Even runner flow

[SchmidtMotorWorks]

The OP touches on one, which is also discussed in the video. But you knew that, right?

I'm trying to guess what you are getting at, why are you making it so difficult?
Why not just say specifically what you mean?

Are you thinking that commercially available SBC manifolds have flow bias built in to make the cylinders more uniform?

[vannik]

I'm trying to guess what you are getting at, why are you making it so difficult?
Why not just say specifically what you mean?

Kevin,

I have to agree with Jon, I did watch the complete video (and found it enjoyable but nothing new) and they were not trying to "even runner flow" but were attempting to maximize the performance of each cylinder.

Vannik

[SchmidtMotorWorks]

Ok I was reading a post in another forum and the guy was porting a sbc single plane intake. They had unported flow numbers and the inner runners 3,5,4,6 all flowed less. Not the same amount less but it got me thinking back to the 4 pattern cams and other ways to even the cylinders out. Makes me almost wonder if the less was by design, but kinda not because it varied from 10-50 cmf less than the outer and those four runners varied much less.

If you look at the manifold with the runners flat to your eye you can see that the inner runners must have sharper turns.
Generally the person that makes the core boxes that mold the sand that forms the inside of the runners makes the radius of the runners concentric like the image here.
If the runners have similar cross section the sharper turn makes them flow less.
Most SBC manifolds, especially those with foundry tooling made in the 70's or 80's were made by pattern makers that never ported a head or manifold.
They made the patterns from wood using band saws and files. For them, making a pattern quickly that is reliable trumps every other consideration.

runner_radius.JPG

[BOOT]

Why would you hold anything back just to try to make things even?

Yah I know I was kinda thinking the same about my question and even with the 4 pattern cams. I know porting dual plane intakes you just try to get the best from each runner. Sometimes you just gotta talk about it before you confirm it's a bad idea. I guess certain things you even out and others you get the best out of each.


I'll watch the video Kevin, thx

[BOOT]

Also in one of the 4 pattern cam discussions awhile back some1 said there is a better way to even things out and i kinda agree. Not with evening thing, but there is a better way and that's to optimize all. The ignition would be a better way to do it and I understand that now.

[Kevin Johnson]

I'm trying to guess what you are getting at, why are you making it so difficult?
Why not just say specifically what you mean?

Kevin,

I have to agree with Jon, I did watch the complete video (and found it enjoyable but nothing new) and they were not trying to "even runner flow" but were attempting to maximize the performance of each cylinder.

Vannik

Neels,

After Jack replied to BOOT and BOOT responded it was then clear that evening power output was a valid subtext in the thread. I certainly hope that Jon picked up on that but perhaps he did not. I will try to be more charitable in the future.

The quote that I provided from the graphic in the video makes it clear that I was working with the concepts of "imbalance" with respect to "even" and the video is also crystal clear that this will result in improved power output.

Kevin

[Kevin Johnson]

The ignition would be a better way to do it and I understand that now.

This is also discussed in the video and you should keep in mind that you may or may not be operating with the same ignition system constraints as NASCAR.

[randy331]

The idea of even flow sounds good,.. but, when porting heads I have yet had a set end up perfectly even on flow. Sometimes casting limits/shift/porters skill/vision etc will not allow it. SO, if you end up with the ports varying from 288-293 cfm and can't get the 288 cfm up, would you lower the 293 for the sake of even flow??? I won't.

And flowing a sbc intake by it's self is useless. And, any time I have added a single plane intake to a set of sbc heads, the outer runners are the ones that flow less, not the inners like the OP stated.

And Comps dual pattern cam makes good mag articles but that's it. I mean if the dual pattern intake profiles made up for uneven flow and all cylinders had the same VE, why would there be a need for 2 ex profiles? I mean the idea was to even flow INTO the cylinders.
Before the dual pattern idea could be validated, the engine would need to have been flogged to the point of having the best single pattern cam, then go down a bit of duration on the strong flowing cylinders and up a bit on the weak flowing cylinders.

