Valve Seat Angles and Flow Area

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randy331
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Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 9:29 pm

GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm
groberts101 wrote:
Sat Mar 10, 2018 12:46 pm
Taht was my exact point.. I don't know if and what he comes up will be better or not. But why would I hamstring him by not supplying as much info as possible?
I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
The main reason they'd end up with similar cams is, the most important paramiters for picking a cam are dictated by rules at the EMC.
The number 1 thing is rpm. The emc sets that.
Compression is one. that's set by the emc.
In a round about way valve acceleration is set by the rules, and some years/classes lift is. Those 2 things impact valve events.

Any flowz difference within the confines of the proper csa for the cubes entered would have no affect on valve events.

That's what I'm trying to say. Thinking cause you gained a few cfm you need a different cam, or if your ex flowz a few more cfm now you need less ex duration.

But isn't it interesting how easy it is to revive a thread with a low lift flow comment, or flowz speced cam comment ??? LOL :D

Randy

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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 9:41 pm

randy331 wrote:
Sat Mar 10, 2018 9:29 pm
GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm


I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
The main reason they'd end up with similar cams is, the most important paramiters for picking a cam are dictated by rules at the EMC.
The number 1 thing is rpm. The emc sets that.
Compression is one. that's set by the emc.
In a round about way valve acceleration is set by the rules, and some years/classes lift is. Those 2 things impact valve events.

Any flowz difference within the confines of the proper csa for the cubes entered would have no affect on valve events.

That's what I'm trying to say. Thinking cause you gained a few cfm you need a different cam, or if your ex flowz a few more cfm now you need less ex duration.

But isn't it interesting how easy it is to revive a thread with a low lift flow comment, or flowz speced cam comment ??? LOL :D

Randy
The term Low Lift Flow really has no meaning in relation to an engine, I think flow at TDC would be far more constructive.

It is interesting how ten yeas ago picking a cam seemed to be a black art but with the info today it seems anyone can do it, so less people fall prey to the cam guy you would call.
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Re: Valve Seat Angles and Flow Area

Post by hoffman900 » Sat Mar 10, 2018 10:14 pm

randy331 wrote:
Sat Mar 10, 2018 9:29 pm
GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm


I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
The main reason they'd end up with similar cams is, the most important paramiters for picking a cam are dictated by rules at the EMC.
The number 1 thing is rpm. The emc sets that.
Compression is one. that's set by the emc.
In a round about way valve acceleration is set by the rules, and some years/classes lift is. Those 2 things impact valve events.

Any flowz difference within the confines of the proper csa for the cubes entered would have no affect on valve events.

That's what I'm trying to say. Thinking cause you gained a few cfm you need a different cam, or if your ex flowz a few more cfm now you need less ex duration.

But isn't it interesting how easy it is to revive a thread with a low lift flow comment, or flowz speced cam comment ??? LOL :D

Randy
The assumption to is that the .050" numbers and lift numbers published tell the entire story.

It's the shape of the flow curve that matters and is what the cam grinders are looking for. Again, it's a metric. If I developed the port via CFD, I'd be likely looking at mass flow, not volumetric flow. Mass flow tells you more anyway, and Mike has revealed this is actually what he's calculating (with some assumptions). Harold and Harvey, were the first ones to understand (that I could find, and going back to the early '70s) that mass flow into and out of the cylinder doesn't necessarily follow what the flowbench shows. Harold stopped designing any symmetrical lobes by the mid 1970s. Harvey used different ramp styles. Mike has true assymetrical profiles. Comp has many lobes with positive or negative offset at max lift.

That said, I'm not going to cam a hemi, where I/E ratios may be way tighter (so higher exhaust flow compared to intake) at low lifts than I would a wedge head. A 4 valve head may even have a negative I/E ratio (exhaust flows more than the intake). It's totally applicable to a point.

I think so many work on one kind of combination (SBC, BBC, or whatever) and a certain style of engine at that (10:1 street engines or the like) that they get trapped into this thinking.

I was going to post a bunch of quotes, but it's better if people just read these threads in their entirey. Lots of fantastic posts by guys like Darin Morgan, Harold Brookshire, Larry Meaux, Mike Jones, and many others.

