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I have no flight experience in a Lancair IV-P, but 23 years flying all sorts
of high-performance singles and twins up through King Air 350s.

We just had the Dukes fuel pump rebuilt for a Lancair IV-P we are working
on, and during ground test runup at 2250 RPM (the max we can get without
chocking the wheels and tying the tail down first), flipping on the High
Boost nearly snuffs out the engine, causing an extreme over-rich condition.
Low Boost increases fuel pressures by about 6 to 7% in the range of 1000 to
2250 RPM, while High Boost more than doubles the fuel pressure at the
sensor.

Seems High Boost is appropriate for very high altitudes and some emergency
ops, but not down low. Does anyone in the know care to comment on the
definitive operating procedures regarding High Boost in Lancair IV-Ps?

Best Regards,

Larry Graves
AirCrafters Builder Assistance Center
140 Aviation Way, Watsonville, CA 95076
Tel 831-722-9141 Fax 831-722-9142
www.AirCraftersLLC.com


----- Original Message -----
From: DOUGLAS W JOHNSON <LANCAIR1@prodigy.net>
> Kirk Hammersmith of Lancair states that use of high boost at 10k feet will
> "snuff out the engine."  Is that really so?  
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