exhaust wrap

[alexwitham]

Ok, ive seen this stuff on a few GP bikes and also on a few track bikes when down at snetty track local to me, i spoke to a few blokes in the pits and they are claiming this wrap helps insulate the pipework, keeping the heat in by up to 50% more than unwrapped headers and pipes, and due to it keeping the heat in, it is 'suposed' to create hotter exhaust gasses which exit the system faster due to decreased density which 'apparently' gives a gain of up to 4% in BHP.

Now, im fairly mechanically minded (although alot of my fiddling has been done on strokers) but this sounds a little bit like pit lane squibble to me.

Has anyone used/beleives this theory?

Thanks

[CMSMJ1]

Used it and noticed no difference at all. It did almost stop the pipes melting my bodywork though and gave me fibreglass itch for a few days!

[jake]

I think your not s'posed to use it in formular rules... but i think thats probs old school dont take any notice acu rules.
Ive also heard not to use it on titainium? thats probs bolox aswell

[mrdidlydingo]

In my mind exhaust wrap is generally used to reduce temperatures within the fairings or the engine bay, being as generally speaking the air intake is located somewhere in this area the actual air being taken into the engine is denser not the exhaust gas, cooler air is generally denser that's why the bikes always run faster during early morning late evening.

With regards to the ruins your exhaust theory, I think that's probably down to the wrapping increasing the temperature of the exhaust itself, any weak points will then be subjected to increased temp and will fracture or break earlier. if there is moisture present the wrap will obviously hold this to the exhaust and so if its ferrous it will rot faster.

With regards to titanium reacting with exhaust wrap - cant personally see this but don't know for sure.

[MexicanGringo]

As fuel is burnt the expanding gas does work to cylce the engine, heat is inevitably transferred to the metal frameworks surrounding that pressurised system.

Unburnt fuel has a certain potential energy, and the combustion cycle is only as efficient as how much of that potential performs work as opposed to how much of that potential is lost through other forms of energy flow. Heat is a loss of that potential to perform mechanical work,and should be contained to the maximum the metals can withstand.

By insulating the exhaust system to some extent, heat is contained in the expanding gasses,slowing this expansion and raising the gas flow velocity. The gas should then exit the exhaust quicker and increase performance, but this increased pipe pressure can also limit performance if it hasnt dropped sufficiently by the time the next combustion cycle arrives.

Id say the motogp guys have done a few tests and if this works which it obviously does, it needs to be in conjunction with the right pipe sizes, port shape and port size

[mick.mh2racing]

Doubt if you'd notice any difference, the power gain would probably be less than an HRC sticker.

[Cammo]

Doubt if you'd notice any difference, the power gain would probably be less than an HRC sticker.

I agree!

I have it on my bike to stop the radiator from touching the pipes.

Yes temperature will affect exhaust flow, but any decent exhaust will be optimised at design stage to do away with wrap. Motogp exhausts are a good example, none of them use this.

[alexwitham]

and a £4.49 per 30cm's it aint cheap. !

thanks chaps!

[seanyUKvfr]

This method is also used in car tuning. As it keeps the engine bay cool and thus the air been taken in by the the engine cool = better performance. How ever on a bike i carn't see many benifits on a bike! As the air intake(s) arn't affected by the high temps of the exhaust. How ever if what they say is right you would need to get the gases flowing better every where else too, to see any benifits at all!