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Old 06-05-2019, 10:30 AM   #31
bottlefed1
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Default Re: Why zoomies?

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Originally Posted by BillyShope View Post
No, I was certainly not referring to "reversion" (which exists...apart from the dictionary definition...only in the minds of some racers.) I was referring to exhaust tuning. Virtually every racer will admit to the existence of exhaust tuning, but only a handful will look into it any further. Exhaust tuning occurs only during that portion of the Otto Cycle when the exhaust valve is closed. For exhaust tuning to be effective, losses during flow reversal must be minimized. In other words, each cylinder must have its own exhaust pipe and each pipe must have a cone at the exit to minimize flow losses during reverse flow. I know of only one NHRA record-holding car so equipped. All other car owners chose not to gain this extra power. And, so long as their competitors choose to do the same, the playing field is kept level.

Yeah kinda funny that you point that out, I agree, I have only seen it on that one car but I have seen it on a ton of two strokes.
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Old 06-05-2019, 10:33 AM   #32
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Default Re: Why zoomies?

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No, I was certainly not referring to "reversion" (which exists...apart from the dictionary definition...only in the minds of some racers.) I was referring to exhaust tuning. Virtually every racer will admit to the existence of exhaust tuning, but only a handful will look into it any further. Exhaust tuning occurs only during that portion of the Otto Cycle when the exhaust valve is closed. For exhaust tuning to be effective, losses during flow reversal must be minimized. In other words, each cylinder must have its own exhaust pipe and each pipe must have a cone at the exit to minimize flow losses during reverse flow. I know of only one NHRA record-holding car so equipped. All other car owners chose not to gain this extra power. And, so long as their competitors choose to do the same, the playing field is kept level.
Maybe take a different approach. Come in a post exactly what you are trying to teach or point out and then defend it. I'm stupid.
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Old 06-05-2019, 12:47 PM   #33
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No, I was certainly not referring to "reversion" (which exists...apart from the dictionary definition...only in the minds of some racers.) I was referring to exhaust tuning. Virtually every racer will admit to the existence of exhaust tuning, but only a handful will look into it any further. Exhaust tuning occurs only during that portion of the Otto Cycle when the exhaust valve is closed. For exhaust tuning to be effective, losses during flow reversal must be minimized. In other words, each cylinder must have its own exhaust pipe and each pipe must have a cone at the exit to minimize flow losses during reverse flow. I know of only one NHRA record-holding car so equipped. All other car owners chose not to gain this extra power. And, so long as their competitors choose to do the same, the playing field is kept level.

I certainly could be wrong, but never really thought those 'megaphones' could have been worth all the extra weight and expense.
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Old 06-05-2019, 01:36 PM   #34
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No, I was certainly not referring to "reversion" (which exists...apart from the dictionary definition...only in the minds of some racers.) I was referring to exhaust tuning. Virtually every racer will admit to the existence of exhaust tuning, but only a handful will look into it any further. Exhaust tuning occurs only during that portion of the Otto Cycle when the exhaust valve is closed. For exhaust tuning to be effective, losses during flow reversal must be minimized. In other words, each cylinder must have its own exhaust pipe and each pipe must have a cone at the exit to minimize flow losses during reverse flow. I know of only one NHRA record-holding car so equipped. All other car owners chose not to gain this extra power. And, so long as their competitors choose to do the same, the playing field is kept level.
Reversion IS flow reversal in the context of exhaust tuning and it does exist in high performance engines.
Exhaust (header) tuning is very complex and utilizes the whole engine combination from camshaft design to exhaust port; header design (tubing diameter, length, collector design), etc., etc. Most maximum-effort race engines have the combination pretty well figured out, however the exhaust is only "in tune" through a very limited RPM range. This is well evident in NHRA Pro Stock and Competition Eliminator where the engines are designed to operate at very high RPM and typically will utilize five-speed transmissions.
These cars typically have very long camshaft duration, with lots of overlap and very early exhaust valve opening. The early opening of the exhaust valve allows some cylinder pressure to escape, however this blow-down helps to reduce pumping losses and creates low pressure in the exhaust tract after the gas "plug" exits, which helps fill the cylinder with intake charge during overlap. As I previously stated, this exhaust tuning is prevelant only during a very limited (high) RPM band, therefore the cars are designed with the necessary gear ratios to take advantage of the exhaust tuning concept.

Sorry, this information has nothing what so ever to do with "zoomie" exhaust design, but it seems that the thread was getting off subject and going into the realm of N/A exhaust tuning/design.
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Old 06-05-2019, 01:59 PM   #35
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I certainly could be wrong, but never really thought those 'megaphones' could have been worth all the extra weight and expense.
Not to mmention the SPACE required ?

Not much SPACE in Modern race Cars, Narrow- Compact- Low ?
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Old 06-05-2019, 05:41 PM   #36
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No, I was certainly not referring to "reversion" (which exists...apart from the dictionary definition...only in the minds of some racers.) I was referring to exhaust tuning. Virtually every racer will admit to the existence of exhaust tuning, but only a handful will look into it any further. Exhaust tuning occurs only during that portion of the Otto Cycle when the exhaust valve is closed. For exhaust tuning to be effective, losses during flow reversal must be minimized. In other words, each cylinder must have its own exhaust pipe and each pipe must have a cone at the exit to minimize flow losses during reverse flow. I know of only one NHRA record-holding car so equipped. All other car owners chose not to gain this extra power. And, so long as their competitors choose to do the same, the playing field is kept level.

