rod bearing tolerance
 

So ive been spec'ing out my lsvtec. With acl race hx bearings my rods are .0017-.0019. Mains with oem bearings are .0015-
0017.

Would you run rods that loose on a motor to daily drive and last a solid 50k miles? I know they are loose for nonvtec specs but fall on the high end of acceptable for itr

Re: rod bearing tolerance
 

i would not call that "loose". Pending peak operating RPM, oil use..etc i would run that all day for a DD.

Re: rod bearing tolerance
 

itr valvesprings and cams, so ill probably wind up around 8400 for the limiter.

there were a few days last winter that were between -5 and -10 degrees f when i left for work in the morning...

i usually cheap out with oil, and just run castrol gtx changed every 3000 miles

Re: rod bearing tolerance
 

Specs are perfect..i would run it!

Re: rod bearing tolerance
 

I try to keep all-motor clearances around 1.8 thou or so, boosted I've gone 2.5 without issue.

Re: rod bearing tolerance
 

ok cool. thanks for the replies guys. i run my turbo motor around .002 for the rods, just wasn't sure about this one.

Re: rod bearing tolerance
 

OT: Since when are oil clearances dictated by how the motor makes power?

Re: rod bearing tolerance
 

Well most guys usually run a turbo engine looser as it makes more power.....and heat, much faster than an all motor. Rolling into the burnout box at idle to jumping on the two step into boost creates heat and expansion very quickly which is why it's built a bit looser. If the all motor car is a race only car, I would run it looser as well.

My personal preference only, but most people tend to go the same way.

Re: rod bearing tolerance
 

Oil use (weight, viscosity etc) and RPM, IMO, are much larger factors in clearancing than the amount of power or aspiration.

Oil does a pretty good job at keeping the lower components from being so susceptible to combustion heat when in reality that combustion heat on a turbo engine is regulated by fuel and ignition timing just the same as naturally aspirated engines so heat through conduction really can't be much of a concern.

RPM is very hard on an engine which is why a given "race engine" with a couple thousand more operating rpm built within OEM tolerances is much more likely to have damage sooner than one that was built with the proper information in mind.