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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Intake/exhaust port CFM flow? Porting the heads? Tech babble.
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I'm not sure about three... let's see if we can find part numbers somewhere, FWIW.
All this info was written 50 or more years ago and has more historical than practical value, IMHO.
G.
All this info was written 50 or more years ago and has more historical than practical value, IMHO.
G.
JasonS
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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.
rustystud
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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" .
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WOW! This thread is getting interesting. Many thanks to all of the guys providing info.
Special thanks to rustystud, I was not aware of any different cams for these beasts. I’ll poke around and see if I can find TM 9-2815-210-35 (it is mentioned in the base operator manual). In general I think the difference in the cam lifts are minor, especially with a turbocharged engine. The three degree of timing is of more interest (to me). I’d bet it was to tweak the engine for the addition of the turbo vs. normally aspirated. My experience is mostly with normally aspirated gassers, so I would ask for expertise from someone who’s done development or tweaking like this on turbocharged diesels. For the debate here about valve timing and the effect on different engines, the issue is in the responsiveness and balance. Any badly under-cammed engine will really wake up with a bit more cam. Once the cam and the rest of the system (heads, intake, exhaust, etc.) are brought more into balance the differences will be less pronounced. As an example, you wouldn’t build a super engine and use a lawnmower carb on top. You’d design and manufacture each part of the system to have relatively the same capability so they all work well together. Tweaking or modifying any one part will not likely gain much without careful consideration of the system as a whole.
If you want to measure the cams, you can CAREFULLY use a good set of calipers and measure the base circle by going normal to the tip of the lobe (lowest measurement) and then across the base circle to tip of the lobe (highest measurement). The difference will give you the lift without the rocker ratio. You may also notice a slope between the fore and aft ends of the cam lobes as they generally design them to make the valve lifter roll as it turns. You could also use a pair of v-blocks & dial indicator to get the lift.
On the valve spring height setting being different between the “tractor” and “military.” I would caution against an anecdote with one of so engines. The multifuel design went through a number of changes, manufacturer, etc. I wonder if Oliver, White, etc. took the design as-is or if they wanted to make any changes of their own. I’ve been intrigued for some time about the RPM limit changes with some of the LDS engines and how they came to that. I would imagine that they would have wanted to increase spring force a bit to control valve float. RPM’s up to 2800 are high in general for a diesel and I bet they had something in mind with making the increase from 2600 RPM. I would imagine the slightly larger 4 series turbos would breathe a bit better than the 3 inch series turbos. Many folks have reported the 3 inch turbo on LDS engines though.
I’m not convinced from JasonS & patracy (**** they finds some neat stuff!) pic that the pistons are different between the tractor and military versions. Why in the world would you license a design and make goofy changes with no benefit? I think the angle and resolution of the pic makes it impossible to make such a conclusion. I would call attention to the INDEXING of the injector spray pattern, i.e. the one and two hole injector tips and the angle of the injector hole in the head likely lines up to spray fuel right into that swirl relief feeding into the main bowl. I’d like to see a 3D model of the whole thing… In another thread on the injectors I mention my youtube video with the two hole injector spray pattern. Interesting stuff if you haven’t seen it. FYI, increasing or decreasing POP pressures is a cinch if you have an experienced injector guy like at Diesel Injection Service in Portland Oregon. I find that it seems the majority of the multifuels were upgraded or retrofitted with the two hole injectors.
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.
Anyway, my take is to enjoy my truck, tweak her while keeping EGT’s in line, get basic mechanics in line for safety and reliability (she was rebuilt over 20 years ago = aging and failing seals), avoid low speed vibration per TM, get the muffler installed, and run it till it pops.
I think all of these discussions are a waste if the truck isn’t properly maintained. I disassembled my front axle to find one failed wheel cylinder on drivers side (brake fluid was sprayed all over) and a seized wheel cylinder on the other side. The outer bearings were badly damaged from debris too. I redid the rears over the Summer and they weren’t any better off. This leads me to think some of these trucks have been badly neglected and need attention. Man, I want 100% properly functioning brakes! My 2 cents.
