Need Help Diagnosing a Port

[wrs]

I am doing some work on the flow bench using a flow box (plastic model of a cylinder head) It is a zero degree port (the valve is inline with the cylinder bore), the head deck suface is completely flat, 2.25" valve, 30 degree valve, .375 stem, approximately 300 cc's, approximate port length of 5.8" and the floor of the port is about 1 inch off the deck current flow at .600 is 308 and at .700 is 313, both @ 28 inches.

Here is the problem - when playing around with a flow ball that is .150 diameter I can increase flow at .700 to 332 by placing the flow ball right in the middle of the port, on the floor, right before the short side (I believe that this location could also be reffered to as the bottom, middle of the window)

I fooled around with clay for about 4 hours and could not pick this flow up, any ideas on what to try next?

Thanks For Your Help
WRS

[maxracesoftware]

a 2.250 Intake and a great designed Intake path should be seeing
400 to 430 CFM at 28 inches near .700" Lift

shouldn't be using a 30 degree seat angle
if you want flow higher than .400" lift

if you are trying to MAX out ports then ;

Minimum_Intake_Lift = Intake_Valve_Diameter * .37

Maximum_Intake_Lift = Intake_Valve_Diameter * .41

Curtain_Area = Valve_Area at .25 * Valve_Diameter

use 45 seat angles for better flow

and

use 52 to 55 deg seat angles for even better hi-lift flow

just depends upon cam/application

but anything under .25 L/D Ratio and valve/curtain area is controlling all the flow

need to get valve out the way and let the port do uts thing
then need .37 to .41 L/D Ratios to maxout a given combo if thats what you want

the BALL is fooling the short turn
indication your Short Turn radius is incorrect, probable cause at those lifts is the 30 deg area - Short Turn combo

if you were to put clay and pickup the flow there
and then be able to actually dyno engine , you will find you will loose
high rpm HP/Torque even though you saw a flow gain

be careful playing with short turn , you can pickup the speed/velocity too much there and be fooled on the Flowbench

also look how thick your radius entry is
sometimes radius entry is too thin and doesn't properly setup flow into intake port

[Guest]

Can you post some pictures?

[speedtalk]

Hi WRS, thanks for stopping by the forum. Let me guess, you're working on a diesel?

Given how much the air has to turn and how little height it has to do it in, you've got your work cut out for you. The flow ball is creating a vortex that is helping the air "stick" to the short turn longer.

A few questions:
What is the area over the short turn?
What does it flow without the valve?
Are you stuck with that port height?

[wrs]

Don, you are right-turbocharged diesel power!!

As for your questions -

1. Area over short turn (right before short turn perpendicular to port centerline) Approximately 3.2 in.^2
2. Haven't flowed it without the valve yet. Flow at .900 is about 317 cfm. After mulling this over of the last few days I am starting to think that I may need some more cross sectional area.
Which leads me to another question - Are there any good calculations for minimum cross sectional area needed for a certain flow that you guys know of? Or are you guys basing it off of a minimum port velocity value?

3. The only thing that I am really stuck to is the port entrance height (have to use the stock manifold) I can go wider with the port because it is a common plenum intake manifold that bolts on the head.

Pictures of the stock flow box and port mold can be seen at the following address:

www.angelfire.com/ne2/antiquepulling/randd.html

The new port has eliminated most of the exaggerated swirl area and is more of a conventially shaped port.

You are right Don, with the air having to turn 90 degrees and having very little port height it is challenging.

Thanks,
WRS

[speedtalk]

Pictures of the stock flow box and port mold can be seen at the following address:
www.angelfire.com/ne2/antiquepulling/randd.html

The new port has eliminated most of the exaggerated swirl area and is more of a conventially shaped port.

I didn't think it was a swirl port from your initial post. A picture paints a thousand words.

I have very little experience with a diesel or swirl ports, but when I did mess with a swirl port I learned one thing right away - don't try to swirl the air AND try to go over the short turn conventionally, pick one or the other. If the short turn gets too wide, the air could actually run into itself.

Again, I'm no diesel expert, but why not use a conventional port? What's the RPM range of this engine?

[wrs]

Don, The engine will turn approximately 4200 rpms, it doesn't sound like much but at over 100 cubes per hole and 60 pounds of boost we are talking about a lot of air.

You are right I learned very early on working with these heads that you must go either with the swirl OR the conventional port. The first head that I worked on like this was quite an experience. Three hours of work on one port turned into a 5% to 8% loss across the board. Quite dissapointing. By eliminating the swirl, a gain of 25% to 30% across the board was realized.

I ordered some BBC valves in both 2.19 and 2.25 to try this weekend, to see if I can pick up some flow by using a more convential 3 angle seat with a 45 degree valve. I am crossing my fingers

Anything about determining cross sectional area?

Thanks,
WRS

[maxracesoftware]

whats the cam's max lift you will be using ??

i didn't realize deisels might use .900" lift ??

[speedtalk]

Three hours of work on one port turned into a 5% to 8% loss across the board.

I'm laughing with you on this one. I also found it very easy to lose flow.

I think I'd give up on the swirl port. I've interviewed more than one person lately that has said they don't want to see any swirl in their racing heads.