[Lloyd-TX]

Great back-to-back comparison, Cliff.

Your numbers also illustrate just how well the OEM CI intake is designed as well.

On another note, it seems like I have read that KRE is working on another cylinder head. Cliff, can you (or anyone else) add anything to that?

[slowbird]

Cliff: do you have the flow numbers for both heads at all the lift points? Also what was the average HP and TQ for the iron heads and the KRE heads and what was the rpm range?

[Cliff R]

Lloyd, LOTS of things going on at KRE. I will not provide any info unless they approve it first...sorry....Cliff

[Lloyd-TX]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Cliff R:
Lloyd, LOTS of things going on at KRE. I will not provide any info unless they approve it first...sorry....Cliff <HR></BLOCKQUOTE>

I understand completely, Cliff, and thanks for the quick reply.

Sue would be nice to have someone cast up an aluminum version RP cylinder head with a stock (or nearly stock) external appearance and all the improvements of the KRE D-port cylinder head!

I still believe there's a market for those, even with JBP (someday!) releasing their repro CI RP cylinder heads.

[Cliff R]

The 6X heads flowed intake/exhaust: .100/88/85, .200/153/122, .300/206/164, .400221/185, .500/232/196. The KRE heads flowed: .100/92/71, .200/166/129, .300/234/169, .400/256/201, .500/261/220.

Average HP/TQ iron heads: 490.7/422.1
Average HP/TQ KRE heads: 525.3/452.5.
Peak HP/TQ iron heads: 5300/3900rpm
Peak HP/TQ KRE heads: 5600/3600rpm

Don't be misled by where the peak tq occurred at with either combo, the numbers start out right at peak at 3500rpm and stay steady or flat till 4300rpm, still making over 500 ft lbs with the KRE heads to 5100rpm and to 4700rpm with the iron heads.....Cliff

[PONTIAC DUDE]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by PONTIAC DUDE:
Brian. there are others. Check with Phil Underwood (Dave's Brother). 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)?
He had run his car quite a lot with his old combo and went right to the track after the installation.

If so, has he posted the results?

No he didn't post them. Don't think he will.

Where can I find them?
Might try and e-mail him., That would be the best deal.
[/QUOTE]

[Skip Fix]

Heck if someone will pay the dyno time and gaskets I'll do a D port, RAIV and E head(KRE also if some one has them) on my next 455 on the stand now! We'll leave the same 239/247 @ 0.050 cam in it and 20cc dish pistons.

[Cliff R]

This is not confirmed, but I was told that Dave Underwood's car picked up a couple of mph and went .45 seconds quicker in the 1/4 mile....Cliff

[PONTIAC DUDE]

Cliff.

You got different info then I was told. Hummmmmmmmmmmmmm.

[Cliff R]

Ken, that info came from an email that he sent to KRE. Can't remember the exact numbers as I just glanced at it. Something like 13.95 down to 13.50 and a couple more mph. Not bad for initial testing as we both know it typically takes several trips to the track and numerous changes to timing and fuel to find the ideal settings......Cliff

[buwalda]

Don't forget that you cannot compare just the flow #'s of both heads as a means of equating hp/tq.. The KRE heads have the spark plug aimed at the exhaust valve, more quench surface & a heart shaped combustion chamber, all proven performance improvements for many years now. The only downside is the alum heads needs a little more compression because of the heat loss. Also, the KRE heads' peak torque at 300 rpm lower, plus the peak hp at 300 rpm higher shows a broader power band, and all obtained with port volumes similar to stock D port heads. To me, Cliff's hp/tq figures show the KRE heads are real winners. If only the exchange rate was better......

[Redlined455HO]

I think we have confusion on which Underwood installed the KRE Heads. Dave has E-heads and has already dipped into the 11's in his 76 455/4 speed TA. His brother Rick won the KRE heads and swapped them for the 6X heads on the 400/auto in his 71 GTO convertible. The ET numbers posted Cliff are what Rick provided to me a couple of weeks ago.

