Tracy Cook de-drive for sale cleaning out shop $2,500 obo.

 Peter Morrison

 2.85:1 or 2.17:1 ?

 Paul Lamar


Being very much a beginner in this project, I have a couple of questions.
At the risk of demonstrating my ignorance:

1. Is 2:17 a good ratio for an RX-8 engine fit to an RV-4? Is this ratio
good for a 3-blade Catto prop?
2. Is this an early version of his reduction drive, and were there
significant changes to later ones?
3. Where is it located?

Thanks

David Walker

Ogden, UT

It depends on how much HP you expect to get from the rotary.
The amount of HP from the rotary increases directly with RPM.

The max RPM a rotary can generate depends on the gear ratio
of the gear box. A 2.17:1 gear box limits the max RPM to 6000 or 6500
depending on the diameter of the prop.

A 2.85 gets the RPM up to 7000 or 7500. The stock RX8 engine is
rated at 8500 RPM with a red-line at 9,000.

This is just for starters. There are lots of secondary factors as well
such as porting, intake runner length and prop pitch.

Paul Lamar

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