Special thanks to rustystud, I was not aware of any different cams for these beasts. I’ll poke around and see if I can find TM 9-2815-210-35 (it is mentioned in the base operator manual). In general I think the difference in the cam lifts are minor, especially with a turbocharged engine. The three degree of timing is of more interest (to me). I’d bet it was to tweak the engine for the addition of the turbo vs. normally aspirated. My experience is mostly with normally aspirated gassers, so I would ask for expertise from someone who’s done development or tweaking like this on turbocharged diesels. For the debate here about valve timing and the effect on different engines, the issue is in the responsiveness and balance. Any badly under-cammed engine will really wake up with a bit more cam. Once the cam and the rest of the system (heads, intake, exhaust, etc.) are brought more into balance the differences will be less pronounced. As an example, you wouldn’t build a super engine and use a lawnmower carb on top. You’d design and manufacture each part of the system to have relatively the same capability so they all work well together. Tweaking or modifying any one part will not likely gain much without careful consideration of the system as a whole.
If you want to measure the cams, you can CAREFULLY use a good set of calipers and measure the base circle by going normal to the tip of the lobe (lowest measurement) and then across the base circle to tip of the lobe (highest measurement). The difference will give you the lift without the rocker ratio. You may also notice a slope between the fore and aft ends of the cam lobes as they generally design them to make the valve lifter roll as it turns. You could also use a pair of v-blocks & dial indicator to get the lift.
On the valve spring height setting being different between the “tractor” and “military.” I would caution against an anecdote with one of so engines. The multifuel design went through a number of changes, manufacturer, etc. I wonder if Oliver, White, etc. took the design as-is or if they wanted to make any changes of their own. I’ve been intrigued for some time about the RPM limit changes with some of the LDS engines and how they came to that. I would imagine that they would have wanted to increase spring force a bit to control valve float. RPM’s up to 2800 are high in general for a diesel and I bet they had something in mind with making the increase from 2600 RPM. I would imagine the slightly larger 4 series turbos would breathe a bit better than the 3 inch series turbos. Many folks have reported the 3 inch turbo on LDS engines though.
I’m not convinced from JasonS & patracy (**** they finds some neat stuff!) pic that the pistons are different between the tractor and military versions. Why in the world would you license a design and make goofy changes with no benefit? I think the angle and resolution of the pic makes it impossible to make such a conclusion. I would call attention to the INDEXING of the injector spray pattern, i.e. the one and two hole injector tips and the angle of the injector hole in the head likely lines up to spray fuel right into that swirl relief feeding into the main bowl. I’d like to see a 3D model of the whole thing… In another thread on the injectors I mention my youtube video with the two hole injector spray pattern. Interesting stuff if you haven’t seen it. FYI, increasing or decreasing POP pressures is a cinch if you have an experienced injector guy like at Diesel Injection Service in Portland Oregon. I find that it seems the majority of the multifuels were upgraded or retrofitted with the two hole injectors.
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.
Anyway, my take is to enjoy my truck, tweak her while keeping EGT’s in line, get basic mechanics in line for safety and reliability (she was rebuilt over 20 years ago = aging and failing seals), avoid low speed vibration per TM, get the muffler installed, and run it till it pops.
I think all of these discussions are a waste if the truck isn’t properly maintained. I disassembled my front axle to find one failed wheel cylinder on drivers side (brake fluid was sprayed all over) and a seized wheel cylinder on the other side. The outer bearings were badly damaged from debris too. I redid the rears over the Summer and they weren’t any better off. This leads me to think some of these trucks have been badly neglected and need attention. Man, I want 100% properly functioning brakes! My 2 cents.
SP5
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Excellent post Brian. The old-fashioned quench area/volume/shape of the engine does'nt really lend it self to the efficient use of fuel, to make horsepower, as you quickly run out of the ability to remove excess heat. In this respect, it's kind like a Flathead Ford, only with over head valves.
One of the real sucess stories of the modern high speed diesel, is the shape of the cumbustion chambers, in such a way as to transfer more excess heat into the heads, and less into the pistons, and keep the EGT temps down.
However, there is an old SS thread from ~8 years ago, where lots of power was made from these engines,,but only for a very short time, to pull a sled, in a tractor pull.
http://www.steelsoldiers.com/showthread.php?6731-Pulling-tractor-with-a-deuce-engine
One of the real sucess stories of the modern high speed diesel, is the shape of the cumbustion chambers, in such a way as to transfer more excess heat into the heads, and less into the pistons, and keep the EGT temps down.
