KRE's New Aluminum Cylinder Heads Dyno and Drag Test

A New Ballgame: They Make More Power and Torque With Less Weight Then the 6X Heads We Tested

By John Carollo, Thomas A. Demauro

Photography by John Carollo

On The Dyno

For some reason, the new KRE aluminum heads reminded us of a company baseball game. Imagine you are at yours with all your work buddies and playing that company from down the street. Everyone is having a good time, and all things are pretty much equal. All of a sudden, a new batter steps up for your competitors. Word quickly spreads that he doesn't even work for that company; he's a ringer sent in to win the game. On top of that, he's got better equipment than anyone else. All of a sudden, your just-for-fun sporting event gets serious.

That's what the new Kauffman Racing Equipment (KRE) heads are to the Pontiac world--ringers. KRE is a well-known commodity in the Pontiac hobby. As you may have guessed, one of the company's specialties is head work. From squeezing more power out of iron units for any stock or slightly larger-sized engine to the big ol' nasty 1,900 horse (no, that's not a typo) anything-goes big aluminum versions, brothers Jeff and Mark Kauffman have a handle on producing power. After grinding enough heads to keep themselves cross-eyed for the rest of their lives, Jeff and Mark Kauffman cut straight to the chase and started making their own aluminum heads. This occurred after seeing the need for an aftermarket head with some modern touches that would satisfy street machiners and the weekend racer alike. Creating a new cylinder head is a huge deal in itself but there is more to these new pieces than some just slick CNC work.

ABOUT THE NEW KRE HEADS
When KRE came out with these heads, it raised the bar in the street/strip performance market by not only providing more modern features like a heart-shaped combustion chamber and improved spark plug placement, but also by retaining the stock bolt and port locations and a stock D-port exhaust configuration. This way, they are virtually a bolt-on replacement for factory iron D-port heads from '65-79 (just be aware of chamber-size differences that will affect compression ratio).

They come in two versions that we'll call mild and wild. While the mild versions have plenty of killer flow cast into them, before they leave KRE, they are smoothed out a little (mostly to remove any casting flash or standing seams). The wild versions stay on the CNC machine a little longer, getting a state-of-the-art port job. Even after that, Jeff still puts them on his grinding bench and gives them a little more. Available chamber sizes are 85 ccs and 65 ccs.

Like any new product, KRE is still on a learning curve with these heads, and with each set they run through the process, they get better and better. KRE believed the new "mild" units would deliver at least 20 more horsepower than street/strip ported factory iron heads--perhaps even 25--but the dyno test will tell us more. By the time you read this, the heads will be on the market.

THE PLAN
KRE offered Engine Masters the chance to watch as they did some serious R&D on their own product. The plan was to take a proven engine with modified 6X heads, bolt it up to the KRE dyno, baseline the motor, swap over to the new heads (mild versions), and see what the difference was. They would change the heads only but would swap carbs on both setups.

That's because the owner of said motor was Cliff Ruggles, a noted carb guru and owner of Cliff's Q-jets who wanted to test his own product (a modified Quadrajet performance carb) against a Holley. The same intake would be used for both tests, as would the dyno headers (1 3/4-inch four-tube with 30-inch long primaries), distributor, the rest of the ignition system, and the roller rockers. The object of the thrash was to learn just how much more power these new heads would produce over the worked 6X Pontiac heads under virtually the same conditions. We want to stress that those would be the only variances between engine configurations.

Part II of the game plan was to put Cliff's car on the track and get more comparison info. He has raced this configuration in his '73 Ventura for quite a while now, so any differences, subtle or not, would be quickly noted.

THE TEST ENGINE
The test engine was chosen because it's a proven, consistent product--having served Cliff well for over three seasons. During that time, he has flogged it relentlessly, always keeping a keen eye on just what every little change has done to his highly effective package. Cliff's engine is a 455 that's gone .060 over to become a 468 and was one of the first to use Crower rods when they came out. The 6X heads are worked in the bowl area and have a very good valve job. They were also modified to install larger 1.77 exhaust valves.

