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LDS-427 turbo

Recovry4x4

Recovry4x4

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I've had one with the LDS turbo. I saw no significant difference between it and the "D" turbo although I've never had both turbos on the same truck. They are not whistlers.
 
JasonS

JasonS

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Understood. I did a search here and some had claimed that it could provide more boost. I bought one anyway but it will be awhile before I get a chance to try it out.
 
rustystud

rustystud

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DavidWymore said:
Anyone ever try and see how much boost they make?
Click to expand...
They don't make much boost. If your planning to up the pressure in your engine then you need to go with a more modern turbo. There is a thread on the differences between the LDS and the LDT engines which really gets into the power differences and mods available to make more power.
 
DavidWymore

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I have an LDS 465 and am familiar with the differences, but this thread is referring to a 427...different animal. Jatonka and others say the 427 has more seat of the pants power than the LDT 465, and that the turbo was there to make power, not just clean up smoke.
 
rustystud

rustystud

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DavidWymore said:
I have an LDS 465 and am familiar with the differences, but this thread is referring to a 427...different animal. Jatonka and others say View attachment Scan0051.pdfView attachment Scan0054.pdfView attachment Scan0053.pdfView attachment Scan0052.pdf I truly hate this sites downloading tools ! OK here goes. David, if you had read the posts I referred you too you would have seen this posted. Since I like you I went ahead and spent an hour to download this again. The first and last pictures show the pages from the TM 9-2815-204-35 which is from the LDS-427 engine manual. The second and third pictures show the pages from the TM 9-2815-210-35 which is from the LDT-465 engine manual. You can clearly see that the LDS engine only makes 140 hp (gross) at 2600 RPM and 340 ft-Ibs (gross) torque at 1400 RPM with a compression ratio of 20:1 , using the Schwitzer 4-450 turbo (later ones used the 4-D).
The LDT-465 engine makes 205-220 hp (gross) at 2800 RPM and 440 ft-Ibs of torque (gross) at 2000 RPM with a compression ratio of 22:1 , using the Schwitzer 4-456 turbo. Basically the same as the 4-450 turbo. So you can see that the LDS-427 is not the high power engine with super turbo you think it is.
Click to expand...
 
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DavidWymore

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Rusty - sorry, I should have been more clear and thorough with how I worded my question and could have saved you the trouble.
I have read that thread (maybe not completely, though, it is long and muddled), others, the manuals, enough that I can quote most of those hp/tq/ci numbers for the different engines pretty close off the top of my head.
BTW, when you refer to the LDT 465, you're actually referring to the LDS 465, right? The T is like 130hp, 330tq if I remember correctly.

I have no illusions that the 427 is a rocket or the most powerful multi. I would love to have one so I could have an original A1, but that's beside the point, my LDS 465 will do.
My thought was this...if the 427 is smaller (ci) than the LDT 465, but makes more power and given the seat of the pants feel that they are reported to have (maybe better midrange power/quicker boost?), maybe there is something to that turbo...I know JasonS has done some turbo testing (4LE-354 like my LDS 465 has) and I was wondering how many psi the the 4-456 might have produced, and how quickly, with gauges and the fuel turned up. Jack in Tucson has told me stories of turning them up in the service in Germany and said they did pretty good.

One detail I learned, or noticed that I hadn't before, is that like you said, the two LDS turbos are almost the same numbers.

Sidenote, I suspect the 427's reputed unreliability may have been from too much boost from trying to make too much power out of too few cubic inches.
 
S

stb64

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23 may 2015 021.jpg23 may 2015 016.jpg23 may 2015 011.jpg23 may 2015 015.jpg23 may 2015 018.jpg23 may 2015 022.jpg
Turbochargers 4-456, the bigger one , used on the LDS 465-1 (not -1A !!!), and 4D-454C, the smaller one, used on late LDS 427-2 engines (TM 9-2815-204-35 is wrong, it's not just 4D).
I moved the turbos around taking the pictures, don't let that confuse you, the 4-456 is the one with the red heat shield.
The last picture shows a 3LM39 non-whistler in the center for size comparison.
The turbos used on the LDS 427-2 are supposed to make a minimum 47"Hg of boost under full load at 2600 rpm, according to the TM. This would mean both, the 4-450, and the 4D-454C.
 
S

stb64

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I was under the impression 47InHg is roughly the same as 23.5 psi, at 2600rpm under full load. InHg(inches of mercury) is not the same as inches of water.
Measuring boost at maximum governed speed is a problem, as the governor won't let the rpm's go any higher under any considerable load, so you don't have any way to know if the pump is injecting maximum fuel. You need a dyno to do that.
The only way I could think of measuring boost, without having a dyno, is to raise governed full load speed to, let's say 2700rpm, and then going up a steep hill under full throttle, 2700 rpm, and wait for the rpm's to drop to 2600, to take the measurement.
 
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JasonS

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47 in Hg = 23 psi. Get the HP48sx calculator for your android phone. It has all of the conversions built in. Who said that they didn't make much boost?
 
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