1962-`1966 Honda GP Motorcycles
did this Individual Pipe to a Cone on their 1 cyl 50cc, 2 cyl 125cc, 4 cyl 250cc, 5 cyl 125cc, 6 cyl 250cc- 350cc World Championship winning GP Bikes ....., 21,500 RPM with Breaker Points Ignitions , 1962 https://www.youtube.com/watch?v=qbHQ...?v=qbHQJvkNh1U


Isn't the 3 Step pipes a form of this individual pipe with a Tapered Cone at the Exit ?

Headers , Kinda a Best of Both , 3 Steps and a Merge Collector ?

All the Naturally Aspirated Pro's can't all be wrong, Pro Stock, NASCAR- GM, Ford, Chrysler, F1--100's of Millions $$$$ Budgets , V-12's 6 into 1's, V-10's 5 into 1's, V-8's 4 into 1's , Ferreri, BMW, Cosworth, Lotus, BRM, Jaguar, Mercedes, Renault, Ilmor, Toyota, Honda...

Honga 3.5 liter, V-10 @ 20,000 rpm ....https://www.youtube.com/watch?v=ZOJkl4Agf4c...
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Old 06-05-2019, 05:53 PM   #37
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Renault 2.4 litre..V-8...2013- 2016....
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Old 06-05-2019, 11:10 PM   #38
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So the thought would be zoomed on a procharger on alcohol?
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Old 06-06-2019, 12:11 AM   #39
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So the thought would be zoomed on a procharger on alcohol?
everybody does, well except me... I kinda run both together
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Old 06-06-2019, 12:12 AM   #40
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Old 06-06-2019, 11:31 AM   #41
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Old 06-06-2019, 05:07 PM   #42
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Default Re: Why zoomies?

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Originally Posted by whittler74 View Post

1962-`1966 Honda GP Motorcycles
did this Individual Pipe to a Cone on their 1 cyl 50cc, 2 cyl 125cc, 4 cyl 250cc, 5 cyl 125cc, 6 cyl 250cc- 350cc World Championship winning GP Bikes ....., 21,500 RPM with Breaker Points Ignitions , 1962 https://www.youtube.com/watch?v=qbHQ...?v=qbHQJvkNh1U


Isn't the 3 Step pipes a form of this individual pipe with a Tapered Cone at the Exit ?

Headers , Kinda a Best of Both , 3 Steps and a Merge Collector ?

All the Naturally Aspirated Pro's can't all be wrong, Pro Stock, NASCAR- GM, Ford, Chrysler, F1--100's of Millions $$$$ Budgets , V-12's 6 into 1's, V-10's 5 into 1's, V-8's 4 into 1's , Ferreri, BMW, Cosworth, Lotus, BRM, Jaguar, Mercedes, Renault, Ilmor, Toyota, Honda...

Honga 3.5 liter, V-10 @ 20,000 rpm ....https://www.youtube.com/watch?v=ZOJkl4Agf4c...
Even in a highly competitive atmosphere, compromises are necessary. Although an exhaust pipe for each cylinder will always be the very best, that does not mean that all designs will be the same.
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Old 06-06-2019, 05:51 PM   #43
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Even in a highly competitive atmosphere, compromises are necessary. Although an exhaust pipe for each cylinder will always be the very best, that does not mean that all designs will be the same.
As I understand it.

We live in a 14.7* per sq inch of H2O @ Sea Level, A Ocean of air Pushing upon us from every direction a 100 Miles tall by 26,000 Miles around the Earth ?

A V-8 fires 4 Cyls per 1 rotation of Crank (360*) Not all on the Same side , back and forth, side to side ?

So a Individual Pipe firing 1 Time every 720* of Crank rotation pushing High Pressure Exhaust out against a Ocean of 14.7*? How High is the Ex Pressure at the End ? Why the Tapered increase to a Cone ?

So a Pipe not Talking to each other ((Sucking-Pressure drop when the Ex Valve Closes and 14.7* rushs in to fill the Void ) is a Good thing ?

I Guess the Pro Stock Bike V-Twin 160" Buell is the Best Example I can think of , using a 3 Step Pipe ?

Seems the Junior Dragsters have Been running the Tapered Cone Pipe forever !

Would a Taper Cone Pipe be Better than a 3 Step? I would think the Buell's would at least Try one ?

Thanks !
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Old 06-06-2019, 06:01 PM   #44
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Default Re: Why zoomies?

The Honda sixes are 2-strokes and it has long since been proven that megaphones are about the worst possible way to make power on one, well designed expansion chambers put all that junk to rest, easily doubled the horsepower.

Bigtime, how's that set-up sound? had thoughts of doing that, didn't know you had already.

Last edited by SAMMY CHRISTIAN; 06-06-2019 at 06:04 PM. Reason: mis-spelled
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Old 06-06-2019, 06:03 PM   #45
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Default Re: Why zoomies?

avatar is of my 4-1 w/bullhorns procharged engine, 2 1/2" to 5" collector. Stand well away, the pulse can knock you off your feet during the burnout.

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