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View Full Version : Venting the cranks with NO maf?


huffandpuff00
06-09-2008, 11:51 AM
So i'v was told by a local shop that you can vent your cranks(the T on your valve cover) by hooking a line up to the down pipe, which will suck the pressure out the same as venting off the intake side. I am going with a D-jetro soon and am going to run no intake pipe. can anyone sheld light on this method. Let me know if you had any problems with it.

Thanks,
Zac

claymans13
06-09-2008, 01:30 PM
You need a check valve and a slash cut welded into your down pipe. Run a -an line to the check valve, it will pull the blow-by into the downpipe. You'll never pass emissions with that setup though if you have to go through that sort of testing.

Why run no intake pipe though? I never understood that. The air filter serves a purpose.

aNskY
06-09-2008, 03:02 PM
makes more sense than blowing-by back into the turbo/intake

steve shadows
06-09-2008, 03:06 PM
You need a check valve and a slash cut welded into your down pipe. Run a -an line to the check valve, it will pull the blow-by into the downpipe. You'll never pass emissions with that setup though if you have to go through that sort of testing.

Why run no intake pipe though? I never understood that. The air filter serves a purpose.

yes this is correct, add the check valve.

There are several pictures of this setup on Supras. 2j guys love it.

huffandpuff00
06-10-2008, 12:52 PM
so a check valve is a one way valve and what does the slash cut do ? any pictures? thanks for all the help.

mmmjesse
06-10-2008, 09:12 PM
why not just use a catch can and vent it to the atmosphere?

huffandpuff00
06-11-2008, 12:27 AM
I was told that you need suction to releave the crank pressure.

SoguRacing
06-11-2008, 01:12 AM
I was told that you need suction to releave the crank pressure.

your statement doesn't make sense. "suction to relieve pressure"? you shouldn't need suction if it's pressurized thus just vent it to atmosphere with a one-way check valve.

GSXRJJordan
06-11-2008, 01:14 AM
your statement doesn't make sense. "suction to relieve pressure"? you shouldn't need suction if it's pressurized thus just vent it to atmosphere with a one-way check valve.

Haha logic > him.

+1 on the Supra setups @ Supraforums. Those guys are serious.

huffandpuff00
06-11-2008, 10:24 AM
idk why i was told that but what about the heat being sucked out. isn't there a good reason to not have it just venting to the atmoshere?

S14DB
06-11-2008, 11:27 AM
I was told that you need suction to releave the crank pressure.

That's why you have the PCV valve on the intake side going into the intake manifold. When you let off the throttle the vacuum sucks the gasses out of the crank case.

Maybe you should research how the system works before you radically alter it by changing to a scavenger system.

http://en.wikipedia.org/wiki/PCV_valve

huffandpuff00
06-11-2008, 11:40 PM
thanks much,

waltnuts42
08-02-2008, 03:49 PM
Sorry to bring up a kind of old thread, but its actually a nice mod to do. On a 350 Chevy motor, for example, 42% of non thermodynamic power loss is from pumping loss. (ie. piston pushing air out etc) Here the pressure the piston presses against as it travels down is part of that as well. By using the exhausts low pressure pulses to "pull" the higher crankcase pressures out it makes it easier for the piston to go down. You wont see a true pro drag car without a form of this on their car. The spot on the intake pipe is more for emissions to burn the blow by but you can do the exhaust (as mentioned you wont pass emissions) or even using manifold vacuum (after throttle body) opposed to the common port vacuum (before throttle body) to relieve more pressure due to the higher vacuum in the manifold.

drftthatshit
08-02-2008, 07:39 PM
yep the guy above me hit it on the nose why do you think you cars came with an airpump system on the exhaust and plus thats not alot of work but i see it as being sencless because i have never seen a top fuel 240 ever so there is really no need for it just run a catch can and call it a day cheap sensible move

waltnuts42
08-03-2008, 12:42 AM
yea top fuel 240 hehe. im talking about real outlaw drags and pro stock n shiz. i was going along the lines of the short block n big block n all that. Different then the 240 of course, but same internal combustion theories. You want all out power do it, but catch can to the intake on a street car? By all means thats fine.

drftthatshit
08-03-2008, 01:48 PM
i do agree walnuts42 why go to the extreme when it would jus be fine to do a simple inexspensive fix

S14DB
08-04-2008, 05:05 PM
We do have a http://zilvia.net/f/private.php function for small talk...

drftthatshit
08-04-2008, 06:54 PM
thnx appreatiate it