Injected Diesel 56cc 2 Stroke, Will it ever work?"

[petertha]

Very nice builds!
And also thanks for including link to your channel, I just subscribed. That Arduino Prony brake dyno is just so cool.

 

[Lloyd-ss]

Very nice builds!
And also thanks for including link to your channel, I just subscribed. That Arduino Prony brake dyno is just so cool.

I am glad you liked the Prony brake build. The concept is very straightforward but the execution of it can use a simple spring scale to measure the force, or it can be much more sophisticated.with full electronics and data recording.

 

[Lloyd-ss]

Final Boring for the Bearings

Really getting into the fun stuff now.
This is the outboard support for the one-piece crankshaft being bored for the insert bearing. The bearing O.D. is 27mm. I really love boring on the mill. When the results are good, it is extremely satisfying.
I have no way of measuring the bore accurately enough for the fit that is needed so I measure tot he point I can and then do the final by tweaking the radius adjustment on the boring head, which is a Criterion knock-off. If I go oversize I might be able to lap a little off the bottom of the bearing cap, but I am trying to get it right the first time.

 

[Lloyd-ss]

ROTATING and RECIPROCATING ASSEMBLIES

Even though everything looked more or less complete in the previous posts, there was still a lot of detail work that had to be done. Most of the material choices were based on general experience and not from any engine building. Considering the light duty cycle the engine will see, I think the failures will be minimal.

The bearing inserts are now all installed with proper crush on the O.D. and minimal clearance of the I.D. to the shaft.

First is the piston and rod assy. The wrist pin is stepped and is a press fit into the piston at both ends. It will have Teflon plugs at both ends. The piston has 3 compression rings (purchased) and will have an o-ring with Par-back rings at the bottom to seal the bottom end of the pressurized scavenging system. The basic bore is 38mm. 2 of the rings are 2mm thick and one is 1.5mm. They use 2 different anti-rotation pinning systems and I won't be able to pin them until the cylinder liner is complete and I have an exact angular location of all the lands between the scavenging ports. The cylinder liner is on the lathe right now.





Here is the rotating assembly and I have to say that I am rather pleased at how it actually turned out. Not just the cosmetics, but the bearing fits and the way it almost rotates completely freely but has no shake in the bearings. The crank is one piece and has 2 tungsten counter weights with which I had help of a program to figure their needed weight. Much more to come on the balancing. Getting the assy to rotate so nicely with the 3 independent bearing blocks was a fun challenge. Difficult and easy at the same time. It was easy to tighten and loosen the caps to find where the tight spots were and either re-bore the rogue bearing block, or change the height or offset of the bearing block. After many steps of "almost have it," it finally settled in nicely.










I am spending way too many hours a day on this but jeezus, it is fun, and the progress is so in-your-face.

Thanks for taking a look!

Lloyd

 

[The Ignoble Troll]

Fantastic!

 

[Nerd1000]

ROTATING and RECIPROCATING ASSEMBLIES

Even though everything looked more or less complete in the previous posts, there was still a lot of detail work that had to be done. Most of the material choices were based on general experience and not from any engine building. Considering the light duty cycle the engine will see, I think the failures will be minimal.

The bearing inserts are now all installed with proper crush on the O.D. and minimal clearance of the I.D. to the shaft.

First is the piston and rod assy. The wrist pin is stepped and is a press fit into the piston at both ends. It will have Teflon plugs at both ends. The piston has 3 compression rings (purchased) and will have an o-ring with Par-back rings at the bottom to seal the bottom end of the pressurized scavenging system. The basic bore is 38mm. 2 of the rings are 2mm thick and one is 1.5mm. They use 2 different anti-rotation pinning systems and I won't be able to pin them until the cylinder liner is complete and I have an exact angular location of all the lands between the scavenging ports. The cylinder liner is on the lathe right now.

View attachment 157628



Here is the rotating assembly and I have to say that I am rather pleased at how it actually turned out. Not just the cosmetics, but the bearing fits and the way it almost rotates completely freely but has no shake in the bearings. The crank is one piece and has 2 tungsten counter weights with which I had help of a program to figure their needed weight. Much more to come on the balancing. Getting the assy to rotate so nicely with the 3 independent bearing blocks was a fun challenge. Difficult and easy at the same time. It was easy to tighten and loosen the caps to find where the tight spots were and either re-bore the rogue bearing block, or change the height or offset of the bearing block. After many steps of "almost have it," it finally settled in nicely.



