IO-320 with 9.1 Pistons

[Bayou Bert]

What are the pros and cons of getting the 9.1-1 pistons
option from Aerosports.
I haven't had time to call them yet, but saw the option on a quote
they sent me.
Not being an A/P, I knew I could get an answer here.

Bert

[Rupester]

With 8.5:1 pistons you can run Mogas. I'm not sure about 9.1:1

[William]

You'll pick up 4-5 hp by going with the 9:1 pistons.

[terrye]

You should check to see if the prop you intend to use has been tested and approved with the engine and pistons you intend to use. If it has not, I'd stick with the standard pistons.

[JoeBlank]

This slightly higher compression ratio will require the use of 100LL, but may be overall more efficient, especially with electronic ignition. Bart estimated my Aerosport IO-320-D1A with this configuration, would turn out ~170 HP. Not an actual dyno number, but his 'best guess'. In an actual side by side run with an RV-9A (O-320), I had about 1 gph favorable fuel burn advantage for the XC trip. With balanced injectors you will have a great efficiency motor with a little more power when you need it. Talk with Bart or Sue for additional details.
Just my $.02 worth...

[brad walton]

Higher compression permits leaner operation of the engine, or operation at a lower gallons per horespower per hour.