[steve25]

Factory iron D ports can be ported to go 290 intake cfm at less then 190 CCs , so why is it so hard to believe that aftermarket aluminum D ports can go 330 when they start off at atleast 188 CCs if not 200?

[performerrpm]

Originally Posted by steve25

Factory iron D ports can be ported to go 290 intake cfm at less then 190 CCs , so why is it so hard to believe that aftermarket aluminum D ports can go 330 when they start off at atleast 188 CCs if not 200?

i thought 260 270 was kinda reaching the limits of an iron d port.

[Formulajones]

From what I've seen CNC Dports from Kauffman to go about 325 cfm are about $3200. CNC eddy round ports from Butler at the same 325 cfm are $3700.

So yeah there is a price difference but that's not where the extra costs stop. There are exhaust differences to consider and when people already have a dport car with d port manifolds they are reluctant to spend the extra money for the change. Now you're looking at RA manifolds or headers that have to be swapped and that doesn't always line up with your existing exhaust system either so there are some cost modifications there to consider.

[Formulajones]

Steve C asked me to post this as he is currently unable.

here ya go, compliments of Steve........

https://www.motortrend.com/how-to/in...head-edelbrock

[Gach]

Originally Posted by steve25

Factory iron D ports can be ported to go 290 intake cfm at less then 190 CCs , so why is it so hard to believe that aftermarket aluminum D ports can go 330 when they start off at atleast 188 CCs if not 200?

I wasn’t going to get into this, but I just can’t let this statement go. Maybe on your flow bench. LOL

A lot of emphasis on flow numbers, which dose mean something but not a hell of allot. What it really boils down to when it comes to a d-port vs round port is what your goal and what your intentions are with a Car.

Yeah maybe can get 290 cfm on iron d-Port, but whats the air speed in the port. Just a little example a set of wide ports done by well known Pontiac engine builder when checked ( because he was very disappointed) in the performance was you ready 425 fps. Finally after going to a guy Who has one of the best reputations, he ended up dropping it to 325 fps. Car pick up a tremendous amount of power. There’s allot more it then air speed in port. But just goes to show how much flow number only matter if its a good port.

Oh yeah of course when he drop the air speed the flow numbers drop also, but he pick up 75 hp.

[Gach]

Bottom line when I see flow numbers posted I cringe. Because it doesn’t tell you anything about the port. A d-port whether it’s an ion D-port or aluminum d-port has its limitations. Yeah we can boast all we want about the flow numbers oh they flow 320 cfm.

[Stan Weiss]

Originally Posted by Gach

I wasn’t going to get into this, but I just can’t let this statement go. Maybe on your flow bench. LOL

A lot of emphasis on flow numbers, which dose mean something but not a hell of allot. What it really boils down to when it comes to a d-port vs round port is what your goal and what your intentions are with a Car.

Yeah maybe can get 290 cfm on iron d-Port, but whats the air speed in the port. Just a little example a set of wide ports done by well known Pontiac engine builder when checked ( because he was very disappointed) in the performance was you ready 425 fps. Finally after going to a guy Who has one of the best reputations, he ended up dropping it to 325 fps. Car pick up a tremendous amount of power. There’s allot more it then air speed in port. But just goes to show how much flow number only matter if its a good port.

Oh yeah of course when he drop the air speed the flow numbers drop also, but he pick up 75 hp.

Gach,
Are the air speed numbers you are quoting average port speed or a measured localize air speed?

Stan

[Steve C.]

I had a set of '69 #16 d-ports race ported years ago by Jerry Goodale and when tested on my engine builders bench at the time they flowed 291 at .600 lift (28").
Intake valves were 2.125".

Looking back I suspect that number could be a bit generous. A few years ago I sold the heads to Paul Knippen, on his bench they were 278-282 cfm at .600".
(he tested 8 ports)

However different flow benches, and the type of bench, and with different operators you can and do get different numbers. Sometimes all over the map !

.

[Gach]

When CV-1 where first introduced, it was established that they flowed 380 cfm out of the box. Which by all means out flowed a wide port head. Pontiac Dude was doing a pump gas builded. Long story short he ran a 10.20 maybe even 10.10.

I went with Wide Port. Both same size motor. Trust me we went back and forth on this. He hong up on me a few times..and I on him…LOL My second pass with wide ports I went 9.80. I had a set of CV-1’s. But went with wide ports. His thing was he kept saying these heads flow 380 cfm. My wide ports only flowed 362 cfm. But at 750 lift.

Finally when he got his CV-1’s to Gabby..Gabby calls me, he says yeah they flow 380 cfm, BUT! The air speed in the port is only 252… so to make up for low air speed he’s going to need a minimum of 275-285 duration. My cam is or was 265/276 hey it was a learning process for both of us, but I already new what air speed was. When Dude would shift that thing into second gear the rpms would drop almost 1000 rpms. Its like the motor wouldn’t recover.

Of crouse theres allot more to it then just air speed in the port.

[Gach]

Originally Posted by slowbird

You have to drive it for the headers to rust.

I was wondering how long it was going to take you…The trolls are out..Stan your next..lOL oh wait Stan beat you to it. Next !!

[Stan Weiss]

Originally Posted by Gach

When CV-1 where first introduced, it was established that they flowed 380 cfm out of the box. Which by all means out flowed a wide port head. Pontiac Dude was doing a pump gas builded. Long story short he ran a 10.20 maybe even 10.10.

I went with Wide Port. Both same size motor. Trust me we went back and forth on this. He hong up on me a few times..and I on him…LOL My second pass with wide ports I went 9.80. I had a set of CV-1’s. But went with wide ports. His thing was he kept saying these heads flow 380 cfm. My wide ports only flowed 362 cfm. But at 750 lift.

Finally when he got his CV-1’s to Gabby..Gabby calls me, he says yeah they flow 380 cfm, BUT! The air speed in the port is only 252… so to make up for low air speed he’s going to need a minimum of 275-285 duration. My cam is or was 265/276 hey it was a learning process for both of us, but I already new what air speed was. When Dude would shift that thing into second gear the rpms would drop almost 1000 rpms. Its like the motor wouldn’t recover.

Of crouse theres allot more to it then just air speed in the port.

Stan