Exhaust Wrap ...Again sorry.

[nellyboyo]

I`ve checked through most of the historic posts I can find but they seem inconclusive.

Is heat wrap a good or bad thing for 2-strokes ?????

Not bothered about the look , just would not mind it a bit quieter.

Got and NK road on my Imola ultimate with 28mm PWK and no filter . Goes really well ( eventualy ) but really would not want to risk overheating it.

Even if I only start wrapping a good 6 inches from the stub. I`ve put so much effort into getting it running spot on and safely I`d throw myself off a bridge if I cocked it up.

[Avantone]

Think the idea is that the wrap insulates the expansion chamber and keeps the exhaust gas hotter and therefore denser. This density increases the strength of the exhaust pulse so the chamber works more efficiently.

The question is whether the cylinder is capable of staying cool enough when the exhaust isn't acting as effectively as a heat sink - probably not on an air cooled motor...

[nellyboyo]

yes , I can see the sense behind that science....Is the heat cylinder heat increase negligible or not though ....I expect that’s really hard to judge unless someones done a before and after test .

[warts]

An air filter will make it quieter, not to mention last longer.

[nellyboyo]

True .....though thats a whole lot of pain.....getting one on that fits with a panal and re-jetting and possibly not performing as well etc etc ...
Whipping the pipe off takes me 10 mins as Ive done it that often ....

[Spanish Fly]

If your concerned about heat why not start your wrap further away from the stub and leave the down pipe area unwrapped? Surely the larger belly section of the pipe is where it is resonating the most and therefore producing the most noise.
SF

[nellyboyo]

Yes, thats exactly what I was thinking of doing. I was only going to from where it clears the LHS of the flywheel cover and around to the muffler connection. I was going to leave a good 10 inches from the stub unwrapped.

[smallyshane]

Im sure i read some interesting info by a German pipe maker who did some dyno tests with this stuff and found that wrapping from the stub to the expansion cone gave the best results and going further along the pipe had negligible results.

Sorry, this is what was said..

That really depends on the engine and the pipe.

I made a back to back dyno comparison with a Polini and a PM 40 pipe, with only the downpipe wrapped, with the downpipe and half the belly wrapped, and with the pipe completely wrapped. Wrapping the downpipe only did not increase power but gave a bit more overrev, with half the belly wrapped this effect was more pronounced, with the complete pipe wrapped there where no further gains though. That doesn't necessarily hold true for all pipes and engines though. The graphs are in a topic on GSF, I'm to thick to find it though.

[nellyboyo]

Why aren`t more pepole using it then ....because it looks ugly and could hide corrossion ???
Is they the only reasons ?

[rosscla]

Why aren`t more pepole using it then ....because it looks ugly and could hide corrossion ???
Is they the only reasons ?

I think that should be ’actively promote' rather than 'hide'...