[LATECH]

I guess there bigger to feed a bigger engine, right outa the box.

[V8&4spd]

Originally Posted by latech

I guess there bigger to feed a bigger engine, right outa the box.

What are the flow numbers for both? It should not be hard to find them. You can't compare apples to oranges without the numbers.

[LATECH]

I agree. You cant compare apples to oranges.

[h0trod389]

Originally Posted by V8&4spd

What are the flow numbers before porting? The Chevy Vortec was made for a 305 and 350 engine. The Pontiac D port head is one size fits all.

ever see a low compression 455 head run on a 326? without forced induction?

[V8&4spd]

I know the 326 is a stepchild.

[V8&4spd]

Even if you port the bezesus out of a Pontiac D port, the Vortec port is still higher.

[ericnova72]

Originally Posted by V8&4spd

Even if you port the bezesus out of a Pontiac D port, the Vortec port is still higher.

I fail to see what you are trying to say here?? These heads are not interchangable, the Vortec is a Chevy small block head and the Edelbrock D-port is a Pontiac V-8 head.

This is not comparing apples to oranges, this is comparing fish to birds. Totally different.

[V8&4spd]

I"m not the one who brought up the chambers. I just ran with it. How about GM to GM. Now instead of everyone doing the two step trying to avoid posting the flow numbers. Lets see the real numbers to see how they compare. ericnova you were the one who told me it was a unfair comparsion before with the iron Vortec and D ports. Now I am compairing them to the aluminum aftermakret heads.

[ericnova72]

Originally Posted by V8&4spd

I"m not the one who brought up the chambers. I just ran with it. How about GM to GM. Now instead of everyone doing the two step trying to avoid posting the flow numbers. Lets see the real numbers to see how they compare. ericnova you were the one who told me it was a unfair comparsion before with the iron Vortec and D ports. Now I am compairing them to the aluminum aftermakret heads.

The flow data is available on Edelbrocks web site. You could go look it up.

They (Edelbrock D's)flow better than a stock Chevy Vortec head, but not by a lot.

If you are wanting to know what stock Pontiac D-ports flow you can take a look at Stan Weiss' cylinder head flow database, shows the 7K3 Pontiac head at 215 intake/170 exhaust cfm @ ".600 lift and 28" drop, and most stock Pontiac D-ports regardless of the casting numbers are within a few cfm of this. His head database has a lot of entries, from a lot of different sources, for many different heads and engine families

[h0trod389]

Originally Posted by h0trod389

its all about the time and money for pontiacs..... people build chevys because they wanna do something everyone and their mother has!

pontiac peope know that these parts are expensive so only the true diehards will take on this endeavor.

putting a chevy engine in a pontiac? might as well go get a 30,000 mile jap create engine.

low budget pontiac enthusiast's will take what they have, and make what they don't, or cant afford. if you want aluminum heads, you must shell out the clams. i myself cannot afford all these high priced items. so i make do with what i got.
lets take a look at the reality of these heads.
what we do know is that aluminum is light and dissipates heat alot faster than cast iron.
and everyone knows the cooler your A/F ratio, the more efficient your power plant will be.
cast iron heads do not transfer heat very well, there heavy as hell, but the one thing people don't realize is that cast iron heads last a hell of alot longer.
esp if its a daily driver.

lets analyze a few different types of heads...

lets take the infamous 6x-4 head which is a rather low compression head compared to some of the other cast iron versions. stock flow (based on intake flow @ .500) for this head, unmolested is ~ 205 cfm(intake) with 2.11(I) and 1.66(E) valves. this is a D port head.... and for 3-400 bucks you can have these redone to new condition depending what valves and springs you use. a bit of porting work and these heads can flow up to 250 cfm.

now for 1600 bucks you can grab a set of edelbrock performer's D ports that flow @ 195 in raw form, same valves and small combustion chamber size.
these heads are awesome because they redesigned the combustion chamber for ignition and flow promotion. jim butler ports these heads to JUST over 300 cfm.
the round ports can flow a bit more. but not much!! 315 CFM

now lets say we won the lottery...... there are way more options for us!

KRE heads 1900 bucks for a set of 250 cfm raw ports another 800 bucks to take them up to 325 cfm.

now if you won the lottery and then robbed a bank, you can get some of the JBP tiger heads, the heads of all pontiac heads, but at the price of 6200 bucks. but flow more than 400 cfm.

and if you wanted to spend 10 grand, i can get you a set of
RA V heads!!!! (cast iron) don't ask the flow, i just know where they are, but he wouldn't let me touch em without the cash in my hands!

suddenly a set of 400-500 dollar headers seems minuscule!

i have built a 77 firebird with a pontiac 400 4 speed and 72 cc edel heads for a friend.
he didn't wanna spend the money on the oval port headers either..
i told him that i would fab up a set for him, but i am going to charge him hourly. it took me about 12 hours @ 60 bucks a hr to make them.
at that time he was really mad because he was gonna spent more on my fabbed headers, than he would have done on a set of Headmen hustlers.
needless to say he bought a set of headman's... and because he decided to use a early block in a later model car, and adapter plates to mount the engine, his 550 dollar headers would not fit his 4 speed car with A/C.
he ended up paying me for my headers and sending the headman's back.

THE BOTTOM LINE IS...... DO AS MUCH OF THE WORK HUMANLY POSSIBLE!!!

flow numbers were posted before you asked....

[h0trod389]

stock chevy vortec heads on the L98 flow @! 195/150 cast iron

LT1 heads flow @ 239/151

[ericnova72]

Originally Posted by h0trod389

stock chevy vortec heads on the L98 flow @! 195/150 cast iron

LT1 heads flow @ 239/151

The L98 is not a Vortec head, not even close to the same. The Vortec heads are L31, and the flow numbers are virtually identical to the LT1 numbers you posted but are better by 10cfm on the exhaust ports than the LT1.

[h0trod389]

Originally Posted by ericnova72

The L98 is not a Vortec head, not even close to the same. The Vortec heads are L31, and the flow numbers are virtually identical to the LT1 numbers you posted but are better by 10cfm on the exhaust ports than the LT1.

what can i say??? when i have a chevy i scrap em