[bmpmdf]

Cliff, When I was at KRE Thursday, Jeff showed me the dyno copies. Good bsfc's too. You have that q-jet thing pegged. I don't think anyone on the board here can really appreciate power increase without seeing how much better the KRE heads are everywhere in the rpm range and the difference in the other parts of the dynoing besides just peak hp and torque. I went thu Mt. Vernon leaving, and we were hungury, but missed the LJS fish so we went on to Sunbury. Wish we would have found Long John Silvers.

[BVR421]

quote
I don't think anyone on the board here can really appreciate power increase without seeing how much better the KRE heads are everywhere in the rpm range&gt;&gt;&gt;
I could better appreciate it if I can see a comparison between 265cfm KRE and 265cfm 6x
What is so astounding about better hp and torque with better flowing heads. kre 265 vs Cliffs 230s?

[rascal455ho]

I want first dibbs on used KRE heads when you get done with them Cliff.LOL

[Cliff R]

We are getting ready for the second round of the testing. The engine is back in place and ready to fire except one header was cracked at a weld so it's out for repairs. I've kept pretty close records on the old combo and will be able to see any benefits from the new heads at the track.

I think that this test is very realistic. Most of us spend some time with our iron "D" port heads in terms of good valve/seat work and minor porting. As in the case with my 6X heads, they have very little material removed from them, but excellent bowl/valve/seat work. I don't think it is or would be practical to port them to near 260cfm for my particular application. I do not have a flow bench or access to one. It is my opinion, that for the vast majority of hobbyists, the level of porting required to obtain 260-270cfm from iron "D" port heads requires a flow bench to not only maintain consistancy but to insure the minimal amount of material is removed in the right places. With the KRE heads, we get heads with very conservative runner volume, a nice straight intake port and an excellent combustion chamber. The results we are seeing from this testing is very typical of what nearly anyone would see with a "mild" street/strip engine. In my particular case, we made 40 hp right out of the box with no other changes. We'll know in a few days if this is going to improve actual vehicle performance. My guess is about .2 to .3 and about 2 more mph.....Cliff

[455Dave]

Barry:

Thanks for sorting all that out.

Rick did the head swap and didn't change anything before going to the track. The old heads were mild ported 6X-8s milled .090. Timing was set a 40 degrees total and no change in jetting so the car was probably running a bit lean. The total timing probably cost more horsepower.

Rick ran a night test and tune at 90 degrees ambient and 90 percent humidity. The car ran 13.59 at 100.61 that night. His best previous run was 13.77 at 99.8 MPH in cooler weather conditions. The numbers that Rick sent to Jeff were ones from comparable weather conditions with the old heads.

The car showed a definite improvement but since it was a true back to back test, I'm sure it will make better numbers in the future. The fun will be running the car in cool weather at Bradenton this winter to see what it will really do in good air. Just don't expect to hear any news of Rick's 400 beating my 455.

[thunder1]

I am Rick not Dave, I am impressed with the KRE's so far . I adjusted the jetting and dropped the timing and had a notable improvement ! In fact I fragged the trans on I-20 doing a test and tune. Understand that when I talked to Jeff Kauffman , my shift points were at 5000 rpm. My new shift points are now at 5700. This created a noticeable increase. The heads are breathing much better. We'll see how it all works out at Norwalk on thursday and friday for test and tune.

[Mo]

Thanks Cliff/KRE for the hard work and effort. Wish you could have put a different cam to match the KRE heads while on dyno. Do you think it would have made much difference? Also have you seen any forced induction motors using these heads yet?

[Cliff R]

At some point I will also do a cam test. The engine really likes the current cam choice as it makes good power everywhere. We tried some lower rpm pulls but the engine was very difficult to hold at low rpm on the dyno.

The engine is up and running, couple more minor troubles to work out, then off to the track. I discovered yesterday that the rockers were just brushing the valve covers so I'll need the thicker gaskets. I'm also going to go .050" longer with the pushrods to get the rockers exactly in the center of the valve tips. Weather permitting will get to the track this weekend.....Cliff