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Re: [turbobike] turbo question

John Williamson (john.williamson5@virgin.net)
Sat, 6 Nov 1999 17:37:06 -0000

Actually it doesn't if you have four cylinders.
The two that go up displace the same as the  two that come down, so it is
not a problem, other than the 1 to 3 hp that you lose pumping it about at
10,000rpm ...
But the reason that the crankcase is vented to airbox / atmosphere is to
keep oil in the motor (oil seals and gaskets),  and prevent it getting past
valves and rings into the combustion area and getting burned - which in the
case of a turbo bike is dangerous since oil drastically lowers the cylinders
detonation limit as it is very low octane.
When your engine runs gas gets past pistons and into the case, if this was
not allowed to escape it would build pressure until it equalled that in the
top of the motor! And something would give.

Why would anyone want to pressure a casing on purpose? What would be the

----- Original Message -----
From: Bryan <bgoodwin@iquest.net>
To: RAW ANT <rawant@webtv.net>; Christer Johansson
Cc: <turbobike@natvideo.com>
Sent: Saturday, November 06, 1999 5:00 PM
Subject: Re: [turbobike] turbo question

> Do not do it! Your crankcase needs to be able to vent any pressure for the
> reciprocating assembly to move freely.
> At 06:45 PM 11/5/99 -0800, RAW ANT wrote:
> >I have compensated for boost pressure in the float bowls and the
> >Someone metioned that it was a bad idea to pressurize my crank case .
> >do you guys think about that?     RAW M.... F..... ANT
> bgoodwin@iquest.net
> FZR1000 turbo EFI
> (aka The Money Pit)