[Cliff R]

Jeff Kauffman called a few weeks ago and asked if I would be interested in doing some direct testing with his new aluminum "D" port heads. The first part of the testing would involve removing the engine from my Ventura and taking it to KRE for some dyno runs. Then, swapping out the 6X heads for a set of KRE's new heads, 85cc CNC chambers (unported). The second part of the testing would involve some dragstrip runs to see how much if any the new heads improved track performance.

I thought about it for about a milli-second then gladly said, let's do it! I removed the engine yesterday, carried it to KRE, installed it on the dyno and made it ready for the testing. It was dyno'd EXACTLY like it is tuned for the street and track. I used two different carbs during the testing, a 1976 q-jet and a Holley 4781-2 850cfm DP carb. I race the car with either carb and it runs identical numbers so figured it would make similiar numbers on the dyno.

Part of the testing would also involve carefully measuring my 6X heads for chamber size and actual port flow on KRE's flow bench.

Well, the testing was done today, in the interest of space I'll just go over the highlights. ALL runs were made with both sets of heads using my modified 1968 iron intake that accepts either spread bore or square flange carbs w/o an adapter. We tested both carbs with each set of heads. Timing adjustments were made to find the best peak power numbers. With the 6X heads my 455 made 455hp and 530ft lbs. With KRE's new heads it made 495hp and 564ft lbs. The qjet made the highest peak hp runs with either set of heads yet gave up a couple ft lbs at peak torque to the Holley carb. Average power with either carb was within .2 hp/.2 ft lbs. No wonder it runs the same numbers at the track with either carb!

The chambers on the 6X heads were right at 91cc and flowed 231cfm intake/196cfm exhaust. The KRE heads were 261cfm intake/221cfm exhaust with 85cc chambers. Cranking compression with the 6X heads was just under 160psi, right at 175psi with the KRE heads. With either set of heads the best hp/tq numbers were made with 30 degrees of total timing. 93 octane fuel was used for all the testing.

Next step, off to the track for some timeslips!......Cliff

[Cliff R]

Jeff Kauffman called a few weeks ago and asked if I would be interested in doing some direct testing with his new aluminum "D" port heads. The first part of the testing would involve removing the engine from my Ventura and taking it to KRE for some dyno runs. Then, swapping out the 6X heads for a set of KRE's new heads, 85cc CNC chambers (unported). The second part of the testing would involve some dragstrip runs to see how much if any the new heads improved track performance.

I thought about it for about a milli-second then gladly said, let's do it! I removed the engine yesterday, carried it to KRE, installed it on the dyno and made it ready for the testing. It was dyno'd EXACTLY like it is tuned for the street and track. I used two different carbs during the testing, a 1976 q-jet and a Holley 4781-2 850cfm DP carb. I race the car with either carb and it runs identical numbers so figured it would make similiar numbers on the dyno.

Part of the testing would also involve carefully measuring my 6X heads for chamber size and actual port flow on KRE's flow bench.

Well, the testing was done today, in the interest of space I'll just go over the highlights. ALL runs were made with both sets of heads using my modified 1968 iron intake that accepts either spread bore or square flange carbs w/o an adapter. We tested both carbs with each set of heads. Timing adjustments were made to find the best peak power numbers. With the 6X heads my 455 made 455hp and 530ft lbs. With KRE's new heads it made 495hp and 564ft lbs. The qjet made the highest peak hp runs with either set of heads yet gave up a couple ft lbs at peak torque to the Holley carb. Average power with either carb was within .2 hp/.2 ft lbs. No wonder it runs the same numbers at the track with either carb!

The chambers on the 6X heads were right at 91cc and flowed 231cfm intake/196cfm exhaust. The KRE heads were 261cfm intake/221cfm exhaust with 85cc chambers. Cranking compression with the 6X heads was just under 160psi, right at 175psi with the KRE heads. With either set of heads the best hp/tq numbers were made with 30 degrees of total timing. 93 octane fuel was used for all the testing.

Next step, off to the track for some timeslips!......Cliff

[Larry Navarro]

Thanks for the info Cliff.
Most likely going "KRE-D" for my next engine!

[Darrell]

Maybe I am way off here, but couldnt you have a set of 6x-4's ported to 260 and come up close to those same numbers? that would save allot of bills wouldnt it?

Larry dont your heads flow that good?
When is there enough flow? A streetable 041 cam can only use so much flow, what is that number?

[KS circutguy]

Cliff,
How about re-testing the same combo, but trying a set of E-heads?
Thanks,
Steve

[mothermuxer]

Are your 6X's stock, or ported?

