[steve25]

Strips your conclusive dyno results show how even on a average for these days 469 build the port size( minimum port area ) of the 215 cc heads slows down the needed average port velocity too much!

Your dyno test show that even though the stock iron Intake can not in anyway shape or form out flow the RPM Intake, but the stock iron intakes smaller port area kept the average port velocity up higher which is what your 469 needed more then overall higher levels of air flow.

In short your combo with the iron Intake was making up for the too large of a port area in the E heads by moving on average more air thru the motor faster, that's really how simple it is!

The more unneeded port area you have, the more you need to build your motor to run in a narrow 2500 rpm power band that starts making big Torque numbers at 3500 and above, and such a set up is no bringing anything to the table for the average 3.23 to 3.55 rear geared street motor, even at 470 cid!

Many of you need to ask yourself this question, if on a 455 cid super stock motor with ported iron 4X thru 6X heads with only 165 CCs of volume and these motors are running deep in the 10s in the 1/4 mile then why is your motor with 215 CC heads and flowing atleast 35 cfm more Only running mid to low 12s, the above explanation is why!

[Stripes]

I agree and remain amazed at how many rpm intakes I see on much milder combinations that ours. It reminds me of the train wreck a torker 1 was on a stockist 400 years ago.

[steve25]

And even on 455s with stock D port heads even if they had 4 speeds with 3.42 rear gears!

Ask me how I know this.

[Steve C.]

474 cid Pontiac
290 cfm D-port heads / 10.2:1 compression
236 / 245 / 112 LSA hyd roller cam
Intakes and heads port matched to Felpro 1233 intake gasket.
SuperFlow 902 dyno

Stock iron intake w/ Cliff Ruggles modified Q-jet:
515hp @ 52-5300rpm and 575 lb/ft @ 4000 rpm.

Edelbrock Performer RPM intake w/ same Q-jet:
541hp @ 5400 rpm and 591 lb ft @ 4000 rpm.



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[Formulajones]

Originally Posted by Steve C.

474 cid Pontiac
290 cfm D-port heads / 10.2:1 compression
236 / 245 / 112 LSA hyd roller cam
Intakes and heads port matched to Felpro 1233 intake gasket.
SuperFlow 902 dyno

Stock iron intake w/ Cliff Ruggles modified Q-jet:
515hp @ 52-5300rpm and 575 lb/ft @ 4000 rpm.

Edelbrock Performer RPM intake w/ same Q-jet:
541hp @ 5400 rpm and 591 lb ft @ 4000 rpm.



.

We found similar results on a 455 I put together. Old Edelbrock round ports CNC ported by Kauffman, 10:1 compression. Kauffman Hydraulic roller 254/262 @ .050 Tried I think at the time 4 different intakes and a hand full of spacers..

Made best numbers with the RPM air gap and a 1" open spacer

[Steve C.]

4.185 x 4.25"/ 467 cubic inches
Nonported KRE D-port heads, 85cc chambers
1.65 roller rockers
The infamous Crower 60919 231 degree hydraulic flat tappet cam
Edelbrock RPM intake / Q-jet by Ruggles
Doug's headers

543.9 ft.lbs. torque at 3600 rpm
560.7 ft.lbs. torque at 4500 rpm (peak)
502.4 HP at a very manageable 5300 rpm (peak)


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[Steve C.]

Questions for Stripes......

Regarding the combination in your post #20

Is that a 4.250" stroke ?

Will you post the amount of torque produced for each intake manifold at their peak torque rpm and at what rpm was it made at.
Also the amount of horsepower produced for each intake manifold at its peak power rpm, and at what rpm that was it at.

Also mentioned the '73 iron intake was port matched. In the 1999 Edelbrock instruction sheet it states their Performer RPM cylinder heads are matched in size and operating range with the Edelbrock Performer RPM intake manifold. In it they specifically mentioned the Felpro 1233 gasket may be used, it's about 2.200" tall if I remember correctly. As I mentioned in my post #5 the Performer RPM intake manifold port exit dimension compared to factory iron heads is a lot bigger at 2.060" tall x 1.100" wide as cast. Your factory intake was port matched to meet this ?


.

[steve25]

The key to making power with aftermarket 215 cc heads is to utilize that port area by getting good levels of port velocity thru those bigger ports!

If your only running .490" lift when out of the box peak air flow takes place at .600" lift or higher then your not getting much of a performance increase for your buck other then lighter weight and maybe now being able to run a good timing curve without ping or knock.

Also you can't excape the fact that Aluminum heads dissipate heat so fast that to make equal power they need to flow 12 Intake cfm more then a iron head to do a comparison.

If you had bowl ported iron D ports flowing 240 cfm then the aftermarket head needs to Camed lift wise to access 250 Intake cfm or better , and even then your accessing 250 cfm moving at a reduced velocity due to the larger minimum port area!

[Steve C.]

steve25, I believe it was you many years ago that made a statement that one would need more intake intake duration as the runner volume increased to make the similar amount of power at the same or similar peak power rpm. Or something to that affect. I don't remember how many degrees increase you mentioned, not much though.

As an example... in my post #26 above I mention a 4.250" stroke combo with nonported KRE D-port heads, they have a smaller runner volume as the Edelbrock head. It made 502 hp at 5300 rpm with 231 degrees intake duration. Years ago my engine builder put together a VERY similar 4.250" stroke combination.... same Performer RPM intake, similar cfm carb, headers, etc. But it used nonported Edelbrock cylinder heads. It was also a HFT cam but with 5 additional degrees intake duration. It made 509 hp at 5200 rpm.

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