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Wow David, that 41ppm seems like a lot. What are the physiological effects of that
concentration? Doctors?

Next question: Where is it coming from? There must be a leak path between the
exhaust and the turbo intake. It would seem likely that you have an exhaust leak in
one of the forward cylinders combined with pressure drop in the air cleaner and an
air cleaner leak or alternate air door leak. If we assume that the lower cowling
pressure is greater than the pressure at the intake of the turbo then it is
conceivable that you could have flow of combustion products into the turbo intake
and therefore into the cabin.

I have maintained that the Lancair air cleaner is undersized for the task (not to
mention flowing backwards). perhaps David's high CO levels are related to a high
pressure drop across his air cleaner. This pressure drop, if large enough, would
allow the undesirable pressure gradient needed to suck CO into the intake.

BTW the round air cleaner is rated at about 600 CFM but the engine needs about 900
CFM at FL250. I used two K&N 800 CFM filters (one for each turbo).

One test would be to fly the airplane without an air cleaner and recheck the CO in
the cabin.

Thanks for the heads up David, where do I get one of those CO sensors?

Regards
Brent Regan


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