exactly,,keep on posting,,the 2 of you.engines must sound killer

I would rater learn from other peoples mistake and prevent mine. Same goes for the others. LOL

I sold my boat last year, just ride with my brother now.

I made quit a few mistakes over the years and learned a little along the way.

One thing I learned 55mm and .937 lifters wont work rite without using a lifter bushing the axel goes into the oil galley and will leak out the bottom.

I've seen the same problem with standard cam and lifters it ends up gauling up the lifters.

bump

My preference is to start out non cnc and have professionally hand ported and assembled taylored to specific application. If I'm going to spend the extra money I'd rather help support someone who not only knows what their doing but themselves also. Plus a good head porter will outflow any cnc head. My personal experience and opinion of course but the power to be had in heads is huge including SC application. I will find the link here on OSO which involved SC build with Merlin heads vs other cnc head if I recall. If I recall it was smitty not sure but regardless the gains where huge.

Post #7. Not a true comparison from same head non cnc'd vs cnc but thought I'd post anyway. Still shows the power of heads.

https://www.offshoreonly.com/forums/...ast-heads.html

When I had my buddys dad port my AFR I picked up 20-30 cfm over cnc... I was told a good hand port will always be better flow over cnc

Why is it always better ? Makes no sense.

Supposedly you can massage the right places better by hand, I have read many times people pick up cfm after a hand port over cnc, that being said people have to know what they are doing also...

I understand, which you know, and I know you understand.

It's just too blanket of a statement for me not to say something about...that's all..

CNC is a copy of whom ever did it and forwhat application. Same as a hand port, because that is what it as.

No two people are a like and thus no two porters are all alike.

I know what you mean, just when I was talking to people last year, many said gains are to be made by hand finish, it was explained why but cannot remember actual details..

That's why we call them professionals. It's what they do and in many cases all they do. I just like the fact that in many cases a good hand porter can take less material than that of a cnc head resulting in flowing more cfm while gaining port velocity at the same time. And all can be done build specific. Plus I'd rather put money in a US hard working knowledgeable mans pocket than that of corporations.

Back to OT question my answer would have to be all depends on build but would favor a cnc head over a non cnc head if I was chasing HP and funds weren't limited.

Don't forget when you waste a set of heads because it drops a valve ask how long the head porter will need to duplicate your port job and will it have the same power as it did before? I will go cnc every time unless your pro stock racing or nascar and most of them start with a cnc head.

this statement is just not true, an engine is a pump for the argument sake, and the better a head functions in terms of flow, the more efficient the "pump potential" is. blower or not

^^^ it's true. They proved that decades ago when doing all the blower development . Swapping out a poorly flowing head for a better flowing head, power skyrocketed, and boost plummeted . If anything, I believe the gains are even more beneficial from a high flowing head with a blower than with NA in some cases.

imo, the cnc vs non cnc, is that it really should be application specific . If a head porter knows that the engine will be lift limited, like most pleasure marine engines, maybe going after the best flow numbers from. 700 and up aren't the key. Maybe he would focus on the valve job, throat, and chamber to maximize flow in the mid to peak lift area. But if it's a max effort 800 lift high rpm deal, maybe he will focus on modifying the port to flow better up there. Anyone can hog out a port and make a big cfm number on a bench, but that doesn't mean the engine will be a hero.

14apache makes a good point. Having a custom set of hand ported heads, and you smoke one, a replacement may not able to be had in a timely fashion

port size is important, but so is cam lift, cam timing, and valve size , relative to how an engine runs at low speeds. Big valves and big lift amplify reversion. Going from a 250/260 cam with 650 lift and a 2.25 valve, to a 250/260 cam with .750 lift and 2.325 valve, you're not gonna get that same idle /low speed manners .

I think it must be an old myth because I recall hearing the same thing many years ago and believed until I began spending more time with real world experience and results from back to back dyno testing. I was fortunate and had the benefits of living less than 3 miles from more power racing spending endless hours learning. Some late nights chasing power but time well spent. I miss those days.

How is it that the new Gen small block hemi's and small block LS's can be 900-1000hp with SC's ? Heads !
Take the same cid, 1980's cyl heads, and same modern SC's...think that HP will happen ? No way.

aren't they using custom cnc brodix heads though?

I was giving example on how much heads can influence power on SC'd engines,

I know and I'm saying my next boat is gonna have a set of small blocks. Daammmm, I looked up some of those builds. Amazing. Light layup 30-32 with couple of those would be the ticket.

fair enough.
I stand corrected.
What you're saying makes sense.