XTREMEZ28

I was curious as to what stock heads flow and how they compare to most stage I and stage II heads?? am i right to say that stock heads are 2.00/1.50 and most stage I's are 2.02/1.57 and stage II's are 2.02/1.6??? looking into some heads and want ot know what are good flow rates basically... how would 275-280@.550 on intake and 220 on exhaust be (stage I)?? Thanks for the input

ArcticFormula

I am wondering the same thing especially with regard to someone leaving valve size constant. How much can one improve upon the stock flow, valve size being equal.

Matt98SS

well on my heads we are keeping stock valve sizes as of right now

will post my before and after flow #s when they are done and valve sizes.

Neil 6.0

Tommy, check this out, (scroll a little more than halfway down the page). Look for "Cylinder Head Flow Rate Comparisons":

http://216.25.85.179/chspeedfreaks/c5_tech_info01.html

XTREMEZ28

i just wanna know if these heads that i am looking at would be a good deal or not.... 275-280 cfm is about a ls6 right at .550??? and 220 on the exhaust.... with my mods of full exhaust and adding in a stage 3 cam and a 150 shot of nos... what do you think??

Mike Morgan

The numbers don't mean much unless you have direct comparisons on the same bench with the same tester.

Since we've had our flowbench we've really been able to see some major difference between our testing and what we've had tested and what we've seen posted.

This is a good example of how numbers can vary.
Here are some stock flow #'s we've tested recently.

LS1 intake port @ .500" - 220.4 (max 231.7 @ .650")
LS6 intake port @ .500" - 255.1 (max 255.4 @ .560")

I've seen these numbers published in a mag. ( Can't remember where, but I saved the data on my computer)
LS1 intake port @ .500" - 237 (max 243 @ .600")
LS6 intake port @ .500" - 268

I've also had LS1 heads flowed on another local bench.
LS1 intake port @ .500" - 231.4 (max 259 @ .700")


Anyways, flow #'s are about 10% of the equation.

[ February 22, 2002: Message edited by: Mike Morgan ]</p>

JNorris

iTrader: (4)

[quote]Originally posted by Mike Morgan:
<strong>The numbers don't mean much unless you have direct comparisons on the same bench with the same tester.

Since we've had our flowbench we've really been able to see some major difference between our testing and what we've had tested and what we've seen posted.

This is a good example of how numbers can vary.
Here are some stock flow #'s we've tested recently.

LS1 intake @ .500" - 220.4 (max 231.7 @ .650")
LS6 intake @ .500" - 255.1 (max 255.4 @ .560")

I've seen these numbers published in a mag. ( Can't remember where, but I saved the data on my computer)
LS1 intake @ .500" - 237 (max 243 @ .600")
LS6 intake @ .500" - 268

I've also had LS1 heads flowed on another local bench.
LS1 intake @ .500" - 231.4 (max 259 @ .700")


Anyways, flow #'s are about 10% of the equation.</strong><hr></blockquote>

WOW! It seems that the LS6 intake makes a big difference even on stock heads at approx. stock lift. How much additional HP does that equate to?


John

Ragtop 99

iTrader: (7)

The LS6 intake does not provide that much gain on a stock head & cam motor.

280 @ 550 and 220 on the exhaust (3.90 bore) could be a good set of S1 heads if the velocity stays high and you match it to the right cam.

Mike Morgan

I've edited my post. It may have been confusing. It was comparing the stock intake port flow #'s on various benches. All these numbers are without an intake manifold. <img src="gr_stretch.gif" border="0">