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

[randy331]

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.

I've tried cams at that ICL and earlier, but none stayed there after testing it there.

Randy

[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

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.

What part do you not believe, and what am I being misleading about ?
The part that doesn't line up with what you've been told ?

Randy

[gmrocket]

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.

So we don't want a high floor that's a gradual drop off into the ssr bowl area?

[GARY C]

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.

What part do you not believe, and what am I being misleading about ?
The part that doesn't line up with what you've been told ?

Randy

The part where you post inconclusive test as absolute fact and then you prove your test inconclusive in post on other builds.
It appears you test in a manner to prove your theory as oppose to trying to find the truth, I don't know if you do it on purpose or just don't realize it.
As best as I can tell from what I have read here your test seem to contradict your statements but it's hard to tell because you don't tell the whole story.

I listen to what I am told but I learn from studying things that go against my preconceived notions... You should try it some time.

[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

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

If I am not mistaken that was the 400M and the cam was around a 97 or 98 LSA, I don't remember the ICL. I have had CM come up with 101 LSA on 400ish engines but due to core cost no one has been willing to try it.

[randy331]

The part where you post inconclusive test as absolute fact and then you prove your test inconclusive in post on other builds.
It appears you test in a manner to prove your theory as oppose to trying to find the truth, I don't know if you do it on purpose or just don't realize it.
As best as I can tell from what I have read here your test seem to contradict your statements but it's hard to tell because you don't tell the whole story.

I listen to what I am told but I learn from studying things that go against my preconceived notions... You should try it some time.

It's inconclusive to you becasue you choose not to believe it.
Not everyone agrees with you. I've had several PM me asking more about that test,... and I willingly told them the truth on it.

It ain't the only time I've seen more cfm with more port energy make less power. The last 2 BBC pulling truck engines I did is another example.
The one with more cfm and more pe made less power and tq. It even had 5 more cubes and a bit more compression,... but still a little less power. I know,.. I know. I just didn't get the cam right again. LOL

You clearly haven't been involved in racing engines much.......You should try it some time.

Randy

[GARY C]

The part where you post inconclusive test as absolute fact and then you prove your test inconclusive in post on other builds.
It appears you test in a manner to prove your theory as oppose to trying to find the truth, I don't know if you do it on purpose or just don't realize it.
As best as I can tell from what I have read here your test seem to contradict your statements but it's hard to tell because you don't tell the whole story.

I listen to what I am told but I learn from studying things that go against my preconceived notions... You should try it some time.

It's inconclusive to you becasue you choose not to believe it.
Not everyone agrees with you. I've had several PM me asking more about that test,... and I willingly told them the truth on it.

It ain't the only time I've seen more cfm with more port energy make less power. The last 2 BBC pulling truck engines I did is another example.
The one with more cfm and more pe made less power and tq. It even had 5 more cubes and a bit more compression,... but still a little less power. I know,.. I know. I just didn't get the cam right again. LOL

You clearly haven't been involved in racing engines much.......You should try it some time.

Randy

I don't recall saying anything about cfm or pe nor am I looking for people to agree with me, I don't have the need to prove anything to anyone, your welcome to keep believing your tests are conclusive, I disagree.

[swampbuggy]

GMrocket, you are on the correct path, of course we do. It has long been known that air flowing through an intake (or) exhaust port does "NOT" want to make a turn/change of direction. That is why modern cylinder heads that make big power have the intake port and the exhaust port openings raised higher from the valve seat area. This of course makes a straighter path (LESS TURNING) for the air/fuel mixture as it heads for the cylinder, also the atomized fuel stays that way better (atomized that is). Mark H. I have NEVER heard anybody suggest lowering the floor of an intake port

[steve cowan]

GMrocket, you are on the correct path, of course we do. It has long been known that air flowing through an intake (or) exhaust port does "NOT" want to make a turn/change of direction. That is why modern cylinder heads that make big power have the intake port and the exhaust port openings raised higher from the valve seat area. This of course makes a straighter path (LESS TURNING) for the air/fuel mixture as it heads for the cylinder, also the atomized fuel stays that way better (atomized that is). Mark H. I have NEVER heard anybody suggest lowering the floor of an intake port

i think this a fair statement BUT it is possible that the roof cant always be raised and the floor filled due to casting and application CSA RPM etc
if you cant get the required CSA in the port via the roof,pinch or dividing wall you may have to work the floor and reassess the height of the SSR,
Also the manifold to head transition has to be carefully considered

[Geoff2]

Jon Kaase's winning engine, as written up in PHR, Feb 09.

403 SBF.

Had all these 'wrong' parts:

- cam with less exh duration [ 246/238 @ 050 ]
- short rods
- 98 LSA, 92 ICL

And it made 663 hp with the wrong parts.....

Go Jon...

[swampbuggy]

Steve C., yes i can agree with what you said above, one has to do what ever to the piece he has to work with to maximize it. Mark H.

[swampbuggy]

Geoff2.....obviously NOT the wrong parts for what Mr. Kaase was trying to accomplish in the contest. That combo would NOT work well in a NASCAR Monster Energy Cup engine, all the varying performance parts we have to choose from are there for our different objectives . Yes there are some things in a build that can be argued, and there are somethings that MOST people agree on. Mark H.

[Erland Cox]

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.

But that is not what happens, read the chamber stall thread and use your pitot tube.

Erland

[Ken_Parkman]

Fundamentally high lift flow drop is usually due to flow separation where the flow can no longer make the corner. The flow separates, and the inboard part of the port bend stops working and your effective flow area gets smaller. You can hear it and probe it with a flow bench. The term often used is turbulence, but that is not technically correct as Reynolds No is well into turbulence territory at most port conditions so the flow is turbulent regardless, and only laminar at very low lift on a bench. BTW notice I did not say which bend. Another thing that promotes flow separation is an expansion. If you do the math you will find flow separation often initiates at the lift point where the curtain area gets larger than the port area, so the valve head is no longer helping keep the port flow attached to the wall.

Fundamentally street type design with a low port by definition have to have a sharp corner, so they are most susceptible to separation. Take stock type low ports, big valves for a port expansion, and high lift so the curtain area is larger than the port area, and it is a recipe for separation, and it is hard (if not impossible) to really solve. But lots of engines have this situation and make lots of power, and flow separation on a bench may be a different thing in a running engine at way higher delta P.

[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.

But that is not what happens, read the chamber stall thread and use your pitot tube.

Erland

I just go by CFM numbers, and I found that when you have an intake port that "backs up", then what you do is cut back the SSR and intake floor and you'll see your high lift numbers go up at the expense of the low lift numbers. In other words, high intake floors produce good low lift flow numbers at the expense of high lift numbers, and low intake floors do the opposite. The objective of an intake port is to aim the maximum volume of intake air at the valve seat area and adjusting the SSR and intake floor height is a big part of this. This is what has given me my best intake flow numbers in the past.