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Old 04-05-2011, 02:46 PM   #61
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Pusha,

Why don't you please visit another thread.

Thank you.
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Old 04-05-2011, 02:47 PM   #62
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Originally Posted by miata2fast View Post
Pusha,

Why don't you please visit another thread.

Thank you.
Unless you can save this beshitted thread in the next two posts, I don't see what me leaving is going to change.
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Old 04-05-2011, 02:56 PM   #63
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Quote:
Originally Posted by nitrodann View Post

4 stroke 4 bangers, like sav said, only have one cylinder on an intake stroke at any one time, and at the top and bottom of that one stroke per 2 revolutions its hardly moving, and the piston is only 78mm, and its sucking through 2 30mm ports with valves only opened 7mm so why the hell would a completely open 60mm hole restrict this
Here is something else you are not factoring. In a log manifold all runners are connected. So as one piston is pulling air into the combustion chamber, it is creating vacuum in the other runners. This causes the charge to go in reverse in the other runners.

In individual throttles, you do not have that problem. The charge is constantly traveling in one direction. Or at the very least, does not have to refill the vacuum created when the other cylinders are pulling from the same source of air.
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Old 04-05-2011, 03:01 PM   #64
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hang on, same airflow over a larger intake area is -increased- velocity? I must be retarded to have missed that.

Sorry.

Dann

edit: clarifying sarcasm
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Old 04-05-2011, 03:03 PM   #65
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If theres no vacuum guage reading difference at WOT between the sides of the butterfly how is there now a vacuum in the runner? If that were tru WOT would be like 80kpa, not 100.

Dann
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Old 04-05-2011, 03:17 PM   #66
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Originally Posted by nitrodann View Post
If theres no vacuum guage reading difference at WOT between the sides of the butterfly how is there now a vacuum in the runner? If that were tru WOT would be like 80kpa, not 100.

Dann
All four valves don't open at the same time...air flows in waves. When the valve closes air inside that runner will flow back out into the plenum.
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Old 04-05-2011, 03:17 PM   #67
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Quote:
Originally Posted by nitrodann View Post
hang on, same airflow over a larger intake area is -increased- velocity? I must be retarded to have missed that.

Sorry.

Dann

edit: clarifying sarcasm
Last time I checked, you can change the choke diameter in any decent individual throttle. Not so much on an off the shelf log manifold.
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Old 04-05-2011, 03:24 PM   #68
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Quote:
Originally Posted by nitrodann View Post
hang on, same airflow over a larger intake area is -increased- velocity? I must be retarded to have missed that.

Sorry.

Dann

edit: clarifying sarcasm
I never said that a larger intake area would increase velocity. Why would you imply that I did?
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Old 04-05-2011, 03:24 PM   #69
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Originally Posted by Braineack View Post
All four valves don't open at the same time...air flows in waves. When the valve closes air inside that runner will flow back out into the plenum.
I see your point here But never the less it applies equally to Quads, And if it were true Runner length wouldnt be tunable like it is, it relies on the facts that this only happens at very low rpm, whether they are quads or otherwise. Momentum is momentum.

And different chokes are great for changing velocity, but down choking itb's to result the same velocity as the stock TB would defeat the purpose completely of the advantage that you have argued it posesses. (ie inceased flow AND velocity...apparently).



Dann
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Old 04-05-2011, 03:30 PM   #70
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Originally Posted by miata2fast View Post
The intake speed is higher on individual throttles (if they are tuned correctly) than any cast log manifold any day. Higher speed results in having more air/fuel in the combustion chamber. And THAT results in more power.

Did I make that simple enough for you to understand?

Heres the quote, intake speed is higher (on your larger total cross section ITBs) apparently. Only way this is actually possible is a smaller total flow area.

The reason that ITBs whether carbies or Quads are choked is that stomping them from low throttle opening fast results in a big flat spot due to not enough intake velocity. This is partially caused by fuel falling out of suspension but thats starting to get to e a long story.

