Advantages of Turbo Blanket for Large Diesel Engines?

[neoneddy]

Starting a new thread related to sizing of a turbo blanket earlier.  It lead me to ask "the Google" some questions but I had trouble finding much scientific data on the matter, mostly anecdotal experiences from truckers.

Edit: Found the paper referenced in the video, it's from a 6.5L cummins Diesel.
https://repositories.lib.utexas.edu/handle/2152/43718   
Direct Link https://repositories.lib.utexas.edu/bitstream/handle/2152/43718/BICKLE-MASTERSREPORT-2016.pdf?sequence=1&isAllowed=y

I did find this video on the topic using a smaller engine as the test bed. https://www.youtube.com/watch?v=FrFeaNGDnOk  I'm wondering if the findings would hold true on larger engine.

In short, they found heat stayed where it should be, that seems intuitive, but they also found 2-3 more PSI at most RPM ranges which lead to more torque sooner, something I think we all care about very much.   Now it appears it does not increase overall numbers, it just shifts where the torque bands starts. 

Edit: I listened closer and from the paper i says during spool up it has the affect of an additional liter of displacement!.. wow.  Look around page 21 for the nice charts and graphs.

I had not even considered a blanket, but now I'm thinking a few C Notes is cheap insurance on this. 

Last Edit: Adding some graphs from the paper

[oltrunt]

Most interesting article.  Thanks for posting it.  Jack

[buswarrior]

If I was considering wrapping the exhaust on my big turbo charged engine...

Fire suppression would be my motivator, any performance improvements would be a bonus.

They burn down when some line bursts, and sprays an oil or fuel around, and it gets onto the hot exhaust, directly or by the fan blowing it there.

Burning Buses became far more common, with the arrival of turbos and their heat...

Either motivation, it is good to wrap your exhaust if there's a turbo in there.

Happy coaching!
Buswarrior

[neoneddy]

I did not know that, but it makes sense.  Fire has been a concern of mine, I love this board, the more ya know.

[oltrunt]

I can't rest asking.  Why, physically speaking, does increasing the interior temp of the blanketed turbo make it spin faster?  Could it have something to do with the fluidity of hot air???  Any physicists out there?  Jack

[neoneddy]

@oltrunt In the study and in the video they mentioned it being about keeping heat in the hot side of the exhaust system, heat increases pressure, more pressure spins the turbo faster.  I think it's that simple.  If I'm honest, intuitively this don't seem like it would be as evident as they show it, but you can't argue with the data.   

Found this little calculator from deflate-gate http://physics.bu.edu/~schmaltz/deflate.html The principal is the same.

The temp numbers I'm using are just even round numbers to show an example.

I put in 400F as an initial temperature, then a final temperature of 450 (simulating adding a Turbo Blanket and wrapping headers).  Initial pressure I set to 14.5 (1 bar) , the final pressure was 16.20 .  Seems the math checks out, that's an extra 2 PSI spinning the turbo, to suck in just a little more air.

[luvrbus]

Just covering the hot housing with the cover dosen't make any difference on the 2 stroke you need the complete that covers the manifolds,pipes and the housing and they are pricey I paid 2000 bucks for my set on 8v92 in 2000 lol I don't think I gained much for the bucks spent in the way of performance,but they did keep the bed room floor cooler

[chessie4905]

Wrapping the exhaust increases the draft like an overheated chimney. I did this a few years back on a 6.2 diesel that I installed a Banks turbo kit on it. It was designed to max boost between 9 and 11 psi. I  match ported and polished the heads, did same to turbo. Wrapped exhaust with that woven fiberglass wrap from turbo to muffler using 3 1/2 inch pipe. Used Flowmastermuffler with 4 inch outlet. It then started producing 18 pounds boost when wound up. Called Banks and explained all I did. He said no wonder boost went so high. He said I would need to install a wastegate. I did and set it to 13lbs max. Btw, the truck was pretty powerful for what it was.
Even wrapping the exhaust on a non turbo engine will result in some power boost. Two things to keep in mind. One is the wrapping can retain road salt in winter and hasten pipe rust through. Second is the wrapping can absorb dripping oil and fuel and keep a potential fire going if it gets hot enough to ignite.

[luvrbus]

2 strokes don't generate the EGT that a 4 stroke will blankets are more for safety on a 2 stroke,my 6.5 turbo the brother to a 6.2 will get up to a 1000F under a load 

[lostagain]

You would get more benefit from reduced heat in the engine compartment and the bedroom above than an increase in power. 1 or 2 psi of additional boost will not make a noticeable difference with a big old 2 stroke.

JC

[bevans6]

My recent investigation into military 8V-71T's found a version that was 440 hp, with completely insulated manifolds, turbo and exhaust ports (inside the head).  Point was to maximize heat at the turbo for more power, it also had a bypassed blower with a big bypass.  What really works well is to take a brand new manifold and piping (you can blast a cast iron manifold) and ceramic coat it inside and out.  We did this on race engines where we didn't want to wrap, and it did a significant job of keeping the heat in.  So did stainless steel headers.

[luvrbus]

Somebody explain to me how you can get so much HP from a marine 8v71T with water cooled manifolds to take the heat out instead of keeping it in ?

[Jim Blackwood]

Can't help with that but I do know the Ideal gas law shows that volume, temperature and pressure are direct multipliers of each other. Meaning, double the temperature and you double the volume or else you double the pressure. Meaning with the blanket you get more gas blowing through at higher pressure. How much depends on how much heat you keep in there.

Jim

[DoubleEagle]

The marine versions can afford to have bigger injectors and more boost because they have greater cooling capacity. The same level of power in a bus would require multiple large radiators to prevent overheating. Wrapping the exhaust retains the heat to increase the gas flow efficiency to spin the turbo a little faster. The ultimate engine would be a military/marine engine setup with multiple turbos. Brian had dug into military specs to help me out when I was considering a military 8V71T. One of the sources indicated that one of the reasons they wrapped everything when the engines were installed in Howitzer Carriers, was to increase the exhaust flow to the outside air to reduce the cooling requirements (a little). That may have been an experiment to be able to boost the power of the engine in a confined space. It probably helped a little, just like the flow of fuel through the injectors to the tank, but then, the military has the big bucks to do things like that. 

[luvrbus]

The marine versions can afford to have bigger injectors and more boost because they have greater cooling capacity. The same level of power in a bus would require multiple large radiators to prevent overheating. Wrapping the exhaust retains the heat to increase the gas flow efficiency to spin the turbo a little faster. The ultimate engine would be a military/marine engine setup with multiple turbos. Brian had dug into military specs to help me out when I was considering a military 8V71T. One of the sources indicated that one of the reasons they wrapped everything when the engines were installed in Howitzer Carriers, was to increase the exhaust flow to the outside air to reduce the cooling requirements (a little). That may have been an experiment to be able to boost the power of the engine in a confined space. It probably helped a little, just like the flow of fuel through the injectors to the tank, but then, the military has the big bucks to do things like that. 

LOL some of the things the military experiment with on the 2 strokes made absolutely no rhyme or reason.Walter those marine engine have almost the same PSI of boost as the highway engines