Turbo blanket/Wrap recommendations

[Rawze]

(09-10-2018 )imalumberjack Wrote:  Thought I would weigh in on this subject, my reply will have nothing to do with an ISX engine or any other diesel engine, it has to do with a theory by Smokey Yunick who was a very famous race car engine builder. His theory was that super heated exhaust traveled faster. What he would do is use an asbestos wrap to wrap the first 4-5 feet of an exhaust manifold in order to move the exhaust out quicker, I just read an article the other day that upheld Smokey's theory. I have wrapped a Cat engine several times based on Smokey's theory that I learned 40 years ago .....I could not give you any performance figures or even say that I know it works ...I felt that it did as I will do almost anything for a few more ponies. I never wrapped a turbo tho.

As air cools, it becomes more dense. When it leaves the exhaust manifold at 800, 900, maybe even more than 1,000 degrees F, it passes through the exhaust system. The exhaust system absorbs a portion this heat and reduces the temperature, increasing gas density. As its density increases, it starts to act like a pillow, causing resistance to the exhaust flow as it cools. This slows down its overall flow, slowing down the flow escaping the engine cylinders by some measure too.

Wrapping the exhaust piping reduces the heat absorption, therefore reducing the restriction in flow. There are gains for doing this in a diesel engine, as anything whatsoever that reduces exhaust gas pressure escaping the engine directly serves to increase its efficiency. The turbocharger in the exhaust stream however absorbs a LOT of heat before the exhaust gases even reach the exhaust piping. Wrapping the turbo, and possibly the manifold makes sense in this manner, however, wrapping them also can cause the turbo to operate much hotter.

The turbo itself absorbs a large amount of heat + adds high amounts of back-pressure to the escaping gases of the cylinders. Wrapping the manifold itself has very little effect on a turbocharged diesel engine though. This is due to the bulk of the restriction being not heat absorption or flow restriction related, but by turbo itself as it makes boost pressure for the intake.

Some turbochargers have thermal limits and must be kept under a certain temperature range so that it lives a long lifespan. Also as a turbocharger gets hotter, it transfers a portion of its heat through into the face where it expands intake air. This can be cuter-productive to some measure depending on turbo designs.

All that aside,... Wrapping the exhaust manifold, putting a sock on the turbo, and wrapping the exhaust piping makes for a much better temperature in the cab of the truck. A pyro gauge senor onto the turbochargers metal housing or manifold near it (underneath the wrap too) would not be a bad thing to monitor if someone does this though.