315 AFRs? I always thought the lower plenum was the restriction? Looking forward to seeing this new "top" BOB

What kind of improvement in TQ & HP might one see if a set of AFR 305s were installed on a 454 mag mpi? Given better exhaust & reprogramed ECU.

I saw 1.2 hp/cubic inch on the dyno (no accessories or marine exhaust) with 305 cc AFRs and custom cams. Started with carb 500 hps. Motor made 615 ft lb of torque at 4200. Bottom line, the boat picked up 5 to 7 mph, the real yardstick.

cdscarab - I have a set of new AFR 305's in the Swapshop if you're interested. Reason for selling them is in my add.

I'll be out of town 4/12 & 4/13 so if interested I will not be able to respond until 4/14.

Nice to see a local guy on board here !!

Bill

Glenn's had a pair of 565cid naturally aspirated engines built with 315cc AFR CNC ported heads, 9.3cr, tunnel ram intakes, MILD hydraulic roller cams and they ended up making something like 718hp @5400rpm on the dyno with alternators, belts and pullies, etc. I kinda thought 700+ HP is pretty respectable @5400rpm for a NA engine with those cubes and mild cam. I wonder what kind of power Glenn's engines would have made if he had wanted RMbuilder to design a cam that made power up to something like 5700-5800rpm??? :)

Dave Wesseldyk built/dyno'd the engines and RMbuilder/Bob Madara did the cam app.

KAMMA - Hopefully, in a month or so, we'll see what a 557 at 5700-5800 RPMs with a rmbuilder tight lash solid roller will do. Oh yeah .... AFR 315s :D