- The engine bearings are one of the most critical
components in making sure that a high performance
engine is going to remain reliable for a long period
of time and I think in the wider engine building world,
there's still a misconception or misunderstanding
about the technology that is being applied
to modern engine bearings.
We've got Ron here from King Engine Bearings,
and he's going to have a chat to us about
some of the technologies that King are using.
So Ron for a start, what is the difference here
between your tri metal and bi metal engine bearings lines.
I've seen there's two different bearing lines
you've got there.
They look very different visually.
What are the difference there?
- Well the major difference is the number of layers
of material,
that're built up to make the engine bearing itself.
Tri metal obviously indicates three layers,
and then the bi metal indicates two.
The tri metal would be, they're both steel back,
they're both aluminium, bi metal and the tri metal.
The steel back and then on the bi metal there's
aluminium alloy on top of that steel,
and then on the tri metal we have copper lead layer
that's on top of the steel plus a babbitt layer
on top of that that's really
a heavy duty reinforced babbitt,
it's not your traditional babit.
It has extra copper for extra fatigue strength.
And we're trying to prevent fatigue in the bearing.
So that's one of the worst things that happens
to a bearing is it fatigues.
So we build all of our product to resist that,
to take all the loading that today's high horsepower
engine will give it.
So that the bearing doesn't come apart during operation.
And so if it were to come apart it would be catastrophic.
- Let's just go back a step,
so talking about those tri metal and bi metal,
when we're visually looking at those,
the bi metal bearing,
that has the shinier finish,
it looks more like an OE bearing surface?
- Yeah the aluminium bearing,
there's a lot of always bearings made out of aluminium.
So we're the only company that has a high performance
aluminium alloy bearing.
It has silicon blended into the aluminium,
plus some other small percentage elements
that give it fatigue strength, imbedability,
conformability.
Another good feature about that bearing
is the layer of material is a minimum of 12000 thick.
So it has a lot of depth to absorb debris
and also to conform to crank deflection
and stuff like that,
that happens to the bearing.
- Now I think that's one of the important considerations
here when we're looking at the engine bearings,
probably from the general population,
there's a misconception that we have a contact
between that bearing shell and the journal
and of course that's not the case,
we should always have a protective layer of oil film.
So if we' aren't actually having the bearing journal
contact the bearing shell,
obviously that's what we should be achieving,
then why is the imbedability so critical,
why is that an important aspect of a bearing shell?
Well there's gonna be debris develop
either maybe parts that are not clean before
they're put together properly,
or particles that break off of moving parts in the engine.
Sometimes an engine can create its own debris.
So we've gotta have a material that's going to absorb that
and not damage the crankshaft.
We'd rather replace bearings than a crankshaft
obviously for the cost reasons.
- So that imbedability allows that debris to actually
be trapped in that top layer of the bearing surface,
hence protecting the actual journal of the crankshaft?
- Yeah 'cause it's floating around in the oil stream
and as it goes through the gap clearance of the bearing,
we want it to be pushed into the bearing material
and actually heal itself so it doesn't disturb
or interrupt the oil film.
- Now between your tri metal and bi metal,
there is a difference in the imbedability from what
I understand and also a difference in the load support
capability of those two bearing shells.
Can you just explain those two differences there?
- That has to do with the size of the particle.
The tri metal bearing has a 5/10ths overlay.
That layer is of course obviously very thin.
It does its job but it doesn't have the capability
of absorbing anything larger than 5/10ths.
Whereas the bi metal bearing has a lot thicker layer
to absorb larger particles and so forth
so it does better in that regard.
Also the conformability is another issue too
because the thin overlay bearing on the tri metal
doesn't have that much room for deflection
where the bearing is worn into.
'Cause the second layer of material is not a really
good bearing surface by itself.
- So reading between the lines there,
essentially the tri metal bearing gives away
some of that imbedability for a higher load support
capability whereas the bi metal bearing,
improved imbedability,
so potentially longer life expectancy in a road going engine
would that be a fair assumption?
- Yes it would be, yeah.
We got to be application specific
and any time we get a call for like
what bearing should I use,
we always ask you know how is the engine gonna be used?
What's the horsepower?
What are the conditions it's gonna run under and so forth.
So we can really make a good recommendation
of using the correct bearing for that application.
- Now there's some other features that I just wanted
to talk about.
In particular we're using a set of King Bearings
very shortly in a Subaru FA20 build.
And there's a feature that you've applied there,
or actually a couple of features that you've applied
to the Subaru FA20 bearing shells,
in particular improving the oil flow
through to the big end bearings.
