LDS VS LDT and the real differences

[jasonn]

I have read plenty of threads about the LDS VS LDT motors. and have found no conclusive evidence that says there is anything more then a bigger turbo making the extra 90hp so as i have both motors siting in my drive way i'm looking to get to the bottom of this once and for all. disassembly time . i'm looking for any thoughts as to these differences. so as they may be proven or dis proven.
here is a list of visual deferences that are easily noted:

drive side starter- this was done on the 5ton to allow for shaft driving wench.
bigger turbo
Elbow that connects turbo to intake manifold
data plate
oil dip stick location- probably done to clear intake tube to feed larger turbo on lds
hydro pump- only if truck had hydro steering

thank you for your feed back
Jason

 

[mudguppy]

there are more rings on the LDS pistons. injectors are different as well as injection pump.

plus the turbo, as you mentioned.

so, with these 4 things being different, well, that's a completely different fueling potential.


are the HGs the same? i thought those were different, also...?

 

[OpieNoTool]

the lds has different pistons, injectors, injection pump, and as you mentioned turbo. Every one on here says the ldt
465 does not have piston coolers. I can tell you mine did, and the parts book i have from memphis equipment says
they all do. As for is the swap worth it, i would say Yes its worth it. The lds i have came out of a wrecker and was a
good runner when i got it. I turned the pump up a little and toasted a perfectly brand new ceramic disc clutch.
So needles to say i backed the fuel off some and she runs great. I will say the lds burns more fuel than my ldt. I
would say to any one thinking of doing the swap, unless your going to do alot of towing its probaly not worth it
if you like your decent fuel milage. I would just put a bost gauge and pyrometer on the truck turn the fuel screw up
a little and run her. For any of you who say turning the fuel up will ruin these engines, i had my ldt turned up as high
as i felt safe doing so for 6 years and over 25,000 miles with no isues, the only reason i swapped out was because
i pull my skidsteer on a regular basses and the engine was just laying around.

 

[jasonn]

ok i'm gonna start with the injectors i will pull them out tomorrow and see what the difference is then its the injector pump.

i gather there is a oil grove in the pistons and while this will definitely help with engine life i don't think it makes more horse power

HG's is this head gasket?

 

[mudguppy]

unless you have the equipment to pop-test injectors and measure orifices down to 0.001", you may not be able to tell any difference between LDT and LDS injectors.

you'll need a fuel bench set up to measure the differences in injector pumps.

increased number of piston rings means increased compression holding capability, which could mean more HP capability.

yes, when i said HG, i meant head gaskets.


if you don't want your LDS, i'll trade you my LDT - i'm pulling it soon anyway.

 

[doghead]

The difference is one hole or two...

 

[jasonn]

i couldn't wait so i went out and pulled the injectors here's what i found:
the LDS had a single hole injector made by united technolodies USA part #akf13056614a rebuilt in 1987
the LDt had 2 hole injector made by international italy part# 130sm-6844b2 rebuilt in 1990

i kinda expected to find that two hole injector in the LDS

 

[jasonn]

just a thought if on all of our LDT engines we have the fuel adjustment screw to increase fuel which i have played with on mine what would be the need to have an injector pump made to increase fuel when a few turns of the screw already do that? i believe it has been widely stated that the 2 hole injectors produce more power is this true?

Mudgupy,
Thank you for your offer but I have a few ldt's laying around already I would however trade for a duramax or a 24v cummins if you have one of those

 

[JOAT 0311]

You have my attention. Lets see where this goes.

 

[joeinaforest]

I agree...lets see where this thread goes...I'm gonna be buying in a couple of years and am looking forward to lots of opinions!

Just gotta finish paying of the homestead!

J

 

[m16ty]

I think the theory behind the oil groove is to help keep piston temps a little lower (more fuel equals more heat).


The way I see it is the injection pump is a moot point. You can turn up a LDT IP up more than enough to melt the engine so I don't see how you'd gain hp with a LDS IP. I could be wrong.

The big thing with me is that there are several people that have driven both a turned up LDT and a LDS. They all say the LDS will make more power. I don't doubt what they say but I have yet to see where the big increase is.