The intake is a '68 400 cast iron model. Intake mods are more of a function nature than for performance and are at the flange, so the intake will accept the square-flange Holley without an adapter or the spread-bore Q-jet. Cliff tests each and every one of his carbs on his own car before he ships them. That way he can tell just how they are working under the same conditions. We joke that Cliff's '73 Ventura is his dyno, but the bottom line here is a potent 455 transmitting power through a Turbo 400 and 3.42 gears. (You can check out the rest of the engine specs in the sidebar.)

HEADS COMPARED PHYSICALLY AND ON THE FLOWBENCH
On the JK&M Custom Flow 400-cfm flowbench, the setting was 28 inches of water. The 6X head flowed 232 cfm on the intake and 196 on the exhaust, and the KRE head flowed 261 on the intake and 220 cfm on the exhaust. All were tested from .100 to .500 lift because the 6X port nosed over after .500 lift, and the aluminum D-port only flowed about 5 cfm more at .600 lift according to Jeff.Kauffman also cc'd the heads using the standard mixture of mostly water and a little alcohol. The 6X heads filled up to 91 ccs while the KREs held 85 ccs. The 468's compression ratio using Cliff's 6X heads is 9.95:1, and with the KRE heads, it jumps to 10.48:1. This is due to the different combustion-chamber size. However, the aluminum head can take more compression than an iron head before detonation because heat dissipates faster from the chamber through the aluminum.

Regarding the valve job, the 6X heads had 30-degree seats on the intakes and 45-degree seats on exhaust with a three to four angle grind. Jeff explained that the 6X can't really fit a full, four-angle valve job, so they usually end up being between three and four in some places. The angles for the 6X intakes are 15-degrees top, 30-degrees seat, 60-degrees under, and 75-degrees bowl. The exhaust angles match those of the KRE head as listed below.

The KRE intake and exhaust seats are both ground at a 45-degree angle with a well-defined four-angle valve job on the intake and exhaust seats. Those angles are 35-degrees top, 45-degrees seat, 60-degrees undercut, and 75-degrees bowl. Ken Criss is the man at KRE who assembles these aluminum heads, and once he has finished a set, the first thing he checks is the height of the valves for consistency. He installed two sets of shims in the heads they used for this test to set the proper spring height of 1.700 inches. When comparing valves, the 6X for this test used 2.11 intake and 1.77s on the exhaust (1.66 exhaust is stock). The KRE heads used Ferrea valves of 2.11 inches intake and 1.66 inches exhaust. When using the KRE heads, the stock head bolts (there are three different lengths) will have to be swapped out for a set of ARP head bolts, PN 190-3605. For our test, once the KRE heads were installed, Cliff would have to ensure the same rockers used on the 6X heads would operate at the correct and most effective fulcrum. He would use a marking pen on the top of a valve stem to see where the rocker was making contact. When it turned out that they were not in optimum alignment as seen by the contact patch being on the edge of the valve, a set of longer Comp Cams pushrods would be used. They are 9 5/16 inches (9.400) long as the geometry of the KRE head's valvetrain is slightly different from the 6X heads. Jeff points out that depending on the rockers used, they could go as long as 9.450.

BASELINE DYNO TESTING
The KRE dyno is a Super Flow SF-901 with a 2,000 lb.-ft. torque brake. After the discussion about how much power a said part or combination should make, the dyno takes all of the guesswork out of it because it's all right there on the readout--or it's not. Dyno protocol was as follows: pulls were made from 3,500 to 5,600 rpm each time; all pulls were up-sweeps not down-sweeps. Why not start pulls lower than 3,500 rpm? According to Jeff, the problem is the dyno uses so much water on the bottom end during a pull with a big engine that it may run out of brake at the top end and uncouple the engine, giving false peak power readings.

