Copyright © AATcorp

Cylinder heads are one of the more important components on any performance engine, and keeping on top of the latest technology is the key to staying out in front. New products, new changes, new modifications keeps this industry progressing at a phenomenal rate. Here is just a hint of what I have been working on lately...

The next thing I will be trying, is different cylinder heads on our Black Thunder '67 Bronco project vehicle. Since our current 427 stroked Windsor is topped with a set of extreme ported '65 289 head that out flow the Edelbrock Performer RPM alloy heads (6025), I needed to go up in the world. The Victor JR heads might capture that number one spot, as seen here in it's unported version, which far exceeds the flow numbers, port and valve sizes, as well as the chamber configuration over the Performer heads.

The swirl-flow chambers, bigger valves, cleaner lines and minimal restrictions look to be the head of choice for those with power output over the 500hp mark. Caution is given by Edelbrock, and by us, that "installation of these particular cylinder heads on lower cubic inch engines (400 and under), or lower output engines (500 and under), or used for anything other than serious performance applications, may actually reduce power output from your particular engine." Of course, each situation requires it's own specialized investigation into the cylinder head needs, but here, bigger may not be necessarily better. For my application, these heads will be pro-ported on top of all this.

(left) Note the more 'unfinished' combustion chamber of the RPM compared to the Victor. Also note the minimal shrouding of the valves of the Victor in comparison, even though the Victor has bigger 2.05" valves.

(right) Note the evidence of the machining for the valve pocket on the Performer, and the lack thereof on the Victor. Even so, I have ported the Performer to exceed the flow numbers

of all other alloy heads, except for those all out race heads, like the Victor. Make no mistake about it, the RPM head from Edelbrock is an excellent piece, which is why I chose it to compare the Victor against, proving the Victor to be quite a formidable configuration in it's own right.

I will be putting up a few pages on how to port the Performer RPM head yourself, or you can have Performance Unlimited do it as well. Here is a table I pulled off our flow bench to show just what we got from our Pro-Porting procedure on the 6025's. Now, with these Victor heads, there's no telling where they'll end up on the chart, but most likely, they'll be off of it!

So, how much did we gain? The comparison chart tells the tale, and proves it was definitely worth our while, gaining nearly 8% over an almost already perfectly designed after market aluminum head. If one could assimilate this percentage into directly into horsepower, that would mean an additional 35 hp for a 500 hp engine. Pretty significant stuff.

Not only did we see notable gains from our modifications, the overall improvement was considerable compared to the stock OEM head, at an impressive 52% increase!

Experts agree that flow readings past 350cfm are rarely unattainable with anything other than an enormous, all out racing straight port design, with no bends or dimensional changes.  A small block head that flows over 254 is pretty darn good in anyone's book. Take into consideration that a high performance 2-1/2" turbo muffler only flows a maximum of 367.58 cfm only a little more than just one single port of our Pro-Ported Performer RPM project head!