Dann
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Old 04-05-2011, 03:37 PM   #71
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Quote:
Originally Posted by miata2fast View Post
Here is something else you are not factoring. In a log manifold all runners are connected. So as one piston is pulling air into the combustion chamber, it is creating vacuum in the other runners. This causes the charge to go in reverse in the other runners.
Google the word "plenum".
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Old 04-05-2011, 03:43 PM   #72
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Quote:
Originally Posted by nitrodann View Post
And different chokes are great for changing velocity, but down choking itb's to result the same velocity as the stock TB would defeat the purpose completely of the advantage that you have argued it posesses. (ie inceased flow AND velocity...apparently).



Dann
Down choking too much will increase speed, but will reduce the volume of air the motor can ingest. Up choking too much will result in reduced velocity and and the motor will not ingest the maximum amount of air it is capable of.

Displacement and rpm are generally what determines what choke size you need. There is a general graph available that determines the size, but good tuning is what is required to find out what is the best choke size needed to gain the most power.

When I tuned my car, I continued to go faster untill I used the choke size that I have currently. I tried 3 different size chokes. Unfortunately, I can not go any larger on choke unless I step up to the next sized throttle housings. However, with the rpm and discplacement I am currently running, I do not think I would go faster with larger chokes at this point.

My point is with a log manifold, I would be stuck with what ever runner diameter the manufacturer built, and I would be stuck with what ever results I was given.
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Old 04-05-2011, 03:48 PM   #73
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Quote:
Originally Posted by nitrodann View Post
Heres the quote, intake speed is higher (on your larger total cross section ITBs) apparently. Only way this is actually possible is a smaller total flow area.



Dann
You made an assumption the area of my intake was larger. I do not know if they are larger or not. What I do know however, is that they are 'adjustable'.
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Old 04-05-2011, 04:02 PM   #74
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Quote:
Originally Posted by nitrodann View Post
I see your point here ...
Just to elaborate...I used Savington's advice:
Quote:

Modern intake manifolds usually employ runners, individual tubes extending to each intake port on the cylinder head which emanate from a central volume or "plenum" beneath the carburetor. The purpose of the runner is to take advantage of the Helmholtz resonance property of air. Air flows at considerable speed through the open valve. When the valve closes, the air that has not yet entered the valve still has a lot of momentum and compresses against the valve, creating a pocket of high pressure. This high-pressure air begins to equalize with lower-pressure air in the manifold. Due to the air's inertia, the equalization will tend to oscillate: At first the air in the runner will be at a lower pressure than the manifold. The air in the manifold then tries to equalize back into the runner, and the oscillation repeats. This process occurs at the speed of sound, and in most manifold travels up and down the runner many times before the valve opens again.
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Old 04-05-2011, 04:06 PM   #75
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And mazda got it horribly wrong?

Dann
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Old 04-05-2011, 04:07 PM   #76
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Thanks Brain. Explained properly.
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Old 04-05-2011, 04:15 PM   #77
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Quote:
Originally Posted by nitrodann View Post
And mazda got it horribly wrong?

Dann
With the stock throttle body, filter, exhaust, noise allowances, mileage yady yady ya, they did ok I guess. Do you have all that on your car?
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Old 04-05-2011, 04:18 PM   #78
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Lol, this will never go anywhere really. I have cams portwork solid lifters etc etc etc but i still have stock Im if that answers your question.

Dann
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Old 04-05-2011, 04:22 PM   #79
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Quote:
Originally Posted by Savington View Post
Google the word "plenum".
If you put a vacuum gauge on a plenum of a normally aspirated car at WOT, is it going to be higher than the ambient outside air? I think that it helps alleviate the symptom tremendously, but does it truely completely eliminate it?

I guess it would if you had a ram air affect, but that is not exactly easy to create. And certainly not cheap.

Last edited by miata2fast; 04-05-2011 at 06:36 PM.
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Old 04-05-2011, 04:23 PM   #80
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Originally Posted by pusha View Post
I would like to be cornholed by a gianormous ban hammer, i don't see what me leaving is going to change.
ftfy
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