The air/fuel ratio was monitored by the brake specific fuel consumption (BSFC) numbers. Jeff said that he was "looking for figures in the .43 to .50 range to tell us the efficiency is good and the air-fuel ratio will be close from that." He reported that the fuel curve was basically the same yet the KRE heads made more power on the same amount of fuel. This means that they were more efficient.Water temperature for all pulls would be between 170 and 180 degrees and oil would be at 200 degrees. Only 93-octane pump gas was used. There would also be back-up pulls for each pull to substantiate the numbers. The only proposed changes were to the jetting and timing, and even those would be more of an adjustment than a big change as it's normal dyno-tuning procedure to tweak with timing and jets. As it turned out, there were no changes in jetting because both carbs were right on according to Cliff and Jeff.

To settle Cliff's personal carb quest, his Q-jet performed close to the Holley he tested, and the numbers prove it. On the best pull, the torque on his motor, right out of his car and still using the 6X heads, was 522 lb.-ft. at 3,900 rpm with his carb and 528.3 at 4,000 rpm with the 850-cfm Holley. Horsepower was close with 455.4 with the Q-jet and 449.7 with the Holley. It pretty much confirms Cliff builds a great Q-jet. In subsequent pulls, timing changes either way showed no increase in power. So, with the baseline set, off came the 6X heads.

KRE HEADS ON THE DYNO
As the KRE heads went on, everyone was getting stoked. It was an exciting time for the brothers Kauffman and proudly, Jeff said the motor is, "looking better already--getting rid of those ugly blue heads." When everything was ready and the first pull was made on the KRE heads, it became apparent that the new combo was creating more torque--MUCH MORE TORQUE. The reading was 548 lb.-ft. at 3,600 rpm. Jeff said, "It needs more brake." So he added 5 percent more brake to the dyno and tried again.

On the second pull, the dyno read 485 horses at 5,400 rpm with 550 lb-ft at 3,800 rpm. That's an increase of 35 horsepower, and the motor is still at 30 degrees timing with the Holley carb. It's only the second pull, and there's more coming.

The next two pulls were at 32 degrees, and both had problems with the amount of brake taking on the new torque and holding until the top end. The power levels stayed pretty much the same, but the boys still wanted a definitive reading. Jeff noticed the power curve at the low and mid range, even with the brake glitches up top, and described it as, "flatter and smoother." They finally got a clean one at 32 degrees of timing but saw no power improvement. Cliff backed it down to 30 degrees, and they tried again. The engine hit 494 horses this time but Cliff said, "It didn't sound right." Jeff answered, "That's because it ran out of brake again. Another adjustment sets the brake as needed.

Then, with the Q-jet swapped on, the best power numbers were 494.2 at 5,400 rpm and 549.5 lb.-ft. of torque without running out of brake. Comparing the two best Q-jet-equipped runs (see charts) reveals an increase of 38.9 hp with peak power moving from 5,300 to 5,600 rpm and an increase of 26.6 lb.-ft. of torque when compared at the same 3,900 rpm for the KRE heads.

CONCLUSION
With the hard numbers from the dyno collected, the only remaining truth is the difference in price. If KRE were to build a state-of-the-art set of 6X heads for a customer that would flow about 240 cfm on the intake, including the cores, all the parts, and labor, the price tag would be about $1,400. Off the shelf and ready to bolt on, the new KRE heads cost $1,950. This prompted Jeff to say, "When can you spend $500 and pick up over 35 horsepower?" When indeed. Advantages and disadvantages are simple. Factor in the above price differential, take into consideration that the technology you are buying is today's and not 30 years old, and add the aluminum-over-iron factor of better-cooling properties and weight (just 31 pounds each for the KRE heads), and you've got a start. Then realize that the engine has the potential to run better with unleaded gas at a higher compression ratio than factory iron heads, and the aluminum heads more effectively prevent detonation. And did we mention more power? Put these ringers on your team and start looking for the wins to come.