what is the benefit of having these in your built motor are they for cranks thank have been cut down what is the extra clearance used for? i was looking on cosworths website and seen these evo main and rod bearings and they have 3 sizes 0 being less clearance then factory , 1 factory clearance size and, 2 .001 more oil clearance then stock. what is your guys opinions on these they are more money but also the rod bearing has the oil groove 3/4 around for extra oiling i have been looking at different options because i have had 3 built motors blow on me all spun bearings and everything new on them each time including crank and it is getting expensive. i have had my oliver rods recondition because that is what my machine shop suggested but this time i am thinking about trying cosworth bearing and a new set of manley or crower rods what do you guys think about these extra clearance bearings are they good for high hp 750 range, are they designed more clearance but using a thicker oil. thanks guys

 

All these views and no comments Wow someone with engine building knowledge please answere I need some input

 

doesn't sound good man, why was it spinning bearings? Detonation, oil starvation, incorrect clearances? Losing 3 motors the same way isn't bad luck, was everything cleaned properley after munching the bearing?

 

yea it was and everything was new also crank and machine work and hot tanked parts and such the only thing is that i raced the car on regular castrol 20w50 i think that there was a problem lying within the rods that were reconditioned. so i am going to build another motor with new rods and i was wondering if i should use these extra clearance bearings.

 

We use the extra oil clearance bearings (they are offered from ACL as well, HX designation) in high horsepower builds with the use of heavy weight (15w50, etc) oils. We do not recommend them for daily drivers or cars that will see significant climate change.

 

Just wondering but did you replace the oil cooler each time?

 

I've used the extra clearance acl bearings in my 2.3 talon build so I could use the 20-50 oil and have a little more cushion.

 

I use stock bearings and cosworth on all my engines running upto a GT4094 at 2.5bar on 5/40 Titan pro S and have never had a problem in 10years and more engines than I can remember.

Mark

 

the first engine that went the second rebuild my builder went with the same oil cooler yea costed me some money i was mad. after that no oil cooler has been on the car. i am building it this time i want to build it and i have had bad luck with spinning bearings so i am trying to be as cautious as possible i was wondering about the extra clearance bearings. if i use these what type of clearances should i be shooting for.

 

Make sure the rod bearing surface is smooth enough for a new bearing first off. The way my chiltons manual recomends testing this is to lightly * Lightly ** scratch / swipe a penny across it and if any of the copper gets picked up by the crank its a no-go. Then once everything is brake cleaned / cleaned apply a slim coat of oil on the bearing ( also used for holding green plastigage onto the rod bearing ) Use the Green fel pro plastigage install rod/ bearing caps then torque to spec, remove then compare squished plastigage to platigage paper and the specs for the 4g63 are ( .0008 to .0020 ) if they range from say between 14-15-17 you should be good to go assuming your using the correct oil weight for your vehicle labled in the factory service manual or google. Best of luck

 

Not to dig up an old post but wouldnt running a "0" which is less clearance only lead to rod bearing issues later on down the road? I am working on a build and would like to see the different opinions as well.

 

factory cranks from mitsi are not all exactly the same size.
there are different mains tunnel sizes too.
best way to do it is to correctly measure your crank, and the mains size with the head bolted on the torqued.
When i built mine, it was 3.6 thou for my mains, and 2.0thou for my big ends. I put in 1thou tighter bearings (not 1thou looser like we are talking about here) get get my mains to approx 2.4thou. This is still far larger gaps than factory, but i'm running 15W50 Motul.
It also goes with the rule of thumb - 1 thou bearing clearance per 1" of journal diameter.

To the OP (if you're still having problems) you need to find out why you're running bearings.
If it's happened 3 times, but your engines have been build perfectly each time, then you're just going to run into trouble again.
Which bearings are running? Number 4? (furtherest away from the oil pump)

p.s. when i was building my engine, i used precision tooling. Not plastigauge.
something like this

 

vw bug engines run .004 stock and can run .006 and still be in tolerance during rebuild. its not because the engines are old technology. its because the crank has only 3 main bearings and an aluminum block. Metals flex. they are not rigid at all. rods in VW engine stretch .025 at just 7000 rpm. modern engines are made with much better materials but there is still stretching and twisting. when you triple the output of a 4g63 it is a darn good idea to have extra clearances if you want the engine to live.with increased HP comes increased stretching and flexing.

 

I took my motor apart and found out mine has the HX .001 extra clearance bearings....I'm now thinking my wristpin noise is really my rods making noise cuz of these bearings and the one had some wear (#1 cylinder) and it all started making noise once I switched to 10w30, although I only had 5w40 in it before which is better in one aspect. Not sure if it was all because of the oil since I had the motor apart but I don't see why else. I deff will be running thicker oil from now on since now I know I have these bearings and making over 550hp range

 

Bringing this back to life bump for a another blown motor the motor made 831 whp on a pte 6766 what are the correct oil clearances I should be using for this high of a hp motor thanks. Btw if anyone has a spare 2.0 crank I need one