I-Love-Jets

Yep, OPS marine engines are offered by Niagaramarinehobbies or Aeromarinerc for instance:

http://www.niagaramarinehobbies.com/OPS.67%20.80_1.htm
http://www.niagaramarinehobbies.com/OPS.45_1.htm
http://www.aeromarinerc.com/opsengines.htm





Indeed it is easy to convert the OPS .45, .67 and .80 marine engines to aero speed monsters:
[ul][*] Just swap the front and the rear end. Because the engine housings are designed symmetrically no problems will occur.
[*] The angled marine exhaust header can also be used for aero application, but it should be extended using the correct diameter aluminium tube featuring same outer diameter as the tuned pipe inlet. Best of course is to gas-weld (true material fusion) the tube extension onto the marine header. You may also bend the tube slightly to achieve a “Fuse-Top“ style header. The 4 water fittings do belong to a separate water cooled exhaust plate that won’t be used for an aero conversion. Or simply buy a MACS header instead: http://www.macspro.com/headers_rear.asp
[*] The golden anodised aero cooling head (#6240) would be the optimal solution but the red anodised marine head having cooling fins as well does the job nicely too – just unscrew both brass water fittings...
[/ul]



So the only parts that have to be purchased additionally are:
[ul][*] the propeller driver/washer/adaptor/nut assy (#6250 for .60 to 80 and #3640 for .40 to .45)
[*] or the integral type speed spinner (#6300 for .60 to 80 and #2300 for .40 to .45)
[*] the aero cylinder cooling head #4021 for .45.
[*] the venturi speed carb assembly #6290 for .60 to .80 and #4290 for .40 to .45.
[/ul]


For the OPS .45 following MACS tuned pipes are recommended:
[ul][*] # 1150 unmuffled[*] # 1250 muffled
[/ul]

For the OPS .60, .65 and .67 following MACS tuned pipes are recommended:
[ul][*] # 1160 unmuffled[*] # 1260 muffled
[/ul]

For the OPS .80 following MACS tuned pipes are recommended:
[ul][*] # 1190 unmuffled[*] # 1290 muffled
[/ul]


Please keep in mind:

- These converted OPS aero engines are much lighter than their marine counterparts due to missing flywheel and water-cooling equipment.

- Please maintain a fuel oil content of a minimum of 20%, even if using the needle bearing conrod versions. The nitro percentage depends on the type of head button used (“standard“ up to 15% and “nitro“ up to 40%).

- All of those converted OPS monsters do require continuous strand carbon fiber props for safety reasons!

- Please always use the electric starter. Never use a chicken stick in combination with carbon fiber props being too brittle!

- The actual OPS .45 (drum valve) is considerably stronger than the OS .46 VX-DF engine and supplies much more torque than the actual ultra-high timed FAI MB .40 pylon engines - so the OPS .45 SPEED VAE does turn oversquared props such like 6.5x10“ with authority...

- The actual OPS .67 redhead (parts are fully interchangeable with the 5-ports OPS .65) is even stronger than the FAI compliant OPS .60 VAE goldhead. However the actual .67 piston/sleeve assy is characterised by refined porting (3 + 2 + 2 port layout = 7 ports, see below pictures) and by slightly higher timing than the OPS .65. For that any OPS .65 owner should also purchase the OPS .67 marine engine (actual drum rotor version preferably) as a spare (parts) engine.

- The actual OPS .67 (drum valve, stock, non-modified internally, venturi carb) as a converted aero speed engine will unload to about 25.000 rpm with the correct sized prop and the right airframe aerodynamics. A highly modified OPS .67 version will gain appr. another 2000 rpm. So it is not really worth the effort to improve peak output by numerous internal mods.

[sm=wink_smile.gif]