LDS VS LDT and the real differences

[Flyingvan911]

I have a pyro on my LDS. I just installed it a while back. I will try to get some numbers this weekend. Speed, rpm, boost and egt.

 

[randini]

I have seen people comment that a "Turbo does not increase power, it was done for emissions only". Is it possible that a turbo could NOT increase power? Not relivant to a LDT/LDS conversation, but it doesnt make much sense to me.

 

[hornetfan]

The pump TM lists different part numbers but identifies no differences for the HH. It is not considered a serviceable component and is to be replaced as a unit. This is due to the lapped fit of the piston. With the exception of an older model that has an extra oil passage and that can be plugged. Hornet you may be onto something, just not sure what, if the head makes pressure and has flow capability, what else is there?
The head does not set the timing, it is just the distributor and the high pressure pump.

Yes, 'just the distributor and high pressure pump" -- but what determines WHEN an injector squirts? When the pressure exceeds the injector pressure rating, right? Depending on the specifics of how the pump is designed that can be varied pump-to-pump. We used to hand grind new 'cam plates" (yah, I know it is more a "throttle plate" but bear with me a sec -- hold yer hp lol) for Bosch inline pumps for early FI petrol/methanol engines and the shape of the 'cam' (don't remember what Bosch called em now darn it) made a HIGE difference whether rich-lean. And THAT gents is EXACTLY what we've been trying to chase down -- when the LDS becomes 'rich' for fuel vs the LDT.

Both engines CAN provide enough air at low rpms but the LDT will burn pistons easily when making "the black smoke" which is HP. I'll wager that the LDS can be turned up more for fuel without having EGT problems (not enough air and/or exhaust restricted -- don't forget the exhaust) compared to the LDT. I've not seen anybody with a seriously turned up LDS but the LDS-2 sounds like such an engine and it REQUIRED other mods to keep up with the 200hp levels of the 8x8 trucks' engines. Such as better oil circ for cooling and narrowed oil clearances on the crank and (prolly) cam bearings -- all indicators of more oil press because otherwise you can't build sufficient pressure -- the excess oil just drains past the journals without going where intended. This does NOT affect journal bearing capacity with regard to crankshaft pressure s due to combustion -- that's is all determined by bearing size because these are "hydrodynamic" bearings and self-pressurize.

Engines are faar more complex than they seem and they SEEM really complex!

 

[hornetfan]

I have seen people comment that a "Turbo does not increase power, it was done for emissions only". Is it possible that a turbo could NOT increase power? Not relivant to a LDT/LDS conversation, but it doesnt make much sense to me.

The short answer is "NO". Yah, the turbos were added to deal with smoke issues for which the DoD was getting grief. And the turbos drastically reduced smoke especially for engines that had been turned up -- when did WarDept/DoD go to seals on the pumps? Did they always have seals?

But the turbos also burned that wasted fuel in the "black smoke" and that means added HP -- it just physics guys.

 

[hornetfan]

What is the DESIGN life of these engines?? How long did the military expect them to last MTBO (mean time between overhaul)??

I've been assuming that the MIL expected something similar to civilian engines but realized suddenly that that is an ASSumption on my part and I have zero data to back it up.

Does anybody KNOW what Continental was promising for engine life when these engines were first delivered? Anybody know a retired Continental or Herc engineer or perhaps a son of same?

hornet on the hunt

 

[hornetfan]

Yes, 'just the distributor and high pressure pump" -- but what determines WHEN an injector squirts? When the pressure exceeds the injector pressure rating, right? Depending on the specifics of how the pump is designed that can be varied pump-to-pump. We used to hand grind new 'cam plates" (yah, I know it is more a "throttle plate" but bear with me a sec -- hold yer hp lol) for Bosch inline pumps for early FI petrol/methanol engines and the shape of the 'cam' (don't remember what Bosch called em now darn it) made a HIGE difference whether rich-lean. And THAT gents is EXACTLY what we've been trying to chase down -- when the LDS becomes 'rich' for fuel vs the LDT.