However, there is an old SS thread from ~8 years ago, where lots of power was made from these engines,,but only for a very short time, to pull a sled, in a tractor pull.
http://www.steelsoldiers.com/showthread.php?6731-Pulling-tractor-with-a-deuce-engine
rustystud
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View attachment Scan0007.pdfView attachment Scan0008.pdfBrianp I agree with your assessment about the engine. There is one thing I would like to bring up, most all modern diesels have 4 valve cylinders now. So I believe the potential of this engine has not been reached regarding air intake and exhaust. That being said, I have posted some more pages showing the proper spray pattern of the injectors and some rebuild info on the 2 types of injectors. One of your answers Brian is that all injectors where to be replaced with the two hole style on rebuild. Also here are the two styles of pistons used, the 20:1 and the 22:1 compression. As far as finding the TM 9-2815-210-35 keep looking. I went to craigslist nationwide , found a guy in Indiana selling off his deceased father's collection. I live in Washington State. So broaden your horizons !
Last edited:
rustystud
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Blasted! I just spent over 1 hour uploading 10 pages and the only thing I see is two ! Sorry Brianp , I'll try again tomorrow. There is two styles of injectors and I posted how they where to be rebuilt. I also had the rebuild info on the Three Finger Clutch assembly. The LDS engines had quite a few differences from the LDT.
rustystud
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View attachment Scan0009.pdfView attachment Scan0010.pdfView attachment Scan0011.pdfView attachment Scan0012.pdfView attachment Scan0013.pdfWow ! This took over an hour to scan and upload these 5 pages. I wish I had faster internet service. In interesting side note I found in the TM while waiting. The multifuel engine is allowed to consume 1 liter of oil an hour at 2600 rpm. I thought it was interesting.
JasonS
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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.
However, I looked into Taylor's book for another view: "...unless maximum pressures are allowed to be high, increasing the compression ratio in a Diesel engine (14 to 20) gives only a small improvement in efficiency. On the other hand, the higher the compression ratio, the higher the engine friction, leakage, and torque required for starting. Thus, diesel-engine designers use the lowest compression ratio consistent with satisfactory starting and operation with the available fuel." Looks like Haddad should have referenced Taylor as it was nearly word for word. It is not clear if Taylor is indicating that thermal efficiency is improved with increased efficiency but mechanical losses eat up more than is gained so lower compression ratios should be used OR the overall efficiency is increased but there are also increased losses. I argue that this is not clear because if high compression ratios advanced fuel efficiency, the OEMs would have done so but the actual trend is downward. The efficiency of the high compression LDT/S465 is actually quite poor. I think that you are mistaking the cold start requirement as the reason for the mulutfuel's high compression ratio. The textbooks are quite clear that this compression ratio is done to enable multifuel capability. There is no mention of this being done for any other reason in any engine texts. There have been several multifuel diesels developed; all utilized high compression ratio. Easy starting is a side effect (maybe poor efficiency, too).
rustystud
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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. The reason the LDS engine went from the 20:1 pistons to the 22:1 was to enhance the multifuel ability I believe.
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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.
rustystud
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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.
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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.
rustystud
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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.
JasonS
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While looking for something else, I found some additional information in "Diesel and High Compression Gas Engines" by Kates and Luck 3rd Ed:
"...Therefore, the improved efficiency obtained with higher compression is not due to the compression itself, but due to the fact that higher compression results in more expansion, which in turn converts more of the thermal energy of the combustion products into mechanical work... ...the gain in thermal efficiency is quite rapid at first, but note that the rate of gain falls off as the compression ratio becomes higher. This is one important reason why it does not pay to use excessively high compression ratios."
The data to which the book refers is below and is for an ideal diesel engine neglecting frictional losses. The question of what happens to overall engine efficiency vs CR when these losses are included is not addressed in the book.
Compression Ratio % Thermal Eff
3 34.3
4 41.0
6 48.9
8 53.5
10 56.9
12 59.4
14 61.2
16 62.8
18 63.9
"...Therefore, the improved efficiency obtained with higher compression is not due to the compression itself, but due to the fact that higher compression results in more expansion, which in turn converts more of the thermal energy of the combustion products into mechanical work... ...the gain in thermal efficiency is quite rapid at first, but note that the rate of gain falls off as the compression ratio becomes higher. This is one important reason why it does not pay to use excessively high compression ratios."
The data to which the book refers is below and is for an ideal diesel engine neglecting frictional losses. The question of what happens to overall engine efficiency vs CR when these losses are included is not addressed in the book.
Compression Ratio % Thermal Eff
3 34.3
4 41.0
6 48.9
8 53.5
10 56.9
12 59.4
14 61.2
16 62.8
18 63.9
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...........and they dropped it right there
and I was just getting interested
and I was just getting interested
rustystud
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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.
gimpyrobb
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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!
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!
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Yes. A 2 stroke detroit with just a roots blower was actually considered naturally aspirated. The turbo was a power enhancer.