I'd like to get a discusion going about selecting cylinder heads for drag racing (i.e., bracket, street/strip). How do you choose the right heads these days with all the choices in the aftermarket? Do you really need to port aftermarket heads or can you match them to the right combinations without porting? Should you choose heads based only on the flow numbers?

I have never supported porting heads without having them on a flow bench. In the last 4 or 5 years with all the choices of heads, we only have port & flow work done on the more higher end jobs. We do put more emphasis on the valve job to optmize what we can.

Selecting the right head (chamber size & shape, intake runner cc, valve size, etc) is the most critical in the matching of componants.

Steve

Plenty of manufacturers provide CNC ported heads out there that any one of them would fit most customers' needs. As noted, only class specific or high end engines need "tweaked" cylinder heads. I believe more times than not, people choose the wrong peripherals rather than the wrong cylinder heads. For example, the LSx based forums are full of shops who "over-cam" their customers' cars in order to obtain a big peak dyno number, all while sacrificing overall performance. Just the nature of the beast I guess. Dyno numbers sell parts.

 

Best advice I have seen latley is the right head for the job & do a good valve job on it. More in the vj than most give credit. Roger

I know this is an old post but noticed some of your questions were not addressed. Cylinder heads can be selected for a give cubic inch or liter by the intake port volume in cc's. To select a head for a 5.7 or 5.0 engine stay below 200cc. For an small block Chevy or Ford engine 400+ cubic inches select a head 220cc up to 250cc.

Flow numbers are considered by most professional head porters to a marketing gimmick. At one time flow numbers were thought to be the ultimate goal. With todays research & development air flow, air speed, and port velocity are more important. The harmonics of air flowing thru the intake ports has become a large factory the last few years.

 There are more brands on the market today than when you made this post. The question today for me is which manufacture is going to give my customer the best product for his dollar. Having been a cylinder head porter for many years I tend to lean toward the better known, been here for years companies, such as Dart, Brodix, Edlebrock and World.

I have personally ported Dart, World and Brodix heads for customers with great results. I am currently porting a set of Trick Flow heads for a customer. I'm impressed with the results we are getting from the flow bench. Yes we are getting good flow numbers from the heads. However we are concentrating on port velocity and where the air is moving within the port.

@ coulterracn - Great info! I'm sure being a head porter you buy the bare heads and finish yourself, but how do the finished CNC'd or as cast heads match up to what you do to the ports? Is there really such a thing as off the shelf, bolt on and go? 

 I could type pages on this.........but I don't like to type that much........All porters should do the math in the beginning as to the air flow requirement of the motor they are bolting the intake and exhaust track on.If there is a out of the box head or stock head will meet those flow numbers I see no reason not just to check the flow claim and scatter between ports and use it! As far as polishing goes, flow loss on the wall of a sand cast port is about4% and 3% after a polish 1% increase.The type of racing you do would dictate whether thats worth it......or not................Paul