Both engines CAN provide enough air at low rpms but the LDT will burn pistons easily when making "the black smoke" which is HP. I'll wager that the LDS can be turned up more for fuel without having EGT problems (not enough air and/or exhaust restricted -- don't forget the exhaust) compared to the LDT. I've not seen anybody with a seriously turned up LDS but the LDS-2 sounds like such an engine and it REQUIRED other mods to keep up with the 200hp levels of the 8x8 trucks' engines. Such as better oil circ for cooling and narrowed oil clearances on the crank and (prolly) cam bearings -- all indicators of more oil press because otherwise you can't build sufficient pressure -- the excess oil just drains past the journals without going where intended. This does NOT affect journal bearing capacity with regard to crankshaft pressure s due to combustion -- that's is all determined by bearing size because these are "hydrodynamic" bearings and self-pressurize.

Engines are faar more complex than they seem and they SEEM really complex!

Y'all forgive me becauswe I don't know how to drive this forum properly but this quote if from TM America back 27 DEC 09 msg #21 from the thread on "max HO out of 465 multi-fuel" http://www.steelsoldiers.com/showth...f-a-465-multi-fuel/page3&highlight=hypercycle , to whit:

"i believe mine is around 200hp i have it turned up i'm running around 27psi boost at 2600 it gets around 15 at 1500 .its way faster than stock i have been running it like that for over 5yrs no problems i dont hold on the gov under load other than that i drive it like i stole it everyengine is diffferent just cuz i get away with it doesnt mean you will . i also want to put a cummins in my truck and am trying to make an excuse to do it but i just cant seem to kill this slow little multi"

200hp with 27psi boost @ 2600 rpm from an LDT-465-1 is WAY turned up as far as I can tell. Is tm america's engine still running? No mods/ops, I haven't stripped searched the entire LARGE site over the past 3 yrs to find out ;-{ Simple question -- if someone knows the answer please post in THIS thread. I'd like to get to an answer about LDT v LDS sometime this year or next -- three years of discussion is plenty long enough for an answer to remain elusive. Spank me if need be and I'll try to learn better.

 

[gimpyrobb]

TM Americas motor is still running.
I have both ldt and lds motors, both run 1200 deg
when I do the head gasket job I will try to measure the heads and rockers as I am putting ldt heads on an lds.

 

[JasonS]

What is the DESIGN life of these engines?? How long did the military expect them to last MTBO (mean time between overhaul)??

I've been assuming that the MIL expected something similar to civilian engines but realized suddenly that that is an ASSumption on my part and I have zero data to back it up.

Does anybody KNOW what Continental was promising for engine life when these engines were first delivered? Anybody know a retired Continental or Herc engineer or perhaps a son of same?

hornet on the hunt

Even in the low compression tractors, these engines were relatively short lived:

Today's Tractors :: View topic - White 2-155 Hercules engine ?

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http://talk.newagtalk.com/forums/thr...ed&setCookie=1

http://talk.newagtalk.com/forums/thr...at&setCookie=1

 

[Katahdin]

I get the impression Continental engineers were just on the cusp of Multifuel engine development when the LDx-465s were introduced. Here's a snippet from a SAE paper written by a Continental Aviation & Engineering employee to explain changes over the LDS-427 model.

 

[hornetfan]

TM Americas motor is still running.
I have both ldt and lds motors, both run 1200 deg
when I do the head gasket job I will try to measure the heads and rockers as I am putting ldt heads on an lds.

If you would include engine hours and mileage (if they are still connected to the engine being overhauled) that would be very helpful. The engine is my LR 110 has it's own small Hobbs meter (I still use the term -- like "Crescent wrench") that's on the fuel control solenoid for true "engine hours". I'll try to remember to PM TM America to see what the engine hours are.

 

[hornetfan]

I get the impression Continental engineers were just on the cusp of Multifuel engine development when the LDx-465s were introduced. Here's a snippet from a SAE paper written by a Continental Aviation & Engineering employee to explain changes over the LDS-427 model.

