LDS VS LDT and the real differences

[JasonS]

You are right, it had more like 40-50 more horses. And it does have the same static injection timing, but I has a different timing curve. I believe that the different timing curve is what helps it keep the pistons from melting with the added power.

Why do you think that it has a different timing curve? Can you point to a TM indicating such?

 

[Jeepsinker]

No, but I can't find anything stating the purpose of the different spring in the advance unit either though. There can only be so many reasons for it.

 

[JasonS]

Which LDS is this for? The -1 or the -2?

At the end of the day, it really helps to put all of this in perspective. Any modern engine of this displacement can have the fuel turned up 60 HP without any other modifications. The LDS-2 literature indicated numerous modifications apparently required to achieve 195 HP. If it takes all of this for 195 HP and head gasket and lower end failures happen at 130 HP, it really isn't a very strong engine. Couple that with the fact that gaskets and hard parts will become even harder to find leads to the fact that this whole thread is really a waste of time.

 

[acesneights1]

You could modify it to do away with the cooling jacket. It has been done. The reason for it in the first place was for cold weather starting, not so much for cooling intake air temps. If you figure out how to stuff an intercooler in there the way things are please let me know.

hang it under the front bumper ?

 

[Jeepsinker]

Which LDS is this for? The -1 or the -2?

At the end of the day, it really helps to put all of this in perspective. Any modern engine of this displacement can have the fuel turned up 60 HP without any other modifications. The LDS-2 literature indicated numerous modifications apparently required to achieve 195 HP. If it takes all of this for 195 HP and head gasket and lower end failures happen at 130 HP, it really isn't a very strong engine. Couple that with the fact that gaskets and hard parts will become even harder to find leads to the fact that this whole thread is really a waste of time.

I have to disagree. From what I've read( granted you've been on here much longer than I have) most of the failures happen when people go to turning he fuel up trying to make LDS power and/or are running the snot out of them. Some fail from improper rebuilding practices. The LDT 465-1d is just fine if it isn't messed with much as far as being reliable. I've put over 16000 miles on mine in the last 8 months, most of that pulling something heavy. I have not turned my fuel up. I see no reason the LDS 465-1a would be any less reliable if cared for and driven sensibly and you don't mess with the fuel too much. And it should have at least 40 more horses out of the box.

 

[m-35tom]

i am convinced that with just the fuel turned up, a ldt will put out 200 hp. the lds -2 had 14 psi boost while the ldt only had 9. i have had both and cannot tell the differance when a ldt also has 14.

 

[Jeepsinker]

I can't comment on boost pressures as I do not have a boost pressure gauge, and I have seen wildly varying claims on boost numbers from other members in other threads here. And I don't doubt that the LDT can make LDS power when turned up, I just don't think it can do it within the same parameters. What I mean is that once you turn up the fuel on the LDT you always have the egt to worry about and keep an eye on. The LDS is tuned to make around 180 horsepower and run safe egt all day long without too much concern. That is the defining factor in my eyes.

 

[rustystud]

[QView attachment Scan0031.pdfView attachment Scan0032.pdfUOTE=JasonS;1563276]Are you talking about the LDS465-2? The LDS465-1/A did NOT have 60 more horsepower or different injection timing. The -2 was spun faster so I can see it having a different camshaft. I can also see it having poorer reliability....[/QUOTE]

Did you not read the data sheets ? The LD-465 had 140HP and 330ft Ib of torque. The LDS had 205HP to 220HP ( do not know why the difference of 15 HP ) and 440ft Ib of torque. By my math that is a difference of 65HP to 80HP . This is the data sheets from TM 9-2815-210-35 . I didn't pull this out of my A$$ like a lot of guys here do with numbers.
You where right about the injection pump timing though Jason. Both engines have a static timing of 20 deg. BTDC with automatic advance of 8 deg. Yes they do have different cams.

