crank case evac?
crank case evac? 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
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From: PA/MD
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
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Joined: Sep 2009
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From: PA/MD
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
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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
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From: PA/MD
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.
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.
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evac 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.
