Below are some of the engines that we have seen used in Zodiacs 601's the links are here to help you decide which is best suited for your airplane and some steps used in making them air worthy.
Lycoming O-235 Power
Stratus EA-81 SUBARU
NSI has Subaru conversions and controllable-pitch propellers. They sell "firewall forward" conversions for a number of airplanes.
Subaru engines - Link to an EAA how-to article
RAM Performance Subaru
Subaru EJ22 - Garrett T-3 Turbo Conversion
Eggenfellner Aircraft Engines sells Subaru conversion and PSRUs
Al Wick- How to install a Subaru auto engine into aircraft.
Subaru Factory Manuals
SubaruEJ2.5-Service Manual - I thought this engine was too heavy, but I see someone is installing one in a CH701
Corvair Manual 1.PDF
Corvair Manual 2.PDF
Corvair Manual 3.PDF
Corvair Manual 4.PDF
How to vent ( duct) your radiator inside the cowling.
Cooling Systems for Automotive Conversions Part II"
Cooling Systems for Automotive Conversions Part III"
Cooling Systems for Automotive Conversions Part IV
Dual Dizzy walkthrough for your EA-81 / EA-82 a complete walkthrough on how to install a dual pickup in your distributor
Graveyard Aeronautical Motors ~ What you need to know for your trip to the graveyard to pick up a new airplane engine.
How to Make Your Own Engine Mount
usjabiru.com: Visit the website for price information and more...
Jabiru factory (Australia)
Mark Langford's-building a Corvair
Turbo-Powered 110 Horsepower Corvair Engine
Firewall forward assembly
Hog Air - You have to hear it to believe !
Raven Rotorcraft & Redrives
Nessa Aircraft ~ A great resource for information.
Firewall Forward Aero Engines Inc.
T62 I have seen it in a 601but cannot find anything on the web, I'll keep looking .
JFS-100 ~ Working on having a better builders guide! I WANT ONE !! ~cdngoose
Great Plains Aircraft
VW Engine Centre
Atkins Rotary Engines has developed an aviation conversion of a Mazda rotary. They've got one flying nicely in an RV-6
Conversion Concepts - Mazda conversions for RVs and canard-type airplanes
Fly Rotary!! discusses aircraft Mazda conversions
J-Wind Designs - Mazda engine for Wittman Tailwind
Mick Duckt N7XR home page - a Long-EZ flying a ducted-fan Mazda rotary.
Mid-West Engines specializing in Wankels
Real World Solutions covers Tracy Cook's Mazda 13B conversion