DLE - 55 Clockwise Rotating Engine
03-24-2013, 12:30 PM
#51
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RE: DLE - 55 Clockwise Rotating Engine
ORIGINAL: Truckracer
Wow, this whole thread is painful to read. earlwb has some good points that I would like to add to. On the one example of an engine that was reversed here, there was reference to greater compression when the engine was rotated in one direction compared to the other. My bet is this engine had some time on it and had established wear patterns. On most any engine that is run in, turning the crank backwards will give you a greater feel of compression than when the engine is turned in the normal direction. This is due to rod angle pushing on the piston and the slight amount of piston rock in the bore more closely approximating real life run conditions than when turning in the normal direction. If one starts with a new piston and sleeve before the reverse process, I firmly believe that reversed engine will have a greater compression feel when turned in the normal CCW direction. Its all about wear patterns and the slight piston rock in the bore when the engine is hand cranked. Has nothing to do with which direction the cylinder and piston are installed. You simply get a better compression feel when the engine is rotated backwards to normal rotation. Don't believe it .... you can test this on most any ringed engine, large or small.
Now to open a new can of worms, if you can rotate the cylinder / piston in a DLE55, the piston skirt will wear less on the bypass side!
Wow, this whole thread is painful to read. earlwb has some good points that I would like to add to. On the one example of an engine that was reversed here, there was reference to greater compression when the engine was rotated in one direction compared to the other. My bet is this engine had some time on it and had established wear patterns. On most any engine that is run in, turning the crank backwards will give you a greater feel of compression than when the engine is turned in the normal direction. This is due to rod angle pushing on the piston and the slight amount of piston rock in the bore more closely approximating real life run conditions than when turning in the normal direction. If one starts with a new piston and sleeve before the reverse process, I firmly believe that reversed engine will have a greater compression feel when turned in the normal CCW direction. Its all about wear patterns and the slight piston rock in the bore when the engine is hand cranked. Has nothing to do with which direction the cylinder and piston are installed. You simply get a better compression feel when the engine is rotated backwards to normal rotation. Don't believe it .... you can test this on most any ringed engine, large or small.
Now to open a new can of worms, if you can rotate the cylinder / piston in a DLE55, the piston skirt will wear less on the bypass side!
The engine's i used were brand new and i reversed one from the beginning. I believe that even an engine with time on it can still be reversed if you also turn the cyl and piston. Sorry i cannot explain the difference in compression in relation to the direction of rotation. I' m told it could be related to the ring but i do not know. However it works the other way around if you know what i mean. If you rotate the reversed engine with the reversed cyl and piston backwards you will also feel the greater compression again.
I cannot explain why you would need a richer mixture on a reversed engine that does not have the cyl and piston rotated. I just know it does because i have tested this. And in many other forums this has been addressed to. I just want to share my solution to this . I have also read that some snowmobile drivers reverse the rotation to get more compression...
03-24-2013, 12:42 PM
#52
My Feedback: (19)
RE: DLE - 55 Clockwise Rotating Engine
Some people build race car engines with altered firing order, longer connecting rods, different bore - stroke ratios, etc. with hopes of gaining an advantage then go out and get their pants blown off by those who just leave things alone. Perhaps some of that is going on here.
If your setup is working well for you and apparently it is, that is all that matters and that is really what our hobby is all about.
If your setup is working well for you and apparently it is, that is all that matters and that is really what our hobby is all about.
03-24-2013, 05:25 PM
#54
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RE: DLE - 55 Clockwise Rotating Engine
ORIGINAL: airraptor
see post 35 
ORIGINAL: av8tor1977
Tee hee Truckracer. You're right, nobody has mentioned rotation thrust wear yet....
AV8TOR
Tee hee Truckracer. You're right, nobody has mentioned rotation thrust wear yet....
AV8TOR
And I do mean that in the nicest and friendliest of ways!
Good info in this thread but somewhat painful to read at times. "Enter big, long groan here!"
03-24-2013, 09:40 PM
#57
Senior Member
RE: DLE - 55 Clockwise Rotating Engine
ORIGINAL: w8ye
On the DLE 55, all ones I've seen, had the port inlets and outlets internal to the cylinder and are the closed type and use a windowed piston to facilitate the air-fuel transfer. There are no ports at the bottom of the cylinder-crankcase mating area to consider. The cylinder gasket is the same, right side up or wrong side down. It is symmetrical left to right.
