Thread: Procomp aluminum heads/ kmj performance heads

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I wouldn't use them---mostly we use Dart and also some afr heads--they been in the racing and head business for years(ever since the rules were changed to where you didn't have to use a factory head)(in fact, Dart and AFR are probably the reasons the rules got changed)
These guys have been in racing from day 1 and all the BS has been engineered out of there product---It isn't done because of cheaper imported castings, a random cnc machine or the offshoot of a family business that manufactures something else---

Yeah, what Pat and Jerry said! If you're looking for an out of the box performance head, I don't think Pro Comp would be my choice. They're cheap, but other then that they don't really have a lot going for them unless you're looking for a bare casting to turn over to a good cylinder head shop and have built for your engine.

Originally Posted by rspears

..... because they have a lot of meat to allow him to bowl port the chambers as he likes to do. However, he buys the bare heads, and then builds them up with quality valves, springs, retainers & rockers as opposed to buying complete units from ProComp. Not sure I would buy complete heads from them.

Originally Posted by pat mccarthy

.... there are many heads i can get and for the price i can get them for i have a very hard time wanting to spend added time on a sub quality part making it work when there is stuff out of the box that fits better

Originally Posted by jerry clayton

I wouldn't use them---mostly we use Dart and also some afr heads--they been in the racing and head business for years(ever since the rules were changed to where you didn't have to use a factory head)(in fact, Dart and AFR are probably the reasons the rules got changed)
These guys have been in racing from day 1 and all the BS has been engineered out of there product---It isn't done because of cheaper imported castings, a random cnc machine or the offshoot of a family business that manufactures something else---

Originally Posted by Dave Severson

Yeah, what Pat and Jerry said! If you're looking for an out of the box performance head, I don't think Pro Comp would be my choice. They're cheap, but other then that they don't really have a lot going for them unless you're looking for a bare casting to turn over to a good cylinder head shop and have built for your engine.

Wes,
Sorry the thread got off course, but if you read around the extra BS I think everyone here has said pretty much the same thing, just with more or less enthusiasm. The common thought is that there are several choices out there that are a better value (most true bang for the buck), but no one would buy their out of the box heads, ready to run. The guy who built my engine uses them because he's willing to invest the time and energy into making them right, he's learned what needs to be done to them and he stands behind his builds 100%. I also trust what Pat says, "..there's no free lunch on heads, and most of the big power guys are using Pro 1 cnc heads..." when you buy from the name US suppliers.

Bottom line, the heads you choose need to be coordinated close with your overall build, and going bargain basement is probably not the best value. All the rest is really not important. Knowing what I know today, I would probably have sprung for the extra cost to go with a DART or AFR head vs the ProComp, but I still trust my guy's choice. Hope your build goes smooth, and that you find 20 extra horses that you did not expect.

Yepper Pat,Jerry,Dave and I all agree.

I did not want to start a problem thread. I am restoring a 70 chevy 2wd truck. I am building this as a daily driver. I will be putting in a 402 .030 over with .180 dome pistons and possibly cast iron 116 c.c.(Ithink) chamber heads. I am going to use edelbrock performer rpm cam, intake and carb with a 700r4 and 3.73 gear. I just want a really goog running truck. I just thought the aluminum heads might be worth the money. I do know you get what you pay for. I have a set of 272292 casting heads I was going to use. Can anyone tell me what c.c. the chambers are?

Thanks, Wes

Wes-it's all good bud.N/P.

This is what the lower dollar sources don't have or can't afford.The process of CAD/CNC porting is key:

CNC

And a example of the wrong way to go about it:

Porting For Performance The Science of Horsepower: Engine Builder

The research on who is doing the process the right way is apart of the purchase of heads for the street as much as it is for a race car.There are companies that are low dollar heads that advertize CNC porting that are not backed with the yrs of R&D.The name brand companies like Dart,World,RHS,as examples are established brand names the certainly have competed on the basis of what they have developed in their R&D programs.Do read the second link at least.It is a interesting informative read.

I am saying those R&D programs impact how the heads are cast.

