To be clear here, I've never

To be clear here, I've never heard of a 645D being used to refer to test bed engines. It is actually a rebuild label.

A little understanding of EMD 2 cycle engine construction and nomenclature will go a long way here.

First the engine consists of the Crankcase and the Power assemblies. The power assemblies are the cylinder, cylinder liner and assorted parts on it. You mention that the Bore and Diameter of the 567 and 645 changed, this is redundant. Bore and Diameter mean the same thing. The 645 and 567 share the same stroke 10", but they have different bores. And the bore is adjusted by changing the size of the cylinder liner the entire power assembly is the same size. So the 567 assemblies and the 645 assemblies are the same size from the exterior. But the 645 has thinner assembly walls. And because of this, a 645 assembly can be fitted to a 567A/C B/C, C and D crankcase. So almost any early 567 engine running today is actually running with it's 567 Crankcase and 645 power assemblies.

The letter suffix in the engine name refers to crankcase mods. As you correctly point out, the A-C suffix refer to changes from water deck to water manifold (Water Jacket)cylinder cooling. The D suffix refers to the crankcase changes to support the turbocharger models. The follow on number then refers to the Turbocharger application. 1 and 2 were early applications, but from GP30 on, 3 refers to railroad turbo, 7 refers to Marine turbo

So a 645D3 is a 567D crankcase with 645 power assemblies and a railroad turbocharger. Likely good for around 2300-2500 HP depending. 

No switchers were equipped with D series crankcases, because no switchers were ever made with turbochargers. They all used blowers. 

Also, your dates on F units is wrong. The last FL9 was built in november of 1960, the last FP9 was built December of 1959 and the last F9 was built May of 1960.

Cool!

I new I had the Bore/Diameter/Stroke thing wrong. I had it visualized in my head, but clearly flubbed it in print.

Thanks for clearing up the water deck/manifold/jacket evolution. I knew that was the primary issue with the early 567's.

The 645'D' I had seen used in reference to the test beds of 1964, Namely 433A (GP40 on a GP35 frame) and the first SD40's 434, 434A to 434H (built on SD35 frames), and EMD F9 462.

William L

What does the E4 on a

What does the E4 on a 20-645E4 designate?

E4 appears to be another

E4 appears to be another Marine Designation.

A 16-645E4 was used in the giant Titan Dump truck, but most other references are to marine engines. So it could simply be that the moved from E4 to E7. I do not claim to understand all of EMD's naming conventions. Only the big picture items.

I know for example that the 710G7 is the only model in marine applications and 647E7/F7 is the stated Marine Application crank/Turbo combination.

So I presume E4 was an intermediate design from the late 60s/early 70s. 

I don't know that for sure though. 

The 6 series Turbo denotes stationary applications. 

The 645'D' I had seen used in

F9 462 was rebuilt from a C&NW F7, so it's a rebuild

These demos being 645D doesn't have to conflict with the more common usage of the term.

As I mentioned before, the physical dimensions of the 567 and 645 crankcase are effectively the same. So  The experimental units likely simply had existing 567D crank cases with the new power assembly installed. This is effectively the same as what GP30 and GP35 rebuilds got. The results of those tests likely showed the need for modifications to the crankcase to support 3000HP resulting in the E series. 

The F series was likely built primarily to support the increase to 950 RPM.

The F9 is presumably the test bed for the roots blown application that would become the 645E in the GP38 and the switchers. 

FT 567s

Interesting stuff

So if the 567 and 645 are basically the same assemblies, does that mean that the Walthers model of the 567 can also represent the 645 fairly closely? Are the differences basically related to the exhaust manifold or blower or turbo mount/assembly (or attached generator/alternator)? Or is there more to it?

Craig

Well, if I recall correctly,

Well, if I recall correctly, the Walters model is a 567A with the square access doors. So that would not be a good example of a 645. 