 

[HETvet]

You could modify it to do away with the cooling jacket. It has been done. The reason for it in the first place was for cold weather starting, not so much for cooling intake air temps. If you figure out how to stuff an intercooler in there the way things are please let me know.

there are a couple ideas I have in my head. a FMIC could work, but I don't know how large you could go, thus how effective/efficient it would be. A side mount could work with a puller fan, or even a top mount. A A/WIC could also work, but I think it would need a closed circuit coolant system using some high efficiency coolant and materials. I also wonder what some time with a dremel could do for the turbo its self.

 

[rustystud]

The LDS-465-1 intake valve opens at 7 deg BTC closes at 43 deg ABC . Remaining open 230 degrees. The exhaust opens at 42 deg closes at 4 deg BTC . Remaining open 218 degrees. The intake valve has a total lift of .4725" , the exhaust valve has a total lift of .4695".
Now the LD-465 (which is the same as the LDT-465) intake opens at 11 deg BTC and closes at 41 deg ABC . Remaining open 232 degrees. The exhaust opens at 41 deg BBC and closes at 1 deg BTC . Remaining open 220 degrees. The valves have a total lift of .450" .
The injection starts at 20 deg BTC on the LDS , while the LD starts at 25 deg BTC .
Looking at these figures you would think the LD had a better cam, while the LDS has a higher valve lift. What I believe is the LDS has a retarded camming, but more air intake which allows more fuel to be pumped into the engine without raising EGT's .

 

[acesneights1]

I don't claim to be any expert on Multifuels and the design of the piston and FDC may play into things,I'll be honest, I am not sure..But...Big Butt...Oprah Winfrey Butt...How many 6bt's have been cranked up over 100 hps with little mods?
**** you can get 50 hp more out of a 6.2 by cranking the fuel and adding boost so that said under the guise of general diesel knowledge I would question that the cam make that huge of a difference. I would prefer to see actual fuel delivery rates and boost numbers. I think that is where more of the difference lies. More fuel is more boost on a non gated turbo.

 

[Jeepsinker]

Rusty, thanks for posting up some real information showing differences in the engines. If people keep insisting they are the same engine and you can just turn the fuel up on the LDT to achieve the same results and reliability, we will never find the truth.

 

[topo]

Pistons I pulled from a LDS have a large oil ports that looks like it lets oil run through the top of the piston and small ports for the oil ring . Piston from the LD has just ports for the oil ring .

 

[Jeepsinker]

Ok, so like has been discussed here already, LDS pistons have better lubrication and a **little** more cooling. It also looks like much better quality machine work.

 

[Heath_h49008]

Yep... and we already covered all of this.

The LDT and LDS-1 have the same turbos, blocks, cranks, rods rockers, cams, and injectors.

In rebuilt engines the pistons, pumps and timing for either can be found. There is no magic here. We already know, in great detail, what the differences are.

The prime desire is to make an LDT make LDS power by understanding the differences. So, adjust the pump to deliver LDS fuel levels into the LDT. Aside from that, get a pyro to monitor. Can you adjust timing? Of course. Is it worth it? Up to you.

Is there a different piston? Yes, to deal with the added heat with 1950s lubes. With modern fluids it is debatable as to if it is needed. The cooled LDS piston reduced temps at the top ring by 100 degrees F.

Guys, this has been beat to death.

Camshaft Fed. stock #2815 808 6978. listed as spec for everything but the LDS-2 as per TM9-2815-210-34P.
One hole vs two hole injectors could be found on either with the same fueling rate.

The power difference is the 80lb/hr the LDS is fueled at vs the 63lb/hr the LDT is fueled at. Now you can increase the fuel buy hunting down the LDS pump, or by turning up the LDT pump to match it. The LDS HH provides that higher VOLUME at a lower system pressure. (The governor assy is different to provide that fuel at different times in the RPM range) The wastegated turbo is used to allow for maximum efficiency to be reached at lower RPM levels, without overspinning at high rpm levels.

It would be better to think of the LDS as the low efficiency "towing tune" version of the engine family, with the LDT being the "fuel efficient cruiser." That's a very rough description, but for folks just getting into the system, it's a start.

 

[Jeepsinker]

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.

 

[Heath_h49008]

Meh.... the LDS is marginally more durable because of the pistons? Maybe?