The limiting factor on the LDT is EGT. The big question is, what does the LDS do to hold the EGT low enough to make more power over the LDT. I'm sure the oil groove helps a little but I just can't see it helping very much.

Now it could be that if the pistons have more rings than a LDT, that the LDS can make more power on less fuel because it can contain more of the compression durring the power stroke.

 

[gringeltaube]

bigger turbo.

Not necessarily, I've seen late rebuilds come with C or D turbos as well.

oil dip stick location- probably done to clear intake tube to feed larger turbo on lds...

Or could it be that 5tons have the oil pan's deep sump oriented towards the rear of engine...?

hydro pump- only if truck had hydro steering

Any 5tons known to come with manual steering....?

G.

 

[SasquatchSanta]

My LDS came with a standard "D" turbo which is more common than not. I believe the cam is different. The LDS sounds different than the LDT. I've turned the fuel down a couple of times on my LDS simply because I didn't need the power. I didn't notice an appreciable difference until I turned down the droop screw setting which controls the lower end fuel delivery.

IMHO the LDS engine is all around a better beast. Mine runs like a scared deer even with the fuel turned down. I've still got loads of power and I get good fuel economy. An LDS Deuce is a whole different animal especially when it's been bobbed.

 

[gimpyrobb]

Yes, it has been stated in other threads that the cam IS different. I have yet to tear into any of my motors so I cannot confirm that statement. Stretch has a pretty "tuned" LDT and when he drove my truck with the LDS, he said it had more power. Not WAY more power, just a bit more. I love my LDS and the tone of the exhaust. On a side note, I have seen LDT motors with out the oil squirters but the 1992 LDT I put in the wrecker had then in it.

 

[jasonn]

Can some one please post some pictures of what is being called a D turbo and A C turbo and what are we calling the third one?

 

[jimk]

I agree with m16ty on the fuel and EGT. My LD had lots of fuel but was a stone. The turbo made for some huge increase in power and egt, so much so I had to turn the fueld down 2-1/2 turns and it still ran much stronger. Power is all about volumetric efficiency(air) and fuel.

I don't know if I agree with an extra piston ring making more power. It may have a very small effect. Leakdown tests in general have a healthy seal at 5-10%, racing 2-4%, gapless 0-2%, problem engines above 20%. These tests are done at rest. There just isn't enough time available at higher RPM for a lot of leakage. Leakage puts combustion heat in an bad area of the piston, the skirt. The piston with one fewer ring still needs to manage leakage for reliability. Piston rings are one way the piston rids itself of heat, transferring it to the relatively cool cylinder walls.

10y ago Wiesco racing pistons came with a groove between the top and second ring. They made some fantastic claims as to how it reduced leakage and made power. The therory was gasses were slowed because they had to expand in this area, then contract. Sounded like hype to me. Do they still do it? Did others adopt it?

The LDS starter is on the left. My LD is on the right, very close to the exhaust pipe. Perhaps the move was to get it away from the heat.

The LDS troubleshooting manual states the LDS induction air flow is rated at 550cfm. My LD filter was labeled 440 cfm.

The LDS turbo also has a wasted gate. That allows designers to make an engine that builds more pressure sooner without getting too high later.

 

[gimpyrobb]

Can some one please post some pictures of what is being called a D turbo and A C turbo and what are we calling the third one?

There is actually 4. The C turbo, D turbo, LDS427 turbo, and the big 5ton turbo with the blow off valve.

 

[gimpyrobb]

Jim, the starter is on the other side for the 5tons because of the blow off valve. It occupies the area where the starter is on the deuce. They were designed at the beginning for the bigger turbo, then they realized there was not much more gained by the design(or something to that effect) and they started putting on the other turbos.

 

[MATT]

I've got a injector pop off tester at work, if I remember, I will test both the single and dual nozzle injectors. The old guy at work who's been putting LDS motors together for 30 years for us always puts the dual hole injectors in the motors. Must be a reason...

 

[SasquatchSanta]

When you put a deuce bellhousing and flywheel on an LDS motor you end up with the same "deuce" starter configuration. There is a spacer ring that must be used. The reason the starter is on the opposite side on the five ton is because of the bellhousing. The dipstick can be easily moved to the standard deuce position.