Wrapping the exhaust and turbo like the Wadeperformance kit won't hurt anything. It will keep more heat in the exhaust stream and this will help keep exhaust gas velocity up. Wrapping the exhaust turbine section of the turbo won't increase temps on the intake side. Wrapping will likely decrease turbo lag. I have done this on a truck. It works. Kalifornia turbo cars have an ARV, or air recirculation valve (at least the 84's do) This valve allows some of the boost to escape back to the intake side of the turbo under part throttle cruise situations. I am guessing it worked simultaneously with the EGR system. It is easy to remove the spring diaphram section of the ARV and drop in a 5/16" nut under the spring to preload the ARV closed. Disconnect or plug the ARV vacuum line to totally disable it. Now the turbo works just like a non-EGR, non ARV turbodiesel. Boost is much more immediate and satisfying. With the ARV functional "matting" the accelerator on the highway was very dissatisfying. It takes a while for the ARV/EGR system to shut down and boost to build. With it all disabled the boost is instant. Try it, you'll like it. RT

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Here's an interesting link...http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4593012389

I would not wrap a street car/truck headers due to shortened life.
The benifits of wrap are so small as to be equivelent of removing the STAR from the hood to go faster !

It cooks the carbon out and causes the mild steel to loose it's strength.

It would be better to do what most japanese manufacturers do with the down pipe/s.....use a loose fit stainless or aluminium cladding. This is primarily to reduce radiated heat.

Wrap a set of RV headers and your maybe get one season out of them.


.

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the truck the turbo is a lot further from the intake (v8 right?), so the benefit would be greater. on the benz the plumbing is all right there and being cast iron it would be more likely to warp from excess heat.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

After reviewing my Thermodynamics book, I can say that wraping the exhaust manifold and cat will help. As far as the turbo goes, efficiency will improve because the reduction in heat loss before the turbine will have the same effect as burning more fuel. Diesels will always improve efficiency and power with more boost using the same amount of fuel. Yes adding more fuel will boost the power more, but as I stated before fuel cost money.

The system can be viewed as a compound Brayton cycle with a very poor (lossy) regeneration cycle feeding back between the compressor stages flowing from between the two turbine sections. The header wrap will reduce the energy in this lossy feedback system and result in a net gain.

The only issue is if the manifold can be wrapped without it warping or cracking. I may just pull the exhaust manifold off and spray it with ultra high temp white paint and wrap the hell out of the cat ( I don't care what happens to the cat).

By the way, I finally got the new air filter in the car and it help with acceleration a bit.

Conn

One of these days I will take mine off and send them off to be jet hot coated inside and out ....when I have time and extra money burning a hole in my pocket.

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AGAIN, increasing boost, increases backpressure. No way around that. Without more fuel you are wasing energy to pressurize the intake beyond what is required for combustion. Boost is a liability, it COSTS horsepower to generate it. If you are not increasing fuel in relation to it, you are throwing your efficiency out the door. If you are assuming that boost is free b/c it comes from energy in the exhaust you are wrong. If you want more boost from the turbo's compressor then you must get more work from it's turbine. Getting more work from the turbine means having a larger pressure difference across it. More pressure before the turbine AGAIN increases pumping losses and costs efficiency.

If you really want to INCREASE your efficiency have the head and manifolds extrude honed and put a free-er flowing exhaust system on it. That way the engine will have less work to do to get any amount of air into it. That will actually get the efficiency you are looking for. Much more than saving an incremental amount of heat before the turbine.

if increasing boost wo increasing fuel will increase power or effeciency. i suspect it may. but in this case it seems that the heat you are putting into the turbo by wrapping would just otherwise be lost in radiation, so how is that costing anything?

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Well, heat loss upstream of the turbo will result in less enthalpy at the turbo inlet, resulting in less shaft energy to compress the inlet air. However, I doubt the loss is significant. Also, it is not clear that this extra energy would result in any extra boost or engine power without making other changes to increase the amount of fuel being supplied. IMHO, this is probably not worth the trouble.

i was there three or four days ago on this.

but the heat still seems free to me.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

No free lunch in thermodynamics.

Higher temperature = lower density (at the same pressure) = higher specific volume = more volumetric flow through the turbo

Seriously, what is the real difference? Maybe one degree? That doesn't translate to a lot in terms of PSI's from heat expansion. And the stock setup gets and stays pretty hot. It doesn't cool the gasses inside very much as they travel that short distance in that hot pipe. How much hotter should it get?

If more pressure is wanted, why not adjust the wastegate? I just don't see a whole lot of gain there.

I agree, I was just trying to answer Tom's question.

On some of the newer diesel trucks they insulate the pipe from the compressor of the turbo to the intercooler. This is done to keep aerodynamic losses low until it reaches the intercooler. If some engineer can convince detroit to spend money to keep gasses hot before you cool them to overcome a small bit of friction in a short pipe run then I maintain that wraping the exhaust is worth it.

As far as extra boost of turbo increasing back pressure causing a loss of power I will point out that most diesels operate with 20% more air in their combustion chamber than they need for combustion. If this was such a problem then why don't auto makers adjust the waste gate to remove it? Simple, its not a problem. Boost = Power

Conn

Can someone explain to me how/why insulating this pipe reduces "aerodynamic losses"? I'm sure they have some reason for insulating this pipe, but I doubt it has to do with friction losses in the pipe.

Okay, the losses are not frictional. What happens is as the air is compressed it heats up. This hot air flowing through a non insulated pipe cools and contracts. This in turn lowers the velocity. Any time you change the velocity of a gas you have to expend energy to do it. In this case its a slight presure drop. They do it to keep the pressure at its maximum at the inlet of the intercooler.

Conn