Can anyone give me a rough guide to the vertical and horizontal forces on a crankshaft? only looking for rough figures on say a 1.6-2.0 litre straight 4?!
wondering just how hard itd be to run an engine on sealed roller bearings? youd need no oil on the crank just a feed to the piston squirters, add the camshafts and the small rod ends and you could have one hell of a smooth engine with very low oil consumption!
May not be viable for mass production due to longterm reliability but after a quick browse at whats available now and what their already being used for im pretty sure it could be done. and some of the newer oil/ceramic bearings look promising.
I believe smokey managed it with needle roller bearings but dont know how long it survived for!
roller bearing crank
Started by
dead_eye
, Feb 17 2007 10:27
5 replies to this topic
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#2
Greg Locock
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Posted 17 February 2007 - 21:05
Just make sure you know how you are going to get the bearings onto the crank. I don't think 'they' make split rollers that small, and a built up crank would be a pain (but possible) to make .
I don't see how it'll affect your oil consumption (loss of oil), as opposed to the oil flow rate.
I am sure that I have seen plots of bearing load on http://ntrs.nasa.gov...h.jsp?N=17&Ne=2 ,
if not any book on mechanics can explain the way to work it out, or a program called balance (search this site for links) will do it as well.
Incidentally once the engine is running I am not convinced you'll see much improvement over plain bearings, so far as friction goes.
I don't see how it'll affect your oil consumption (loss of oil), as opposed to the oil flow rate.
I am sure that I have seen plots of bearing load on http://ntrs.nasa.gov...h.jsp?N=17&Ne=2 ,
if not any book on mechanics can explain the way to work it out, or a program called balance (search this site for links) will do it as well.
Incidentally once the engine is running I am not convinced you'll see much improvement over plain bearings, so far as friction goes.
#3
desmo
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Posted 18 February 2007 - 02:10
"Plain" bearings need a sexier name. They really are marvels.
#4
Joe Bosworth
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Posted 18 February 2007 - 07:26
dead_eye
You ask, "wondering just how hard itd be to run an engine on sealed roller bearings".
If you have ever taken apart and re-assembled a 356 Porsche Super or any number of racing two stroke engines you will find out that it is either relatively simple but fiddly or way beyond your capabilities.
A better question is what are you going to build/convert to roller bearings? In either case the job is likely to be way way beyond your abilities if you are asking the question in the first place. Converting an existing block to rollers will be difficult and designing a new one will be even tougher.
Stop now and make a list of what you intend to accomplish by running sealed roller bearing.
If it is to be smoother, forget it now because you will gain nothing in smoothness.
If it is to reduce oil consumption, again forget it because you will save nothing.
If it is to convert internal friction HP to usable HP at the flywheel, again forget it because the HP gain will be barely measurable if at all. There are cheaper and easier ways to make extra HP.
Why don't you post your list of expected benefits and let us have a look.
Regards
You ask, "wondering just how hard itd be to run an engine on sealed roller bearings".
If you have ever taken apart and re-assembled a 356 Porsche Super or any number of racing two stroke engines you will find out that it is either relatively simple but fiddly or way beyond your capabilities.
A better question is what are you going to build/convert to roller bearings? In either case the job is likely to be way way beyond your abilities if you are asking the question in the first place. Converting an existing block to rollers will be difficult and designing a new one will be even tougher.
Stop now and make a list of what you intend to accomplish by running sealed roller bearing.
If it is to be smoother, forget it now because you will gain nothing in smoothness.
If it is to reduce oil consumption, again forget it because you will save nothing.
If it is to convert internal friction HP to usable HP at the flywheel, again forget it because the HP gain will be barely measurable if at all. There are cheaper and easier ways to make extra HP.
Why don't you post your list of expected benefits and let us have a look.
Regards
#5
McGuire
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Posted 18 February 2007 - 12:08
Originally posted by dead_eye
wondering just how hard itd be to run an engine on sealed roller bearings?
*Sealed* roller bearings won't work. Insufficient lubrication and especially cooling. Could never survive in a crankcase, they weren't designed for that environment.
But lots of engines have used *non-sealed* (constantly cooled and lubricated) roller, needle and ball bearings quite successfully. Especially in motorcycles, both two and four-stroke. Also Porsche (Hirth system) and Bugatti (no system).
Advantage: require considerably less oil volume and pressure than journal bearings. In some applications can run on mist (two-stroke crankcase compression engines).
Disadvantage: far greater weight, bulk, cost, and complexity.
#6
dead_eye
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Posted 23 February 2007 - 23:08
Theyd be vented roller bearings with a difference. Theres a company we do fair bit of trade with in the moulding buisness that have a new cerametallic bearing compound. Theyve got test engines running with no oil flow what so ever to the head (all bearing surfaces are coated in the new compound) and so far mid term durability tests are showing good signs.
Im currently building a straight 4 turbo for a friend and the company are offering to use the engine as a test dummy for the heads which all involved are happy with (friction losses are suprisingly large for a product of this nature) but weve been talking about doing the crank aswell (the engines not expected to last more than 200 hours without a rebuild anyway but we dont want to destroy it for nothing)
due to processes in the coating we can either use roller bearings, ball bearings. journal bearings could be done but i had a gut feeling roller or ball bearings would give less friction givent hat youve got the motion of the internal parts aswell as the external surfaces slipping.
As ive never done anything like this before its a bit of a gamble, the friend involved is happy that his engine could fail catastrophically but i still dont want to step into it until ive had a few more opinion and views.
For those interested the company also has a harder compound in the early testing stages that has no frictional losses over oil and still a fairly short lifespan BUT has been used on small rod ends and cylinder walls in 1 engine to completely eliminate the lubrication system, this is still a long way of from being even close to ready and even then itl be extorsionately expensive but its getting closer by the day
Im currently building a straight 4 turbo for a friend and the company are offering to use the engine as a test dummy for the heads which all involved are happy with (friction losses are suprisingly large for a product of this nature) but weve been talking about doing the crank aswell (the engines not expected to last more than 200 hours without a rebuild anyway but we dont want to destroy it for nothing)
due to processes in the coating we can either use roller bearings, ball bearings. journal bearings could be done but i had a gut feeling roller or ball bearings would give less friction givent hat youve got the motion of the internal parts aswell as the external surfaces slipping.
As ive never done anything like this before its a bit of a gamble, the friend involved is happy that his engine could fail catastrophically but i still dont want to step into it until ive had a few more opinion and views.
For those interested the company also has a harder compound in the early testing stages that has no frictional losses over oil and still a fairly short lifespan BUT has been used on small rod ends and cylinder walls in 1 engine to completely eliminate the lubrication system, this is still a long way of from being even close to ready and even then itl be extorsionately expensive but its getting closer by the day
