Exhaust wraps

[CitroenFreak]

Since thread71-99579 is closed, I'm opening new one,

What about NA engines? Do they benefit anything having exhaust wrapped?

Cheers

Ziga

 

[MikeHalloran]

Well, in the instance where the crossover pipe is very close to the oil pan, or tucked into the corner between the shallow sump and the slope to the deep sump, the wrap would reduce heat transfer from the pipe to the oil.



Mike Halloran
Pembroke Pines, FL, USA

 

[reidh]

An exhaust wrap can also change the tuning of an engine.

For example:

I was calibrating some equipment on a dyno not too long ago, and running an engine slowly up to full load and back down as a post test. It was obvious on the engine run up that the peak power was higher and occurred at a higher engine speed than when I was reducing the load. When I was reducing the load, it was a flatter curve. The reason was that on the way up the temperatures were cooler, so the exhaust pipes were effectively shortened. On the way down when everything was hot, the pipes were longer. The exhaust wrap will have the same effect in that it can change the effective length of the pipes.

Reidh

 

[patprimmer]

It also changes the temperature of the gas, if ever so slightly which will change the speed of sound and therefore effective tuned length but this really is gnat's whisker sort of magnitude.

Exhaust wrap has been covered extensively in several previous threads. From memory the bench racers were for it, but generally the consensus among the professionals was except for manifolds between head and turbo, or for getting the catalytic converter up to temp quicker, it increases corrosion for no real benefit.

It can help prevent intake charge warming in some cases, but so does wrapping the inlet air duct, and it does not corrode as a result.

It can help reduce heat transfer to other items, but so can a heat shield. The heat shield will not encourage corrosion.

It can help reduce noise ever so slightly.

Basically, except for some very specific problems, it does more harm than good.



Regards

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[Azmio]

i've seen it many times in races. By simply wrapping the exhaust system with heat resistant wrapper, the heat transfer from the exhaust gas to the surrounding is minimized.

This preserves its enthalphy. High energy content of the exhaust gas can simply means that it will flow faster inside the exhaust pipe. With high kinetic energy of the exhaust gas, you can run the engine with higher valve overlap to pull in more air into the cylinder.

 

[evelrod]

Opinions differ, it seems. From my point of view it has been a great help in keeping underhood temps down. On several in line engines I have used it for that reason and on my current race Mini Cooper I use it to keep temps down in the engine compartment, in the cockpit and, to keep exhaust heat away from my inlet manifold. Works just fine. As to the added wear on the steel tubing...perhaps but not in any race application I have encountered. I even wrapped my exhaust system on my T-Coupe back in the 80's and it worked just fine for 200,000 miles...What more can I say?

Rod