For clarity, the crankcase is mostly the same with changes made as horsepower increased. so stiffining, refinements etc etc. The assermblies were different, But  big picture yes, the differences would be in the generator/alternator attached and the turbos

EMD Diesel Engines

Hi Yoho, EMD 645 and 710 has round air box covers and crankcase covers. The 567 has the square air box covers and crankcase covers.  

The Alternator or Generator, depending on locomotive model is always attached to the crankshaft at the rear of the diesel engine. Remember the front of the diesel engine faces the rear of the locomotive. The roots blowers or turbo are always attached to the rear of the diesel engine on 567, 645 and 710 diesel engines. The turbo on the 1010 is now on the front of the diesel engine just like GE diesel engines. On EMD diesel engines you either have roots blowers, one roots blower for each bank or a turbo, which is actually a super charger, meaning the turbo is gear driven from notches 1 thru 5, at notch 6 the clutch pack disengages and the turbo is driven off the exhaust gases. What's the biggest differences between the 567, 645 and 710, the displacement and I'm guessing everyone already knows 567, 645 and 710 is the displacement of one cylinder? Also the 567, 645 and 710 are all two stroke diesel engines, hence they need constant air box pressure to push out the exhaust and force clean air into the cylinder, while the new 1010 is a four stroke, so it now has intake values in addition to the exhaust values. In the two stroke EMD diesel engine, the piston acts like the intake valve. 

Also while talking about EMD diesel engines, it worth noting the 567 and 645 diesel engines are mechanically controlled, i.e. they have mechanical governors, the 710 and 1010 diesel engines have electronic governing devices known as EMDEC. Now instead of having a mechanical device determine when the injector fires, a electronic device determines when the injector fires and how much fuel the injector fires based on the injectors cal code. Without getting too deep into the subject, this helps the diesel engine meet EPA requirements. 

Corrections galore. Hi Yoho,

Corrections galore.

Again, this is not true. The early 567A had square covers the 567C and 567D had round covers just like the 645 see picture.

What you say is mostly true, but you're confusing things.

1: A roots blower is a supercharger. Blower is another term for supercharger as any hotrodder could tell you.

EMD 2 Cycle diesels require positive airflow for the scavanging to work. It's not like a lawn mower or chain saw.

2: The turbocharger on an EMD 2 cycle diesel is NOT a supercharger. It i a true turbo...AND a supercharger at the same time. It has a free running clutch. At low speeds it is engaged and positive airflow is provided like a supercharger. At high speed the clutch disengages and the turbo free runs like a real turbocharger.

It's an ingenious design. 

Also, to be clear, the EMD 2 strokes use what's called unit injection on the intake. It's driven off the cam. your statement that all 710s have electronic unit injection is false. Only units built after 1995 or rebuilt have it. The GP/SD60s do not.

Engine cross section

If anyone's interested, here's an EMD engine cross section with the parts labeled.

Question for YoHo

Regarding the Roots Blower as a Supercharger.    Just had this discussion with my brother who is more automotively interested.   He was asking about how big block automotive engines typically use the roots blower from smaller Detroit Diesel models.   The most common are from the X-71 series, i.e. 6-71 or 8-71.   Just because it is used as a super charger on the automotive block does not seem to me to make it a Supercharger on the diesel prime mover.    Correct me if I am wrong, but the purpose of a true supercharger is the same as a turbocharger....to force more air into the intake stream to allow more fuel to be atomized, thereby creating a larger combustion in the same volume.

I was under the impression that the Roots Blower, as you mentioned earlier, is simply to scavenge air through the system to clear the exhaust and remove unburned fuel, depleted oxygen, what have you from the cylinder combustion chamber before admitting the next cycle of air and fuel before compression.

To me, that makes supercharging vs roots blowing completely different entities.  IIRC, the primary difference between supercharging vs turbocharging is the means of spinning the impeller...turbo uses exhaust gas to spin a small turbine geared to the compressive mechanism, whereas the supercharger is direct geared to some take off on the mechanical side of the prime mover(i.e. shafts/gears on a diesel, a belt take off of the crank on an automotive engine.)

looking forward to your take on this.

