Intake valve job causing high-lift stall / drop-off?

[JoePorting]

A high lift CFM drop-off is usually caused from a high floor or conservative SSR. If you cut down the floor by .025" and see a rise in CFM, then you know you're going in the right direction. If you cut back the SSR and see another rise in flow, then you know that's the issue too. If the flow numbers don't change or go down, then that's not an issue.

[GARY C]

Does improving the chamber for flow improve it for combustion?

It’s not a one way street..

Hard to say without dyno testing but it would tell you if that part of the chamber was the cause.

It just seems to me chasing chamber shape on the flow bench is a not seeing the forest for the trees

Just something to learn on what effects what, interestingly a past EMC winner told me of a test with 2 sets of heads one with a heart shaped chamber and the other was older style like a Sportsman II all other things being equal they made the same power at the same timing and a lot of stuff being done now with soft chambers or full dish pistons that eliminate the quench make me wonder what is the best chamber design.

If chamber work increases flow and then that leads to more power then it would be worth it, even if it decreased power then you would learn if it worked or didn't.

[swampbuggy]

Joe porting, you entered the words..... A high lift CFM drop off is usually caused by a HIGH floor or............would you please explain in detail what you mean by HIGH floor Mark H.

[swampbuggy]

EDIT: to above, caused "FROM" not BY .

[JoePorting]

I'm saying the floor of the intake port is too high causing the high speed air to pull off the SSR area and cut across the bowl area cutting off the SSR area.

[swampbuggy]

Thanks Joe for the clarification, I guess cylinder heads that flow a LOT of air, and make LOT of power, and have an intake port that is raised a LOT, were (designed in such a way) that your mentioned air flow problem does NOT happen Mark H.

[randy331]

interestingly a past EMC winner told me of a test with 2 sets of heads one with a heart shaped chamber and the other was older style like a Sportsman II all other things being equal they made the same power at the same timing

Not sure I'd believe those EMC winners !
I know one that claims they had a head that flowed more and had more "port energy" but made LESS power and score !!!

I mean we all know that ain't possible ..

Randy

[steve316]

I have always wondered about those EMC guys myself.

[RevTheory]

Good grief, Randy. How long are you going to keep trying to pick a fight on the internet?

[fordified]

Thanks Joe for the clarification, I guess cylinder heads that flow a LOT of air, and make LOT of power, and have an intake port that is raised a LOT, were (designed in such a way) that your mentioned air flow problem does NOT happen Mark H.

I don't believe that's what he's saying. You can have a raised port head but the port floor is to high causing problems at high lift.

[CGT]

Good grief, Randy. How long are you going to keep trying to pick a fight on the internet?

Are you stating that your opposed to testing that doesnt match your own beliefs? Im confused

[BradH]

...

Since the head that has very little done to the chamber, and has nothing unusual done with the valve job....... doesn’t have the flow regression issue...... it would stand to reason it’s the combination of the way the chambers are done along with the valve job that’s allowing it to happen with those other heads.

...

That makes the most sense at this point. My "crash test dummy" head also has the same valve seat config as the 72 cc Victors, and with less chamber work done by hand, didn't have the .700"+ issue on 2 of 3 test ports. Even with the 1 test port that I thought I was doing the short turn incorrectly, it only dropped off about 2 CFM between .700 & .750, not 10-ish like the Victors.

[GARY C]

interestingly a past EMC winner told me of a test with 2 sets of heads one with a heart shaped chamber and the other was older style like a Sportsman II all other things being equal they made the same power at the same timing

Not sure I'd believe those EMC winners !
I know one that claims they had a head that flowed more and had more "port energy" but made LESS power and score !!!

I mean we all know that ain't possible ..

Randy

I don't believe you so I guess I don't believe all of them but that has nothing to do with you being on an EMC team, it has to do with you misleading people with your posts.

[Stan Weiss]

interestingly a past EMC winner told me of a test with 2 sets of heads one with a heart shaped chamber and the other was older style like a Sportsman II all other things being equal they made the same power at the same timing

Not sure I'd believe those EMC winners !
I know one that claims they had a head that flowed more and had more "port energy" but made LESS power and score !!!

I mean we all know that ain't possible ..

Randy

Didn't Jon Kasse win the EMC one year with his cam's ICL set at less than 100? So how many people have ever ran a cam degreed there?

Stan

[CGT]

interestingly a past EMC winner told me of a test with 2 sets of heads one with a heart shaped chamber and the other was older style like a Sportsman II all other things being equal they made the same power at the same timing

Not sure I'd believe those EMC winners !
I know one that claims they had a head that flowed more and had more "port energy" but made LESS power and score !!!

I mean we all know that ain't possible ..

Randy

Didn't Jon Kasse win the EMC one year with his cam's ICL set at less than 100? So how many people have ever ran a cam degreed there?

Stan

Ive had quite a few there back in the Ultradyne days.