Two-stroke motorcycles often have reed valves on the inlet side, I don't
know if this would be worthwhile on a four-stroke engine. As I understand
things the problem that is that exhaust gases go backwards and can not only
contaminate the incoming mixture but also send it back out past the inlet
valve. So a non-return valve in the inlet might work almost as well as one
in the exhaust port.
Neil
----- Original Message -----
From: "Larry Colen" <lrcar@red4est.com>
To: <british-cars@autox.team.net>; <mgs@autox.team.net>
Sent: Thursday, February 27, 2003 8:32 AM
Subject: Anti reversion flappers
> One side effect, for me anyways, of doing lots of modification and
> tuning on a car is that I get ideas that I can't tell whether they are
> brilliant, stupid, or just plain weird.
>
> I was reading about porting heads a while back and they mentioned that
> you don't want to port the exhaust larger than the hole of the gasket,
> because the lip inside the header helps prevent reversion,
> i.e. exhuast gasses being sucked back into the cylinder.
>
> Having the exhaust gasses only travel in one direction, was also
> important on pulse jets, hence the flapper valve on the inlet, which
> keeps the exhaust from blowing back, at least until such a velocity is
> achieved that it starts working as a ram jet.
>
> Does anyone on this list (these lists) know of any work where someone
> installed passive flapper valves at the entrance to a header, such
> that exhaust gasses coming out of the motor would easily blow them
> open, but any gasses trying to blow back into the motor would close
> the valve, preventing further reversion.
>
> If these have been tried, did they do any good?
>
> Larry
>
>
> --
> I've found something worse than oldies station that play the music I used
to
> listen to. Oldies stations that play the "new" music I used to complain
about.
> lrc@red4est.com
http://www.red4est.com/lrc
>
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