Cam Profile In Relation to Airflow Curve, Harold? (2007)
viewtopic.php?f=15&t=4680

Area Under the Curve (2005)
http://www.speedtalk.com/forum/viewtopic.php?f=1&t=1148

Head Flow vs Cam Choice (2007)
http://speedtalk.com/forum/viewtopic.php?t=8306

Discharge Coefficient
(2004)
http://speedtalk.com/forum/viewtopic.php?t=458

Longer Exhaust Duration... Why and When?? (2011)
http://www.speedtalk.com/forum/viewtopi ... =1&t=29382
I think flow at TDC would be far more constructive
Yes!
Last edited by hoffman900 on Sat Mar 10, 2018 10:35 pm, edited 4 times in total.
-Bob

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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 10:30 pm

Yes, everything has to be taken into consideration, to assume that 5* of valve angle is everything and 5* of cam duration means nothing would be overlooking a possible gain.

4* at .050 and tweaking valve lash from an EMC competitor claims 7 to 12 ft lbs. Is he wrong? I think what he presents is worth considering when you are looking for every last pony.
Complete article. http://www.hotrod.com/articles/0903phr- ... vy-engine/
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Last edited by GARY C on Sat Mar 10, 2018 10:35 pm, edited 1 time in total.
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Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 10:33 pm

hoffman900 wrote:
Sat Mar 10, 2018 10:14 pm
The assumption is that your engine was developed to the n'th degree. If I were to call Illmor up with a blank check and say "enter this EMC class", do you think they could find more? Maybe they would actually look at and take advantage of that information.

The assumption to is that the .050" numbers and lift numbers published tell the entire story.
I've made assumptions, but the 2 you posted aren't included in them.

Randy

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Re: Valve Seat Angles and Flow Area

Post by hoffman900 » Sat Mar 10, 2018 10:39 pm

GARY C wrote:
Sat Mar 10, 2018 10:30 pm
Yes, everything has to be taken into consideration, to assume that 5* of valve angle is everything and 5* of cam duration means nothing would be overlooking a possible gain.

4* at .050 and tweaking valve lash from an EMC competitor claims 7 to 12 ft lbs. Is he wrong? I think what he presents is worth considering when you are looking for every last pony.
Complete article. http://www.hotrod.com/articles/0903phr- ... vy-engine/
Absolutely, but that change occurred after getting to some baseline. hey didn't just pull those numbers out of thin air. They didn't run a dual pattern cam just because. :wink:

A hemi at the same RPM range and lift rules may have the same duration or less duration and/or less or equal lift than a wedge head. The rpm range and compression don't decide that.

Everyone I know that plays with a hemi head seriously, always kills low lift flow or runs less exhaust than intake, no matter what the calculators say. Paying attention to the flow curve is the first sign of this, what happens on a running engine is another.

Edit to finish a train of thought:
I can think of several applications that run varying durations, due to the efficiency of the head, to peak at all around the same peak RPM. For example, we’re running 268-270* @ .050” on an engine that peaks at 6700rpm. LSM, Crane, and Crower came up with those numbers blind. More efficient ports would need less duration for that power band. How would I, or the cam grinder have known to go there if I just gave them RPM range, compression, and something like rod ratio?
Last edited by hoffman900 on Sat Mar 10, 2018 10:59 pm, edited 3 times in total.
-Bob

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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sat Mar 10, 2018 10:45 pm

hoffman900 wrote:
Sat Mar 10, 2018 10:39 pm
GARY C wrote:
Sat Mar 10, 2018 10:30 pm
Yes, everything has to be taken into consideration, to assume that 5* of valve angle is everything and 5* of cam duration means nothing would be overlooking a possible gain.

4* at .050 and tweaking valve lash from an EMC competitor claims 7 to 12 ft lbs. Is he wrong? I think what he presents is worth considering when you are looking for every last pony.
Complete article. http://www.hotrod.com/articles/0903phr- ... vy-engine/
Absolutely, but that change occurred after getting to some baseline. They didn't just pull those numbers out of thin air. They didn't run a dual pattern cam just because. ;)
Oh without a doubt, I don't think you can get to that level without doing the testing and there is no telling what could be had from this engine if the budget allowed.
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Re: Valve Seat Angles and Flow Area

Post by randy331 » Sat Mar 10, 2018 11:38 pm

hoffman900 wrote:
Sat Mar 10, 2018 10:14 pm
That said, I'm not going to cam a hemi, where I/E ratios may be way tighter (so higher exhaust flow compared to intake) at low lifts than I would a wedge head. A 4 valve head may even have a negative I/E ratio (exhaust flows more than the intake). It's totally applicable to a point.
Maybe you'd be willing to share the results of your back to back cam testing and the type of engines it was on with us?

