LDS VS LDT and the real differences

[JasonS]

And what you said right there is more useful than most of the rest of this thread. At least you acknowledge that there are some differences in the two other than a couple of turns of the fuel screw. That is what I'm getting at. Yes you can get power from both motors, but the LDS is more suited to support that power, however small the differences are.

You should know that one owner of an LDS powered deuce posted EGT results indicating that it was pretty well maxed out for temperature (ie. NO margin at 175 HP). In the end, those minor differences don't really matter.

 

[Jeepsinker]

Alright good. That is useful information that I've not seen. Anyway, just this past couple days conversations with you guys brought out a little more information and a few more good educated opinions on the matter. I have two LDS 465-1a engines that I just acquired and will be making a swap soon. I traded a couple days work for them. I do want to see the difference for myself anyway. I will post pertinent info on the subject if any arises.

 

[Flyingvan911]

The LDS egt report is on page 33, post 314.

 

[gringeltaube]

...................I have two LDS 465-1a engines that I just acquired and will be making a swap soon. I traded a couple days work for them. I do want to see the difference for myself anyway. I will post pertinent info on the subject if any arises.

I'm sure you will feel- more then see- the difference. Been there; done it, more than once...

FWIW, I pulled the valve covers off today and measured the actual cam lobe heights, 1) on one 0-hours, rebuilt 5ton-LDS465-1A; 2) one very low-hours LDT465-1D; 3) one LDS427-2 with less than 2 hours of operation since rebuilt. About the same values came out, for all three engines: Intake = 0.315"; Exhaust = 0.318". To me this was no surprise since the parts books show the same camshaft part number for all MF-engines: #11610283.

For better reference:
LDS427-2: TM 9-2815-204-34P, Jun73; Fig.6, Item 7.
All other 465-versions: TM 9-2815-210-34P, May74; Fig.17, Item 6.


G.

 

[gimpyrobb]

Maybe this diagram will help you out. Some of our older members might recognize it(hehe).

 

[Jeepsinker]

So I suppose they must have had different cams from the factory, but went to the one standard cam when they were rebuilt for logistical purposes. That makes sense. So the differences are almost negligible. G, can you offer an explanation for the one differing spring in the timing advance units? It would be so wonderful to just sit down and have a chat with one of the engineers on the original Continental multifuel project.

 

[rustystud]

View attachment Scan0035.pdf

So I suppose they must have had different cams from the factory, but went to the one standard cam when they were rebuilt for logistical purposes. That makes sense. So the differences are almost negligible. G, can you offer an explanation for the one differing spring in the timing advance units? It would be so wonderful to just sit down and have a chat with one of the engineers on the original Continental multifuel project.

I've been going over the data sheets, and I see a marked difference from the data in TM 9-2815-210-35 (1964) and TM 9-2815-210-34-2-2 (1981) . The LDS-465-1A horsepower in 1964 is 205-220HP , now in 1981 the horsepower is now rated at 175-185HP . I know for a fact ( I already posted the data sheet ) that in 1964 there where 3 different cams used. This now confirms for me that the military did indeed go to a single cam design for all multi-fuel engines by 1981.
What is interesting is that the LDS-465-2 engine has all the same specs as the 1964 LDS-456-1A engine (just a slight derating of the HP). So I'm sure they continued to use the old style cam in that engine. I see no specs for this cam in the late edition TM's.
For all those who like to argue over data, start supplying your own. Stop pulling figures from whatever empty space in your brain. It is hard to argue facts when you never supply any.

 

[59apache]

As far as i remember, in this time period the SAE switch from BHP to net horsepower. You can see this on every old car ad .... around 1970 you can see a significant drop in HP for the same engines......

 

[rustystud]

All the Military manuals list Brake Horsepower.

