[PAUL K]

Originally Posted by 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?

Sure, it was a ported Warrior that flowed less and it was replaced with a basic ported Victor that showed a lot of promise on the flow bench. Both combinations were thoroughly tested with spacers, shift points and different size carburetors.

We've also ran into this on a couple of BBC that we ran on the dyno, picked up intake flow considerably and found zero change across the board.

[PAUL K]

Originally Posted by racegto65

The one on the left looks like stainless from the picture and even if it is titanium I don't consider that a "tulip" face. Just my 2¢

Interesting you look at a tulip valve from the dimple in the front. I always looked at it by the Hershey Kiss shape on the back. You can have one without the other but can't have much of a dimple without the cone shape on the back. I Googled "tulip valve" and it seems to be described both ways.

I'm quite certain that's a titanium valve in the picture I posted.

[PAUL K]

Originally Posted by Tom Vaught

After seeing the RA-IV disaster (Valve head came off a race car engine) I personally would never put one of those "2 piece" manufactured valves in any engine I would ever own. Might be ok on a show car driven on and off a trailer but not on a engine that is raced, street or track.

Tom V.

I agree with you 100%. At one time the factory valves were all that we had to choose from for a "shelf" deal. The fact they are all atleast forty years old is another good reason to avoid them.

Tom what is your opinion on a tuliped valve? I'm seeing quite a few four valve heads that the OEM is stuffing tuliped valves in.

[Formulas]

Flow is constant on a flow bench, Flow in a real engine it is pulsing ( stopping starting ) with each valve hit

You have pockets of air / fuel pushing and pulling each other ( pressure differentials ) making their way through the intake tract ( simplified )

Seemingly useless open areas may be a good place to bunch up ( storage of higher pressure) waiting for a place to go on the next hit

And where the pulse is of lower pressure you would want minimal CSA to generate speed quickly

Pulses can be thought of like a frequency on a oscilloscope display that change with rpm