View attachment 157629

View attachment 157630




I am spending way too many hours a day on this but jeezus, it is fun, and the progress is so in-your-face.

Thanks for taking a look!

Lloyd

Why the stepped gudgeon pin?

 

[Lloyd-ss]

Why the stepped gudgeon pin?

Nerd,
A couple of reasons. The wrist pin hole passes over the pressurized intake ports so the ends of the pin need to be sealed to keep pressurized air from being blown around the pin and into the crankcase. In the Detroit Diesel the pins float and there is a cupped disk (like a Bellville washer with no hole) that is pressed in at both ends of the pin to keep it from coming out and also to from an air-tight seal.

1)I didn't want to try making the sealing cups so instead decided on a press fit to seal the holes in the piston and lock the pin into place. The wrist pin bearing insert in the small end of the rod is 12mm ID x 20mm long, so plenty of bearing surface, so the need for a full floating pin seems unnecessary. The rod only swings +/- 12.5 degrees on the wrist pin, so no high speed rotation to worry about.
2)I didn't want to press the pin all the way thru both sides of the piston, all at the same diameter, so the stepped design only requires a short press for each end, which both occur at the same time. I didn't want the pin to pick up any aluminum from the piston and then deposit it in the rod bearing.
3)Just because I wanted to do it that way, LOL.
4) Not a real reason, but I used 316 stainless for the wrist pin and I had forgotten just how nice a finish you can get on the lathe with the 316. New carbide and all adjustments done properly and you can get a mirror finish.

Lloyd

 

[Nerd1000]

Nerd,
A couple of reasons. The wrist pin hole passes over the pressurized intake ports so the ends of the pin need to be sealed to keep pressurized air from being blown around the pin and into the crankcase. In the Detroit Diesel the pins float and there is a cupped disk (like a Bellville washer with no hole) that is pressed in at both ends of the pin to keep it from coming out and also to from an air-tight seal.

1)I didn't want to try making the sealing cups so instead decided on a press fit to seal the holes in the piston and lock the pin into place. The wrist pin bearing insert in the small end of the rod is 12mm ID x 20mm long, so plenty of bearing surface, so the need for a full floating pin seems unnecessary. The rod only swings +/- 12.5 degrees on the wrist pin, so no high speed rotation to worry about.
2)I didn't want to press the pin all the way thru both sides of the piston, all at the same diameter, so the stepped design only requires a short press for each end, which both occur at the same time. I didn't want the pin to pick up any aluminum from the piston and then deposit it in the rod bearing.
3)Just because I wanted to do it that way, LOL.
4) Not a real reason, but I used 316 stainless for the wrist pin and I had forgotten just how nice a finish you can get on the lathe with the 316. New carbide and all adjustments done properly and you can get a mirror finish.

Lloyd

Makes sense. I do worry about the stress riser from the step given the heavy loads in a diesel, but your pin is pretty big so it will probably be ok.

316 and 304 do turn beautifully, except for the stringy swarf! Not so nice to drill however. I make my gudgeon pins from silver steel.

 

[Lloyd-ss]

Makes sense. I do worry about the stress riser from the step given the heavy loads in a diesel, but your pin is pretty big so it will probably be ok.

316 and 304 do turn beautifully, except for the stringy swarf! Not so nice to drill however. I make my gudgeon pins from silver steel.

Agreed, the 316 swarf could be used for prison razor wire. I have had reasonable success drilling 316 with a sharp drill and as soon as I feel it get under the skin and start to cut, keep the pressure on so that the chip load stays sufficient. And it takes a healthy push to break thru the skin, especially if it has already been inadvertently work hardened in a previous operation.

SILVER STEEL?
What is this silver steel I keep hearing mention of?? It must have a different name in the US.???

Thanks!
Lloyd
P.S. I am not to concerned about the wrist pin breaking (the G word is not spoken in the US.)
But there are plenty of other potential failure points in the system, LOL.

 

[The Ignoble Troll]

SILVER STEEL?
What is this silver steel I keep hearing mention of?? It must have a different name in the US.???

Drilling rod.

The high carbon low alloy steel that is easily tempered. Because it comes bright and clean it got the name "Silver Steel".

Similar to the spring steel around the edges of mattresses.

It is excellent for machinable but can then be tempered to making machining tooling.


