routing crankcase breather to exhaust -Illegal!

[Eric Kelcher]

Just for information there are some threads wandering around, one of which is on the WERA site,  talking about the added hp of crankcase scavenging..

Just for everyone's information routing the crankcase anywhere other than into the air box or intake stream is a saftey violation repeat this is not a SS legal, SB or GP legal mod it is a safety violation as if/when the engine pukes it deposits its oil into the exhaust and out onto the track.

There are other methods that could be legal but direct routing into the exhaust is NOT!!!


FYI here is the rule.

5.2.15 On 4 stroke machines, crankcase ventilation must be routed into a heat resistant
catch can of at least 350cc capacity or the air box.
A. If ventilation is routed into the air box, any drains from the air box must be sealed.
B. If ventilation is routed to a catch can, the overflow tube from the catch can must
be routed into the intake area of the carburetors so that any overflow from the
catch can will be drawn into the engine.
C. Radiator overflow and battery vent tubes may be routed into a separate catch can
that need not be vented into the intake area.
D. Final approval of the catch can system rests with the Tech Inspector.

[EX#996]

Thanks for setting the record straight!

 ;)

[Super Dave]

Was there a question on this?  It was a hot topic in 2001...  What happened to revisit it?

[Jeff]

Yep, good topic.  I believe in 03 there was a single Supersport race at BHF which had 2 of the top 3 DQ'd because of this...

[grasshopper]

I'm not planning on doing this but how do you route the crankcase breather into your exhaust without melting the hoses.

To me it sounds like that could become a mess really quick.

[Zac]

To do it properly you have to have a verturi effect in the exhaust where the breather is piped in.  I've heard of some vintage guys getting busted for this setup.

-z.

[Eric Kelcher]

There are ports and such built into some of the bikes that connect to the exhaust system for emmsion control. The Suzuki PAIR valve is one of them and connecting this to oil breather is one of the things that is illegal.

Dave it was brought up on the WERA board as a great bit of of "free" hp, well that hp is not free and comes at a price and that price is safety.

[Super Dave]

I'm not sure how the oil might get out of the exhaust.  Any part of the exhaust would be a much bigger area to hold oil.  I know of no documented times when it was done and oil was lost.

If the same line is routed to the air box, which it is, the oil would go through the cylinder and then the exhaust...same place.

[Eric Kelcher]

Dave the oil vapor is sucked into engine and burned if routed into airbox in normal situation. If routed into exhaust the vapor is expelled out the exhaust unburned and onto the track. As a motor becomes more tired the amount of blow-by increases and oil vapor increases this results in more oil going into airbox or exhaust.  

Now when an engine blows, the oil that is puked out of engine must be blown into airbox as engine is no longer running it has no suction or minimal suction to suck oil into the engine from airbox and push it out the exhaust. If it is routed to the exhaust the "puke" power is straight out the back of the bike.

[Super Dave]

Or it gets into the engine, it hydro locks and tosses the rods out with the oil.

[r6_philly]

so a catch can of a sufficient size is the way to go?