It would probably be better to simply let this thread die, but I read through both of the articles above and it seems to me that there's a misunderstanding of the process, saying that a CNC produced head is "superior". CNC, by definition is a "computer numerical control" machine, and those for complex milling operations are generally 5-axis machines. Their strength is that once programmed they can churn out very precise copies of the same item, within the tolerance capabilities of the particular machine. They are used to mass produce items, where the unit cost can offset the investment that is required to develop the program. To be sure, the product is only as good as the program driving the cutters, in this case for cylinder heads. The key here is the question, "How is that program developed?" I would suggest to you that it is not some R&D engineer or computer designer in a CAD program, but instead is an experienced cylinder head machinist that ports and polishes a head, flow tests it on the bench to verify his result, and continues to iterate this process until he has the performance he's chasing. Once there the CNC guy pours over the "master head" taking measurements and storing the data to program the machine to duplicate the design. Bottom line, "the CNC produced ports are only as good or as bad as the man who did the original that was used to write the program" (thanks for the words, buddy, and you know who you are).
My point is that the guy who turns out one-off, custom ported heads that are flow benched to equalize the ports and milled/polished using only his experience and knowlege may well be better (for that specific engine) than an out of the box set of CNC produced heads. Read the article by Larry Carley - he says it himself,

There are two ways to port and match cylinder heads: the right way and the wrong way. The right way is to refine the flow characteristics of the head and manifold so as much air as possible enters the cylinders at the engine’s peak power curve. Every engine is different so there’s no "standard" port configuration that is guaranteed to deliver maximum airflow on every application. The port profile that works best will be limited by the physical dimensions of the cylinder head.

and further,

Porting can unleash hidden horsepower by increasing airflow — but it requires know-how, a flow bench and special tools to successfully pull it off.

The way I see it a fellow looking for a good, out of the box set of heads is going to be better off buying the proven name brand, be it AFR, DART or another, but even those heads can be made to give him more power by being tweaked by a guy who knows what his doing for the specific engine they're going on. Bottom line, the guy who has years of experience porting & polishing and thousands of hours of flow bench time is by no means a neanderthal, and the only way they could justify having a CNC machine is if they're going into the crate engine business cranking out multiples of the same design for the the market. The CNC machine is nothing without a program, and the program needs that guy with the bowl mill. The guy doing the one-off engines that go into record setting machines is an artist, pure & simple. Just my thoughts, and I'm done.

Originally Posted by rspears

It would probably be better to simply let this thread die, but I read through both of the articles above and it seems to me that there's a misunderstanding of the process, saying that a CNC produced head is "superior". CNC, by definition is a "computer numerical control" machine, and those for complex milling operations are generally 5-axis machines. Their strength is that once programmed they can churn out very precise copies of the same item, within the tolerance capabilities of the particular machine. They are used to mass produce items, where the unit cost can offset the investment that is required to develop the program. To be sure, the product is only as good as the program driving the cutters, in this case for cylinder heads. The key here is the question, "How is that program developed?" I would suggest to you that it is not some R&D engineer or computer designer in a CAD program, but instead is an experienced cylinder head machinist that ports and polishes a head, flow tests it on the bench to verify his result, and continues to iterate this process until he has the performance he's chasing. Once there the CNC guy pours over the "master head" taking measurements and storing the data to program the machine to duplicate the design. Bottom line, "the CNC produced ports are only as good or as bad as the man who did the original that was used to write the program" (thanks for the words, buddy, and you know who you are).
My point is that the guy who turns out one-off, custom ported heads that are flow benched to equalize the ports and milled/polished using only his experience and knowlege may well be better (for that specific engine) than an out of the box set of CNC produced heads. Read the article by Larry Carley - he says it himself, and further,

The way I see it a fellow looking for a good, out of the box set of heads is going to be better off buying the proven name brand, be it AFR, DART or another, but even those heads can be made to give him more power by being tweaked by a guy who knows what his doing for the specific engine they're going on. Bottom line, the guy who has years of experience porting & polishing and thousands of hours of flow bench time is by no means a neanderthal, and the only way they could justify having a CNC machine is if they're going into the crate engine business cranking out multiples of the same design for the the market. The CNC machine is nothing without a program, and the program needs that guy with the bowl mill. The guy doing the one-off engines that go into record setting machines is an artist, pure & simple. Just my thoughts, and I'm done.

