Odd flow test results

[SWR]

Did post this over on Speedtalk a while ago,but it was an intriguing result,so I'll post it here too: Did a flowtest on a Mitsubishi 3000 GT VR-4 head, flowed the intake at every two millimeters,both valves at the same time.
I flowed all the way up,1-3-5mm etc to 13 mm of lift. And then I noticed something...

Being tired...I had missed increasing the lift on both valves the same amount...at the 9mm lift point I had one at 8mm and one at 9mm...this error moved on to the 11 mm LP,one at 10 and one at 11. This should have yielded less flow,as one valve hasn't lifted as much as the other one...but they flowed more. I had more flow at the 9mm lift point with the valves "staggered" than I had with both valves at 9,10,11,whatever...?? Actually I got more flow with "staggered" valves at 8 and 9mm than I've ever measured in any stock 3000 GT head... any ideas??

Numbers...stock heads flow about 230 - 233 cfm @ 28". Staggered valves gave me 246 cfm,same depression...

BTW,doing one valve at a time and "adding them up" doesn't work at all in this head...one valve alone did flow close to 150cfm,and if I'd added them up I'd be at 290+ cfm and be done.. :laugh:

[larrycavan]

Some pics of that port would be nice.

I'd go pitot probing next to see if you can get anything to hellp unwravel that mystery...

What happens if you reverse the lift stagger? I mean if the left valve was the lesser lift, try switching and give the right valve the lesser lift.....

Next I'd slowly sneak open the lesser lift valve to see at what point flow losses begin, then I'd try decreasing lift on that valve again until flow picked back up to the max reading it would yield.

I'll bet if you had a junk head to play with and experiment with bowl shape and size you could learn some interesting points with that head.

[SWR]

[larrycavan]

[SWR]

[Erik]

Back at 1995 or so I recal that a company in England was making som cams for Kawasaki super bike they caled scaterd cams were one lobe was runing a litle befor the other one.
They did clain that it made a big differens.

Erik

[1960flh]

I saw something about this idea on SpeedTalk i think from the from Rhear & Morrison I am going to try to make one for my application. Sorry for the rough pic but it gives the idea, he was saying to make a probe as pictured and then you can sweep the 360deg of the port at the curtain. I thought if you threaded the end of the valve for a cap and o-ring you could make the probe adjustable for dirrerent valve openings. i/e being able to measure at the margin or the seat at different valve lifts you could get some good data.

Just thinking to much

Rick

[SWR]

Hmm....I have to try and make one of those for those heads...might see something explaining the test results...

Erik: Did they claim just a bazillion hp,or did it improve on the full curve?

[Jesse Lackman]

SWR expanding on Larry's idea do you think staggering the valve opening might be upsetting some sort of problem where the port splits into two? Do you have any way of checking what is going on at the divider with string, smoke or something?

[SWR]

[Erik]

I dont remember but I shuld see if i can get the article.
One reason why the head flows mor air with diferent valve lift can be the way the air thumbels down the cylinder. If you dont get the air to thumbel forward in a 4V head it will be beter to get it to folow a wall. Test with the string and se if you bending the air stream in the cylinder.

Erik

[larrycavan]