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Main and rod bearing clearance

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Hi Andre

what oil viscosity you take into account for bearing clearance in 4G63 evo9 as well oil temperature , geometry of the part and engine load. hope you can help to decide to pick the right main and rod clearance.

thank you.

What will the car be used for?

What power levels are you chasing? Is this a circuit, drag car or street? Anything special about the motor i.e Alloy rods etc?

the car will be use for drag racing.

In a drag racing application typically we would run around .002" on the big end and .0025" on the mains. However, if you're running alloy rods as opposed to steel rods you would increase the big end clearance to around .0025".

These are the specs Andre has run in his high powered 4G63 Setups.

thank chris wall

i will running GRP aluminum rods

Chris,

what about circuit cars with steel rods? boost max 2.5bar

I would personally still stick with the .002" for big ends and .0025" for the mains.

What about the oil viscosity do you recommended for this type of clarance and for drag racing

With steel rods you can't really go awry aiming for the lower (looser) end of the factory specs for your engine. I've got no experience with ally rods but more clearance detailed above makes sense since the expansion ratio will be a fair bit higher than steel.

Personally I wouldn't go higher than a 50 without other modifications to the oil system as the drain-back is slower and you can run into starvation problems.

We usually run Motul 300V 15W-50

We usually reply within 12hrs (often sooner)

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