Roger of course the program matters.For one thing I think it matters in being able to duplicate the same thing from port to post let alone head to head.And what goes hand and fist with that R&D is a better known brand name companies that can afford it.
The program also can simulate air flow without cutting a master.Then run the program for a given result.And mod and change the program to see what the end result is.

These CAD/CNC programs that impact the end product is light yrs away from a hand die grinder Roger.

So Roger I still consider you as a friend even through we disagree on these points.I am asking you to stop being so defensive about your friend/shop and open up to the advances the high performance industry has to offer.

BTW-Roger I still think you buy cheap and pay long to try to get the product to work as the little better product does and still don't get there.Roger trust me we have spent yrs working on a combo that wins and that has never,never ended..........

I believe that you need to study the CNC process a bit more, Gary, and in fact read the articles that you posted, paying attention to the details of how the CNC process is supported. With that said, you will not hear from me again on this thread or this subject. I'm done.

There's really nothing "cutting edge" about a CNC'd head.... All the CNC controlled cutter does it duplicate an original head that was done by someone with a flow bench, a dyno, and some race time.... The individually done heads by the porting guru's are the state of the art heads with port and chamber work that will probably never make it to a CNC program!!!! The hours and hours with the grinder, polisher, and the flow bench are were the really top of the line, state of the art heads come from, not from a CNC machine......

I've stayed out of this but I'll offer my 2 cents now "Just Because". CNC is first and foremost a tool for churning out multiple items needing to be "exactly" the same over and over! Add an autoloader and it'll just go and go until an operator tells it to stop! In the vast majority of shops I see, the "operator" is some young man who may not know his knee from his elbow and usually a shop foreman. Then add in tool bit wear and any number of factors as small as temperature differential and what was once "perfect" soon isn't! But it is Usually within tolerance. If the CNC unit doesn't have an autoloader, then someone has to insert the billet material and then zero the machine, and this adds another degree of misalignment.

I offer the above only to say it's an imperfect world! both methods are only as good as the people (company) behind the product. Heck, Carroll Shelby put his name on some terrible pieces! But, he had/has the name so they commanded top dollars! But you can probably make more power using someone elses parts.

I've been thinking of buying/building a stroker SBF and want to use aluminum heads, although I've been eyeing some Ford Motorsports! LOL...

Forgive my senior moment.I don't remember his name,but I did talk to the guy who is the head of Dart and he explained the hrs of hand work it took to port heads from Yrs ago.That the duplication by hand head to head or port to port was in the range of 20 to 25 %.Since the development of the CAD programs and CNC 5 position porting duplication was in the range of 3 to 5% and a set of heads took 8 hrs to do.He made a point of that percentage saying it could never be done by hand.To imply that work or QC is flawed I do think is misguided.3 to 5% is a very tight spec to hold.

In our history of yrs going to the drag racers auction at Indy we got the benefit of getting to know these guys afterwards at dinner over the three day event because we where one of the top purchasers of blem sell offs.

Sadly one thing about porting is not knowing what you could have had if done correctly.One link does speak to that about the removal of too much material and that is kind of my point why having each port matched exactly the same is so important.

You know the best surgical hands do from time to time need to add a stitch.

It all comes down to if your selling or buying

if your running on the street, bracket racing (any index class) or actually racing all out--going as fast as you can and having to beat others going as fast as they can---

We have sold lots of cnc heads---I've never run a ste myself and will never let someone have a set of my heads to copy---

GOOD porters verify their results with a flow bench....why do you always want to leave that part out??? Hand porting verified by testing on a flow bench, engine runs on a dyno, and actual track testing is where the information to write the CNC programs comes from!!!!!!!!!!!!!!!!!!!!!!!!!!!!!