Any benefit to keeping the turbo hot?

[MarkR]

.....i wonder if anyone with EGT sensor in the turbo housing has done a comparison test, with and without a jacket?

 

I'll do it once I finish my single project, but it'll only be in the new year...

[Alex]

Yes, I get that. My point is that the heat has already escaped from the gas if the turbo/manifold/downpipe is hot, so heat wrapping traps the heat in the metal, not in the gas.

 

House insulation keeps the house warmer, not just the walls.

[Digsy]

Yes, if you keep the metal hot then there will be less heat rejection from the gas to the metal.

 

Turbine inlet gas temps of up to 1000degC are beneficial in getting engery into the turbo. Anything higher than that and you'll start to cook things.

[Ark]

House insulation keeps the house warmer, not just the walls.

 

And where is the insulation? It's not plastered to the outside, like we're talking about by wrapping a manifold. It's always as close to the inside as possible, given cosmetic considerations. The idea being to keep the heat away from the walls, where it's wasted.

 

Following on from Digsy's point, why can't the inside faces of a manifold be ceramic coated to improve heat rejection before it gets into the metal where we don't want it?

[Digsy]

Following on from Digsy's point, why can't the inside faces of a manifold be ceramic coated to improve heat rejection before it gets into the metal where we don't want it?

 

Probably because it would eventually come off and go through the turbine

[dandan]

An unwrapped housing/manifold will increase the heat drawn out of the gases themselves compared to a wrapped one.

 

The wrap/blanket is not there just to reduce heat lost from the metal......it will (as a result) also reduce heat transferred to the metal from the gases.

 

The amount of heat shed from the gases will (amongst many other things) be affected by exterior insulation - that is a fact. Go check out some heat transfer theory if need be, I think even GCSE level covers it but if not some real basic A level physics will. As Digsy rightly said - the hotter the housing is kept, the less heat will be drawn from the gases with all else being equal.

 

I am not advocating or condemning the wrapping/blanket process...I just want to point out a few misconceptions about heat transfer that have been banded about.

[MarkR]

An unwrapped housing/manifold will increase the heat drawn out of the gases themselves compared to a wrapped one.

 

The wrap/blanket is not there just to reduce heat lost from the metal......it will (as a result) also reduce heat transferred to the metal from the gases.

 

The amount of heat shed from the gases will (amongst many other things) be affected by exterior insulation - that is a fact. Go check out some heat transfer theory if need be, I think even GCSE level covers it but if not some real basic A level physics will. As Digsy rightly said - the hotter the housing is kept, the less heat will be drawn from the gases with all else being equal.

 

I am not advocating or condemning the wrapping/blanket process...I just want to point out a few misconceptions about heat transfer that have been banded about.

 

Thanks for the info. I think I'll heat coat the manifold, DP and turbo housing, and use my blanket to keep the remaining heat from boiling my brake fluid.

[SimonB]

...But it only has to last one race, not months/years of daily use.

 

Have you ever seen the Le Mans 24hr race? It's 24 hours of pretty much continuous flat out racing. They do the same milage as an entire season of F1 racing. That's over 3000miles. Which must be the equivalent of 10 times that distance of normal driving at the very least.

[harley-jm]

I wouldnt wrap mild steel pipework as the wrapping apparently holds moisture and will rot the exhaust.

I had some headers in mild steel and wanted to change the wrapping already on them but when I took the wrapping off the exhaust crumbled in my hands. From where the wrapping ended the exhaust was fine! Does very significantly reduce underhood and surrounding temperature though.

[Terminator]

A great discussion.

 

I know Jamie's question has been answered, but I wanted to clarify my thinking. As I see it a turbo blanket rarely can cover the entire hot side. When a turbo blanket is removed it is clear to see where is in contact with the housing and where it is not. So the housing is not at a uniform temperature. At the gas speed and temperatures involved I am not sure if an uneven housing temperature will cause addition drag inside the housing. Take the analogy of a ported head, it is well known that a slightly roughened surface enables better gas flow into the head than a polished surface. If uneven temperature do alter gas flow then it would be beneficial to achieve a more uniform temperature. If this were the case then perhaps an insulating cartridge with an air gap between the insulated interior and the housing might eliminate uneven temperatures.

 

To develop a high power single turbo car cost £K's, we spend a lot money on carefully cooling the charge, heat wrapping where we can, ensuring gases can get in and out of the turbo as quickly as possible, and use the best components we can afford. It just seems odd that we leave it a bit to chance with insulation of the turbine housing by just dropping on a fibre blanket. It just seems a little amateurish.

Edited September 26, 2008 by Terminator (see edit history)

[little num]

Thought id start this thread back up again to see what peoples thoughts are since 2008.

As ive just started my single for the first time and felt how hot the turbo got when i accidently put my thumb onit after running for 5 mins lol, now i have no skin on my thunb and its very sore.

What do people reccomend use a blanket or not, i have wrapped the manifold and will insulate around things that will see heat anyway and do my best to keep the engine bay temps low.

Edited April 22, 2012 by little num (see edit history)

[Wez]

Ever since going single I have always used a turbo blanket.

[mark newman]

Thought id start this thread back up again to see what peoples thoughts are since 2008.

As ive just started my single for the first time and felt how hot the turbo got when i accidently put my thumb onit after running for 5 mins lol, now i have no skin on my thunb and its very sore.

What do people reccomend use a blanket or not, i have wrapped the manifold and will insulate around things that will see heat anyway and do my best to keep the engine bay temps low.

 

mybe you should wrap your thumb.

[little num]

mybe you should wrap your thumb.

 

Lol thats funny, i tell you what i only touched it for a split second and it was gone.

Tried to feel where my V band was blowing.

[Chris Wilson]

I would only put a turbo blanket on a turbo I knew to have a Ni-Resist turbine housing. If the housing is flaking (scaling) externally it's not Ni-Resist (high nickel content cast iron) and wrapping it will make this even worse. If it's scaling on the outside it's scaling on the inside, too, which will eventually damage the turbine wheel due to erosion. Wrapping tubular turbo manifolds, especially cheap ones with no slip joints or bellows in them, promotes cracking. Heat shields are the way to go on cheap installations. Wrapping proper manifolds and turbine housings may give a tiny bit better efficiency, but whether it's noticeable.... ??? A decent ceramic thermal coating works well, but is costly.

[imi]

Ever since going single I have always used a turbo blanket.

 

likewise. coming upto 40K miles without any issues.