But the cylinder is relieved differently front and back for the rear bearing and the reed plate.
Also like several people have mentioned, there is no real mechanical reason to turn the cylinder around 180 degrees. And there is no pin offset.
On the DLE 55, all ones I've seen, had the port inlets and outlets internal to the cylinder and are the closed type and use a windowed piston to facilitate the air-fuel transfer. There are no ports at the bottom of the cylinder-crankcase mating area to consider. The cylinder gasket is the same, right side up or wrong side down. It is symmetrical left to right.
But the cylinder is relieved differently front and back for the rear bearing and the reed plate.
Also like several people have mentioned, there is no real mechanical reason to turn the cylinder around 180 degrees. And there is no pin offset.
I am going to take a Zanax and go to bed.
We used to reverse a lot of Zenoah G-45s for P-38.All we did was move the magnet. Sometimes the reversed engine outurned the other. We adjusted timing to match them up. I'm done with this.Of course there guys that think if you put the prop on backwards it will push and not pull.
BCCHI
03-25-2013, 08:56 AM
#59
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RE: DLE - 55 Clockwise Rotating Engine
I am impressed with the knowledge that you engine experts have and have learned a lot reading this link. I have been wondering about this issue for some time, as I would like to build a twin. I am curious though if any have experimented with a gear box setup with one designed to counter rotate?
03-26-2013, 10:37 AM
#60
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RE: DLE - 55 Clockwise Rotating Engine
Read post 43 again, the reason you see higher compression on an engine that has been run in when turning it backwards is that the ring seal both to the cylinder and the ring land on the
piston is partially influenced by the side of the piston that sees the high thrust generated by high cylinder pressure when combustion is taking place. Obviously this high thrust occurs only on one side of the cylinder/piston, when turning the engine backwards by hand the compression pressure puts the higher thrust on
the same side as a running engine resulting in a better seal so you feel the increased compression.
piston is partially influenced by the side of the piston that sees the high thrust generated by high cylinder pressure when combustion is taking place. Obviously this high thrust occurs only on one side of the cylinder/piston, when turning the engine backwards by hand the compression pressure puts the higher thrust on
the same side as a running engine resulting in a better seal so you feel the increased compression.
03-27-2013, 02:20 AM
#61
Senior Member
RE: DLE - 55 Clockwise Rotating Engine
I don't know why 2 strokes confuse me, as I can strip and rebuild a car engine without too much stress.
If you look at the following http://science.howstuffworks.com/tra...wo-stroke2.htm
If you reverse the rotation of the crank, wouldn't the sequence of the vapours be stuffed up?
It would depend on the ports and the attributes of the crankcase, but reversing the cyl and piston makes sense to me.
If you look at the following http://science.howstuffworks.com/tra...wo-stroke2.htm
If you reverse the rotation of the crank, wouldn't the sequence of the vapours be stuffed up?
It would depend on the ports and the attributes of the crankcase, but reversing the cyl and piston makes sense to me.
03-27-2013, 02:42 AM
#62
RE: DLE - 55 Clockwise Rotating Engine
ORIGINAL: 3136
I don't know why 2 strokes confuse me, as I can strip and rebuild a car engine without too much stress.
If you look at the following http://science.howstuffworks.com/tra...wo-stroke2.htm
If you reverse the rotation of the crank, wouldn't the sequence of the vapours be stuffed up?
It would depend on the ports and the attributes of the crankcase, but reversing the cyl and piston makes sense to me.
I don't know why 2 strokes confuse me, as I can strip and rebuild a car engine without too much stress.
If you look at the following http://science.howstuffworks.com/tra...wo-stroke2.htm
If you reverse the rotation of the crank, wouldn't the sequence of the vapours be stuffed up?
It would depend on the ports and the attributes of the crankcase, but reversing the cyl and piston makes sense to me.
03-27-2013, 07:56 AM
#63
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RE: DLE - 55 Clockwise Rotating Engine
Once it is broke in then it favors that direction unless you put in a new ring and start over in the new direction.
