[steve25]

Hi Paul!

I would very much love it if you could go into more detail about that manifold swap without any performance gain story that you posted here about please?

In peticular if the manifold you swapped on had more port runner area on average per runner then the Intake that was being run before on the motor?

Let me relay a similar end result story that I had with a buddy of mines 408 cid SB Mopar that was running in the top of the 9s in the 1/4 at the time.

I had ported his Brodix heads up to a 315 cfm@28" flow level and cleaned up / port matched his Mopar performance Intake a few years before and now, as we all do wanted more power.


I took a look at his heads again and it seemed that I could pick him up more Intake flow if I could get a bigger valve in the motor, but that could not be done without making a bad cylinder shrouding situation take place.

In then looking at his intake manifold which had a huge runner expansion rate I found that with clay I could neck the runner down and pick up 30 to 35 cfm, all in the same lift range his Cam was providing.

I then broke out my Tub of epoxie and made the changes.

That next weekend at the track with no less better air then what he had the last time the car ran he lost darn near a full second in ET.

This is proof positive that too much port velocity created by a combo of unneeded air flow and not enough minimum port area is a guarantee disaster, just like on the opposite side of the coin where you have too much port area and not enough average port velocity that the motor wants in the power band it's built to run in!

In terms of header size needed just concider this tid bit.
The Butlers 446 cid 1200 hp twin turbo , 8000 plus rpm motor makes that 1200 hp thru 2" headers!!
Why you folks making well under that hp level think you need 2 1/4" tubes is beyond me?