Why do they have more blow by?

My 632 has short el cheapo K&N breathers and not a drop of oil comes out. Previous 598 not a drop with same breathers. 598 6100rpm 632 6500rpm.

1. tons of stroke whipping air and oil around in crankcase
2. Unless the block is super ultra tall deck the piston pins are prob way up in the pistons with short skirts to clear that mongo stroke which causes the piston to rock in bore easier and compromises ring seal
3. as mentioned, the volume of crankcase is no kore than stock vs pumping action of pistons with a long ass stroke. I have a 2 cyl OMC air cooled engine in something that has tiny crankcase but large bore pistons and stroke, if you open the oil fill while its running it pumps air out of crankcase like a air compressor and whips oil around ferosiously

I would also tend to believe there is some ring seal issue, did the original builder "freshen" motors or test run them and say they are good to go? I would think about a leakdown test if we are talking alot of blow by. Everyone crys about them not working but I have had excellent results with my blown 540 using zero gap rings, less than 5% leakdown after dynoing and until it hits 80-120 hard hours very little blow by, I do also run tall breathers on front of valve covers, Smitty

I understand what you are saying and it makes sense. But I've been around these types of motors and have seen the opposite. I had an 865 in front of me running with the valve cover off and didnt have oil all over me. Granted it wasn't wide open spinning 9000 rpm but I noticed no signs of excess windage. Honestly, what I've noticed with these types of motors is that it seems like they have less windage. I mean the crank and rods practically hit the block. Oil gets scraped off the crank and rods by the block. I had a 496 that puked way more oil than the 598 or 632 I've had. Same valve covers and breathers on all 3 motors. And the 496 spun 1000 less rpm...

Are they blown? Are they dry sump? I feel when you get to 600+" dry sump is in order and even more so with boost.

No I'm poor. Can't afford cool stuff like a blower or dry sump. No, actually I was gonna go with a dry sump but engine builder talked me out of it said it was a waist of money on a motor like that.

A pair of 704cid's will have more Blow By Me's.

On a serious note,

I think blow by is being confused with windage and drainage. These are not the same.

It's like people calling water intrusion, water reversion. These are not the same.

Yeah I know what he was laying down. The point I was trying to get across is no matter how big the motor is it should not have so much windage that it pushes oil out the breathers. If the breathers are baffled and oil is being pushed out there is probably an internal problem. As Arcticfriends said I think a leakdown may be in order.

BB - I only quoted you so I could add the 'Blow By Me's" As in Blow Right By Me . LOL