Venting heads

[Bsmith153]

When I put the 124" in my 04 bagger my buddy,  who a life long drag racer in cars,  suggested venting the head in the exhaust. Apparently an old drag race trick.  Since i run a carb we used the o2 sensor bungs in my Thunderheader 2 into 1 pipe.  My buddy knew all the specifics like what angle the pipe had to enter the exhaust to get the proper pull and everything. Im a good wrench but this was a little over my pay grade.  We came to the conclusion that this would only work with an open exhaust and not my baffled thunderheader.  You guys are more knowledgeable than me so was wondering if we totally wasted our time or theres a way that this may work and be useful. Thanks in advance for any knowledge I may attain.

[Don D]

There are a lot of reasons to do this on a drag only vehicle and not on street driven bike. There is a good thread here about how the vent system works on the twin cam https://harleytechtalk.com/htt/index.php/topic,117941.0.html

[jsachs1]

When I put the 124" in my 04 bagger my buddy,  who a life long drag racer in cars,  suggested venting the head in the exhaust. Apparently an old drag race trick.  Since i run a carb we used the o2 sensor bungs in my Thunderheader 2 into 1 pipe.  My buddy knew all the specifics like what angle the pipe had to enter the exhaust to get the proper pull and everything. Im a good wrench but this was a little over my pay grade.  We came to the conclusion that this would only work with an open exhaust and not my baffled thunderheader.  You guys are more knowledgeable than me so was wondering if we totally wasted our time or theres a way that this may work and be useful. Thanks in advance for any knowledge I may attain.

Imo, exhaust reversion would be your enemy with that pipe and set up.
John

[hrdtail78]

If you plan on living in the rpm range from 6000-7500.  You might see some benefits.  If you plan on street riding rpm's.  Route to atmoshere or even a catch can.

[Hossamania]

I can see where venting into the exhaust with normal street riding will cause problems, as hrdtail78 suggests. The exhaust pulses pushing back against the breather valves trying to push the other way. At high rpm not as much a problem, not nearly as much reversion or mistiming on the pulses.

[Bsmith153]

That was just a experiment,  I vented to atmosphere. Just wanted to see other peoples opinions or ideas on the subject.