[Cliff R]

"Maybe I am way off here, but couldnt you have a set of 6x-4's ported to 260 and come up close to those same numbers? That would save allot of bills wouldnt it?" Darrell, no doubt they could port my 6X heads pretty hard, cut them for more compression and get closer numbers. I don't think KRE's intension is to port iron heads to run with their new heads!

"Cliff,
How about re-testing the same combo, but trying a set of E-heads?
Thanks,
Steve "

Steve, we've already tested that combo except we used the RPM and T-II intakes, not my iron intake. I posted the info some time ago when we tested the first 455 with KRE's new heads. The E head engine made 505hp/551tq peak power using a Demon 850 and T-II intake, and was down a bit at lower rpm in comparison to the KRE heads.

"Are your 6X's stock, or ported?" My 6X heads are very mildly ported. No porting done under the valves other that running my bowl hog into the bowls then blending the result into the port. I opened them up a bit at the pushrod bulges, ground out the smog bumps and removed any casting flash and smoothed any sharp edges. They made pretty good numbers considering the small amount of work done to them.......Cliff

[Larry Navarro]

Darrel,
my iron-D heads flow 277cfm @ .550".
Sure thats alot of flow but the KRE-D's most likely have better low lift numbers than mine, plus less weight.
My heads are more suited to a high rpm motor for a car with a lower set of gears and less weight.

[Brian Baker]

Darrell,

I hear ya', but like Cliff said that wasn't the point of the test. My 62's are race ported and only flow 254-cfm @ .600" (28 inches). I think a d-port flowing 231-cfm is more representative of what would be on a typical street engine. Porting a set of iron d-ports to flow over 250-cfm would obviously take more time (and cost more money) than it would to merely get 230-cfm out of them.

A gain of 40-HP and 34 ft/lbs. torque over that of the mildly ported 6X heads is a very good result, I think. I would imagine that had the 6X heads been unported, the gains would have been greater. Can't wait to see the dragstrip results.

[Brian Baker]

I'd also like to add that, to the best of my knowledge, this is the first time anyone has done a "back to back" test of iron heads and aluminum heads, where the only thing changed were the heads, and the figures posted.

That's what alot of you "tire kickers" have been wanting, right?

Kudos to KRE and Cliff.

[David Jones]

"tire kickers"
?

[lugnutt]

How much would the heads tested (Kaufmans) cost delivered to the customer? Just went to the site and the link was down.

[Larry Navarro]

.....and another plus, is the benefit of running a bit more compression, over a set of iron heads.

[Cliff R]

Brian, that is EXACTLY why KRE wanted to do the test. They already have numbers on a couple of combo's....but....the ONLY way to really know how these heads are going to work is to add a set on an existing combination and change NOTHING else. My combo was chosen because I'm close by and have very good numbers on the car. A couple of weeks ago I made 6 back to back runs without shutting off the engine and all runs were between 7.71 and 7.78 right at 90mph. The increased power should be pretty easy to pick up by the timeslips.

To be perfectly honest I was a bit surprised by the power my engine produced with the iron heads and iron intake/q-jet. My intake is modified at the flange to accept both square and spread bore carbs, but very little material removed in the runners. Even so KRE was convinced it would not make power past about 5100rpm. Remarkably it pulled right past 5500rpm with their heads (495hp @ 5600rpm) and made peak power at 5300rpm with the iron heads...and....only fell off a few hp at 5500rpm.

We're headed to the GTOAA even this weekend, will get to the track ASAP to back up the numbers......Cliff

[GS470]

Pricewise, I think the out-of-the-box KRE heads are extremely close to what I paid for my 260+cfm 6X street/strip heads from Dave at SD Performance. If the KREs would have been available when I bought my heads, I would have given them serious consideration.

[PONTIAC DUDE]

Brian. there are others. Check with Dave Underwood. He is the dude that won the KRE heads at VMP.

He changed just the heads.

[rascal455ho]

Real world testing it doesn't get any better than that.Can't wait to see the difference on the track.

[rascal455ho]

Hey Dude did Trice run at Farmington a couple weeks ago?I could not make it.Just wondered how he done.

[6567GTO]

How far back ordered is KRE these days. I couldn't get a set when I wanted to.

[Brian Baker]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by PONTIAC DUDE:
Brian. there are others. Check with Dave Underwood. He is the dude that won the KRE heads at VMP.

He changed just the heads. <HR></BLOCKQUOTE>

Did Dave do any back to back testing (on dyno or on track)?

If so, has he posted the results?

Where can I find them?