06X6spdGTO

iTrader: (6)

Anyone ever use the collectors on a set of longtubes to evac there crank case? Remember my dad saying the did this to free up some power on older SBC/BBC stuff. Wondering if the same principles applied to the genIII/IV SBC

mark21742

Yes, my friend bills98ta on hear uses this setup on his 98ta.....one tube on each side running from the valve cover to AFTER the muffler and mounted in the exhaust at about a 45 degree angle...that was his setup last year, this year he built a 2 quart catch can the tubes run into and back out of and down to just after the collectors.....if you don't run a catch can you need to go into the exhaust after the cats and mufflers

66LeMans

Whats the reason for running behind the muffler or cat if ur not using a catch can?

mark21742

You don't want raw oil and vapor to build up in the cat or muffler, ignite and blow off

DONAIMIAN

iTrader: (18)

Its a verry dirty method of clearing the crankcase. Oil gets sucks out and would clog the cats and mufflers.

66LeMans

This is going to be in a full drag car with no cats. It will have race mufflers directly behind the headers. Still possible? Still 45 degree angle if installed in the collector?

mark21742

Id still run the catch can/cans and then right into the headers....45 degree angle and let the tip of the evac Bing hang down into the exhaust flow 3/4-1".....you would be amazed at just how much oil this will suck out of the motor...everyone that runs after you will thank you for running a catch can. Bill could get as much as 1/2 pint out of the catch can after each run and you don't want to dust that onto the track

06X6spdGTO

iTrader: (6)

Could u evac using the exsiting egr ports? Or dont they produce enough vacuum?

Driftunit

iTrader: (5)

Wait a sec.. from the factory its run into your intake manifold.. would that not have the same vacuum as the exhaust because the air comin in is going the same speed as the air going out?... and if this is so, wouldnt you think that 1/2 a pint from one run seems a bit much? i would think the only oil comin form the case would be in the form of steam, which would mostly get blown out of your exhaust anyway if you had that setup. either way the catch can seems to be the best idea anyway you look at it. im just trying to get some details straight before i decide my own setup

mark21742

Once your pushing it on the edge and if you have lose rings toth a 200+ n2o shot on top of that while pulling a good vacuum through the catch cab you would be suprised just how much oil you can get in the catch can from just one hard high rpm run.

My friend Bill built a tall narrow can that can hold up to 2 quarts of oil.

Most ls motors stock after you get some miles on them will have a coat or even a puddle of oil in the intake because of this.

buschmec

yes they do work, the trick is to create a "good location" to keep from pulling oil into the evac system. think of them as a siphon, as the exaust passes it siphons air due to the angled tip and the velocity of the flow. if you restrict the flow (muffler or cat) it won't function as well if at all. the catch can is a great move if you can package it in the intake. on a side point for the car that pulls a pint, i would look for another location to pull from (its difficult on the ls engine). on my downpipe with a turbo system i've seen as much as 8in. of vacuum in the crankcase.........its all about placement.