90build

.......................

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

Brad

..................

Looking good!!

Brad

....................

Thanks SPP for the pipe..

David Ashcroft said:

Thanks SPP for the pipe..

Click to expand...

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.
Sent from my SAMSUNG-SM-G891A using Tapatalk

David Ashcroft said:

Thanks SPP for the pipe..

Click to expand...

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.

Sent from my SAMSUNG-SM-G891A using Tapatalk

The pipe is full carbon Rev pipe.

David Ashcroft said:

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

Click to expand...

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

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

What happened to all the photos??

Brad

Brad I put a gas motor in it rather..

David Ashcroft said:

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

Click to expand...

Post a picture

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