Nice running example of this engine! Liked the fire and sparks from the exhaust! From what I just read on "Wiki" (not verified--someone must have the manuals on these), the "Series 51" actually displaced 54 cu. in./cylinder; the "51" designation was the year of intro (from the same article, the "2-51" and "4-51" were produced 1951-59)...
This is a Schnuerle ported engine, like a 2 stroke gas engine. But unlike the gas engine it is blown rather than crankcase scavenged. This type porting does not have a flat torque curve nor is it as efficient, but it’s very simple and a good fit for many apps. A 2cycle variation is the stepped piston (gas) engine (Bernard Hooper Engineering) that eliminates the supercharger, (but has reed valves) Wet sump lubrication. Applied to a diesel...can’t get simpler. During 70’s fuel crunch, DDA tried spinning up the turbo with lube oil power to rid the supercharger. I guess it didn’t work out. Cheers
Welp, thanks to the internet l just learned about a engine l thought l knew a lot about. I've got a 1954 4/71GM in my boat. And a big fan of the Jimmy. Very cool! Edit: what a engine for a light weight 4x4!!!
First 51 series I've heard run. Very similar to my 53, but I can understand the advantages of the valve-less design. Thanks for the look-see. Be neat to see one of these all cleaned up on a running display stand!
themotorfreak1 Yeah, anything mechanically powered by the engine zaps some HP. It all adds up. That's why I've always liked the idea of the turbos over the Roots, but in this case the Roots is a necessity right from start up. Plus, no spin-up delay as in the bigger turbos. Electric cooling fans are a plus, too. Still like to see one of these 51's in person! ;-)
@@anthonyyoung7344 Yes, that is true as I was comparing his valve-less 51 to my exhaust valved 53. The 51 simply negated the need for the crankcase induced scavenging required during the intake stroke by using the blower. Aside from that, the 51 series was as simple as most all other valve-less 2 strokes while maintaining a common crankcase containing lube oil.
This engine did not have valves. Another video of the engine shows only the injector pushrods/rockersDD experimented with this but found better performance using an exhaust valve configuration. If you watch this video carefully you can se the exhaust ports on the closeups.
The sled engines are loop scavenged and make well over 3hp/cubic inch, just look at the Rotax 850 ETEC with direct injection. But the uniflow 2 strokes were probably faster accelerating and were easier to tune, not sure.
+Turbo617 Since I am unaware of the depth of your knowledge of Detroit Diesel engines, I won't focus on an explanation in that direction. What you can not see, however, is that I had in fact, plugged the holes and filled the water jacket during the running process and subsequently drained it off afterwards just to see how much it warmed in the two to three minutes of running. There was hardly a change in temperature, most likely because that there is so much iron in those engines it takes forever to warm them up. The exhaust manifold never warmed either. I had a dump truck with a 500 c.i. DD and it would take 8 miles of driving under load before it would throw any heat.
Just think if DD would have used a regular injection pump (like a Bosch rotary) you could have had a complete "flat head" with just water and injector holes. I even thought about an 8 port pump running half crank speed (for durability) and DUAL alternating injectors per cylinder...when one injector fails you only loose 1 power pulse out of 2 crank revolutions...its not a simple as the rack and rocker injection...but more precise.
I was just reading that they were extremely noisy engines . I wonder what one would sound like with a turbo on it ? Turbo 4:53 s are a lot Less noisy than a non turbo 53 series engine .
I have some turbo injectors off a low hour 6v53t they are freed up and had clean diesel in them engine just had water in it so it rusted the cylinders very bad
This early design was very similar to a gasoline powered two stroke in that there are ports in the cylinder walls on opposite sides. One for relieving exhaust and the other set for admitting fresh air for combustion. The exhaust ports in this video are visible with flames. The addition of actual exhaust valve(s) similar in function to a four stroke engine was made to more efficiently move gasses through the engine. However, more mechanisms mean more complexity and more weight. But, it did improve performance.
No...The 51 series did not, they were *loop scavenged* with Intake AND Exhaust PORTS much like a normal 2-Stroke gasoline engine (but with crankcase oil instead of premix), and the injection system was designed to spray the fuel upward against the head, not into a piston bowl...Now, the 53/71/92/110/149 Series were *uniflow scavenged* with Exhaust valves.