Edit to add this link

https://www.metalsupermarkets.com/what-is-drill-rod/

 

[Nerd1000]

Agreed, the 316 swarf could be used for prison razor wire. I have had reasonable success drilling 316 with a sharp drill and as soon as I feel it get under the skin and start to cut, keep the pressure on so that the chip load stays sufficient. And it takes a healthy push to break thru the skin, especially if it has already been inadvertently work hardened in a previous operation.

SILVER STEEL?
What is this silver steel I keep hearing mention of?? It must have a different name in the US.???

Thanks!
Lloyd
P.S. I am not to concerned about the wrist pin breaking (the G word is not spoken in the US.)
But there are plenty of other potential failure points in the system, LOL.

Silver steel is water hardening tool steel typically made to BS 1407 and supplied normalised and centerless ground.

 

[Lloyd-ss]

My shop is getting messier and messier as I can almost sense the finish line in the distance. But I still can't see it!

The cylinder liner was a real test of my patience, but it finally worked out. I started out with some 4340 cond N, chrome moly steel, 2" O.D. x.25" wall. It was expensive. The liner is about 5" long and I machined the O.D. well enough, but darn if I could get the I.D. bored. I used a 4 jaw chuck that gripped the tube for 1.25", along with a steady rest. I tightened up the gibs, tried different tool geometries, speeds and feeds, and even fabricated a 1" dia boring bar. But as soon as I loaded the bar the least little bit, a bad chatter/vibration set in. I could not get it smooth and finally gave up on the 4340.

Next, I bought a piece of A513 Type 5 DOM medium carbon steel. I have used lots of this in the past in .065 and .095" wall and it always came right on size with a beautiful I.D. finish. I even did a hydraulic test-to-failure of a 7/8" O.D. x .065" wall, and it burst at 15,000 psi, which is several percentage points above the mechanical spec.

But the .250" wall was a different animal. Not as pretty in the I.D. and there was a faint witness line from the ERW process, but the I.D measured right on the money. This time I started by honing the I.D. to 38mm, which meant removing only a few thou. I honed out nicely and the new 38mm rings fit nicely. Machining the O.D. wasn't too bad, but the scavenge ports were a chore. The thick wall was needed for the liner flange, but the thick wall had some inclusions and defects, but almost all of them honed out cleanly. The compatibility of the mild steel liner and the aluminum piston has yet to be seen. But it doesn't have to last for a half million miles, LOL.

Here is the finished liner along with the piston. The odd spacing of the ports is to place wider lands for the ring ends at 3 different locations. I think some of the .120" wall A513 Ty5 would have been more defect-free.

Thanks for taking a look.
Lloyd



The photo doesn't show the cross hatch marks but they are very faintly there. I just used a brake cylinder hone with a fine stones.

 

[Lloyd-ss]

Gents, @The Ignoble Troll and @Nerd1000
The silver steel sound like W1 high speed steel/drill rod in the US. Good to know! Thanks for that info, and it is readily available in the US.

 

[Nerd1000]

My shop is getting messier and messier as I can almost sense the finish line in the distance. But I still can't see it!

The cylinder liner was a real test of my patience, but it finally worked out. I started out with some 4340 cond N, chrome moly steel, 2" O.D. x.25" wall. It was expensive. The liner is about 5" long and I machined the O.D. well enough, but darn if I could get the I.D. bored. I used a 4 jaw chuck that gripped the tube for 1.25", along with a steady rest. I tightened up the gibs, tried different tool geometries, speeds and feeds, and even fabricated a 1" dia boring bar. But as soon as I loaded the bar the least little bit, a bad chatter/vibration set in. I could not get it smooth and finally gave up on the 4340.

Next, I bought a piece of A513 Type 5 DOM medium carbon steel. I have used lots of this in the past in .065 and .095" wall and it always came right on size with a beautiful I.D. finish. I even did a hydraulic test-to-failure of a 7/8" O.D. x .065" wall, and it burst at 15,000 psi, which is several percentage points above the mechanical spec.

But the .250" wall was a different animal. Not as pretty in the I.D. and there was a faint witness line from the ERW process, but the I.D measured right on the money. This time I started by honing the I.D. to 38mm, which meant removing only a few thou. I honed out nicely and the new 38mm rings fit nicely. Machining the O.D. wasn't too bad, but the scavenge ports were a chore. The thick wall was needed for the liner flange, but the thick wall had some inclusions and defects, but almost all of them honed out cleanly. The compatibility of the mild steel liner and the aluminum piston has yet to be seen. But it doesn't have to last for a half million miles, LOL.

