rustystud
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Gerhard, did you see on the data sheet that there is 3 cams listed. 2 High profile and 1 normal.
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I think your right Jason. The "IHC" DT466 is looking better everyday. The "Rockwell" differentials will be with us for years. So we're looking at the brake system and engine transmission units. I bought 2 gasket sets today, so as long as nothing major blows I'll be good for awhile. But when it does I'm pulling the plug and going "IHC" .Given the fact that the aftermarket is abandoning this engine (see the head gasket thread), gaskets and other hard parts will become increasingly hard to find. Don't reinvent the wheel. Put your money into something with better engineering, better parts support, more horsepower potential, and higher efficiency.
I interpreted this as increased compression ratio does not improve efficiency: From Haddad "In practice, the higher the compression ratio, the higher will be the engine friction, leakage, and torque for starting. Thus, diesel engine designers use the lowest compression ratio consistent with satisfactory starting and operation with the available fuel." This is also evident in modern diesel engines wherein the compression ratios have moved downward; aided by improved cold start systems.In response to Post #72 “high compression hurts overall efficiency.” This is completely untrue, compression helps efficiency. Pick up an engineering thermodynamics book or other text that details the differences between a mechanical cycle or thermodynamic cycle. Also, compression is static and dynamic. The ratio of displacement to combustion chamber volume is static while when you take other issues into account you’re talking about dynamic compression (includes engine speed and loading, how the system flows, valve timing, forced induction, etc.). Another of the statements “The engine texts say to use the lowest compression ratio that meets the cold start requirements.” is CORRECT! Hence the very high multifuel static compression ratio in part to allow for cold starting. The original design didn’t have a turbo in mind so the addition of boost and create some very high dynamic compression and cylinder pressures. There’s not nearly the proper of attention given to WHEN the compression or cylinder pressure increases. It’s much easier to transmit energy at higher frequencies than it is lower frequencies and shaft HP (or power in any units) is a function of torque at shaft speed. The same torque at a higher speed will give higher HP. To develop high power at low speeds requires massive pressures and these put a huge strain on parts. Ask the gasser guys if it is OK to use nitrous at low engine speeds. No! The crazy high pressures will crush connecting rods, pop head gaskets, etc. on ANY design, no matter how robust. Use it at higher speeds and it usually works fine.
Not exactly. The "supercharger" isn't actually a supercharger. But rather a positive displacement air pump. It wouldn't be able to draw air in due to the port construction of a two stroke. Only the turbos on 2 strokes were added for actual power.I agree with you Jason about the compression and efficiency, that is why I'm sure Detroit Diesels are actually low compression and without there superchargers would not start. But I believe the higher compression reached by the use of Turbochargers gives us more power. You always sacrifice something, there is no free ride.
Can you site one that doesn't have a positive displacement system? Because I'm not able to understand how it could work due to the port design.My point was that the Detroit Diesel engine was a low compression engine and the use of Turbo's helped bring up it's power level. Also other 2 stroke diesels do not have to have a supercharger to be able to run.
I know, since the engine will burn it's own oil. That still has nothing to do about the engines lower then average compression. The Deutz 2 cycle engine does not use a blower as most do not.Can you site one that doesn't have a positive displacement system? Because I'm not able to understand how it could work due to the port design.
Edit, would you happen to know the emergency cut off for a run away detroit? It's not fuel. It's actually a spring loaded door that causes the positive displacement blower to vent air.
It was turning into an argument about superchargers and turbo's. Since the Detroit Diesel did indeed use a "supercharger" (mostly Roots brand ) it was getting pointless to argue anymore............and they dropped it right there
and I was just getting interested
Yes. A 2 stroke detroit with just a roots blower was actually considered naturally aspirated. The turbo was a power enhancer.Ahh but many dont realize that the supercharger wasnt used to boost the cyl pressure, it was needed for the motor to run.
This was explained to me by an old DD tech long ago, and what he said is a little fuzzy, but that is why some have just SC and some have both!