53 and they did have exhaust valve's as far as I know, at least every one I opened up did, only in my late 20s, spend a few early summers fixing pumps and power units with 4 and e 71s and 4 53s all had air starters unfortunately think there was a buda in there with an electric start. I'd like to see a valveless design, what's under the valve cover?
I've got a video of that somewhere..... but no, the only rockers on this motor were for the injectors. If you watch carefully in this (crude) video you can actually see the exhaust ports being lit up when I shoot in the manifold. I'll see if I can find the old "pre" start video when I first got the motor. Long time ago...
@Mr Sunshines... if YOU were paying attention to what DRNEGOLICIS was saying... He was referring to the series 53 & 71 engines having exhaust valves. He even said in his closing sentence that "I'd like to see a valveless design, what's under the valve cover?".
Hekili..... Unlike the other series of GM Diesels (they were Not marketed as Detroit Diesel until mid-1965), the Series 51 engines (only inline, 2 & 4 cylinder versions made) were numbered by the first year of production, whereas the other 5 series were numbered by the ci displacement per cylinder.... ie: 53, 71, 110 etc. The 2 cylinder series 51 was used mostly in smaller generator & welding sets and occasionally in irrigation pump systems, whereas the 4 cylinder series 51 engines were largely used in marine applications in smaller commercial fishing & crew boats, etc. and were revered for their fuel efficiency and reliability. They also were the only GM Diesel series that was Loop Scavenged ("Day Cycle" - valveless), but did use a Roots-type Blower (Non-pressurizing, positive air displacement) to provide air for combustion and scavenging. The other 5 series were all of the Uniflow design (aka Clark Cycle) utilizing Intake ports in the cylinder liner and exhaust valves only in the head (both, 2 & 4 valve heads were available for the Series 53 & 71 engines up until around 1964 or 65, after that... the heads were available with 4 valves per cyl. only.
I think he meant low ash motor oil..All the 2 cycle detroits perform the best with monograde 30 or 40 weight low ash motor oil. they slobber much less with that inside of them rather than something like rotella 15w-40...lol
Exactly! You see a lot of guys out there trying to cold start diesels with the throttle in idle position. You should put the throttle in max setting while starting and as soon as it catches release the throttle.
A Detroit Diesel whatever series starts in full fuel even when the throttle is in the idle position. When the engine turns over and starts, the flyweights in the governor fly outward and slow the speed down to where the throttle lever is at when it starts. It’s best in cold weather to hold the stop lever and crank the engine over a bit and then let the stop lever go, doing that creates heat in the cylinders first then letting the stop go let’s fuel to be injected into a warm cylinder, resulting in a faster start. If you don’t do this your injecting maximum cold fuel into a cold cylinder. A lot of people in cold weather use either on a hard starting engines and only make things worse because they spray too much in the intake and ends up breaking the top rings when whatever cylinder fires first.
@@harryward1608 That makes sense now that I think about it. I am most familiar with Macks, which were externally injected and you had to hold the throttle down to get full fuel. Thanks for the clarification.
Does this have oil injection or a force fed oil from the bottom. It looks like it could have a lot of power for its size. Valveless 2 stroke like the new 850 Rotax hit well over 3hp per CID. I think this was a 9 port motor, not sure?
you don't know much about Detroit diesels this is a 4-71 not a 4-51 which means is has 4 cylinders at 71 cubic inches each and yes it has exhaust valves the older ones had 2 valves per cylinder and the later ones had 4 valves per cylinder . it has no intake valves the air is pumped IN by the Roots blower through port holes in the cylinders and the blower also pushes the exhaust gasses out .
My other video on this engine shows the rocker cover off, clearly viewing one rocker per cylinder, which is the injector. This design proved ineffective, thus later models had valves added. Close observation of the engine running in the video one can see the exhaust ports in action. This engine is often misinterpreted as you describe.
@@kendallmarquardt9583 my appoliges i have been schooled i have been working on and still run Detroit diesels for about 38 years now and i have never herd of the 51 series engines . i am now very interested in these engines and am trying to find information on them . again my apoliges .
@@crankycrow7371 this engine came from a Road grader. I came across an excellent article with more info but can’t find and will have to re-dig. I believe it said that the 51 was for the year production started and actual displacement was 53 ci per cylinder. Production ceased in ‘59 as I recall. No worries, it’s a common misconception because everyone is used to the DDs with exhaust valves. I didn’t realize how rare it was when I owned it. I’ll link the article…..when I find it again.