Can you just talk about how you've achieved that?
- On the Subaru, the number two and number three
rod bearing, this is on the EJ and the FA,
are fed by one main bearing.
So the oil has to be shared from one main.
So what King has done is we've designed
the main bearings to actually flow more oil to the rods
so that they get full lubrication and we prevent failure.
We just actually are just putting more oil there.
And that's gonna keep the bearing from wearing so bad
and actually failing at the end.
We put, some of the design features are a smart lug,
what we call, it's a lug that,
it has a protrusion on the back
but it does not have an indentation on the ID side.
- So what you're talking there,
smart lug, your terminology there,
you're talking about the locating tang
on the back of the bearing shell
that locates into the engine block?
- Yeah that's another terminology to use
to explain that particular part of the bearing.
It's a locating lug is what we generally refer it to.
It does nothing but locate the bearing in the housing.
The other features that we put in the mains
is that we four grooved that particular position.
It actually also fits in number one,
so it's number one and number three on the EJ.
But we've got the smart lug, we've got four groove,
we've got elliptic oil holes in the groove
that supply more oil.
And that's the whole key is getting more oil to those rods.
- I just wanna go back and just focus
again on that smart lug
because it's a subtle aspect but conventionally
when that lug is formed in the bearing shell,
it also results in an indentation on the surface
that the crankshaft runs against.
So your smart lug technology eliminates that,
and the upshot of that is it reduces a potential
area for oil leakage?
- Yes it closes off the area at the parting line
which could be a potential leak path,
and so one of the things we're trying to do
is prevent bleed off.
And to keep the oil pressure where it needs to be
you need to stop all the leaks, and the smart lug does that.
It accomplishes both things, locates the bearing,
and cuts the leak off.
- Now I just wanna change tack a little bit
and talk about bearing clearances,
and we've seen sort of a couple of different trends
between rebuilding a conventional road going engine
and what they're doing in professional motorsport.
In professional motorsport the trend seems to be
towards tightening bearing clearances.
Generally I've always been of the opinion
with road going engines that when I'm building
high performance, high RPM, high power engines,
I tend to err on the side of adding
a little bit of clearance.
Can you give us your thoughts on those two
contrasting techniques?
- Well clearance is a matter of having the right clearance
for the application.
If you've got really good parts, really stiff components,
you want everything to stay true,
in alignment and so forth.
Versus parts that maybe are flexible,
a little bit more, they move around more,
that's when you have to determine
what your clearance is gonna be.
But generally the tighter the clearance,
the better for the bearing,
because it puts less peak loads on the bearing,
as opposed to a larger clearance,
peak loading goes up,
which stresses the bearing more.
So it's really a balance that's gotta be determined
by the engine builder.
He needs to use experience with it to determine it.
But generally tighter clearances mean less peak
bearing loads, better oil pressure,
and you also have to match the oil viscosity with that.
'Cause if you use the wrong viscosity,
with either tight or loose,
could give you some problems.
- So essentially there if you do wanna run
tighter clearances you do have to be using
quality parts that aren't going to be flexing at high RPM
and under high load, otherwise you're likely
to end up with some metal to metal contact?
- Yeah that's correct.
And preventing metal to metal contact
is the key to the whole thing.
Any time there's metal to metal contact,
there's always a probability of problems,
catastrophic failure,
so we gotta maintain that oil film 100% of the time.
- Now one other aspect I wanted to talk about
is just transferring heat back out of the bearing shell
through the shell into the engine block.
How critical is that to the life of the bearing?
- That is a very critical part of the function of an engine
bearing is get the heat out of it.
You're oil is being shared,
and this is especially true with your tighter clearances,
you're sharing the oil more,
you're generally generating more heat,
so proper contact of the bearing to the housing
is vitally important to get the heat out of there,
'cause if the bearing doesn't do that,
it's gonna retain the heat,
it's actually gonna build.
And then if it starts building,
then the material maybe reaches its thermal capabilities
and it can cause a problem.
- Look it's been really interesting getting some insight
into those bearings Ron,
I appreciate your time there.
How can our followers find out more about
King Engine Bearings?
- Anyone that's interested in bearings
and especially King Bearings
can go to kingbearings.com
We have a very good website that has a lot of material,
a lot of good reading, a lot of technical.
Our catalog is electronic,
can also find and look up any King Bearing part number,
any application that we have parts for.
So that would be the best source.
Plus our cataloging, our paper catalogs are also available
for anybody that's looking up for more information
and so forth.
- Perfect thanks for the chat.
- Thank you.
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