Starting research ld 465 1c turbo upgrade

V8srfun

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I am starting to research and plan the turbo upgrade for my truck. Because I am planning on using a aftermarket wastegated turbo there are a few more variables than just buying the military upgrade kit and calling it a day. Let’s hear your ideas and opinions on what will work, what precautions need to be taken, and what will not work. The plan is to fund a turbo that will overcome the shortfalls of the factory turbo that is miserably inefficient and can not control its own boost levels. We should not have to be limited to the fuel screw when we want to change how much boost the engine gets. I am trying to keep this as basic as possible and not dump a fortune in it so please keep this in mind.

Some of the obvious things
- Need a turbo only things I am settled on at the moment is it must be t4 flange and internal wastegated
- correcting the injection timing
- pyro and boost gauges
- exhaust size and placement
- boost levels and how it reacts with fueling and egt

I am liking the turbos being sold as Cummins hx35 replacements they seem to have most everything I want. Some of the problems is the compressor outlet is v band and I would rather just have a barb style end where I can directly attach my boost hose. And the wastegate spring pressure is not openly advertised on some of these but the ones that do usually are at 20 or 25 psi. I would rather it be set at 15 and I could adjust for more if desired.

boost pressure threshold of the engine is a factor but I don’t know what to believe on this subject as there are so many opinions and they are wildly different. For example as long as my egt’s are safe I think 25 psi would be safe but I don’t know. Remember I will be using a turbo that will be efficient enough to make boost regardless of where my fuel is set at. For example what will be the difference in how the engine responds to 20 psi at factory fueling compared to turning the fuel up some. For example if I am running 20 psi of boost and can’t get my egt over 975 degrees would you think that that is to much boost.

when adding the turbo in military spec there is a preset injection timing mark that needs to be adjusted. I have read threads where guys have tried to skip this step and the truck wouldn’t run well until the adjustment was made. I am not suggesting to avoid this step but would rather know more about what it actually does and how it effects the engine. For example I understand spark advance timing on a gasoline engine and how adjustment effects the engine but I know nothing about diesel injection timing and what advance or retard will actually do in the combustion cycle.

lets hear your ideas thoughts and concerns
 

gimpyrobb

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I have personally put a turbo on 2 different trucks without changing the timing and they ran great. Could you post a link to the threads that the trucks didn't run well?

These motors have a high comp ratio, I don't think 25psi would be a good idear, but I've only run a pyro, not a boost gauge to know for sure.
 

davidb56

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Bonners Ferry Idaho
I am starting to research and plan the turbo upgrade for my truck. Because I am planning on using a aftermarket wastegated turbo there are a few more variables than just buying the military upgrade kit and calling it a day. Let’s hear your ideas and opinions on what will work, what precautions need to be taken, and what will not work. The plan is to fund a turbo that will overcome the shortfalls of the factory turbo that is miserably inefficient and can not control its own boost levels. We should not have to be limited to the fuel screw when we want to change how much boost the engine gets. I am trying to keep this as basic as possible and not dump a fortune in it so please keep this in mind.

Some of the obvious things
- Need a turbo only things I am settled on at the moment is it must be t4 flange and internal wastegated
- correcting the injection timing
- pyro and boost gauges
- exhaust size and placement
- boost levels and how it reacts with fueling and egt

I am liking the turbos being sold as Cummins hx35 replacements they seem to have most everything I want. Some of the problems is the compressor outlet is v band and I would rather just have a barb style end where I can directly attach my boost hose. And the wastegate spring pressure is not openly advertised on some of these but the ones that do usually are at 20 or 25 psi. I would rather it be set at 15 and I could adjust for more if desired.

boost pressure threshold of the engine is a factor but I don’t know what to believe on this subject as there are so many opinions and they are wildly different. For example as long as my egt’s are safe I think 25 psi would be safe but I don’t know. Remember I will be using a turbo that will be efficient enough to make boost regardless of where my fuel is set at. For example what will be the difference in how the engine responds to 20 psi at factory fueling compared to turning the fuel up some. For example if I am running 20 psi of boost and can’t get my egt over 975 degrees would you think that that is to much boost.

when adding the turbo in military spec there is a preset injection timing mark that needs to be adjusted. I have read threads where guys have tried to skip this step and the truck wouldn’t run well until the adjustment was made. I am not suggesting to avoid this step but would rather know more about what it actually does and how it effects the engine. For example I understand spark advance timing on a gasoline engine and how adjustment effects the engine but I know nothing about diesel injection timing and what advance or retard will actually do in the combustion cycle.

lets hear your ideas thoughts and concerns
the EGT could be misleading. Be careful of a over lean situation...too much boost, not enough fuel.
 

