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Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars

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Old 06-20-2016, 12:42 PM   #1
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RB25 ACL bearing Clearance

I'm currently assembling my motor and I measured my main bearing clearances with plastigage. I only put the plastigage on one side of the bearings and came out with about .038mm all around. I torqued the crank down to 36 ft lbs as the fsm says. The fsm also says the clearances should be in between .020mm to .040mm. Im going for 700whp as my goal. So I know I need more oil clearance for high hp.

So my main question is do I double my clearance measurements since I only put plastigage on the top bearings? Or Should I get some bearings that have more clearance before I assemble it for good?

Any help is great, thanks.
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Old 06-20-2016, 01:35 PM   #2
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Your measurement is fine, and you do not need any extra clearance than what you have already. The "extra clearance for extra power" mentality is dated. With today's machining capabilities and oil technology that practice isn't needed. All of our engines at the shop are built to FSM spec whether it's a 200hp stock rebuild or a 1400hp drag engine.
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Old 07-06-2016, 11:39 PM   #3
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+1 to this guy ^^
You don't have to double the measurement of the plastigage
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acl, bearing clearance, nissan, rb25

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