It's not crankcase scavenged, there's a roots blower for scavenging. And he's talking shite, it has valves. Google it if you want to see how exactly it works. Some Turner diesels or the Sachs D500 engines, now that are actually valveless, port controlled two-stroke diesels. Turner usually with a blower and conventional sump lubrication, the Sachs with crankcase scavenging and total loss lubrication. Shit just gets burned together with the diesel fuel, and surprisingly they don't smoke that much, usually even way less than a gasoline two stroke with 2% premix. Maybe the right oil is able to ignite in a diesel cycle or they just need way less than a conventional gasoline two-stroke, idk.
If it is truly a 51 series and not a 53 then no it did not have valves. Plenty of info out there about them. They were not produced for a long time as the 53 series quickly replaced them.
@@heinzhaupthaar5590 You're the only one talking "shite" the 51 series is NOT THE SAME as the 53 Series... This Video is of the 51...Which ONLY has the Unit Injector in the cylinder head, it has Exhaust Ports and Intake Ports much like the Fairbanks-Morse 32 Series engines, but unlike the F-M engines this one doesn't use crankcase intake pressure for scavenging, it uses the Roots Blower...
Tom Christman.... Sorry, that is Not true... the series 51 engines were Very fuel efficient and the fishermen (most all of the 4 cylinders were marine apps for small commercial fishing boats) back in the day, loved them for their reliability and fuel efficiency.
@@Romans--bo7br Yes they were fuel efficient compared to a gasoline engine, but obviously Detroit didn't pursue that way of producing their engines. You'll notice that there are no 2 stroke Diesels made this way anymore. The only valveless 2 stroke made now is the opposed piston-like Fairbanks Morse and Achates (excited about this engine!).
These are blower loop scavenged..not uniflow..only made 2-51 and 4-51...anyone who thinks this isn't true hasn't opened up one of these odd pieces of DD engineering.
M Shultz-Very true my uncle has one sitting in his shop on a homemade stand with very low hours its an odd but cool piece of iron...only thing that that rocker assembly works Is the injectors!! Not a lot of these around running that ive seen or heard of anymore except for on here.
Not this one and an850 ETEC rotax has a sliding variable exhaust valve and it produces much more power for it size than any 2 stroke detoit. These were great engines for its time but they would melt with the HP per cubic inch of a modern 850 Rotax Etec as they produce nowhere near the power for ther size as a moderns Rotax engine can. Todays 2 strokes are way more powerful!
Nice running example of this engine! Liked the fire and sparks from the exhaust! From what I just read on "Wiki" (not verified--someone must have the manuals on these), the "Series 51" actually displaced 54 cu. in./cylinder; the "51" designation was the year of intro (from the same article, the "2-51" and "4-51" were produced 1951-59)...
It looks like plasma coming out of the exhaust ports.
This is a Schnuerle ported engine, like a 2 stroke gas engine. But unlike the gas engine it is blown rather than crankcase scavenged. This type porting does not have a flat torque curve nor is it as efficient, but it’s very simple and a good fit for many apps.
A 2cycle variation is the stepped piston (gas) engine (Bernard Hooper Engineering) that eliminates the supercharger, (but has reed valves) Wet sump lubrication. Applied to a diesel...can’t get simpler.
During 70’s fuel crunch, DDA tried spinning up the turbo with lube oil power to rid the supercharger. I guess it didn’t work out. Cheers
quantos hp ?
@@aliriogomes5451 I don’t know.
Detroit Diesel Power The sound of victory. USA1 GM1
Welp, thanks to the internet l just learned about a engine l thought l knew a lot about. I've got a 1954 4/71GM in my boat. And a big fan of the Jimmy. Very cool!
Edit: what a engine for a light weight 4x4!!!
Any sighting of parts, or rebuild tips?
