Hmm lots of numbers to be crunched. Get the heat away from the turbo, increase velocity into the turbo, but NOT heat. I always thought that the outer shell of the turbo would benefit from a heat sink. A good synthetic oil will take care of the turbo bearings.

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ConnClark,
You know, I've already spent too much time trying to explain this to you. I'm just not that interested in debating undergraduate thermodynamics and you are not listening. I understand exactly what you are trying to say, and it is incorrect. Repeating it over and over will not change the laws of thermodynamics. You seem to have a fundamental misunderstanding of this cycle. Apparently I haven't done a very good of of explaining it, so I'm going to give up. I just don't want others on the forum to read misinformation. Good luck.

I have the undergrad thermo down. You want a post doctorate analysys. I have posted pure theoretical results showing a trend. You have posted nothing as far as calculations to show otherwise. I gave the website that has the software to do the calculations with and its not that hard to learn. Feel free to come up with a more accurate model that shows otherwise. I will revise my model more when I have time.

The only thing that will realy solve this is a dyno test. Mabey someone with access to one of these can help settle it once and for all.

Craig, I applaud your efforts.

Conn, You can tweak your wastegate to infinity and beyond, but it aint getting no faster without more fuel.

That's not speculation. I've repaired my share of M/B waste gate hoses and test driven them all before and after. They are not one damn bit faster when making as much boost as the turbo is capable of.

going to pretend that i follow all that formula. but it sounds like craig is on the right track in questioning your inputs for heat values and other basic stuff.

i have done a lot of other types of formulas and i know if the inputs are wrong the outcomes will be too.

you know, "junk in........

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.

I have tried to get things as accurate as possible. I have used the bore and stroke of the OM617 engine. I have the same compression ratio and combustion chamber size. The only thing the model is missing is thermal mass and effects of the cooling system. I will work on the duel cycle model tonight but I need to do some calculations for the volume of the cylinder 15 degrees before TDC. This software is supposed to be able to do combustion so I hope to have that figured out some time.

Also Gas temperatures do not equal metal temperatures.

i was driving back from mich and thought about this thread.

i guess i am thinking of changing sides, sort of.

if you wrapped the exh manifold (theoreticaly, as i think as a practical matter it isnt very feasible on a 300d), that would increase the heat in the exhaust gasses which in turn increases the energy delivered to spin the compressor side of the turbo. now the turbo pushes more air into the engine. the alda valve senses more boost and increases fuel to the engine. and hence more power... until the upper limits are reached by the fuel injection system. so i guess i am proposing that power will be increased in any condition less than full power applications. or in other words at take off and acceleration but not at full power constant speed situations.

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.

I don't think you've changed sides, Tom. We all agreed that more boost with more fuel would provide additional power. Also, insulation on the exhaust piping upstream of the turbo could reduce energy losses and provide a (very small) increase in turbo performance.

The most recent question was whether increasing the boost without providing any additional fuel would do anything to increase power. My point was that the additional boost only provides additional O2 to the engine for combustion. If you do not provide additional fuel to combust with the O2, the power will remain the same, or possibly decrease due to the increased back-pressure and reduced combustion temperatures. This whole discussion is a little silly because we are talking about negligible affects anyway.

I am beginning to think that, in a theoretical sense, there may be some increase in power with increased boost and no additional fuel. However, any such theoretical increase would be tiny, indeed.
In the real world, you know the one outside of Mercedesshop.com, where we actually drive these diesels, there is no power gain withour additinal fuel.

There is a world outside of Mercedesshop.com?

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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Wow looks like this thread is still going Seems like the same old same old.

The hardest concept to grasp with a turbine engine is that mass flow and turbine designe are the key components. Heat is a byproduct. A turbine is not a heat recycler(that would be a sterling cycle engine). I'm not going to waste my time reading the thread... Looks like it is still the same issues.

Interesting design in the cdi engines is a variable turbine. While this would seem to be less reliable it should allow the turbines to be feathered to the appropriate angles to work at lower level of mass flow and get boost at slower rpms.

Sure a loss of heat will cause a kinetic energy loss in the exhaust. I'm just not buying it is the dominant or significant factor. I think the system will balance out. I also think a cooler turbo will enable it to push more air into the cylinder which means there will be more mass based energy in the exhaust in addition to more heat. Now obviously this will balance out as well. I have never seen a complex diesel cycle diagram with a turbo factored in. It should be a facinating graph.

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Using varying levels of energy added to the ideal diesel cycle I get anywhere from 2.9% more power at the low end to 10.2% more power at the high end. Actual gains might only be 1/4 th of this. On the low end it may not be noticible but on the high end it might.

Conn

What is the heat loss assumption in this equation? If you are really concerned that a hotter engine will be more efficient run a thermostat on the high end of manufacturer spec. The liquid coolant will cause much greater heat loss then the air going over the exhaust header and pipes. Now if there is a major leak in the exhaust manifold or pipe plugging that would make a significant difference to the turbo.

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

The heat loss is asummed to be zero for an ideal diesel cycle. However I will still maintain it will end up with a net gain in the real world.

I agree that a hotter thermostat will make it more efficient, but thermostat temps have a greater effect on engine longevity than boost maps.

I thought of an additional benifit of wrapping the exhaust manifold and oxidizer trap. It keep the damn oxidizer trap hotter and help keep it from plugging up.

Conn