could be a loop hole ??? o-200

[tim]

hey all i was doing some looking for parts and what not for my dad any way i went on to dons dream machines web site and saw that he has a stc to use a o-200 crank cace instead of the c-85 and we all know about the c-85 / o-200 change stc what im thinking is what if some one could use the to to put basicly an all o-200 in are much wanted tcraft ???

what yall think ??

[astjp2]

Re: could be a loop hole ??? o-200

That is what I am planning on doing....Tim

[tim]

Re: could be a loop hole ??? o-200

really cool so if we could do this why not just get an stc for the o-200 then but how much did don say the stcs are ???

[astjp2]

Re: could be a loop hole ??? o-200

about 4 years ago, they were 350 each...Tim

[pftcraft]

Re: could be a loop hole ??? o-200

Could be a loop AND a hole if yer not careful. The Harer STC shows mods for the wing attach fittings as well as some others. I would think they are done for a reason...maybe wing loading etc coming from more horsepower and ...speed...

[Guest]

Re: could be a loop hole ??? o-200

from higher gross weight is also a reason

[astjp2]

Re: could be a loop hole ??? o-200

Well I checked on some of the cub line of aircraft, and they did not do the Harer style wing attach mods and went up to 135 hp and gross weight increase to 1600, I think that the mods were to satisfy some FAA enginerd fresh out of home school...I guess I am not real impressed with the feds today...The biggest limiting factor is HP, the O-200 will not make the Tcraft 35% faster for the 35% hp increase, and most fly over gross already and are not peeling off wings...Just my observations...Tim

[Guest]

Re: could be a loop hole ??? o-200

Hi Tim,

For what its worth the structural mod listed on the Harer STC match exactly the structural changes that the factory made for the 85 hp and higher gross weight model (bc85 and f19...).

In fact rather than make the mods to the parts you can just replace them factory parts from the later models.

That may or may not boost you opinion of engineerds!

Dave

[tim]

Re: could be a loop hole ??? o-200

ya well she is a bc12d-85 with stc to make it a -4-85 and i wont more power with the higher gross want to make it some what of a bush plane

[Dano"T"]

Re: could be a loop hole ??? o-200

Don't be too disapointed if the O-200 doesn't perform any better than a C-85....you have to spin an O-200 to 2750 rpm to get the rated horsepower....that means a short flat prop....and if you look at approved props you may be dissapointed. I have an FAA certified letter allowing the use of the Harer STC without the wing mods and engine upgrade up to C90. All you have to do is the fuel mods. I sent it all to the foundation....If you want a copy PM me and I'll e-mail the pdf's. Be advised that yor GW remains 1200 lbs.

Buy the Harer STC for $250, do the fuel mods, attach the letter and a copy of the approved 337 and put a C85 or C90. Why is the C90 approved? Because the FAA allows up to 10% increase in HP on a Field approval level....since the Harer STC allows a C85...then 85hp x 10% = 93.5 HP.

A C90 will likely outperform an O200....C90 gets 95HP on takeoff at 2475 Rpms. I have a AK76-2-40 prop on my C90 powered BC12D and It is a rocket

here is what it says on wikepedia:

[edit] C90
While the C90 is approved for takeoff power of 95 horsepower (71 kW) for 5 minutes, the designation derives from its continuous power rating of 90 hp (67 kW). As noted above, certain models of the C90 replace the usual carburetor with a fuel injection system. In addition, there are models which provide for the installation of a controllable pitch propeller and one, the C90-12FP, designed for pusher installation. [1] While slightly less horsepower than the O200, many floatplane operators prefer the performance of the C90 over the O200, due to its higher torque at lower rpm. This is primarily due to the C90's camshaft design.

[Robert Lees]

Re: could be a loop hole ??? o-200

I was going to post the following request for information as a new thread. I see Tim got there ahead of me. So ahead with my enquiry:

C85 to O-200 conversion STC

I'm interested in doing the STC from a C85 to "the equivalent of an O-200".

I have a lot of historic emails from the old Topica List days, on the pros and cons of this conversion, and I would welcome some fresh blood to offer their opinion.



Questions:

1. Is there more than one STC, and if so, who offers what?

2. Fresno have quoted $3850 for the parts (0-200 crank, pistons and conrods) and the STC paperwork, and they suggested that all the other mechanical parts remain the same. Is this a reasonable price, and if not, where else might I look?