Here is the finished liner along with the piston. The odd spacing of the ports is to place wider lands for the ring ends at 3 different locations. I think some of the .120" wall A513 Ty5 would have been more defect-free.

Thanks for taking a look.
Lloyd

View attachment 157723

The photo doesn't show the cross hatch marks but they are very faintly there. I just used a brake cylinder hone with a fine stones.
View attachment 157724

That's real pretty, excellent machine work!

 

[ninefinger]

Keep the progress coming. Getting excited to see this thing come together.

 

[minh-thanh]

My shop is getting messier and messier as I can almost sense the finish line in the distance. But I still can't see it!

The cylinder liner was a real test of my patience, but it finally worked out. I started out with some 4340 cond N, chrome moly steel, 2" O.D. x.25" wall. It was expensive. The liner is about 5" long and I machined the O.D. well enough, but darn if I could get the I.D. bored. I used a 4 jaw chuck that gripped the tube for 1.25", along with a steady rest. I tightened up the gibs, tried different tool geometries, speeds and feeds, and even fabricated a 1" dia boring bar. But as soon as I loaded the bar the least little bit, a bad chatter/vibration set in. I could not get it smooth and finally gave up on the 4340.

Next, I bought a piece of A513 Type 5 DOM medium carbon steel. I have used lots of this in the past in .065 and .095" wall and it always came right on size with a beautiful I.D. finish. I even did a hydraulic test-to-failure of a 7/8" O.D. x .065" wall, and it burst at 15,000 psi, which is several percentage points above the mechanical spec.

But the .250" wall was a different animal. Not as pretty in the I.D. and there was a faint witness line from the ERW process, but the I.D measured right on the money. This time I started by honing the I.D. to 38mm, which meant removing only a few thou. I honed out nicely and the new 38mm rings fit nicely. Machining the O.D. wasn't too bad, but the scavenge ports were a chore. The thick wall was needed for the liner flange, but the thick wall had some inclusions and defects, but almost all of them honed out cleanly. The compatibility of the mild steel liner and the aluminum piston has yet to be seen. But it doesn't have to last for a half million miles, LOL.

Here is the finished liner along with the piston. The odd spacing of the ports is to place wider lands for the ring ends at 3 different locations. I think some of the .120" wall A513 Ty5 would have been more defect-free.

Thanks for taking a look.
Lloyd

View attachment 157723

The photo doesn't show the cross hatch marks but they are very faintly there. I just used a brake cylinder hone with a fine stones.
View attachment 157724

Project is getting more interesting.....
Maybe...not right for engine machining.....please update...fast...
.

 

[Lloyd-ss]

I am at my laptop trying to post a few picture that I just took, with my hands still dirty and oily. Didn't stop to wash them. Getting too greedy. Need to slow down, clean the shop, and re-group before I mess something up.
Anyone else ever have this dilemma? OK, I count almost 100% of you holding a hand up.


This first picture with the piston at BDC just screams Detroit Diesel.
Very exciting!

And here is the big picture. It seems like the to-do list keeps getting longer, not shorter.

Thanks for taking a look and commenting!
Lloyd

 

[The Ignoble Troll]

That cylinder liner looks just like you stole it from a shipyard and shrink rayed it to size.

 

[GreenTwin]

My sister runs a Detroit Diesel 671 in her boat, and it is at least 60 years old, perhaps older (it was bought used in the early 70's).
It has been rebuilt a few times, but still starts and runs like a top.
The 671 is quite a reliable engine.
.

 

[NapierDeltic]

I am at my laptop trying to post a few picture that I just took, with my hands still dirty and oily. Didn't stop to wash them. Getting too greedy. Need to slow down, clean the shop, and re-group before I mess something up.
Anyone else ever have this dilemma? OK, I count almost 100% of you holding a hand up.


This first picture with the piston at BDC just screams Detroit Diesel.
Very exciting!
View attachment 157767


And here is the big picture. It seems like the to-do list keeps getting longer, not shorter.

View attachment 157766

Thanks for taking a look and commenting!
Lloyd

Hi Lloyd, I really admire your work!
I have a question for what might seem a potential issue, unless -of course - is not the complete design; which I believe is the case.
The link between cylinder liner and crank case, as seen in the picture, looks not that rigid and prone to cyclic bending during engine run. Will you add more reinforcements?
The nice part of any project is that only the owner has the final image of how it will look like. And it's a mix between design concept and methods to reach there.