First 51 series I've heard run. Very similar to my 53, but I can understand the advantages of the valve-less design. Thanks for the look-see. Be neat to see one of these all cleaned up on a running display stand!
enginenut5 no valves to reduce HP, i would guess. valves take HP away from the engine to operate.
themotorfreak1 Yeah, anything mechanically powered by the engine zaps some HP. It all adds up. That's why I've always liked the idea of the turbos over the Roots, but in this case the Roots is a necessity right from start up. Plus, no spin-up delay as in the bigger turbos. Electric cooling fans are a plus, too. Still like to see one of these 51's in person! ;-)
The 453 Detroit did have valves just like all the other Detroit's if that didn't have valves Thay want run.
@@anthonyyoung7344 Yes, that is true as I was comparing his valve-less 51 to my exhaust valved 53. The 51 simply negated the need for the crankcase induced scavenging required during the intake stroke by using the blower. Aside from that, the 51 series was as simple as most all other valve-less 2 strokes while maintaining a common crankcase containing lube oil.
@@enginenut5 qwantos hp ??
So silky smooth
This engine did not have valves. Another video of the engine shows only the injector pushrods/rockersDD experimented with this but found better performance using an exhaust valve configuration. If you watch this video carefully you can se the exhaust ports on the closeups.
The sled engines are loop scavenged and make well over 3hp/cubic inch, just look at the Rotax 850 ETEC with direct injection. But the uniflow 2 strokes were probably faster accelerating and were easier to tune, not sure.
bruce, pull your head out. this is a diesel engine running in this video.
I love these old high tech 2 strokes they are awesome, all I have is a boring old fart omc rotary sled motors,
qwantos hp ??
The engine has been sold. Thanks for watching. Who knows what the next project will be. Got a couple of ideas...
+Turbo617 Is this literally all you do? Sit at your computer and shit on everyone else's videos and forum posts?
+Turbo617 Since I am unaware of the depth of your knowledge of Detroit Diesel engines, I won't focus on an explanation in that direction. What you can not see, however, is that I had in fact, plugged the holes and filled the water jacket during the running process and subsequently drained it off afterwards just to see how much it warmed in the two to three minutes of running. There was hardly a change in temperature, most likely because that there is so much iron in those engines it takes forever to warm them up. The exhaust manifold never warmed either. I had a dump truck with a 500 c.i. DD and it would take 8 miles of driving under load before it would throw any heat.
*****
Turboshit.
Just think if DD would have used a regular injection pump (like a Bosch rotary) you could have had a complete "flat head" with just water and injector holes. I even thought about an 8 port pump running half crank speed (for durability) and DUAL alternating injectors per cylinder...when one injector fails you only loose 1 power pulse out of 2 crank revolutions...its not a simple as the rack and rocker injection...but more precise.
If I remember correctly
These engines had 54
Cubic inches per cylinder
They were called 51
Series because they were introduced in 1951
I was just reading that they were extremely noisy engines . I wonder what one would sound like with a turbo on it ?
Turbo 4:53 s are a lot
Less noisy than a non turbo 53 series engine .
its already supercharged, recirculation like that wouldnt work from my understanding
Have a Marinized 4-51, NEED INJECTORS or tips on finding them, or rebuild if possible.
I have some turbo injectors off a low hour 6v53t they are freed up and had clean diesel in them engine just had water in it so it rusted the cylinders very bad
man that thing sounds pissed off
Wonder what service these were used for? It sounds like it can be used for serious work!
This one was reportedly out of a road grader; serious work you bet!
I find your description interesting...how is a valveless 2-stroke engine any more 2-stroke than one with valves?
This early design was very similar to a gasoline powered two stroke in that there are ports in the cylinder walls on opposite sides. One for relieving exhaust and the other set for admitting fresh air for combustion. The exhaust ports in this video are visible with flames. The addition of actual exhaust valve(s) similar in function to a four stroke engine was made to more efficiently move gasses through the engine. However, more mechanisms mean more complexity and more weight. But, it did improve performance.
All GM 2strokes have exhaust valves. Some 2, others 4 per cylinder
No. This is a 4-51 the 51 series does not have valves.
No sir, the 51 series did not.
No...The 51 series did not, they were *loop scavenged* with Intake AND Exhaust PORTS much like a normal 2-Stroke gasoline engine (but with crankcase oil instead of premix), and the injection system was designed to spray the fuel upward against the head, not into a piston bowl...Now, the 53/71/92/110/149 Series were *uniflow scavenged* with Exhaust valves.
@@misters2837 qwantos hp ??
@@vilivuorinen8096 qwantos hp ??
