[Jim Hand]

Skip,
Just to clarify for everyone what those other "variables" were when I replaced iron heads with the KRE heads, will list them one more time:

1. KRE heads flowed an average of 273# .55 lift. The iron heads that were replaced flowed an average of 253# .55 lift.

2. The iron heads averaged 165cc port volume. The KRE heads averaged 186.5cc port volume

3. The iron heads provided actual CR of 10.08. The KRE heads provided actual CR of 10.38.

4. The KRE heads weighed a total of 42# less then the iron heads as installed.

5. With no other changes to the engine, trans, converter, rear axle, or shift point of 5500. the car ran between .15 and .2 seconds poorer in the 1/4 with the KRE heads.

6. With the KRE heads, the car ran to the 60' distance between .1 and .15 poorer then with the iron heads.

This was not a "test" of heads. I spent a lot of time and effort getting the KRE heads ready to install and fully intended to leave them on and not worry about cracks or leakage in the ported iron heads. After three trips to the track and all normal tuning optmized for the new heads, it was painfully obvious to me that the car had lost performance. And it also was obvious that it was a loss of low and early mid range power, exactly as every researcher that has tested such changes in port volume has found.

So I ordered a new cam to pick up the low end, a 233/235 on 108. It did, but also lost two MPH for no ET gain!

What I did and found is in no way related to what Cliff Ruggles experienced when he changed heads. I was already running .5 second quicker then Cliff with a car that weighed 300# more. I already had excellently prepared small port good flowing iron heads, as opposed to Cliff's basically stock iron heads. So please don't try to confuse this issue by dragging up Cliff's car.

As a result of the loss of low and early mid range power due to the larger ports on the KRE heads, even though they flowed 20 cfm added flow, and the loss of performance with the car, even though it was 42# lighter with the KRE heads, I yanked them off.

I did a bit more porting on the iron heads which also added a small amount of port size (13 cfm/5 cc) and reinstalled them. The car immediately regained the 60' time, and not only the earlier ET but an additional .1 second! And the added airflow also picked the MPH up equal to what the KRE heads provided.

Skip, why not discuss what actually happens when small port heads with equal flow as larger port heads are compared? We all know that the loss of some low and early mid-range power can be hidden by looser converters, deeper gears, or no traction. And we also know that many folks don't care if it is lost. But none of this changes the basic facts of the effects of port volume/cross sectionall area on real power development.

You can believe that if my new KRE heads had worked as well as my heavier iron ones on my car at the RPM range I run, they would sure as heck still be on the car!

Jim Hand