90build

[David Ashcroft]

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[brad nichols]

Just use the front passage and leave the other open, is what I have done. Nice boat!!

Brad

 

[David Ashcroft]

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[brad nichols]

Looking good!!

Brad

 

[David Ashcroft]

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[David Ashcroft]

Thanks SPP for the pipe..

 

[TraceyJacoby]

Thanks SPP for the pipe..

What is the coating on the pipe? Is it an aluminum pipe and the wrap reduces expansion? Or, is it a heat wrap to reduce scavenging? Thanks.
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[TraceyJacoby]

Thanks SPP for the pipe..

I found this explanation on Reddit, by grunge_ryder Jul 7, 2011, 3:25 PM:


Well, if you're a serious tuner, you'll know why wrapping the header works, but if you're Joe Dirt you're probably just aping the tuners.

Wrapping the headers is a way of optimizing the temperature of the exhaust gasses in the pipe so the speed of sound in the gasses will be "tune" with the length of the individual pipe from combustion chamber to collector junction.

The speed of sound in exhaust gasses is around 1700 feet per second and the length of the header pipe is critical if the sound wave is going to travel from the combustion chamber to the collector and echo back to the combustion chamber while both the exhaust valves are still open and the intake valve has opened during the camshaft overlap period.

Then the echo turns around and goes back down the header pipe, sucking fresh mixture in through to already-open intake valve.

How much effect does this exhaust tuning have on the engine?

It has an acoustic supercharging advantage of about 3 pounds per square inch.

(2-stroke engines get even greater effects, an expanision chamber increases the pressure in the cylinder by 6 or 7 psi.)

If you have a 4-stroke engine with 12:1 geometric compression ratio, it will crank about 176 psi with no acoustic effects.

But when the engine comes on the pipe at ~8000 RPM, the total of geometric and acoustic effects makes the pressure in the cylinder about 212 psi just before the spark plug lights the mixture off.

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[David Ashcroft]

The pipe is full carbon Rev pipe.

 

[Michael Costanzo]

Like this pipe..?The other pipe is full carbon Rev pipe.

dave,how are you liking the N/R .91 and what props does it pull? thanks mike.

 

[David Ashcroft]

Still finishing the build Michael ..I have actually been spending my time on a 72" Cat which requires a lot of hull body prep..

 

[brad nichols]

What happened to all the photos??

Brad

 

[David Ashcroft]

Brad I put a gas motor in it rather..

 

[julianconde]

Still finishing the build Michael ..I have actually been spending my time on a 72" Cat which requires a lot of hull body prep..

Post a picture

 

[David Ashcroft]

Sold the cat now Julian ,just lost drive to continue building.And here is the Mono nearly done.