C-85/0-200 vs C-90

[akndrifter]

Well it's commercial fishing season for me again, and if we do well enough I was thinking of investing in a slightly souped-up tcart with a large(er) baggage. The two that I am really looking at are pretty similar (I think less than 20lbs). One has a C-85 with 0-200 crank, and the other has a C90-12. I've heard the C85/0-200 can do anywhere between 93-97hp. Has any one had experiance with both? Whatever I got would probably end up on bushwheels, and maybe haul a moose if I was that fortunate. And that is besides the tons of pounds of food we bring back from Cosco when we go to Anchorage. So far I think I like the C-90 better, because you can put a longer prop on it. But I wanted to see what the advantages of the C85/0200 where. So, most things the same, which motor would you choose?
Ps. If I don't write back on here, it's not because I don't like you guys I'm writing this real quick cause I probably won't have Internet access again for a week.

[N5002M]

Re: C-85/0-200 vs C-90

Well..I've flown both an 85hp BC12D and I own the 90hp BC12D with Harer mod. I'd say the 5 hp difference is a wash considering I have a full electrical system (which I like by the way..hand propping in -30 sucks!!!). Both planes perform real close. I have the Microvortex gens on mine and quite honestly I can't tell the difference...maybe if I jumped out of one directly into the other. As for mine..I will say that I've loaded it heavy. I have the 1500lb gross on mine and it 'could' probably exceed that...ummmm, not that I would know anything about that..... I own and work out of a 800' strip with normal size spruce trees at both ends..probably 30' to 50' tall. Under normal loading (two people and survival gear)...and full fuel in the front (12 gal) I can safley get out of there. I haven't tried (and probably won't) with all three tanks full. I pop out of there and then fuel up in Kenai for any long trips. With just myself, it's a rocket. I'm off in 200 feet and am about 300 feet above the tree's at my place by the end of the strip. I have the 72-42 Sensenich prop and cruising is slow....90mph on a dead calm day. More like about 75-80 with any kind of head wind. I've been passed by cars on the highway before..I hate that!!!..but it's the price you pay to get off the ground in 200 feet.

Other things to consider as far as engines is the cost and availability of parts and support. I can really only testify to the C90-12F. I am overhauling it myself this winter. So far, I'm predicting $5000 - $7000 tearing it down myself and farming out the steel and case work. I had three quotes at about $15,000 to have it overhauled at a reputable engine shop in Alaska. Jugs and all that are a snap since they are the same as the O-200. Cranks are easy too in that an O-200 crank can by machined to fit the C90 case (something to do with the thrust bearing seal). Cases are a whole different matter though. They can be a bit of a problem finding...fortunately, Nicksons, Divco and alot of other specialty shops have a bunch of approved repairs...so unless yours has been milled a million times and the cases are thin...it can be repaired. Don's Dream machines has an STC to convert an O-200 case to C90...so there are options for sure albeit be prepared to spend $$$$.

There are alot of people that understand the cross compatibility of engine parts way better than me although almost all of it can be self researched on the web.

For myself I think the C85 and C90 are pretty dang close in performance considering the weight differences...so that being said, I'd lay the decision more on the package deal (airframe, TT's, TSMOH...skis, floats..blah,blah..all that) as opposed to just basing it on the engine. I think either the C85 or C90 T-Cart will do what you need it to do and don't let the lack of flaps deter you...that can be overcome with good techniques.

If you have any specific questions about the C90 or my plane, I'd be happy to answer them. Good luck....

Chris

[wlas]

Re: C-85/0-200 vs C-90

That 90-12 and the 85 with the 0-200 crank should be pretty close to the same. I had a guy come in with an 85 that had a cracked crank so we put the 0-200 crank with the STC and it made a big difference in rpm, from what it was, using the same prop. He was pretty happy with it.

[N5002M]

Re: C-85/0-200 vs C-90

wlas - question: why does the O-200 crank in an C85 case result in a higher RPM with the same pitch prop? I'm trying to wrap my head around that one. I can see how they would 'allow' a higher RPM with a beefier crank and let you pitch down the prop but since you still have the same bore / stroke, I can't see how that would result in a higher static RPM. Do you use the same rods / pistons and jugs with the O-200 crank STC? School me please......

Chris

[Dano"T"]

Re: C-85/0-200 vs C-90

wlas - question: why does the O-200 crank in an C85 case result in a higher RPM with the same pitch prop? I'm trying to wrap my head around that one. I can see how they would 'allow' a higher RPM with a beefier crank and let you pitch down the prop but since you still have the same bore / stroke, I can't see how that would result in a higher static RPM. Do you use the same rods / pistons and jugs with the O-200 crank STC? School me please......

Chris

They put in an O-200 crank, connecting rods, and pistons.....How that changes the operation....stroke for one....I'm not sure.

[Dano"T"]

Re: C-85/0-200 vs C-90

I have 2 BC12-D's...one has C85-8, the other C90-12F....Both are great so get what is available based on TT SMOH and Overall condition....The C90 if equipped without Electrical will outperform the C90 by a fair margin due to Prop availability and torque curve, Rpm....etc....I estimate a 15% increase in takeoff/climb between the two....I've never tried a stroker C85/O200....I heard they are about a 10% improvement over stock C85.....These number are estimates from other people I've talked to.....I will say, on floats, I can get out shorter and heavier and climb much better with the C90...I have Sensenich 76AK-2-40 prop....cruises @ 94-97 on floats....103-105 on wheels.....verified by GPS during flight tests for Baumann Floats Certification.

[NY86]

Re: C-85/0-200 vs C-90

I would give a slight edge to the C90 because of its higher torque at lower RPM's.

Installing an O200 crank in either an early C85 or C90 case requires a modification to the case, not the crank. The mod can be done "in the field" using common tools.

The claims of 97 HP from a C85 with the O200 crank are from a test stand with a test club. Actual power in the field with a fixed prop is probably similar to the C90, but at higher RPM.

TMSAISTI, YMMV...

[akndrifter]

Re: C-85/0-200 vs C-90

Thanks for the food for thought. We aren't planning on getting rid of Miss T, just need the ability to carry more. I can get off in 200ft, just not with more than myself in the plane. I think N5002 and Dano"T" are probably right, whatever one is in better over all shape is going to be best in the long run.