View attachment 401011

I guess the LDS-465 referred to w/210 hp must be the -2 version. I'd sure like to know what the MTBO was intended to be and what they considered normal MTBF.

If the multi-fuel capability was a design goal which seriously compromised longevity for military reasons (reasons I agree with BTW) that should affect a person's decision to repower or rebuild their deuce. The A3 I now have will be a daily driver and will be built for serious longevity. Fortunately the Cummins will burn a very wide variety of fuels if the fuels are prepped a bit e.g. 60-70% wmo together with diesel or even gasoline. The Cummins "B" series engines will tolerate quite a high % of gasoline w/o adverse effects.

Looks like a WTSHTF M35A2 with carefully rebuilt LDS-465-2 with Waterloo 3053A gearbox is going to be getting on my list soon. Nothing increases an engine's longevity as much as building it very carefully to spec and doing the little extra things which require so much more time. Polishing oil returns to the sump and paint with Glyptal, polished and fitted rods, balanced crank and carefully weight matched set of pistons. Bearing clearances at minimum. Maximize oil pump output and external full flow low restriction oil filters and fuel filters. Pre- & post- engine run lubrication to maximize engine and turbo life. Thermal coated lowest weight high compression pistons and hollow wrist pins (I don't want to use ether in cold weather) I'll have to think about which ring pattern is more likely to give longevity -- bet it's the 3-ring or 4-ring set off-hand. Is the 4th ring a second oil scraper ring? Yah, yah -- I'll go look

I know that purists will groan but I'd like something more than 300 hr MTBO. The Viet Nam longevity numbers posted earlier in this thread work out to about 50 hrs/month (figuring 2000 miles at 40mph up-against-governor operation gives about 50hrs. Overhaul at 12,000 mi gives 300 hr MTBO).

Any reason an LDS-465-2 oil pump can't be used in an LDT or LDS-465-1 or 1A engine?

 

[gimpyrobb]

I'll try to remember to PM TM America to see what the engine hours are.

TM america doesn't own that truck anymore.

My motors are not original to the trucks, I put them in there. No way to tell hrs and milage. Anyone here can tell you I have put thousands of miles on the LDS one though.

 

[jesusgatos]

I get the impression Continental engineers were just on the cusp of Multifuel engine development when the LDx-465s were introduced. Here's a snippet from a SAE paper written by a Continental Aviation & Engineering employee to explain changes over the LDS-427 model.

View attachment 401011

Would sure like to know what they had in mind when discussing those more powerful configurations. Would be absolutely thrilled if I could get anywhere near 500ft/lbs out of my LDS.

 

[hornetfan]

TM america doesn't own that truck anymore.

My motors are not original to the trucks, I put them in there. No way to tell hrs and milage. Anyone here can tell you I have put thousands of miles on the LDS one though.

Just so. That's why I put a little mini-hourmeter on the engine itself. Pull the engine and the hourmeter goes with it. Tyvek pocket tag attached for rebuild data for when the times eventually comes along.

 

[Flyingvan911]

Here it is...

LDS pyro/boost info.

I drove the deuce some today and with the help of Soldier B and a camera I got some numbers to report. Since I am a novice at diesel engine workings I will leave it up to the experts on the site to draw conclusions and interpret the data. The outside temp was 30 degrees I started the deuce and let it warm up. I then drove about four miles on the side streets to let it warm up everything else. Then I hit the highway. Here are the numbers and what was going on at that moment.

Speed-mph; RPM; Boost; EGT, Engine Temp

1) 0; 750; 0; 250; 150
I let the engine warm up all that it would. About 10 min time.

2) 0; 1,200; 0; 262; 150
After the engine starts and the oil gets flowing I pull the hand throttle and let the engine warm up at about this rpm.

3) 40; 1,750; 9; 1,057; 160
On the street going up a slight grade.

4) 0; 750; 0; 357; 160
Stopped at a red light.

5) 55; 2,450; 8; 891; 160
On the highway. Slight downgrade.

