What do Breather tubes do and...
Road Captain
Joined: Dec 2009
Posts: 646
Likes: 1
From: Rockford, IL
There is a certain amount of combustion gases that "blowby" the rings. This gas goes into the cases, then forced up through a hole in the cylinders, and out the cylinder head (out through the breathers. The reason why they aren't used is because of emissions. Instead of vented this gas to the atmosphere it is sucked back into the intake where it will be burned up with the other intake air. The bad part about this is over time the gas coats the intake with an oily residue and decreases the quality of "good" air that is going to the engine, reducing its performance.
If you look at an "old school" muscle cars most of them don't even have the blowby gas going back into the engine. The gas is just vented through the heads. You can usually see two breathers on the valve covers.
so.....in short it's emissions reasons and another EPA rule that reduces performance! Sorry about all the blabbing!
If you look at an "old school" muscle cars most of them don't even have the blowby gas going back into the engine. The gas is just vented through the heads. You can usually see two breathers on the valve covers.
so.....in short it's emissions reasons and another EPA rule that reduces performance! Sorry about all the blabbing!
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
The heavy breather passages from the heads to the intake tract are integral."The back plate features integral breathers and sealed breather bolt plug."
Don't worry about vapor from the crankcase impeding performance, todays motors offer more power per cubic inch than any previous Harley motor.
Crankcase venting into the intake tract became standard on US cars in 1962 ( EPA created in 1970) and you can read the whys and wherefores here:
http://en.wikipedia.org/wiki/Crankca...ilation_system
If you watch old movies, you'll often see that the centers of traffic lanes were well coated with oil from the "road draft tubes" which vented the crankcase previous to 1962----which leads to the other forum thread about the rider hitting a bunch of oil on the road...
Mike
Don't worry about vapor from the crankcase impeding performance, todays motors offer more power per cubic inch than any previous Harley motor.
Crankcase venting into the intake tract became standard on US cars in 1962 ( EPA created in 1970) and you can read the whys and wherefores here:
http://en.wikipedia.org/wiki/Crankca...ilation_system
If you watch old movies, you'll often see that the centers of traffic lanes were well coated with oil from the "road draft tubes" which vented the crankcase previous to 1962----which leads to the other forum thread about the rider hitting a bunch of oil on the road...
Mike
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Joined: Mar 2011
Posts: 65
Likes: 0
From: Denver, Colorado
There is a certain amount of combustion gases that "blowby" the rings. This gas goes into the cases, then forced up through a hole in the cylinders, and out the cylinder head (out through the breathers. The reason why they aren't used is because of emissions. Instead of vented this gas to the atmosphere it is sucked back into the intake where it will be burned up with the other intake air. The bad part about this is over time the gas coats the intake with an oily residue and decreases the quality of "good" air that is going to the engine, reducing its performance.
If you look at an "old school" muscle cars most of them don't even have the blowby gas going back into the engine. The gas is just vented through the heads. You can usually see two breathers on the valve covers.
so.....in short it's emissions reasons and another EPA rule that reduces performance! Sorry about all the blabbing!
If you look at an "old school" muscle cars most of them don't even have the blowby gas going back into the engine. The gas is just vented through the heads. You can usually see two breathers on the valve covers.
so.....in short it's emissions reasons and another EPA rule that reduces performance! Sorry about all the blabbing!
Thanks
Road Captain
Joined: Dec 2009
Posts: 646
Likes: 1
From: Rockford, IL
The heavy breather passages from the heads to the intake tract are integral."The back plate features integral breathers and sealed breather bolt plug."
Don't worry about vapor from the crankcase impeding performance, todays motors offer more power per cubic inch than any previous Harley motor.
Crankcase venting into the intake tract became standard on US cars in 1962 ( EPA created in 1970) and you can read the whys and wherefores here:
http://en.wikipedia.org/wiki/Crankca...ilation_system
If you watch old movies, you'll often see that the centers of traffic lanes were well coated with oil from the "road draft tubes" which vented the crankcase previous to 1962----which leads to the other forum thread about the rider hitting a bunch of oil on the road...
Mike
Don't worry about vapor from the crankcase impeding performance, todays motors offer more power per cubic inch than any previous Harley motor.
Crankcase venting into the intake tract became standard on US cars in 1962 ( EPA created in 1970) and you can read the whys and wherefores here:
http://en.wikipedia.org/wiki/Crankca...ilation_system
If you watch old movies, you'll often see that the centers of traffic lanes were well coated with oil from the "road draft tubes" which vented the crankcase previous to 1962----which leads to the other forum thread about the rider hitting a bunch of oil on the road...
Mike
Not only will this imped performance but it also heats up your intake temperature which will also make performance suffer
Not trying to start an arguement or anything
Outstanding HDF Member
Joined: Oct 2009
Posts: 2,488
Likes: 30
From: Maryland near DC
I don't know what type of heavy breather you have, but on my SE air cleaner it still has the vents to the air cleaner...it just does it a different way ( there are holes drilled through the mounting bracket, and it uses hollow bolts)...you must have some way for the motor to equalize the case pressure or it will blow out a gasket somewhere...
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