This is a simple answer. The

This is a simple answer. The definition of Supercharger is: "An air compressor that increases the pressure or density of air supplied to an Internal Combustion Engine."

That is what the device on the EMD does.

Technically a Turbocharger is also a supercharger, but common American English usage is that Supercharger only ever refers to mechanically driven compressors.  

The Roots Blower company was founded in 1859 in Connersville Indiana by Philander and Francis Roots

They invented(and patented) the Roots Blower.The Roots Blower is the most common type of positive displacement supercharger used in Automotive applications. It is also the manner in which EMD AND DD get air pressure for the 2 cycle intake. 

Daimler was the first car company to use a Roots Blower on a car with their Kompressor models.

The Eaton Supercharger in my 1999 Ford Lightning (G-d rest her soul) was a roots blower. 

An interesting paper on the EMD 567

http://utahrails.net/pdf/EMD_567_History_and_Development_1951.pdf

This is written by E. W. Kettering, the chief engineer of the 567 development team. It gets into the nuts and bolts of the design decisions.

EMD Diesel Engines

YoHo, You need to re-read my answer, you're splitting hairs now, but I stand behind what I said, A GE has a true Turbo, i.e. it only runs off the exhaust gases, a EMD Turbo is gear driven from notches 1 thru 5, at notch 6 the clutch pack disengages and the turbo then runs off the exhaust gasses. Ask your hot rodder buddies if a supercharger is gear, chain or belt driven?  Also your term "scavenging" is not correct. The EMD diesel engine maintains a positive air pressure in the air boxes to force the spent gases out the exhaust valves and into the exhaust system, while at the same time supplying fresh air to the cylinder. The only place you should not find a positive pressure is the crankcase.

Yes I agree and I forgot the early SD60's still have a governor, all others up to and including the current SD70Ace's, use EMDEC. SD80's run three ECM's. Rebuilds are also being equipped with EMDEC to help meet current EPA rules. Also you don't have to explain to me how a EMD or GE diesel engine works, I work on these things 5 days a week for a class one railroad. 

Roots Blower vs. Turbo.

They say a picture is worth a thousand words so here goes

Very simply the Roots blowers seen in the photo above supplies pressurized air to the air boxes on the diesel engine, when the piston reaches the bottom of it's travel the ports between the cylinder and the air box are uncovered (the piston acts like a valve in a EMD diesel engine) allowing the pressurized air to force the exhaust out the top of the cylinder while also providing fresh air for the next combustion cycle. When the piston reaches top dead center, the air has been compressed and the injector fires which causes ignition, forcing the piston back down, aka the power stroke. When the piston reaches the bottom of the power stroke the cycle repeats. On a EMD the slang for this is "Blow Bang" on a 4 stroke like the GE diesel engine, it's "Suck, Squeeze, Bang, Blow".

Now on a EMD with a Turbo, (seen in the photo above right above the crankshaft) the turbo replaces the two roots blowers, it supplies compressed air to both the left bank and right bank air boxes. As you mentioned, since it's a turbo it's providing a higher amount of compressed air than a roots blower, allowing the engine to create more horsepower. In other words, what's the difference between a 645 diesel engine in a GP38-2 rated at 2,000 HP and a 645 diesel engine in a SD40-2 rated at 3,000 HP? The GP38-2 has roots blowers and the SD40-2 has a Turbo. Also like I explained above, the EMD Turbo is gear driven up to notch 5, at notch 6 the clutch pack disengages and the turbo is then driven off the exhaust gases.

The purpose of this blog IS

The purpose of this blog IS to split hairs. It's a blog on the details of these engines. The details count.

Scavenging is a term of Art for 2 cycle engines

The EMD requires constant positive air pressure on the intake to enable scavenging is a correct statement.  

Rich, you're the one splitting hairs on the concept of a "true turbo."

A normal turbocharger only does something once engine RPM is sufficiently high that the turbo will work. Otherwise the air charge is just normal air.

So, the EMD turbo and the GE turbo effectively act as turbochargers in the same way. Engine RPM (Exhaust gas speed) hits a critical value and then they boost air pressure.

