You should bring a set of those iron gm peanut ports off your cruiser motors too. I have some of those demon carb venturi sleeves we can install in the intake ports to shrink them down a bit. I'd like to see if we can get marks 565 making 850 FTlbs at 1800RPMs, and 267HP at 3800RPM. You know, for the guys who like low end response more than top end . I have a low mile flat tappet from a 74 caprice wagon we could install. :popcorn:

When we were racing, were used the AFR published numbers as a baseline on our 500 CI BBC low compression NA build. Jim V reworked 2 sets of Dart Iron Eagle heads (new at the time) that were similar in size to the AFR. My engine builder and my goal was to try and equal the published results of the intake ports on the AFR head and Jim was confident he is could significantly outperform the AFR exhaust ports published numbers. The AFR head is a nice piece, Jim's exhaust ports are just better. In a top notch 500 CI NA race engine at 6800 RPM, maybe this is worth 15-25 HP = + 1 MPH.....to die for in racing :flag:

and a loose/stretched timing chain.

I will tell you this, if it's only worth 1-mph, I will tell you right now that I am not interested---not for the time or the added expense for having an exhaust port improved upon....maybe for racing, yes, for that one last MPH, but not for a pleasure boat that already has a pretty good exhaust port design to begin with.

How many CFM's does it take to make one 1-HP?

If we do this dyno test, how are we going to make EVERYTHING equal???...i.e. valve springs, valve job, etc. etc??? With all due respect, I am only interested in testing the AFR heads...factory vs my JimV/AFR exhaust port mods.

I would think the valves themselves, need to be the same. IE, if one head has tulip ex valve, so should the other, if intake valve is backcut, so should the other, etc.

I think rather than the test be just about ex port vs ex port, maybe it should be factory CNC as delivered, vs factory cnc plus hand work by a head porter, to see whether or not the head is delivered the best it can be, or if in fact it can be improved on? idk

I do know, that it is common for some big name cylinder head porters, to take a off the shelf cnc head, and improve its flow, and make more power. Ask customers of Curtis Boggs, Darin Morgan, etc. Its very common for those guys to get a shelf cnc ported head, whether it be from Dart, whoever, do a really nice valve job, a few tweaks of the ports concentrating on their areas that may be lacking, and pick up power. Some go as far as changing valve size, etc. I read a post on another site from Curtis boggs, when someone mentioned he 'heard" of their being 100hp left in a set of dart 355 cnc heads stock. Curtis said absolutely not, but he has done some tweaking on them, and while some variances, 35HP is typical on those heads.

I know the shop Mike Tkach and I use, have a newen CNC machine that costs over 100k, for doing their valve jobs and guide work. A good valve job by a good shop, can be worth quite a bit of power/flow over some shop that does a half azz valve job, irregardless on how good the ports flow.

Do the AFR 315's come standard with a back cut intake valve?

I`m sorry but there`s no way a CNC machine replaces guys like Jim V or my guy Mike @ High Flow Heads.
Plus those guys paved the way for those those CNC programs thru tons of trial and error.
I`ve heard of the great work Jim V does and locally to me what Mike did with the combustion chambers is an art. These guy s are like sculpters .
That being said those fully ported CNC heads are pretty damn good out of the box compared what was available years ago.

ok, on this one i am sure you are incorrect!!

And the heads failed within 2 hr's....

Actually to a degree they have already been replaced. When you get into the exotic billet heads I think the hand porters would have a very difficult time competing. I don't think Jim and Mike want to sit down and grind on a solid chunk of billet. The industry has changed and keeps changing. The CNC's are getting better and better. I think if you ask Jim or Mike how much they could improve on a CNC port from 10 years ago to a port today they (if honest) will tell you that the margin of improvement is getting smaller. Don't get me wrong these guys still have their place but it's different than it has been in the past.

most of the gains lately have been wet flow around the seat area.Darren Morgan worked over a set of nitrous heads for us,,he got us 3cfm,but in top sportsman and 600-800hp of nitrous,you need every bit of flow.