6) 55; 2,450; 12; 1,032; 160
Level highway.

7) 50; 2,200; 13; 1,085; 165
Highway. Going up a substantial hill. (I-635 south between I-70 and I-35 in Kansas City.) Gradually slowing down the the pedal all the way down.

8- 45; 1,900; 12; 1,192; 165
The slowest point just before the hill starts to level off. Pedal still all the way down.

9) 55; 2,450; 5; 708; 160
Going down the other side of the hill.

10) 0; 700; 0; 477; 160
At a red light at the bottom of the off ramp from the highway.

11) 0; 700; 0; 242; 150
I parked the deuce for the day and let it idle for five minutes before shut down.

The columns of numbers didn't come out right.

 

[m16ty]

Speed-mph; RPM; Boost; EGT, Engine Temp


6) 55; 2,450; 12; 1,032; 160
Level highway.

7) 50; 2,200; 13; 1,085; 165
Highway. Going up a substantial hill. (I-635 north between I-70 and I-35 in Kansas City.) Gradually slowing down the the pedal all the way down.

8- 45; 1,900; 12; 1,192; 165
The slowest point just before the hill starts to level off. Pedal still all the way down.

Looks like this engine is about maxed out as far as EGT is concerned.

 

[Flyingvan911]

Yep. The few times I have run up that hill since installing the pyro it has never reached 1200. That is one of the steepest highway grades you'll find in Kanasa City. I put the pyro on this fall and even at 70 or 80 degrees outside air temp the EGT is about he same. Maybe just a few degrees more but still not up to 1200.

I also forgot to meantion that I was burning 100% auto diesel.

 

[hornetfan]

Here it is...

LDS pyro/boost info.

I drove the deuce some today and with the help of Soldier B and a camera I got some numbers to report. Since I am a novice at diesel engine workings I will leave it up to the experts on the site to draw conclusions and interpret the data. The outside temp was 30 degrees I started the deuce and let it warm up. I then drove about four miles on the side streets to let it warm up everything else. Then I hit the highway. Here are the numbers and what was going on at that moment.

Speed-mph; RPM; Boost; EGT, Engine Temp

1) 0; 750; 0; 250; 150
I let the engine warm up all that it would. About 10 min time.

2) 0; 1,200; 0; 262; 150
After the engine starts and the oil gets flowing I pull the hand throttle and let the engine warm up at about this rpm.

3) 40; 1,750; 9; 1,057; 160
On the street going up a slight grade.

4) 0; 750; 0; 357; 160
Stopped at a red light.

5) 55; 2,450; 8; 891; 160
On the highway. Slight downgrade.

6) 55; 2,450; 12; 1,032; 160
Level highway.

7) 50; 2,200; 13; 1,085; 165
Highway. Going up a substantial hill. (I-635 south between I-70 and I-35 in Kansas City.) Gradually slowing down the the pedal all the way down.

8- 45; 1,900; 12; 1,192; 165
The slowest point just before the hill starts to level off. Pedal still all the way down.

9) 55; 2,450; 5; 708; 160
Going down the other side of the hill.

10) 0; 700; 0; 477; 160
At a red light at the bottom of the off ramp from the highway.

11) 0; 700; 0; 242; 150
I parked the deuce for the day and let it idle for five minutes before shut down.

The columns of numbers didn't come out right.

Good data Time stamps would be perfect lol! Seriously though thank you for gathering the data. Looks like a healthy engine operating under design load. EGT didn't peak real fast and stayed same under cruising load until you got well into the hill and slowed to 45. Boost stayed down as did EGT under light load. 12 psi boost is the high end of spec from the TM. 55 mph @ 2450 rpm: was that against the governor or just full pedal?

M35A2 6x6 right?

How many hours on engine?

This is an LDS-465-1 engine, right?

Empty bed no cargo to speak of?

Stock air cleaner with clean filter (10" Hg restriction or less)?

stock exhaust?