53 and they did have exhaust valve's as far as I know, at least every one I opened up did, only in my late 20s, spend a few early summers fixing pumps and power units with 4 and e 71s and 4 53s all had air starters unfortunately think there was a buda in there with an electric start. I'd like to see a valveless design, what's under the valve cover?
I've got a video of that somewhere..... but no, the only rockers on this motor were for the injectors. If you watch carefully in this (crude) video you can actually see the exhaust ports being lit up when I shoot in the manifold. I'll see if I can find the old "pre" start video when I first got the motor. Long time ago...
@Mr Sunshines... if YOU were paying attention to what DRNEGOLICIS was saying... He was referring to the series 53 & 71 engines having exhaust valves. He even said in his closing sentence that "I'd like to see a valveless design, what's under the valve cover?".
Second old post for this engine: th-cam.com/video/ZXImcVzqZ7M/w-d-xo.html
I’ve never heard of 51 series 🤔
Hekili..... Unlike the other series of GM Diesels (they were Not marketed as Detroit Diesel until mid-1965), the Series 51 engines (only inline, 2 & 4 cylinder versions made) were numbered by the first year of production, whereas the other 5 series were numbered by the ci displacement per cylinder.... ie: 53, 71, 110 etc.
The 2 cylinder series 51 was used mostly in smaller generator & welding sets and occasionally in irrigation pump systems, whereas the 4 cylinder series 51 engines were largely used in marine applications in smaller commercial fishing & crew boats, etc. and were revered for their fuel efficiency and reliability.
They also were the only GM Diesel series that was Loop Scavenged ("Day Cycle" - valveless), but did use a Roots-type Blower (Non-pressurizing, positive air displacement) to provide air for combustion and scavenging.
The other 5 series were all of the Uniflow design (aka Clark Cycle) utilizing Intake ports in the cylinder liner and exhaust valves only in the head (both, 2 & 4 valve heads were available for the Series 53 & 71 engines up until around 1964 or 65, after that... the heads were available with 4 valves per cyl. only.
Getting to close to the exh ports and that thing backfires, ouch
Still for sale?
Are you using a low ash oil? Its supposed to burn cleaner in 2 strokes.
Bruce Miller: you don't mix the oil like a 2 cycle engine
I think he meant low ash motor oil..All the 2 cycle detroits perform the best with monograde 30 or 40 weight low ash motor oil. they slobber much less with that inside of them rather than something like rotella 15w-40...lol
They do burn some of it though as it works its way past the ports
They do burn some of the oil up
Raridade este 51.
qwantoz hp??
Qwantwz hp??
I watch so many of these guys dickin around with diesels and none seem to know that you start them at full fuel and pull it back when they start.
Exactly! You see a lot of guys out there trying to cold start diesels with the throttle in idle position. You should put the throttle in max setting while starting and as soon as it catches release the throttle.
A Detroit Diesel whatever series starts in full fuel even when the throttle is in the idle position. When the engine turns over and starts, the flyweights in the governor fly outward and slow the speed down to where the throttle lever is at when it starts. It’s best in cold weather to hold the stop lever and crank the engine over a bit and then let the stop lever go, doing that creates heat in the cylinders first then letting the stop go let’s fuel to be injected into a warm cylinder, resulting in a faster start. If you don’t do this your injecting maximum cold fuel into a cold cylinder. A lot of people in cold weather use either on a hard starting engines and only make things worse because they spray too much in the intake and ends up breaking the top rings when whatever cylinder fires first.
@@harryward1608 That makes sense now that I think about it. I am most familiar with Macks, which were externally injected and you had to hold the throttle down to get full fuel. Thanks for the clarification.
@@harryward1608 qwantoz hp ??
Does this have oil injection or a force fed oil from the bottom. It looks like it could have a lot of power for its size. Valveless 2 stroke like the new 850 Rotax hit well over 3hp per CID. I think this was a 9 port motor, not sure?
a oil sump like a 4 cycle
you don't know much about Detroit diesels this is a 4-71 not a 4-51 which means is has 4 cylinders at 71 cubic inches each and yes it has exhaust valves the older ones had 2 valves per cylinder and the later ones had 4 valves per cylinder . it has no intake valves the air is pumped IN by the Roots blower through port holes in the cylinders and the blower also pushes the exhaust gasses out .
