Summary

Which main bearing and big end bearing is better, ACL or King Bearings? Look there's not necessarily one is better than the other, there aren't a lot of fly by night bearing companies out there. I've used both ACL and I've used King Bearings and I've got good results with both of them.

00:00 - Mitsu has asked, which main bearing and big end bearing is better, ACL or King Bearings? Look there's not necessarily one is better than the other, there aren't a lot of fly by night bearing companies out there.
00:16 I've used both ACL and I've used King Bearings and I've got good results with both of them.
00:21 A lot of it's going to come down to personal choice, access to the bearings and of course cost is always a driving factor.
00:28 I've also used in some of our Mitsubishi race engines, our 4G63 race engines, I've also used factory bearings and in some instances the factory bearings do a perfectly good job.
00:40 What we do need to understand is that with a lot of the aftermarket bearings, the likes of ACL's race series bearings, King's bearings as well, these use a different construction to factory bearings.
00:52 They use what's known as a bi metal construction and this is why we see with some of these race series bearings that they have a, what looks like a blackened surface.
01:01 This isn't actually a treatment, this is just due to the construction of the bearing itself.
01:05 A factory or OE bearing shell on the other hand uses a tri metal construction.
01:10 What this does is it has an outer layer, the outside layer of the bearing which is closest to the journal of the crankshaft, has a layer that provides some embeddability so that debris that goes through the oil, inevitably goes through the oil, can be trapped in that top layer, the embeddable layer of the bearing shell.
01:28 The bi metal construction that these aftermarket race series bearings have removes that embeddability, removes that top layer and the advantage is that this produces a stronger bearing shell, better suited to very very high output but the downside is that because there is no embeddability on these bi metal bearings, we do tend to see a little bit more wear showing on the crankshaft journal due to the debris that's inevitably going to flow through the oil system, no matter how clean everything is.
02:01 So what this means is the bi metal race series bearings are more suitable for an engine that's going to see regular tear downs, regular rebuilds.
02:09 If you are building an engine that's expected to produce maybe 50,000 to 100,000 km of use between tear downs, often using a bearing shell that's tri metal construction is going to be superior.
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