Randy

[BOOT]

The idea of even flow sounds good,.. but, when porting heads I have yet had a set end up perfectly even on flow. Sometimes casting limits/shift/porters skill/vision etc will not allow it. SO, if you end up with the ports varying from 288-293 cfm and can't get the 288 cfm up, would you lower the 293 for the sake of even flow??? I won't.

And flowing a sbc intake by it's self is useless. And, any time I have added a single plane intake to a set of sbc heads, the outer runners are the ones that flow less, not the inners like the OP stated.

And Comps dual pattern cam makes good mag articles but that's it. I mean if the dual pattern intake profiles made up for uneven flow and all cylinders had the same VE, why would there be a need for 2 ex profiles? I mean the idea was to even flow INTO the cylinders.
Before the dual pattern idea could be validated, the engine would need to have been flogged to the point of having the best single pattern cam, then go down a bit of duration on the strong flowing cylinders and up a bit on the weak flowing cylinders.

Randy

When I recently mild ported/cleaned-up my 1st set of heads, I thought at 1st it kinda sucks I won't know the variance in flow because I don't have a flow bench. At the time I just did my best and figured even if they aren't the same they will all be better some.


edit: yah I never got the exhuast part of those cams.

[GARY C]

Also if you got get the lesser port to flow as well as the better port on the bench (intake installed) because of the runner size increase needed to do so it most likely would not perform as well on the track.

[Kevin Johnson]

In many, most?, cases intake manifolds were designed by engineers that were familiar with flow and tuning -- and in the 1970s, with meeting increasing emission requirements. They would certainly receive feedback from pattern makers (who can also be engineers, of course) as to whether it would be practical to manufacture a manifold in a given way. This is very different from implying that pattern makers were free to do what they wished with manifold design because it made their job easier.

They made the patterns from wood using band saws and files. For them, making a pattern quickly that is reliable trumps every other consideration.

Not trying to be an ass, rather just attempting to slow down the rewriting of history that will be cited from SpeedTalk. Across town, an engineer trained at Yale in the 1940s and running Engine Design in the 1950s through the 1980s did not seem to have a problem coming up with intake designs and blueprints for the full gamut of engines produced by Mopar.
http://www.allpar.com/corporate/bios/we ... chron.html
I don't think things were so very different at GM or Ford.

If you look at the manifold with the runners flat to your eye you can see that the inner runners must have sharper turns.
Generally the person that makes the core boxes that mold the sand that forms the inside of the runners makes the radius of the runners concentric like the image here.
If the runners have similar cross section the sharper turn makes them flow less.
Most SBC manifolds, especially those with foundry tooling made in the 70's or 80's were made by pattern makers that never ported a head or manifold.
They made the patterns from wood using band saws and files. For them, making a pattern quickly that is reliable trumps every other consideration.

[SchmidtMotorWorks]

In many, most?, cases intake manifolds were designed by engineers that were familiar with flow and tuning -- and in the 1970s, with meeting increasing emission requirements. They would certainly receive feedback from pattern makers (who can also be engineers, of course) as to whether it would be practical to manufacture a manifold in a given way. This is very different from implying that pattern makers were free to do what they wished with manifold design because it made their job easier.

They made the patterns from wood using band saws and files. For them, making a pattern quickly that is reliable trumps every other consideration.

Not trying to be an ass, rather just attempting to slow down the rewriting of history that will be cited from SpeedTalk. Across town, an engineer trained at Yale in the 1940s and running Engine Design in the 1950s through the 1980s did not seem to have a problem coming up with intake designs and blueprints for the full gamut of engines produced by Mopar.
http://www.allpar.com/corporate/bios/we ... chron.html
I don't think things were so very different at GM or Ford.

If you look at the manifold with the runners flat to your eye you can see that the inner runners must have sharper turns.
Generally the person that makes the core boxes that mold the sand that forms the inside of the runners makes the radius of the runners concentric like the image here.
If the runners have similar cross section the sharper turn makes them flow less.
Most SBC manifolds, especially those with foundry tooling made in the 70's or 80's were made by pattern makers that never ported a head or manifold.
They made the patterns from wood using band saws and files. For them, making a pattern quickly that is reliable trumps every other consideration.