V8srfun

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Altoona pa
I have personally put a turbo on 2 different trucks without changing the timing and they ran great. Could you post a link to the threads that the trucks didn't run well?

These motors have a high comp ratio, I don't think 25psi would be a good idear, but I've only run a pyro, not a boost gauge to know for sure.
I don’t know if I can find the thread any more. I just remember the guy saying the truck ran like crap until he changed the timing. This may have been a isolated incident.

I do not have a target boost number but would not be opposed to running 25 psi if it would be safe.
 

V8srfun

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the EGT could be misleading. Be careful of a over lean situation...too much boost, not enough fuel.
correct me if I am wrong but the way I understand you can not run a diesel to lean. Unlike gas engine that will run high egt spark knock and melt pistons when lean. Where a diesel will run high egt with lack of oxygen and surplus of fuel.
 

davidb56

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correct me if I am wrong but the way I understand you can not run a diesel to lean. Unlike gas engine that will run high egt spark knock and melt pistons when lean. Where a diesel will run high egt with lack of oxygen and surplus of fuel.
 

V8srfun

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That article is talking about extreme lean condition that causes preignition. I have read about this before and it is not easy to get the condition right to do this in a diesel. Basically you need to have a combustion chamber or a piston that has a (hot spot) that causes the preignition. With as much excess fuel that is present especially when turned up these trucks should not have issues with preignition due to lean condition.

note I am just thinking out loud I encourage different opinions so that we can all learn more. My purpose is to learn and put more valuable information in one place.
 

SCSG-G4

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25 psi of boost in an engine that is running 22:1 compression w/o a turbo may be asking for trouble. Just something to think about. If your foot is easy on the pedal, it may last a good long time, conversely if you are trying to set a record sled pulling, you might not make it to the finish line. YMMV.
 

davidb56

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correct me if I am wrong but the way I understand you can not run a diesel to lean. Unlike gas engine that will run high egt spark knock and melt pistons when lean. Where a diesel will run high egt with lack of oxygen and surplus of fuel.
Over boosting with a huge turbo, would show up with low EGT temps but with lack of power, without the addition of more fuel. When you add fuel to your high boost pressures, the EGT goes up. 15-20lbs of boost should be fine for this engine, but I don't know how much more boost would cause head gasket failure, since the engine was originally designed as a NA, and the turbo was added for smoke clean up, rather than much more power. Then there is the piston design for multi fuel configuration. Would that come into play?
 

V8srfun

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I have personally put a turbo on 2 different trucks without changing the timing and they ran great. Could you post a link to the threads that the trucks didn't run well?

These motors have a high comp ratio, I don't think 25psi would be a good idear, but I've only run a pyro, not a boost gauge to know for sure.
 

Crf450x

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It is absolutely 100% IMPOSSIBLE to run a diesel too lean. You can not “over boost with too big a turbo due to lack of fuel”. The boost is DIRECTLY determined by the amount of fuel. (Given a specific engine obviously)

Max boost while maintaining reliability will be determined by how much power/cylinder pressure the engine can stand. It’s also worth noting that advanced timing increases cylinder pressure and temps. I don’t know the answers to that stuff but surely someone has tested the limits before.

I’d start by measuring or researching the stock turbo size and going from there. An hx35 or similar sized turbo would be too restrictive. They’re also t3. You’ll want a larger turbine wheel and housing in relation to the compressor side. Larger displacement engines need a freer flowing turbine side than a similar output, smaller displacement engine.
 

davidb56

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It is absolutely 100% IMPOSSIBLE to run a diesel too lean. You can not “over boost with too big a turbo due to lack of fuel”. The boost is DIRECTLY determined by the amount of fuel. (Given a specific engine obviously)

Max boost while maintaining reliability will be determined by how much power/cylinder pressure the engine can stand. It’s also worth noting that advanced timing increases cylinder pressure and temps. I don’t know the answers to that stuff but surely someone has tested the limits before.

I’d start by measuring or researching the stock turbo size and going from there. An hx35 or similar sized turbo would be too restrictive. They’re also t3. You’ll want a larger turbine wheel and housing in relation to the compressor side. Larger displacement engines need a freer flowing turbine side than a similar output, smaller displacement engine.
I stand corrected. too big would have lag. too small would have excessive exhaust back pressure.
 

V8srfun

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So it seems like there is no negative to regarding the timing when adding the turbo. It will help the turbo be more responsive and decrease static cylinder pressure.

the turbo I am looking is a t4 hot side on a hx35 they are sold as a upgrade for the 5.9 Cummins. I want to do a little more research on a adjustable wastegate that is not crazy expensive so I can dial it down from what it is factory set at.

my goal is not to turn my truck in to something it is not but rather find a more efficient turbo than the ones the military put on them.

 
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