siadam

Yea, thats what my cousin and I were talking about. I was thinking w/o the piston on the end of the rod and the rings in place, it would move and skew the numbers.

Btw, when assembling the rods/pistons..which way do the tabs (where the bearings go) on the rods face, exhaust or intake.

I know on B-series they face the exhaust side, but since our motors spin the opposite direction, does that mean they go on the intake side or is it still the exhuast side.

siadam

Bump.

Anthrax-VX

sorry to bring up an old thread from dead but... no one seams to be addressing oil pressure. i am building my motor, and am aiming for in between .025 and .038mm. i am supercharged and i was under the impression that using larger tolerances would drop the oil pressure. from what i have heard - around 10 psi. i am supercharged doing abotu 12psi. what do u guys think about doing it that way?

i am speaking of mains btw

setup - aebs t sleeves
BC rods -
CP 11.5-1 pistons
oem bearings

Anthrax-VX

Well just an update for all of you wondering -

so i ran about 2k miles on this motor - tuned by church .

im super ocd when it comes to my car and building, so every measurement and full blueprint is DEAD NUTS . here they are

mains .025mm across the board (sucks cuz ocd made me wait for bearings to come in, stock was not at .025)
rods are all at .038 (.0015")

so after 2k of running 10w30, went to church for final tune. motor started loosing oil pressure.

you can see the parts posted in previous post (right above)

so speaking with a lot of people, this happened most likely because of the lack of clearance (too tight) for 2 reasons.

1) aftermarket rods tend to flex/twist and need a little extra clearance from bearings
2) the extra boost (14-15 psi) could definitely use the extra "cushion"

so, got the car back, going to be doing a tear down this week, taking it apart to check everything, and probably be putting back the motor with looser tolerances.

.045mm (.0020") on the rods
and depending on how the mains look, i may just leave the mains if they are not damaged, from what i understand if this theory is correct the mains should still be in good condition as they are in the center of the ballanced rotational mass and should not be as affected as the rods. but we will see.

so from my experience i think a little looser is best for a forced induction BUILT motor.

MorngWoodStewie

I didn't read all that crap but that saying about loose and tight and people knowing refers to p2w clearances.
Mains, an rods totally different lol

skool u

Just wondering how this would affect oil consumption if they were built a bit looser.

NWDyno

It should not cause any consumption, but it will decrease oil pressure a bit due to the fact that its oiling the journals more.

R-Poizon

so its 0.0020" the holy grail measure mains&rods to built motors with turbo?

how many miles can i expect from this oversize clearances vs normal clearances?

I will build a f22c turbo and I think it will hit 700hp or more. darton sleeves , aftermarket rods and pistons

And thrust bearing clearance?

tunermt

there are many factors to take into account when setting bearing clearances. What materials, what will the engine be used for, Torque/hp, Rpm limit, dry or wet sump oiling, etc?

Most common mistake I see for "diy" engine builds are usually do to thrust clearances (crank and rods) as well as contaminates from machining, painting, sand blasting, silicone, etc.

Anthrax-VX

so i finally am taking this thing apart (busy with work) 8 months later ish - and about go get into the motor ( just got motor out and head off etc ) . Very curious about what u say about thrust clearances, i put new thrust washers in and measured my end play etc, i measured my crank end play to be .20mm (new .10-0.35) service limit is .45mm. is this correct, the reason im asking is i'd assume most people do this and you are saying you see a lot of issues in this area. Thanks for response ahead of time.