Catch can/Breather hose sizing

sorry to bring up an older subject

A 4.0 6cyl running approx 30-35 psi and on E85, I'm going to keep the PCV system but through it's own baffled catch can, but was going to run 2 bigger lines to catch can/s, would 2 x -8 fittings and hose be sufficient or just go 2 x -10 size?

I'd suggest 2 x -10 myself, When it comes to breathers within reason, bigger is better.

Thanks Andre

That was my thoughts as well and especially after watching the webinar, but I have a habit of over thinking things at times

I recently worked with an LS7 with a dry sump arrangement that was built rather loose, so a massive amount of blow-by from the combustion chamber. This led to a massive amount of frothing in the oil sump and carryover through the single -10 vent line to the breather (not my design). We initially closed off the valve covers and vally vent and ran the engine at a vacuum, using a 1 bar MAP sensor to monitor crank case vacuum and ensure we weren't drawing too much with the scavenging pump. This worked well up until about 5000RPM on the dyno at full load and then beyond that, carryover began again.

Our final solution was (3) -12 breather hoses from the sump to the catch can and the added diameter reduced the velocity of the gas escape enough to prevent carryover of oil droplets to the breather tank.

I never would have imagined before this that three -12s would have been needed.