Nice engine. I'd love to see a shot of your dash and how you added the gauges. I've been thinking to get one of Westach's dual boost/egt gauges.

hooyah! data!

 

[Flyingvan911]

I have not modified any settings of the IP or engine except to add spin-on oil filter adapters. I changed my fuel filters this summer and they have less than 1,000 miles on them so the engine is getting as much fuel as the IP will allow. It also has the stock deuce air filter. No muffler yet. The engine is a LDS-465-1A with a C turbo. And the whistler screams on the highway. Rotella 15W40 oil. I have never had a hiccup out of the engine. (Except for delaying changing the primary filter. Changed it and everything was back to normal.) The truck has 45,265 miles and 1,526 hours on the engine if the gauges are original.

The whole drive was 45 minutes or less. 10 minutes or so warming up while doing pre-trip checks.

It is a M35A2 with 9.00x20 NDT’s. The truck was empty with bows and tarp on. As well as the winter cover over the grill. The boost gauge is a basic yet quality one from the auto parts store. I used copper tubing instead of the plastic it came with. I temporarily bolted it to the bottom of the dash using one of the empty bolt holes below the instrument panel. The pyro is a 24vdc Auber off of Ebay. It came with the probe which it into the manifold about 1/2" or a little more. The meter is tie-strapped to the rifle mount for now. I have a piece of metal to make a mount for both. It will also hold switches for a back-up light and an IR lamp for the front.

2,450 at 55 is my max speed by self control. The engine and truck will go up to 2,900 and just over 60 mph with the pedal on the floor on level highway. We only did this once just to see what it would do.

 

[hornetfan]

I have not modified any settings of the IP or engine except to add spin-on oil filter adapters. I changed my fuel filters this summer and they have less than 1,000 miles on them so the engine is getting as much fuel as the IP will allow. It also has the stock deuce air filter. No muffler yet. The engine is a LDS-465-1A with a C turbo. And the whistler screams on the highway. Rotella 15W40 oil. I have never had a hiccup out of the engine. (Except for delaying changing the primary filter. Changed it and everything was back to normal.) The truck has 45,265 miles and 1,526 hours on the engine if the gauges are original.

The whole drive was 45 minutes or less. 10 minutes or so warming up while doing pre-trip checks.

It is a M35A2 with 9.00x20 NDT’s. The truck was empty with bows and tarp on. As well as the winter cover over the grill. The boost gauge is a basic yet quality one from the auto parts store. I used copper tubing instead of the plastic it came with. I temporarily bolted it to the bottom of the dash using one of the empty bolt holes below the instrument panel. The pyro is a 24vdc Auber off of Ebay. It came with the probe which it into the manifold about 1/2" or a little more. The meter is tie-strapped to the rifle mount for now. I have a piece of metal to make a mount for both. It will also hold switches for a back-up light and an IR lamp for the front.

2,450 at 55 is my max speed by self control. The engine and truck will go up to 2,900 and just over 60 mph with the pedal on the floor on level highway. We only did this once just to see what it would do.

Excellent data. Thanks again! I love the 'temp' gauge setup. My first Land Rover has such a temp setup for about five years My excuse is "I was in college" and I'm stickin to it!

Weren't the LDS engine uprated to 2800 rpm? Closer bearing clearances and higher volume oil pump I believe. Yes, I know that the increased oil volume coincided with increased oil spray cooling for the pistons but the bearing clearance changes help with higher rpm loading of the journal and rod bearings, too. See wiki for hydrodynamic bearings.

Gentlemen, we have an instrumented baseline with good engine gauge data and at least reasonable engine hours. Sound like this deuce didn't see service in The 'Nam. It seems clear (and perhaps obvious) that how hard the trucks are used/abused has a great deal to do with actual longevity. If a design combat life of 300-500 hrs MTBO was the target then I would wager that moderate well maintained MTBO is on the order of 1500-2000 hrs and careful use together with careful maintenance (think "the CO's truck") could increase that out to maybe 2500 hrs. And that ain't bad gents, not bad a'tall.