3. The 85 that I'm looking at buying as a basis for the conversion is a -12 (with electrics), so I need a -8 accessory case. Where might I get one of these from? Is it true that an A-65 accessory case can be machined and become a C85-8 accessory case?

4. Is anyone flying behind one of these conversions, who would be willing to offer an opinion?

5. Any other pointers?

Thanks in advance for any help.

Rob

[astjp2]

Re: could be a loop hole ??? o-200

Well I can say from personel experience, a -8 is a -8 is a -8, the A-65 accessory case is the same as a 90-8. If it was me, Don's charges 350 for the stc to convert a c-85 to a -8 and its 350 to use the O-200 crank and rods stc. There is also a an stc to use an O-200 case on a C-85 engine. I would shy away from the O-200 case because the lord style mounts move the engine foreward 5/8" and causes havoc with the baffling. The biggest mods to convert the engine is to change the stud locations, one oil passage is blocked for the accessory case and the top of the case is trimmed. You will need to get an A-65 accessory case and gears, oil pump and gaskets. I would use a 35 degree overlap C-90 cam, the 24 is the same as the O-200. and for those of you think that the O-200 has to have a short prop needs to rethink that philosophy, a borer prop is 80-88" + for the O-300 and a stock prop is 76, the only reason for the short prop is to accomodate the C-150 series airplanes. I can honestly say that the M74ck-0-46 prop is rated to 100 HP @ 2650 but needs to be repitched to 43 to get the RPM for a 90/O-200. on a short mount, your takeoff roll is 250' at sea level. If I could find a 76" prop, that fit an O-200 flange (sae #2) I would in a heart beat. With 8.50's you will still have 28" clearance taxiing and 16" in takeoff attitude. Now everything that I have mentioned would need to get approved for each application! I think that it would be worth the hassle to get a C-85 with the O-200 crank and rods and convert it to a -8 and use a 74-76" prop. Thats my 2 cents worth for tonight. Tim

[Guest]

Re: could be a loop hole ??? o-200

Well I can say from personel experience, a -8 is a -8 is a -8, the A-65 accessory case is the same as a 90-8. If it was me, Don's charges 350 for the stc to convert a c-85 to a -8 and its 350 to use the O-200 crank and rods stc. There is also a an stc to use an O-200 case on a C-85 engine. I would shy away from the O-200 case because the lord style mounts move the engine foreward 5/8" and causes havoc with the baffling. The biggest mods to convert the engine is to change the stud locations, one oil passage is blocked for the accessory case and the top of the case is trimmed. You will need to get an A-65 accessory case and gears, oil pump and gaskets. I would use a 35 degree overlap C-90 cam, the 24 is the same as the O-200. and for those of you think that the O-200 has to have a short prop needs to rethink that philosophy, a borer prop is 80-88" + for the O-300 and a stock prop is 76, the only reason for the short prop is to accomodate the C-150 series airplanes. I can honestly say that the M74ck-0-46 prop is rated to 100 HP @ 2650 but needs to be repitched to 43 to get the RPM for a 90/O-200. on a short mount, your takeoff roll is 250' at sea level. If I could find a 76" prop, that fit an O-200 flange (sae #2) I would in a heart beat. With 8.50's you will still have 28" clearance taxiing and 16" in takeoff attitude. Now everything that I have mentioned would need to get approved for each application! I think that it would be worth the hassle to get a C-85 with the O-200 crank and rods and convert it to a -8 and use a 74-76" prop. Thats my 2 cents worth for tonight. Tim

Hey Tim,

is this cam the old one that was the subject of a service letter many years ago?

I heard that it caused some feilds to start on fire because of the flames it puts out the exhaust.

Does it give more power?

I have re-conditioned one that I plan to use in my c-90.

Just wondering.

Dave

[astjp2]

Re: could be a loop hole ??? o-200

Well the torque curve is at a lower RPM from what I have read, which means more torque at 2650 than the 24. But you could always get a custom grind if you know were to look....If its not an AD I wont worry about it. Dave have you seen the interchange manual on the flybaby site? good reading. Tim

[Ragwing nut]

Re: could be a loop hole ??? o-200

The O-200 crank STC does not allow a higher HP or RPM rating legally. Legally it is still a C-85. Still runs the 85 cam which has a different profile than the O-200. The C-90 cam referred to above does have a service bulletin against it, not suppose to be used in a legal engine, and straight stacks (no mufflers) have to be used with it. It is simple mathmatics that even ran athe same rpm, due to displacement increase, it will make more power, but not much.