Just a thought on a split needle roller bearing for crank

[ZimNismoboy34]

Hi guys was thinking about this and realised it already exists but how come not one has ever tried it or implimented this ?
Imagine how much more reliable a crank would be running on a needle roller bearing as apposed to a floating normal softmetal bearing with oil film in between.

http://www.ntn.co.jp/english/news/news_ ... 60927.html

Let me know your thoughts and if some one has tried it how successfull they were?????

[djtreble]

That is interesting! But I don't see how it's more "reliable", if normal bearings weren't reliable they wouldn't be used accross pretty much every engine.

Problem I foresee with roller bearing on engine internals is there is more parts that "could" fail. The normal bearing that uses an oil film is reliable and proven (and simple, less to go wrong). As long as measurements are VERY accurate on any bearing mating surfaces, I see no reason for the extra work involved to have extra clearence put in existing engines to fit roller bearings.

Just my 5c

[ZimNismoboy34]

Thanks for your reply, apparently yes more parts to go wrong, but there is some method to the madness, say you aiming for soem serious power and there are many ways of doing this, low revs boost and other mods etc, but say you have a small engine and want it reliable as hec and you want power at crazy RPM like 15,000 rpm thats high, now imagine what happens to oil pressure at this rpm..... Drops sadly.
So imagine having to feed bearings lower oil pressure, and getting away with still the high or higher rpm that would work magic.
Just a thought again but this stuff might actually work ?
And due to the needle rollers you would need to run a thinner synthetic oil and also keep the oil clean

Thats a hard task but for a strong high rpm high HP car then this would be the business

[djtreble]

My technical knowledge is not extremely advanced but what you are saying makes sense.

The biggest issue would be making sure their roller bearings can handle that kind of RPM without parts failing, and doing so for a much longer period of time that justifies the outlay to replace the normal bearing with roller bearings (machining of block and heads to very precise sizes).

Look at bikes, they rev to those kinds of RPM's and as far as I know they use normal bearings?

And there are cheaper/reliable methods of sorting out low oil pressure at high RPM

[ZimNismoboy34]

I would like to know about the cheaper methods of sorting out oil pressure at high rpm.
As far as i know when it comes to rpm at a certain stage the centrifugal force starts suckiong the oil out of the crank and causes low oil pressure.
Tomei did counter act this with one type of crank shaft they made that had a patented X type oil feed system ?
I know of very little other ways ?
unless you have a great oil pump that can supply a feed thats proportional Rpm??

[djtreble]

Couldn't a dry sump setup help?

[300sx]

there is nothing new under the sun guys, this idea has been around for ages, in fact afaik, most outboard engines from yamaha,evenrude ect. run roller cranks, its partly why they make so much hp out of small cc engines.

also have seen vw beatle/porsche engines modded this way.. main reason you dont see it much on road cars is because its hellish expensive to implement and service..

[Enzio]

Jip, old bike engines had roller bearings for cranks (Kawa for sure and Yamaha or Suzuki - can't remember which).

One of the issues with these is they require very good maintenance practices, but otherwise proved to be very reliable.

[300sx]

Imagine how much more reliable a crank would be running on a needle roller bearing as apposed to a floating normal softmetal bearing with oil film in between

like enzio says ,in fact a softmetal bearing is much more forgiving to lazy maintenence as opposed to rollerbearings, particles gets imbedded in the soft metal, where they cause minimal harm, while an average metal sliver going through a needle bearing will screw it up..