My other video on this engine shows the rocker cover off, clearly viewing one rocker per cylinder, which is the injector. This design proved ineffective, thus later models had valves added. Close observation of the engine running in the video one can see the exhaust ports in action. This engine is often misinterpreted as you describe.
Wrong. It’s a 4-51. They were only produced for 10 years, they were made obsolete by the 53 series
@@kendallmarquardt9583 my appoliges i have been schooled i have been working on and still run Detroit diesels for about 38 years now and i have never herd of the 51 series engines . i am now very interested in these engines and am trying to find information on them . again my apoliges .
@@TugboatMatt my apoliges i was wrong and have learned something new . what were the 51 series found in and how many cylinders were offered .
@@crankycrow7371 this engine came from a Road grader. I came across an excellent article with more info but can’t find and will have to re-dig. I believe it said that the 51 was for the year production started and actual displacement was 53 ci per cylinder. Production ceased in ‘59 as I recall. No worries, it’s a common misconception because everyone is used to the DDs with exhaust valves. I didn’t realize how rare it was when I owned it. I’ll link the article…..when I find it again.
What keeps the oil from being pushed out the exhaust port?
It's not crankcase scavenged, there's a roots blower for scavenging.
And he's talking shite, it has valves.
Google it if you want to see how exactly it works.
Some Turner diesels or the Sachs D500 engines, now that are actually valveless, port controlled two-stroke diesels. Turner usually with a blower and conventional sump lubrication, the Sachs with crankcase scavenging and total loss lubrication.
Shit just gets burned together with the diesel fuel, and surprisingly they don't smoke that much, usually even way less than a gasoline two stroke with 2% premix.
Maybe the right oil is able to ignite in a diesel cycle or they just need way less than a conventional gasoline two-stroke, idk.
If it is truly a 51 series and not a 53 then no it did not have valves. Plenty of info out there about them. They were not produced for a long time as the 53 series quickly replaced them.
A second set of rings on the bottom of the pistons. When the piston is at top dead center the oil rings are still below the intake port
@@heinzhaupthaar5590 You're the only one talking "shite" the 51 series is NOT THE SAME as the 53 Series... This Video is of the 51...Which ONLY has the Unit Injector in the cylinder head, it has Exhaust Ports and Intake Ports much like the Fairbanks-Morse 32 Series engines, but unlike the F-M engines this one doesn't use crankcase intake pressure for scavenging, it uses the Roots Blower...
Ok
qwantuz hp ??
Hello, I do not know that information- sorry
3 minutes of running with no coolant to cool them kits down..
No where as fuel efficient. That's why all other Detroits have exhaust valves.
Tom Christman.... Sorry, that is Not true... the series 51 engines were Very fuel efficient and the fishermen (most all of the 4 cylinders were marine apps for small commercial fishing boats) back in the day, loved them for their reliability and fuel efficiency.
@@Romans--bo7br Yes they were fuel efficient compared to a gasoline engine, but obviously Detroit didn't pursue that way of producing their engines. You'll notice that there are no 2 stroke Diesels made this way anymore. The only valveless 2 stroke made now is the opposed piston-like Fairbanks Morse and Achates (excited about this engine!).
Another old post for this engine:
th-cam.com/video/OW_ZhZ_wCcU/w-d-xo.html
Ex valve's
All GM -Detroit engines have EXHAUST -VALVES (2 or 4 )but no inlet ones !
These are blower loop scavenged..not uniflow..only made 2-51 and 4-51...anyone who thinks this isn't true hasn't opened up one of these odd pieces of DD engineering.
M Shultz-Very true my uncle has one sitting in his shop on a homemade stand with very low hours its an odd but cool piece of iron...only thing that that rocker assembly works Is the injectors!! Not a lot of these around running that ive seen or heard of anymore except for on here.
Not this one and an850 ETEC rotax has a sliding variable exhaust valve and it produces much more power for it size than any 2 stroke detoit. These were great engines for its time but they would melt with the HP per cubic inch of a modern 850 Rotax Etec as they produce nowhere near the power for ther size as a moderns Rotax engine can. Todays 2 strokes are way more powerful!
but they don't make 1/3 of the torque as these did or do...
I wished that I’ve known it was for sale if would had brought it asap