In the last issue, we introduced you to the brand-new aluminum D-port heads from Kauffman Racing Equipment (KRE)--which were designed to be high-performance street/strip alternatives to finding factory iron cores--and had them ported and completely rebuilt. These heads were developed to be a direct bolt-in replacement for '65-79 cast-iron factory D-ports and have many innovative features that were discussed in detail in Part I.
HPP was invited to observe as these new heads were tested against a set of 6X heads on the same dyno on the same engine, which happens to be a 468 cubic-inch (455 +.060) Pontiac out of Q-jet-builder Cliff Ruggle's '73 Ventura. The idea was to see the difference in results with the only change being the new KRE heads; everything else would remain the same, and testing would be done on the same day under the same conditions.
Actually, the only variance was a sort of test within a test. That's because Cliff owns Cliff's Q-jet, and he wanted to test his Q-jet carb against an 850 Holley using his cast-iron intake that he modified to accept both carb's flange styles. However, before/after comparisons will only be made with the Q-jet in this story.
Cliff's 6X heads had been reworked, including bigger 1.77 exhaust valves, port matching on the intake side, and bowl work. They had 91cc chambers resulting in a 9.95:1 compression ratio. The 6Xs flowed a maximum of 232/196 cfm at .500 lift at 28 inches of water on KRE's flow bench compared to 261/220 cfm for the KRE aluminum D-port heads. These were the basic KRE heads, not seriously ported but merely cleaned of burrs and seams and then port-matched to the intake. KRE offers its heads in two versions, with the second one getting a longer ride on the CNC machine (resulting in even better flow).
Jeff and Mark Kauffman bolted Cliff's 468 Pontiac to the dyno, and after a couple of pulls, got a baseline of 522 lb-ft of torque at 3,900 rpm and 455.4 hp at 5,300 rpm with the 6X heads and the Q-jet carb. With the baseline set, the old 6X heads came off, and the spanking-new KRE aluminum versions went on. KRE changed the heads only, still using the same carb and intake. The best pull of many revealed 549.5 lb-ft of torque at 3,600 rpm with 494.3 hp at 5,600 rpm.
The price for this performance was $1,950 for the KRE heads ready to bolt on. Jeff Kauffman explained in Part I that he would charge about $1,400 to build a set of 6X heads that flowed like Cliff's did (including the cores). So for $500 more, you can purchase the KRE aluminum heads and get over 35 more horsepower and cut weight at the same time.
STRIP TESTINGBut this new set of heads wasn't designed just for dyno pulls. Jeff and Mark Kauffman are hardcore Pontiac guys and wanted to know more about how their new heads perform at the track. The next step in the test was to return the motor to Cliff's '73 Ventura and make some passes on it. And that's where we pick up this month.
Prior to the head swap, Cliff's Ventura, with its 6X heads, was a consistent 12.30-12.50 piece. His best ever e.t. was a 12.10 with a speed of 111.96 that was, in part, attributed to running at sea level at Virginia Motorsports Park.
Once he reinstalled the engine after receiving the new KRE heads, it was time for the first test session at Norwalk Raceway Park. The year before, the 6X head combination in the same Pontiac on the same track with the same driver ran 12.41 and 12.42 at 110 mph with a 1.77 and a 1.78 60-ft. A year later with the KRE heads installed, Cliff was ready to go but described the day as "an unbelievably hot one of 90-plus degrees with very high humidity." Even so, he ran an 11.91 at 113.65 mph, a great improvement. One more run that hot day yielded a best-of-day 11.81 at 114.20 mph. Again, the configuration he used was the exact same iron intake and same '78 Pontiac reworked Q-jet carb used in the dyno tests.
One or two runs do not make conclusive evidence, so more testing was still needed. Besides, Cliff felt there was more to be found. He had to get used to this new package and explore the nuances of it.
