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Even runner flow

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Even runner flow

Postby BOOT » Fri Nov 08, 2013 10:03 am

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.
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Re: Even runner flow

Postby SchmidtMotorWorks » Fri Nov 08, 2013 1:37 pm

Even that won't even it out because the firing order causes some adjacent runners to compete against eachother (not to mention the other wave chaos going on in there).
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Re: Even runner flow

Postby PackardV8 » Fri Nov 08, 2013 4:12 pm

The slight variances in flow bench results don't always have the penalty we might think.

A friend with more money than sense has a high dollar, thoroughly scienced-out 347" SBF in a Cobra clone. He got all excited and spent $10,000 converting from a single 4-bbl to the IR EFI Weber-look. It took quite a number of tuner-hours to equal the RWHP he was getting with the 4-bbl. He hasn't yet been bragging about huge gains.
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Re: Even runner flow

Postby BOOT » Fri Nov 08, 2013 8:48 pm

PackardV8 wrote:The slight variances in flow bench results don't always have the penalty we might think.


What if you increased the variance to more than slight? For example only ported the outer runners.
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Re: Even runner flow

Postby tt 383 » Fri Nov 08, 2013 9:34 pm

Didn't Smokey Yunick build an engine designed to be two 4 cylinders and tuned them separately taking into account runner length and exhaust scavenging, usinv differeng lobes respectively. Seem to remember it having 2 torque peaks and being somewhat unimpressive...
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Re: Even runner flow

Postby SchmidtMotorWorks » Fri Nov 08, 2013 10:31 pm

BOOT wrote:
PackardV8 wrote:The slight variances in flow bench results don't always have the penalty we might think.


What if you increased the variance to more than slight? For example only ported the outer runners.


Why would you hold anything back just to try to make things even?
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Re: Even runner flow

Postby Kevin Johnson » Fri Nov 08, 2013 11:59 pm

Thermodynamic balance is different for the inner versus outer cylinders.

You should watch that NASCAR engine video.

http://youtu.be/rBZCnG1HwDM?t=1s
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Re: Even runner flow

Postby SchmidtMotorWorks » Sat Nov 09, 2013 12:39 am

Kevin Johnson wrote:Thermodynamic balance is different for the inner versus outer cylinders.

You should watch that NASCAR engine video.

http://youtu.be/rBZCnG1HwDM?t=1s

What specifically?
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Re: Even runner flow

Postby Kevin Johnson » Sat Nov 09, 2013 1:07 am

SchmidtMotorWorks wrote:
Kevin Johnson wrote:Thermodynamic balance is different for the inner versus outer cylinders.

You should watch that NASCAR engine video.

http://youtu.be/rBZCnG1HwDM?t=1s

What specifically?



Eight minutes in. Thermal efficiency. Engine architecture which would include coolant flow, radiative losses from the cylinders being different and so on. The inner cylinders sacrifice less energy to maintain a local equilibrium than the outer cylinders. The general theme is understanding of the V8 as being a collection of eight separate engines that affect oneanother.
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Re: Even runner flow

Postby SchmidtMotorWorks » Sat Nov 09, 2013 1:14 am

Kevin Johnson wrote:
SchmidtMotorWorks wrote:
Kevin Johnson wrote:Thermodynamic balance is different for the inner versus outer cylinders.

You should watch that NASCAR engine video.

http://youtu.be/rBZCnG1HwDM?t=1s

What specifically?



Eight minutes in. Thermal efficiency. Engine architecture which would include coolant flow, radiative losses from the cylinders being different and so on. The inner cylinders sacrifice less energy to maintain a local equilibrium than the outer cylinders. The general theme is understanding of the V8 as being a collection of eight separate engines that affect oneanother.


That's obvious so what?
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Re: Even runner flow

Postby Kevin Johnson » Sat Nov 09, 2013 1:40 am

I guess I am at a loss as to why I need to explain what is obvious to those that needed to ask.
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Re: Even runner flow

Postby SchmidtMotorWorks » Sat Nov 09, 2013 1:56 am

Kevin Johnson wrote:I guess I am at a loss as to why I need to explain what is obvious to those that needed to ask.


Because you post a link implying that it answers the question being asked without explaining how it does.
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Re: Even runner flow

Postby Kevin Johnson » Sat Nov 09, 2013 2:30 am

SchmidtMotorWorks wrote:
Kevin Johnson wrote:I guess I am at a loss as to why I need to explain what is obvious to those that needed to ask.


Because you post a link implying that it answers the question being asked without explaining how it does.


I apologize. I was under the plainly mistaken impression that you had watched that video from start to finish, as I did, after you commented on it in the other thread. If you had watched it then you would not need to ask. If you could not remember what was in the first nine minutes then only nine minutes of reviewing the video would have answered the question.

So, once again I will trot out how irritating it is when someone has not done the primary task at hand, reviewing the material, prior to discussing it but attempts to conceal this by asking pointed and apparently incisive questions. This plays well in a situation where others have not reviewed the material as well but very poorly when others have.

So, to other readers, it is worthwhile watching the video if you are interested in "other ways to even the cylinders out."

Kinderspielen.
Last edited by Kevin Johnson on Sat Nov 09, 2013 2:38 am, edited 1 time in total.
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Re: Even runner flow

Postby SchmidtMotorWorks » Sat Nov 09, 2013 2:37 am

Kevin Johnson wrote:
SchmidtMotorWorks wrote:
Kevin Johnson wrote:I guess I am at a loss as to why I need to explain what is obvious to those that needed to ask.


Because you post a link implying that it answers the question being asked without explaining how it does.


I apologize. I was under the plainly mistaken impression that you had watched that video from start to finish, as I did, after you commented on it in the other thread. If you had watched it then you would not need to ask. If you could not remember what was in the first nine minutes then only nine minutes of reviewing the video would have answered the question.

So, once again I will trot out how irritating it is when someone has not done the primary task at hand, reviewing the material, prior to discussing it but attempts to conceal this by asking pointed and apparently incisive questions. This plays well in a situation where others have not reviewed the material as well but very poorly where others have.

So, to other readers, it is worthwhile watching the video if you are interested in "other ways to even the cylinders out."

Kinderspielen.


Kevin, please explain specifically how that video answers the OPs question.
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Re: Even runner flow

Postby Kevin Johnson » Sat Nov 09, 2013 2:47 am

SchmidtMotorWorks wrote:
Kevin, please explain specifically how that video answers the OPs question.


Imbalance degrades power through several mechanisms.


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

Right.

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