LDS VS LDT and the real differences

[gringeltaube]

....................... If the LDS IP and injectors deliver that much more fuel, what keeps the LDS from melting down?..................

Same Q. here!

G.

 

[Recht71]

Lds

I would think there's something else but can't find any thing . The only spec's in the TM thats diffrent is( Fuel consumption at rated power and speed)
LDS 465 2 90lb/hr I don't know if this engine exsists
LDS 465 1 , LDS 465 1A 80 lb/hr
LD 465 61lb/hr
LDT 465 1C 64lb/hr

That comes from TM 9-2815-210-34-2-1 Page 1-13 It also shows the LDS 465 -1 two hole injectors (interesting ) and the LDS 465 1A single Hole injector , the LDT and LDS pump timing the same. Anyways The LDS is a Power house do I know exactly why that would be no. The cfm a little diffrent,some running temps can't find anything more in the TM's Till Later Randy

Check out the Tm's on the site the # above Page 1-9 you will see the spec's

 

[midcounty]

I'm still not buying the whole IP/injector deal on the LDS. I know they're different but can they really make that much more power? You can melt down a LDT with the factory fuel pump and injectors. If the LDS IP and injectors deliver that much more fuel, what keeps the LDS from melting down?

I'm begging someone to prove me wrong on this. It's just with my knowlege of the LDT and diesels in general, I don't see it. Am I missing something?

I haven't had time to search it out myself in the manuals, but there has to be a difference that is permitting more air into the engine. With out more air to add to the extra fuel it would be know different then a turned up LDT, and we all know there is a difference. It would also create more exhaust temp and be prone to melting down the engine. I am wondering if the original LDS cams in the engines are the same as the replacement. Gooberment may have only wanted one replacement p/n to make it GI proof. Just because they will fit in the same engines and work, doesn't mean the lobe specs are the same. It also could be a cam timing issue as well. If the cam timing gear p/n is different on a LDS, that could be an indicator.

 

[gimpyrobb]

Just so you know gang, there are different pistons available for the motors too. This is part of a PM I got from a member in Alaska:

The latest LDT465-1D engines that I have been into last had pistons with a black coating on the top. If my memory is correct these were lower compression pistons. To verify use a piece of plexy glass with a small hole in it place it over the sphere in the piston fill it with a 50cc syringe, measure what it takes to fill it. The higher compression pistons have smaller spheres. the latest pistons had 3 rings and older higher compression pistons have 4 rings I believe. The 5 ton pistons have cooling holes in the bottom of them that look like funnels for the single nozzle piston coolers.

 

[mikew]

I just finished putting an injector pump into an LD motor, and while reading the manual I saw where it discussed the centrifugal injection timing advance mechanism.

TM 209-2910-226-34, the injector pump rebuild manual, says the LDS pumps use a different "advance" spring than the LD pumps so the timing curve is different between the two applications.

Although "static" pump timing is the same for both motors, I wonder if the timing of fuel injection could be a major contributor to differences in power.

 

[jimk]

Interesting.

(conjecture) I'd guess they made the timing change because a LDS w/wategate can be designed to make boost sooner while not getting to high later. It may have a wider power band but this would seem to have little effect on the peak power output.

 

[Recht71]

All good comments I would like to fined a Diffrent part # on the cam shaft but haven't yet .Here's some pictures of the latest LDS piston and sleeves. I have a call into a sergent that I know that works in the depot in michigan that dose a lot of repairs and some rebuilds. See if he can enlighten us on this subject

 

[mudguppy]

I'm still not buying the whole IP/injector deal on the LDS. I know they're different but can they really make that much more power? ...

i believe this is consitent with everything that i've learned and read about modifying diesel performance.

what i've learned is that fuel rate is a very simple measurement that estimates and defines power ratings but is not necessarily a defining characteristic of power delivery. changing injection pressure, fuel delivery velocity, injector orifice (and maybe even spray pattern), and dynamic injection advance all have a tremendous affect on diesel characteristics. most notibly, each of these have a large effect on combustion and resulting EGTs.

simple example, 5.9 Cummins: take a 215hp injection pump and injectors and put them on a 160hp block (with identical static advance, cam, rotating assembly, heads, turbo, IC, etc) and you now have a 215hp engine. except it isn't just the fuel ratings that are different: the changes in the plungers/barrels, IP cam lobe, internal retard/advance mechanisms, injector springs, and injector orifice size have all contributed to completely changing the fueling characteristics as well as power delivery at different rpms and, most importantly, egt control. both 160hp and 215hp engines will run to 1200°F WOT uphill in stock form - but one is deliverying 35% more power on the same hardware.

that's why i said you'd need a bench to acurately measure the differences between the pumps and injectors to truly fill in the unknowns. this would also be why you can get similar power of an LDS out of a 'turned-up' LDT but you can't get the same heat control; because you haven't changed the other variables.

someone - put an LDS-tuned IP and injectors on an LDT and see what the results are.