Randy

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Re: Valve Seat Angles and Flow Area

Post by Erland Cox » Sun Mar 11, 2018 10:01 am

CamKing wrote:
Sat Mar 10, 2018 5:37 pm
groberts101 wrote:
Sat Mar 10, 2018 5:05 pm
My 1st instinct is to spread the lobes a tad more than typical for similar combo's and/or run less exhaust duration with less lift?
You leave the intake centerline alone. You reduce the exhaust duration, and you move the exhaust centerline to keep the same overlap. This will give you a narrower LSA.
That sounds right to me and is also what I would do and what I am going to try on heads with bigger valves than I am currently running.

Erland

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Re: Valve Seat Angles and Flow Area

Post by Stan Weiss » Sun Mar 11, 2018 10:02 am

randy331 wrote:
Sat Mar 10, 2018 9:29 pm
GARY C wrote:
Sat Mar 10, 2018 4:23 pm
randy331 wrote:
Sat Mar 10, 2018 2:41 pm


I was talkin to one of the guys from Bullet Cams about emc cams. He said of the teams he was involved with, that actually tested some cams, they all ended up very similar to what we had.
Think about all the different platforms and flowz of the various engines, yet you end up at the same location on cams.

This wouldn't include the ones that picked one cam and went with it.

Randy
That begs the question, if the flowz guy and the non flowz guy arrive at the same cam then who's right and who's wrong?
The main reason they'd end up with similar cams is, the most important paramiters for picking a cam are dictated by rules at the EMC.
The number 1 thing is rpm. The emc sets that.
Compression is one. that's set by the emc.
In a round about way valve acceleration is set by the rules, and some years/classes lift is. Those 2 things impact valve events.

Any flowz difference within the confines of the proper csa for the cubes entered would have no affect on valve events.

That's what I'm trying to say. Thinking cause you gained a few cfm you need a different cam, or if your ex flowz a few more cfm now you need less ex duration.

But isn't it interesting how easy it is to revive a thread with a low lift flow comment, or flowz speced cam comment ??? LOL :D

Randy
Randy,
Are you talking the same engine platform or different engine platforms? Because on different engine platforms the same CSA can be a somewhat different shape due to lifter bore / push rod placement, head bolt placement, water jacket placement, etc.

Stan
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Do you use engine simulation software that uses cylinder head flow files?
We have a package of more than 3000 DFW or FLW Files

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Re: Valve Seat Angles and Flow Area

Post by Rick360 » Sun Mar 11, 2018 2:31 pm

hoffman900 wrote:
Sat Mar 10, 2018 4:03 pm
As for camshaft designers not knowing the flow curve, that's silly. Lots of chest beating going on here :roll: . Someone, somewhere in the decision making process has to know the flow curve in order to pick out the events. I don't think any cam designer is going to say they get it 100% out of the gate - that's stupid. It's their first, best guess. Where to go from there is contingent on testing. I know Mike Jones has laid out what he wants the customer to do.
Why do you HAVE to look at airflow? Why not avg csa of port, throat csa, mcsa, port shape, valve seat design, header size, desired rpm range and cubc inches.

If flowbench cfm isn't a great indicator of HP, then why does it HAVE to be used for cam selection?

I've seen 2 different heads that have the same cfm and 1 set will peak 500rpm higher.

Engine builders need a good cam guy to design the lobes, but as an engine builder you should have a better understanding of the cam that YOUR induction and exhaust system require than a cam guy.

