AFR BBC Heads
 

There were a couple of guys interested in the AFR 315 CNC heads that I am using on my 540's. We finally flow tested them this week on a Superflow SF600 flowbench.

Here are the results and comparisons to what AFR claims @ 28" H20. The heads are "out of the box" with no additional porting or epoxy.

We tested with an out of the box Manley Severe duty intake valve, and then with a backcut inconel Del West Intake valve of the same diameter which I am using.

..........AFR CLAIMS.......MANLEY SEVERE........B/C Del West
.200........169.0..................169.28......... .............177.45
.300........249.0..................248.64......... .............261.45
.400........312.0..................306.36......... .............327.60
.500........353.0..................352.98......... .............363.59
.600........380.0..................375.18......... .............391.40
.700........387.0..................390.72......... .............394.74
.800..........N/A....................391.12......................3 94.91

I would say that AFR's claims are pretty accurate. The discrepancy's are around 1% which can be accounted for by atmospheric conditions and variations between flowbenches.

With the right combination, these heads could support 750-775 hp in an NA application.

Interesting, the average airflow between .200 and .600" is AFR=292.6, Manley=290.4(actual), and B/C Del West 304.2. Nice.

cobra questions
 

Hey Marty,its tripps,2k's friend,i want to ask some questions about your boat!here goes,how fast,how much power,what C.I. what drive and how high is the propshaft from the bottom of the sponsons,how much does it weigh,do you use a tranny,how is it in rough water and does it loose speed in flat water? Is yours glass or kevlar. The reason i'm asking is cause i know of a 30 made with kevlar i can get and i have a 598 and a sternpower speedmaster that im contemplating putting together. wadda you think Thanks Tripps

Hey Tripps, Stock 502 MPI mag with a huge intercooler and 10-11 lbs boost and 725HP. The boat went right at 100MPH with a HP bravo and 30" bravo prop. Will literally leap out of the water when starting out and great inthe rough water.

The drive is best described best as where it is located relative to the center tunnel V. It is 3" below it ( about 5" above the sponsons) and that is with a 2" spacer in it. It is kevlar, never weighed it. Use bravo one, no trans.

This last 2 years it has been in pieces in that I glassed the transom and lowered the drive 5" and now the engine will be under the hatch and the exhaust will be out the transom and not over it, adding a stellings ext box with my dyno unit, 380S k planes and a tubular step platform. I will take the spacer out and use a 2" shorter lower and the prop will be 1" lower than it was and I think it needed it as at about 80mph I would loose the speedo(in the nosecone) and the the boat would want to paddlewheel to the right. Need more skeg in the water. I now trying to decide on the motor to put back in? 500EFI, HP500, add Tomcats intercooler, my supercharged 502 or build a 540 or 572. I need to decide. I just want it in the water this year.

I love the boat/hull just hate the builder.

Monty

Are those cnc'd. What are the numbers on the exhaust side? thanks JimV

Jim,

Yes, they are the CNC'd versions. I bought them as bare CNC castings with copper-berrylium seats installed and finished them off with my own choice of valves and hardware.

We flowed the exhaust side, but I forgot to bring the numbers home. We didn't use a 6" pipe though, which AFR does. So the flow numbers were slighly less, but within 10 cfm or so, which leads me to beleive AFR's claims are pretty accurate on the exhaust side as well.

,I think the back cut is a 15 degree cut in which some people do,usally thats included in a 5 angle valve job?



Does Del west make a inconel Intake valve?

We backcut the valve ourselves - a 30* backcut. I'm not sure if they have an inconel intake valve. It's not really needed though as they aren't subjected to the exhaust heat, and they benefit from the intake charge cooling them. I was tempted to use a TI intake but at the rpm I'm building for they really aren't necessary. I used inconel for exhaust and stainless for intakes.

Q----We tested with an out of the box Manley Severe duty intake valve, and then with a backcut inconel Del West Intake valve of the same diameter which I am using.

They way I read I thought you were using a inconel on the intakeThe reason I asked?I didn,t think any body made them?
I wonder if you did the back cut in the Manleys if it would have been the same . I guess it depends on the neck just above the head.
I have heard on the Titauim on a blower motor they get brittle.heads pop off.ouch I guess they have a short life span.

I though the copper-berrylium seats where for the Titainum valves only? Not sure?

Re: AFR BBC Heads
 

I was doing a search and thought this was an interesting thread considering all the talk about AFR heads lately so, I brought it back to the top.

Re: AFR BBC Heads
 

Monty put the exhaust flow numbers on a later thread and I wrote them down. While using the Del West exhaust valves, and WITHOUT the use of a 6" pipe as he stated above, here are the flow numbers on the exhaust side of the AFR 315cc CNC ported heads and they look to be quite impressive...

Lift...CFM
.200 147
.300 187
.400 245
.500 281
.600 304

Re: AFR BBC Heads
 

With that % of around 80% your looking at a single pattern cam @ .050" and probly a reverse split of 4 degrees at .200". It will also require a split ration rocker set.

Chris

Oh yeah, when back cutting a valve in my schooling, no this does not represent one of the angles on the valve job. 3, 5, 7 whatever is cut/ground on the seat in the head.

Re: AFR BBC Heads
 

Kaama,
AFR offers an upgrade for the 305cc/315cc exhaust side that will increase exhaust flow by about 9% throughout the lift range. The upgrade (part#7632) includes tulip exhaust valves for a $40.00 premium at the time of purchase. This brings the exhaust flow inline with the 335 CNC port. Considering the 315 intake port outflows the 335 head until .600" lift, adding the tulip valve on the exhaust side makes for the best of both.
Bob
AFR 315 Intake
0.2 169
0.3 249
0.4 312
0.5 353
0.6 380
0.7 387
335cc AFR 335 Intake
0.2 164
0.3 240
0.4 304
0.5 352
0.6 385
0.7 404

Re: AFR BBC Heads
 

CStraub,

What ratio of rocker arm? Also, which side should it go on---intake?


rmbuilder,

Does AFR have the actuall flow numbers available with the tulip valves for the 315cc head on the exhaust side? I also wonder if the Del West valve will out flow the upgraded exhaust valve from AFR? I suppose the only way to find out would be to buy a Del West exhaust valve and test it against the AFR exhaust valve part #7632. I know I may be splitting hairs here but I am curious and if I am going to buy the AFR heads and new valves I might as well buy the ones that work the best---right?

Re: AFR BBC Heads
 

Kaama,
It will vary per application but the exhaust will have quite a bit less lift then the intake side for optimum performance.

Chris

Re: AFR BBC Heads
 

Thanks for the info guys,GREATLY appreciated as ive got a set of 315 cnc's coming any day now!! :D :D
Kaama,are you buying a pair to try or are you interested in trying mine,the offer still stands but i see you mentioned"santa" getting you some,Smitty

Re: AFR BBC Heads
 

Smitty,

Thanks---that is one awefully kind offer, but I believe this time around I have gotten good, reliable info. Therefore, I am going to take my chances, and just give it a "GO" on this one. I am going to do a cam and head swap. Should be interesting none the less. :)