The LDTs seem to have a failure issue mostly because of the drivers, and the higher number exposed to abuse. Watch any number of youtube vids of these guys starting them cold and then screaming them up to 2500rpm. Or not shifting until 2500 when they "hear it whistle!" ... all while feeding it any crap oil they find by the side of the road or in a craigslist posting for used oil.

I strongly suspect that if half of the M35s had LDS engines, there would be an equal number of LDS grenades due to lack of maintenance and owner stupidity.

 

[welldigger]

There's no doubt the lds in bone stock form is more potent than the ldt. But to say the lds isn't the same basic motor is ridiculous.

Is a sbc suddenly a different motor if you install a different cam and carburetor?

If you have access to a cheap lds and need to swap motors anyway then by all means take advantage of the extra power.

I doubt I'd spend the money on swapping a perfectly good ldt for an lds just because. Especially since the ldt can be tuned to at least similar power levels as the lds.

 

[brianp454]

Best Ayatollah post ever!

Yep... and we already covered all of this.

The LDT and LDS-1 have the same turbos, blocks, cranks, rods rockers, cams, and injectors.

In rebuilt engines the pistons, pumps and timing for either can be found. There is no magic here. We already know, in great detail, what the differences are.

The prime desire is to make an LDT make LDS power by understanding the differences. So, adjust the pump to deliver LDS fuel levels into the LDT. Aside from that, get a pyro to monitor. Can you adjust timing? Of course. Is it worth it? Up to you.

Is there a different piston? Yes, to deal with the added heat with 1950s lubes. With modern fluids it is debatable as to if it is needed. The cooled LDS piston reduced temps at the top ring by 100 degrees F.

Guys, this has been beat to death.

Camshaft Fed. stock #2815 808 6978. listed as spec for everything but the LDS-2 as per TM9-2815-210-34P.
One hole vs two hole injectors could be found on either with the same fueling rate.

The power difference is the 80lb/hr the LDS is fueled at vs the 63lb/hr the LDT is fueled at. Now you can increase the fuel buy hunting down the LDS pump, or by turning up the LDT pump to match it. The LDS HH provides that higher VOLUME at a lower system pressure. (The governor assy is different to provide that fuel at different times in the RPM range) The wastegated turbo is used to allow for maximum efficiency to be reached at lower RPM levels, without overspinning at high rpm levels.

It would be better to think of the LDS as the low efficiency "towing tune" version of the engine family, with the LDT being the "fuel efficient cruiser." That's a very rough description, but for folks just getting into the system, it's a start.

 

[JasonS]

[QView attachment 499884View attachment 499885UOTE=JasonS;1563276]Are you talking about the LDS465-2? The LDS465-1/A did NOT have 60 more horsepower or different injection timing. The -2 was spun faster so I can see it having a different camshaft. I can also see it having poorer reliability....

Did you not read the data sheets ? The LD-465 had 140HP and 330ft Ib of torque. The LDS had 205HP to 220HP ( do not know why the difference of 15 HP ) and 440ft Ib of torque. By my math that is a difference of 65HP to 80HP . This is the data sheets from TM 9-2815-210-35 . I didn't pull this out of my A$$ like a lot of guys here do with numbers.
You where right about the injection pump timing though Jason. Both engines have a static timing of 20 deg. BTDC with automatic advance of 8 deg. Yes they do have different cams.[/QUOTE]

Not sure why the quotes above are messed up.... You really need to keep the -2 and -1 engines separate for the discussion to be meaningful. According to TM9-2815-210-34-1, the LDTT465-1C has 130 HP at 2600rpm and LDS-465-1A has 175HP at 2600 rpm. By my math, that is a difference of 45 HP. The LDS465-2 has 195 at 2800 rpm. If you look closely at the data, you should realize that both the LDS-1 and -2 have the EXACT same torque at the EXACT same rpm: 425 ftlb at 2000 rpm. That also means that they have the EXACT same horsepower at 2000 rpm. It isn't much of a stretch to assume that the chief means of the -2's higher horsepower is higher rpm (2800 rpm). Something that seems contrary to long engine life.