So I was recently asked by a fellow flyer which engine would be the better "upgrade" for a Super Duper Chief, a pimped out C85 or an equally doctored 0-235 L2C. This isn't a "legal" question, more of a power for weight and expense question. The C85 is lighter and can be nicely tuned up. The L2C well heavier, offers more HP in it's natural form but can be improved on as well.

Neither.....C-90 all the way. Lighter and lots of power.

MTV

I agree. Also turns slower and doesn't sound like it is hurting.

contactflying wrote:I agree. Also turns slower and doesn't sound like it is hurting.

Good analogy

contactflying wrote:I agree. Also turns slower and doesn't sound like it is hurting.

Good analogy

I would say the C85.
The Chief TCDS sez the C85-8 is approved on an 11BC Chief.
And that an 11AC Chief can be converted to an 11BC per Aeronca service letter #17.
Not sure what it would take to (legally) install an O235 -- or even a C90.
If the stock 85 doesn't have enough steam, it can be upgraded using the O-200 crank ("stroker") STC.

https://rgl.faa.gov/Regulatory_and_Guid ... /A-761.pdf

I'm not sure on a chief, but I know a 235 on a C140 blows a C90 or C85 powered C140 out of the water. It makes a real performer out of it. Even a C90 with High Comp pistons doesn't compare to the 235. I'd go 235.

So correct me if I've got something wrong but here's where it gets a bit confusing for me.

A Conti 0-200 tips the scales at 170 lbs and produces 100 hp and the Lycoming 0-235 is 240 lbs for 100 hp do you see my confusion.

Full disclosure I gleaned this off of Wiki so take the numbers with a grain of salt but the underlying theory stands, power to weight ratio

Mapleflt wrote:So correct me if I've got something wrong but here's where it gets a bit confusing for me.

A Conti 0-200 tips the scales at 170 lbs and produces 100 hp and the Lycoming 0-235 is 240 lbs for 100 hp do you see my confusion.

Full disclosure I gleaned this off of Wiki so take the numbers with a grain of salt but the underlying theory stands, power to weight ratio

The 235 should be putting out 115 hp... power to weight ratio may be higher for the Conti, but that won't necessarily make the plane perform better. But if you are going strictly for power to weight ratio then the 0-200 or C90 is better. I just wanted to give you a on aircraft comparison. On the airplane, it's really not even close.

A1Skinner wrote:

Mapleflt wrote:So correct me if I've got something wrong but here's where it gets a bit confusing for me.

A Conti 0-200 tips the scales at 170 lbs and produces 100 hp and the Lycoming 0-235 is 240 lbs for 100 hp do you see my confusion.

Full disclosure I gleaned this off of Wiki so take the numbers with a grain of salt but the underlying theory stands, power to weight ratio

The 235 should be putting out 115 hp... power to weight ratio may be higher for the Conti, but that won't necessarily make the plane perform better. But if you are going strictly for power to weight ratio then the 0-200 or C90 is better. I just wanted to give you a on aircraft comparison. On the airplane, it's really not even close.

Your insight is welcome; thanks, how it flies is the true test.

I have no experience with a O235. I loved my stroked C85. STC owner told me on the dyno the test engine delivered 106hp at 2575 and 130hp at just over 3000. It’s an O200 rotating assembly so if I was experimental I’ll be comfortable turning it up to 2800 for takeoff which puts you in the 118hp range.

I always thought it would be interesting to try a C90 cam in a stroker C85. People say the C90 cam delivers more torque.

My understanding is that the preferred model of the 0-235 is the L2C variant, it specs out at 115 hp however the lessor variants only develop 108 hp

Mapleflt wrote:My understanding is that the preferred model of the 0-235 is the L2C variant, it specs out at 115 hp however the lessor variants only develop 108 hp

There is actually only 3 of the variants that make 108, one makes 100, and the rest make 115-135. So more choices available to have over 115hp then under.