 

[rustystud]

View attachment Scan0035.pdfView attachment Scan0034.pdfView attachment Scan0033.pdfView attachment Scan0036.pdfView attachment Scan0037.pdfView attachment Scan0038.pdfView attachment Scan0039.pdfView attachment Scan0039.pdf
The LDS-465-2 has 145 CFM more then the LDT-465-1C . How is that done since they both share the same cubic inch displacement and valve size ? Cam size. For those who are saying that the cam makes no difference in a diesel engine really do not know what they are talking about. After all who started using roller cams ? Diesels. Why ? It wasn't because of there extremely fast RPM's ! It was because they where using extreme cam grinds which a flat tappet could not work at. Now before someone says it is the Turbo let's stop right now and think about that. The CFM remains constant, density of air/fuel mixture can change with a Turbo and is in constant flux with a running engine. So when the manufacturer says there engine has a CFM of "X" that is a constant. The LDS-465-2 has a CFM of 550 while the LDT-465-1C has a CFM of 405. The only way you can change that is with larger bore (Nope the same) larger valves (Nope the same) different stroke (Nope the same) or a better cam (YES !) .

 

[gimpyrobb]

I could care less one way or the other, I just know my LDS has more power than an LDT but, I have always said it sounds like it has a hot cam!

I'm a genius and didn't even know it.

 

[RAYZER]

I could care less one way or the other, I just know my LDS has more power than an LDT but, I have always said it sounds like it has a hot cam!

I'm a genius and didn't even know it.

You are a genius!!
I would like to get my hands on one of those cams!

 

[gringeltaube]

Recommend using gloves... (they are HOT!)


G.

 

[Squirt-Truck]

Gimp has a point, a healthy LDS sounds significantly different that a healthy LDT. This has even been noticed by people that are not into these machines. Just a comment that something has to be making that difference. Sure seems like it may be the cam. I have also noticed (completely un-scientific) that an LDS seems significantly louder at cruse speed than an LDT.

 

[rustystud]

Yes gimpyrobb your a Genius ! Another thing to consider is the LDS engine is using 3.5 gallons more of fuel an hour then the LDT engine. That must mean the pump is either turned up or they are using a different pump with larger bores for the extra fuel flow. Just like using a larger Carburetor on a HiPo-cam Chevy 350.

 

[Heath_h49008]

Also, stop looking at the LDS-2 as ANY comparison to the LDT.

The LDS-2 was totally different, and IIRC not used in any common production truck. It was a prototype that went no where, and had huge changes to the fuel management system.

 

[m-35tom]

Yes gimpyrobb your a Genius ! Another thing to consider is the LDS engine is using 3.5 gallons more of fuel an hour then the LDT engine. That must mean the pump is either turned up or they are using a different pump with larger bores for the extra fuel flow. Just like using a larger Carburetor on a HiPo-cam Chevy 350.

this should be taken as what it really says. it would at max fuel rate continuously. not the way it is driven. it still takes the same amount of fuel to move a given load at a given speed, other inefficiencies being the same.

 

[rustystud]

Also, stop looking at the LDS-2 as ANY comparison to the LDT.

The LDS-2 was totally different, and IIRC not used in any common production truck. It was a prototype that went no where, and had huge changes to the fuel management system.

If you read my previous posts I was using the LDS-465-1 engine with the data sheets from TM 9-2815-210-35 dated 1964 . I just threw in the LDS-465-2 since you commented on it. The fact remains if you own a 1964 or older LDS-465-1 you have a hotter cam . The specs show that. They also show this same cam was used in the "Experimantal" LDS-465-2 engine. I don't know when the military decided to go to one cam design, but it was finished by 1981 . That just leaves the Hydraulic Head. Is it different ? or did they just pump it up ? Also all engines went to the 2 nozzle oil cooling system for the pistons at about this same "unknown" time and all went to the 22:1 compression pistons with cooling passages. So to recap, the early LDS-465-1 had over 80HP more then the LDT-465-1c (due to the cam & hydraulic head) . The present LDS-465-1 has only 40HP more then the LDT-465-1c (due to the hydraulic head) .

 

[59apache]

Has anyone the cam data? Regrind a cam isn't the problem....

 

[rustystud]

Has anyone the cam data? Regrind a cam isn't the problem....

If someone has the older LDS-465 engine with the better cam we could have it sent out to a speed shop or even ISKY cams . I know they will do one off cam grinds. Costly but doable. I also thought why not get a modern grind on our cams ? The knowledge of diesel engines has gone up tremendously in the last decade ! So some smart tech at a cam manufacturer can come up with a much better cam grind then they had in 1964 ! Also lets adapt roller lifters to our engines, can't be to hard . That will really give use some great cam lifts and approach angles !