It wasn't until the Ames Performance Pontiac Nationals at Norwalk Raceway Park later that same week that the chance came for Cliff and the Kauffmans to finally put together a bunch of runs. The weather had improved with temps dropping to the 80s, but there was still a head wind to contend with. The Ventura ran consistent 11.80s at 114 mph with 1.67-1.69 60-ft times during the three-day event, and Cliff had even won the Stock class.
On the last run of the weekend at 8:00 p.m. on Sunday, with the temperature dipping to the low 70s and the headwind gone, Cliff was in the semi-round of King of the Hill. Though he redlighted, he took advantage of the cool night air, wrung it out to 5,600 rpm before shifting, and cranked out an 11.79 at 114.49 mph--marking the quickest pass yet for the new combination. Cliff says the higher shift rpm (he had been shifting at 5,000 rpm) didn't make the Ventura go quicker; the head wind dropping off and the lower temperature were the real factors.
DRIVING IMPRESSIONS
According to Cliff, "It has more power than I thought it would. You can feel it make more power everywhere." He's also noticed better idling due to the now-higher compression, and it's now smoother coming off that idle. Overall, the engine heats up to operating temperature quicker but doesn't run hot. Cliff looks to keep on tweaking it and realistically sees dropping e.t.'s into the 11.50s.
CONCLUSION
From 12.41 at 110 mph to 11.79 at 114.49 mph shows that the dyno did not lie and, in fact, these KRE aluminum D-port heads do make impressive power as compared to the modified 6X heads. With the old heads and a half-tank of fuel, the race weight with driver was 3,805 lbs. With the KRE heads and a quarter-tank of fuel, race weight is 3,760 lbs.
As we said from the beginning, these KRE aluminum D-port heads offer a more modern design than traditional Pontiac D-port iron heads, make more power, and weigh less. We have presented our story; the rest is up to you to decide if KRE's heads are right for your combination.
ABOUT THE TEST CAR Model of Car: '73 Pontiac Ventura Race Weight: 3,760 lbs Converter Stall Speed: 3,400 rpm Transmission: Turbo 400 Rear: 3.42:1 Safe-T-Track Slicks: Mickey Thompson ET Streets, 11.5x28, Tread width 8.6" Launch Technique and RPM: 1,400 rpm Shift Points: 5,000/5,600 rpm RPM at the Traps: 5,{{{100}}} rpm 60-ft Time: 1.67-1.69 1/8-mile Time: 7.49-7.52 1/4-mile Time: 11.79-11.86 Trap Speed: 114.49 ABOUT THE TEST ENGINE Block: .060-over 455 = 468 ci Crank: Stock nodular iron, 4.21 stroke, rotating assembly balanced Rods: Crower forged steel, stock 6.625" Oiling System: Stock Pistons: TRW forged, flat-top, zero-deck Compression Ratio: 10.48:1 Heads: KRE Aluminum D-port Valves: Ferrea stainless, 2.11/1.66 Valve Job, Intake, and Exhaust: 35° top, 45° seat, 60° under, 75° bowl Chamber Size: 85 cc Head Gasket: Fel-Pro 8518 Rocker Arms: Crane, 1.65:1 roller, Rhoads lifters Valve Springs: Crower PN 68405, 1.700 height Seat Pressure: 115 lbs Open Pressure: 310 lbs Pushrods: Comp Cams 9.400 Cam: Crower PN 60919, hydraulic Duration at .050: 231°/{{{240}}}° Lift: .517/.517 with 1.65:1 rockers Lobe Separation Angle: 113° Installed Position: Intake set at 109° centerline Intake Manifold: OEM '68 cast iron Mods: Reworked at carb flange to fit Holley flange (without an adapter) as well as Q-jet Carb: Q-jet, .073 primary jets, .048 custom-sized secondary rods Distributor: GM HEI, 20º mech. adv. Timing: 30º total, all in by 2,500 rpm Plugs: NGK R5671A-8 Exhaust: Hedman 4-2 Headers 1 3/4" primaries, 3" collectors, 3" H-pipe, Flowmater 40 Series mufflers with 3" inlet/2 1/2" outlet, full-length compression-bent tailpipes