[Jim Hand]

Guys,
What and where is the "one point more CR" rule listed and documented?

I am sorry that the technical facts I (and many others) have presented about the effects of different port sizes on engine power are being disregarded. I fully understand we don't like to give up pre-conceived concepts about how to go fast.

I will close my portion of this discussion with this comment:
The next time anyone wonders why my 4070# wagon with 3.31 gears, a mild cam, and a Q jet can possibly be competitive with lighter cars running much higher flowing heads and larger cams, you may want to reread some of the facts I have posted and referenced. My car doesn't just magically run what it does by following pre-concieved ideas and "rules" that have no basis.

I have tried to help others understand the subject, and that is all I can do. I don''t have time or the inclination to argue about material I have tested and confirmed.

The KRE heads I bought and ran are long gone - I learned and confirmed all I needed to know about the effects during those weeks of trying to make them work at least as well as what I had.

As always, we should each build our cars exactly as we want them, regardless of what others say. So keep those Pontiacs running!

Jim Hand

[scott70]

A good working combination is the name of the game!!!!Ive seen pontiac cars at my track with e heads and such and they couldnt come close to running with my 250 cfm iron headed car.A good combo VS a bad combo.I'm going to some ported jbp e eheads this winter but like last time,i'll tell him my entire car combo and tell him what I expect in the end and hope all ends up well.And it will end up on the engine dyno again to see the results.

[harry k]

overall what i learned here is : a street / strip car with 455 to 462 ci pure pump gas up to 91-92 octane (no EMC exotic stuff) compression ratio no more than 10.5 (alluminum head)& cams up to 240 does NOT require a head more than 270 cfm to make it the best combo as we call it .

[ponjohn]

Originally Posted by harry k

overall what i learned here is : a street / strip car with 455 to 462 ci pure pump gas up to 91-92 octane (no EMC exotic stuff) compression ratio no more than 10.5 (alluminum head)& cams up to 240 does NOT require a head more than 270 cfm to make it the best combo as we call it .

I would agree with this - I have: 9.5-1, 462, 220cfm d-ports and run 11.90's at 3680 race weight.

[gearbanger]

Originally Posted by Jim Hand

Guys,
What and where is the "one point more CR" rule listed and documented?

I am sorry that the technical facts I (and many others) have presented about the effects of different port sizes on engine power are being disregarded. I fully understand we don't like to give up pre-conceived concepts about how to go fast.

I will close my portion of this discussion with this comment:
The next time anyone wonders why my 4070# wagon with 3.31 gears, a mild cam, and a Q jet can possibly be competitive with lighter cars running much higher flowing heads and larger cams, you may want to reread some of the facts I have posted and referenced. My car doesn't just magically run what it does by following pre-concieved ideas and "rules" that have no basis.

I have tried to help others understand the subject, and that is all I can do. I don''t have time or the inclination to argue about material I have tested and confirmed.

The KRE heads I bought and ran are long gone - I learned and confirmed all I needed to know about the effects during those weeks of trying to make them work at least as well as what I had.

As always, we should each build our cars exactly as we want them, regardless of what others say. So keep those Pontiacs running!

Jim Hand

Jim, I'm not disputing you. All I am saying that you had your iron heads maximized for pump gas. You did not have the KRE heads maximized for pump gas. So therefore you sold them short.

How do you know that a bigger port would slow your car down? Have you tried a bigger port in your 6x heads and had to go back down? I am simply saying that if you would have taken the compression on up to the limit of 93 like you are now with your 6x's, then you would have out performed them with the KRE's. How can you dispute that? Did you test it and prove that it is not the case?

And why do you keep asking about the one point rule? It's not a rule, it's a estimation on how much more compression you can run on the same fuel with aluminum versus cast iron. That is well documented in hundreds of aluminum headed combos of all makes. Have you never heard of this?

[speedshopmike]

harry k, i disgree:
what we've learned here is little to nothing.
i'd say the major point is that there are no hard and fast rules, and a good combination will beat a bad one with "better" parts.
we build small fords all the time with 300 cfm heads - they're a 150 cubes shy of a routine poncho motor.
there's a ton more to this then just flow numbers - far, far more.

[70 Lemans]

This is my first time ever build. (Not in service yet) I’ve been wonting to build a decent Pontiac engine for over 20 years. Now I'm not sure if I went about it the right way.
Seems the lack of above knowledge cost me.


69 400 Block .030 over, eagle stroker kit, ported 87cc CNC e-heads 305 310 cfm, port matched RPM, Cliff’s q-jet, comp cam Hydraulic roller 236/[email protected] 585/600 lift 110 LS with 1.5 rockers, butler timing chain, butler valley pan with pcv, 3500 stall with 3.55’s gears Lifter bore brace and 4 bolt billet mains, 1 7/8 dougs headers Race weight is approximately 3700lbs Looking for 11.5 Et
Very upgradeable but overkill.

90% street 10%strip

[Bruce K]

70, Looks pretty f'n nice to me! Good luck, let us know how it runs.

[Ron H]

Well, I have learned a few things.
1. is I am making at least 75 more RWHP with my 310 cc KRE 74 cc d ports over my 6x-4 heads. Mainly because,the flow went up and they have a better chamber design. The CR helped a bit as well. I was thinking that I may have lost some throttle response earlier. But with a bit more tuning yesterday on the way home, the low cruise throttle response is there, there is just so much more power in heavy part throttle and a huge amount more power in WOT.
2. I think my cam actually may be better for these heads and may have been a bit big for my old combo as my CR was only 9.4 to 1 and they only flowed 240ish. If the CR is higher 10 to 1 or so and the heads flow 240 @ .550 lift that cam is spot on.
3. Higher lift cams without a huge amount of duration and overlap can produce great torque and HP numbers providing you have the heads to use it.

[Skip Fix]

Good job tuning Ron! I'm sure there is more there.

Jim you have refined your combination from the air cleaner all the way out the exhaust so well you can run much faster than most other guys with "similar" parts. I'd bet you could dominate the stock FAST classes if you decided to go there! You can do more with less than most of us.

I'm a little less patient and dense so I need the extra buffer of more airflow to help me get there. My combination would be easily duplicated by others as I've gotten there with less tuning time. The only refined piece I have is my "high port" welded Torker II. For me 6000 isn't a big deal.

It's all about your goals for your car using the same general theory to get there.