 

[SCSG-G4]

Here's a couple of pics of the LDS-1A piston (kit NSN 2815-00-134-0077). The cup is 40 mm wide and 42 mm deep. How big is the LD or LDT cup?

 

[midcounty]

someone - put an LDS-tuned IP and injectors on an LDT and see what the results are.

Sounds like the only waybto know for sure

 

[Recht71]

We put LDS single hole injectors in a LDT turned up the fuel no differents. We did watch our exhust temp ,the probe is preturbo.When I do find an LDS pump reasonable that will be next

 

[m16ty]

i believe this is consitent with everything that i've learned and read about modifying diesel performance.

what i've learned is that fuel rate is a very simple measurement that estimates and defines power ratings but is not necessarily a defining characteristic of power delivery. changing injection pressure, fuel delivery velocity, injector orifice (and maybe even spray pattern), and dynamic injection advance all have a tremendous affect on diesel characteristics. most notibly, each of these have a large effect on combustion and resulting EGTs.

simple example, 5.9 Cummins: take a 215hp injection pump and injectors and put them on a 160hp block (with identical static advance, cam, rotating assembly, heads, turbo, IC, etc) and you now have a 215hp engine. except it isn't just the fuel ratings that are different: the changes in the plungers/barrels, IP cam lobe, internal retard/advance mechanisms, injector springs, and injector orifice size have all contributed to completely changing the fueling characteristics as well as power delivery at different rpms and, most importantly, egt control. both 160hp and 215hp engines will run to 1200°F WOT uphill in stock form - but one is deliverying 35% more power on the same hardware.

that's why i said you'd need a bench to acurately measure the differences between the pumps and injectors to truly fill in the unknowns. this would also be why you can get similar power of an LDS out of a 'turned-up' LDT but you can't get the same heat control; because you haven't changed the other variables.

someone - put an LDS-tuned IP and injectors on an LDT and see what the results are.

Travis, You may be onto something. Somebody give me a LDS IP and a set of injectors and I'll try it out .

Seriously though, I wish somebody would try this and post the results.

 

[Billy Bobbed]

Has anyone check the boost of the bigger turbo on the LDS engine.Dont go by what they say it puts out.I have a LDT 465 with a C turbo putting out more than 15 plus lbs of boost,not the 9 or 10 they say it puts out.If the turbo on the LDS has a better low end or top end response, it will fell like its got more power.I would say these turbos are making more power than you think.For a 11,000 pound truck going up a hill,mine moves very well.

 

[Flyingvan911]

Because the LDS puts out a higher volume of exhaust maybe the C and D turbos turn faster and are able to pull a higher volume of air into the engine. I am curious if anyone has done a flow test on the Deuce air filter to how much air can be pulled through it. (Besides the manufacturer or military however many years ago.) Maybe the newer filters let more air through than we think?

 

[gimpyrobb]

Well, the(deuce) air filter says 410cfm on it, I bet thats what it can flow. Westy put an LDS pump on an LDT ans said it made a big difference.

 

[JasonS]

I seem to recall that the LDS troubleshooting manual stated that the one-hole injectors are to be replaced with two-hole.

 

[Billy Bobbed]

The only way I see the LDS pump is better is if It puts more fuel in the injector faster than the LDT pump.But both are going to hit the high EGTs sonner or later when turned up.You can turn a LDT pump up to melt the pistons.

 

[jasonn]

I'm meeting with a guy today that can test these two ip's. It might take a few days but I hope to have an answer. It would be nice to find out that you swap out a spring in all our ldt's and then the injector pumps are the same.
I know there's been a lot of talk about the single hole vs two hole injectors. I just wanted to point out again that this LDS had the singles and this LDT had the two hole ones

 

[jasonn]

I'm meeting with a guy today that can test these two ip's. It might take a few days but I hope to have an answer. It would be nice to find out that you swap out a spring in all our ldt's and then the injector pumps are the same.
I know there's been a lot of talk about the single hole vs two hole injectors. I just wanted to point out again that this LDS had the singles and this LDT had the two hole ones

 

[Dunegoon]

I have a chance to rob some parts off a LDS that is getting taken back to forrestry. Sounds like it need to take the IP and the injectors. Anything else? What do you guys think.