On a 2 cycle engine, you ALSO need boosted pressure at low engine RPM for the process to work at all. The GE does not.

So, EMD developed the free running clutch so that the turbo charger engages below critical RPM. The physical design of the turbocharger is different from the roots blower Superchargers. So if anything, the EMD is a true turbo + additional features.

Turbo chargers allow higher peak engine HP in EMDs for a number of reasons, not the least of which is parasitic loss. The mechanical drive of the roots blower uses up a portion of the HP across the curve. I'm not sure if that accounts for the full amount. I assume it doesn't and that the turbo is just more effective.

I can't find the HP curves right now (The guys over on trains.com probably have them), but I'm pretty sure that the HP curve for a GP38 and a GP40 are the same up until Notch 6 when the clutch disengages. Any differences below notch 6 are likely due to the efficiency differences between the turbo and the roots blowers. 

Also, Rich, sorry, I don't

Also, Rich, sorry, I don't mean to "Fansplain" to you.

Also, The Kettering book in the definitive resource on the EMD 2 cycle engine.  

Agree to Disagree

Yoho, at this point I'm just going to agree that we disagree over terminology, In my mind a GE has a true exhaust driven turbo while the EMD turbo is only exhaust driven above notch 5. At the end of the day you really don't need to know any of this to change a turbo, power assembly or enter new Cal Codes into the Sender and Receiver when new injectors are applied to a engine with EMDEC. As far as the horsepower curve on a GP40 vs. GP38, I've never calculated the HP for each notch, we are only concerned that the locomotive is making within 10% of the rated HP in notch 8. On older locomotives like the GP38 and GP40 (all of ours have been upgraded to dash 2 electronics) horsepower is calculated using the main alternator voltage and amperage output. 

EMD Turbo Terminology

Hey guys, for the EMD turbo, let's just term it a hybrid turbo.  Close enough? 

Then there is the fun C

Then there is the fun C rebuilds, that use C lower blocks and liners, but the original A/B upper deck and covers with external fuel lines,  or the A/B lower block, and an C airbox and upper deck, thus having square lower crankcase doors, and round airbox doors.  

Rich, I'm all for agreeing to

Rich, I'm all for agreeing to disagree if needed, but maybe we don't need to. 

Do you happen to know, at what throttle position, does the GE Turbo actually provide a boost. My guess is it's close to notch 6. I doubt any Locomotive has a boost gauge the way a car with a turbo does. 

That was my only point, no turbo ever ever in any application provides a boost across the RPM curve. It's takes a certain engine speed for it to engage. So in notch 1, a GE turbo does nothing at all for boost, an EMD turbo is doing something due to the clutch. 

So the EMD does everything the GE does, but then it also does something more.  

I agree none of this is important to a mechanic or shop supervisor working on them...but there are engineers, designers, parts suppliers and yes, fans who either do need to know this or just want to know it.

It's a thing worth knowing to some. 

If calling it a hybrid makes people happy, then sure. If Rich wants to call it not a "true" turbo then sure, but I think that specifically implies it doesn't work like a turbocharger, but it does. Wikipedia calls it a Turbo-compressor, but that makes no sense since a turbocharger is a type of compressor. 

Also, clarification of terms. I was calling it a free running clutch, but it's really an overrunning clutch like a bicycle going down a hill where the wheels are spinning faster than you can pedal.

The clutch is set for 16,000 RPM. When exhaust gases are going strong enough to make it run faster, it goes above 16,000 RPM. I think max is 20,000 RPM. 

Good Discussions

I'm enjoying the discussions and info being provided on this thread. Thanks YoHo and Rich!

Pelham 1-2-3 Can you provided visual documentation. Over. 

William L

GE Turbo

Actually a GE turbo does provide a small amount of boost at idle and notch 1, but really starts producing boost at notch 2 all the way up to full boost at notch 8.

The new tier 4's are even better as they have two turbo's, a low pressure and high pressure turbo.