Info on 250 with turbo's

[kota]

Can some people with turbo's on their comanche singles give me some pro and cons on having turbos and their maintance issues. How does it effect take-off etc. I live in Montana @ 4000ft and it takes about 9500 to get out of valley

[Jay]

I was waiting for someone with a single to reply, but so far nothing and I hate to see you hanging.

The Ray-Jay turbo system has the virtue of being extremely simple. You turn a vernier that opens and closes the waste gate to get more or less boost. No pressure controllers, no hydraulics, no electronics, just your right hand, so you have complete and direct control and there are few things to go wrong.

The downside is that there is nothing automatic, you HAVE to control things directly, and yes people have overboosted Comanches and damaged engines, but it's quite unusual. The key to success is a smooth right hand.

So far as maintenance goes, when I had the engines on my Twinkie overhauled last year the turbo overhauls were $1,200 each (on top of the engine overhaul cost). I budget about 500 dollars a year for tweaking on the turbos on my engines (occasional new seals, hoses, clamps and chasing leaks) but most years I don't spend that.

Operationally, they slow time to climb somewhat from sea level to about 8,000 feet. For most of your initial climb you are unboosted, so you are carrying the dead weight of the turbo for no benefit, plus the induction system is a bit less efficient than the NA Comanche. But once you get higher, the benefit is clear. I figure a 700 FPM cruise climb all the way up to about 14,000, then it gradually decreases to about 300 FPM when I'm at FL 200 (the highest I've taken my Twinkie).

I fly in mountain country and I wouldn't be without my turbos. In your neck of the woods you'll get benefit on nearly every flight.

Jay

[Tony Scarpelli]