Kevin, you live in a fantasy dream world.

The OP is about single plane manifolds made the aftermarket.

The design of those manifolds is mostly dictated by the cost of the casting.

[Kevin Johnson]

Kevin, you live in a fantasy dream world.

Please feel free to provide interviews with GM pattern makers from the 1970s who designed manifolds. Really, it would be interesting.

Now, my "dream world" consisted of consulting with a Cosworth Engineer who explained the degree of freedom that pattern makers have with castings and allowable variations. He worked with Danielson when I spoke with him. Do you need his contact info? http://www.danielson-eng.fr/en/

Here's an example. Gate variation in Zetec E sump castings. In the picture of eleven sumps with the same part numbers there are four distinct variations introduced by pattern makers.* They are separated by group in the picture.

* A second set of variations was surface or casting finish.

zetec sump a.jpg

group of aluminum sumps.jpg

My friend, Jean-Claude, was in the Porsche factory in the 1950s, as well as the Renault factory and was an engineer for Matra. We had many discussions about common practices.

Look, your technique clearly works 95% of the time. You should be happy with that and not be so troubled by people who can call you out. Maybe some more sims will help.

[SchmidtMotorWorks]

Kevin, you live in a fantasy dream world.

Please feel free to provide interviews with GM pattern makers from the 1970s who designed manifolds. Really, it would be interesting.

Now, my "dream world" consisted of consulting with a Cosworth Engineer who explained the degree of freedom that pattern makers have with castings and allowable variations. He worked with Danielson when I spoke with him. Do you need his contact info? http://www.danielson-eng.fr/en/

Here's an example. Gate variation in Zetec E sump castings. In the picture of eleven sumps with the same part numbers there are four distinct variations introduced by pattern makers.* They are separated by group in the picture.

* A second set of variations was surface or casting finish.

zetec sump a.jpg

group of aluminum sumps.jpg

My friend, Jean-Claude, was in the Porsche factory in the 1950s, as well as the Renault factory and was an engineer for Matra. We had many discussions about common practices.

Look, your technique clearly works 95% of the time. You should be happy with that and not be so troubled by people who can call you out. Maybe some more sims will help.

You are off in left field, the post was about SBC single plane manifolds made by the after market in the USA. They are not designed by OEMs.
Cosworth has zero relevance.

The technique I describe isn't my technique, it is how it was done.

By the way, Cosworth uses the software I develop to design engines.

Most of the patterns that were made for aftermarket manifolds in the 60s, 70s, 80's and even 90's the the USA, never had any drawings made for them, there really wasn't any point to it.
It usually went like this, you bring a hand sketch or describe to a to a pattern maker what you want that cuts out the cores and pattern pieces from mahogany on a band saw and files them to shape.
This isn't a guess on my part, I have seen about 75% of the patterns as almost every US after market casting is or was cast at the same foundry at one time or another.

One of the few patterns that had drawings were the Offy stuff, but the drawings are so crude and incomplete, the pattern maker didn't have much to follow and the fidelity is rather approximate (they didn't even have draft on the drawings).

[Kevin Johnson]

Jon, no charge on doing your homework for you.

http://67-72chevytrucks.com/vboard/show ... ostcount=2

I have a 300-36 which is only a little taller than the 35.
The design goes all the way back to the '69 Z/28.
Holley (and many others) just copied Chevy on that intake.

http://www.chevytalk.org/fusionbb/showt ... id/145580/

This is the direct quotes from the Holley Technical Support:

"That intake is for a small block Chevy
it makes power from Idle to 4800 RPM
it is a good street intake"

"It was from the late 1960�s
It came in the trunk on some performance cars from GM
To do a mild hop up---"

It was cast at the Winters Foundry. You would have been about seven or eight years old at the time.