Rick

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Re: Valve Seat Angles and Flow Area

Post by Walter R. Malik » Sun Mar 11, 2018 2:54 pm

Rick360 wrote:
Sun Mar 11, 2018 2:31 pm
hoffman900 wrote:
Sat Mar 10, 2018 4:03 pm
As for camshaft designers not knowing the flow curve, that's silly. Lots of chest beating going on here :roll: . Someone, somewhere in the decision making process has to know the flow curve in order to pick out the events. I don't think any cam designer is going to say they get it 100% out of the gate - that's stupid. It's their first, best guess. Where to go from there is contingent on testing. I know Mike Jones has laid out what he wants the customer to do.
Why do you HAVE to look at airflow? Why not avg csa of port, throat csa, mcsa, port shape, valve seat design, header size, desired rpm range and cubc inches.

If flowbench cfm isn't a great indicator of HP, then why does it HAVE to be used for cam selection?

I've seen 2 different heads that have the same cfm and 1 set will peak 500rpm higher.

Engine builders need a good cam guy to design the lobes, but as an engine builder you should have a better understanding of the cam that YOUR induction and exhaust system require than a cam guy.

Rick
I think the point is, (or at least should be), that a lot of so called engine builders, (assemblers???), probably have little idea ... ](*,)
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Re: Valve Seat Angles and Flow Area

Post by user-9274568 » Sun Mar 11, 2018 3:21 pm

I compare cfm/area used vs max cfm/area (based off 350fps/146cfm) for THAT head on THAT engine.

Tells you the efficiency of THAT engine.

Low port vs High port. Low compression vs High Compression. It all has an impact.

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Re: Valve Seat Angles and Flow Area

Post by hoffman900 » Sun Mar 11, 2018 3:26 pm

Rick360 wrote:
Sun Mar 11, 2018 2:31 pm
hoffman900 wrote:
Sat Mar 10, 2018 4:03 pm
As for camshaft designers not knowing the flow curve, that's silly. Lots of chest beating going on here :roll: . Someone, somewhere in the decision making process has to know the flow curve in order to pick out the events. I don't think any cam designer is going to say they get it 100% out of the gate - that's stupid. It's their first, best guess. Where to go from there is contingent on testing. I know Mike Jones has laid out what he wants the customer to do.
Why do you HAVE to look at airflow? Why not avg csa of port, throat csa, mcsa, port shape, valve seat design, header size, desired rpm range and cubc inches.

If flowbench cfm isn't a great indicator of HP, then why does it HAVE to be used for cam selection?

I've seen 2 different heads that have the same cfm and 1 set will peak 500rpm higher.

Engine builders need a good cam guy to design the lobes, but as an engine builder you should have a better understanding of the cam that YOUR induction and exhaust system require than a cam guy.

Rick
hoffman900 wrote:
Sat Mar 10, 2018 10:14 pm
It's the shape of the flow curve that matters and is what the cam grinders are looking for. Again, it's a metric. If I developed the port via CFD, I'd be likely looking at mass flow, not volumetric flow. Mass flow tells you more anyway, and Mike has revealed this is actually what he's calculating (with some assumptions). Harold and Harvey, were the first ones to understand (that I could find, and going back to the early '70s) that mass flow into and out of the cylinder doesn't necessarily follow what the flowbench shows. Harold stopped designing any symmetrical lobes by the mid 1970s. Harvey used different ramp styles. Mike has true assymetrical profiles. Comp has many lobes with positive or negative offset at max lift.
Me*tric (me-trik) n. - a standard for measuring or evaluating something, especially one that uses figures or statistics: new metrics for organization's diversity.

Randy331, it's not my information to share. :wink:

There are two arguments here. The flowbench may help look at the shape of the curve and look at splits to get a baseline. If I'm working within a tight box and I'm already close, then yeah, a 10cfm here or there won't make any difference (which could be <1-2% of total flow @ 28") at that point you're experimenting with other things, but you have to start somewhere.

IMO? Mass flow is what I'd be looking at and it would all be looked at with high end simulation software which will work off simulated (and measured) running depressions.
-Bob

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Re: Valve Seat Angles and Flow Area

Post by GARY C » Sun Mar 11, 2018 4:04 pm

I assume all of that being taken into account in these discussions but yet very little to nothing is ever discussed about valve angle or port size on the exhaust side.

It's been brought up and passed by probably 4 times in this thread alone, my guess is that most who have explored it are not willing to share due to the fact that it is the one area many engine builders don't give much thought to so it give others an advantage.
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

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