C-85 upgraded to 100hp

[CarlM]

I've studied the threads comparing the C-90 with the O-200 and it seems clear that the C-90 is superior, especially for seaplane operations.

Where does the C-85 converted to 100HP by Don's Dream Machines fit in the small Continental spectrum?

Carl

[behindpropellers]

I am still not sure how you can convert 85hp (C-85) to 100hp (0-200) with just the crank and pistons. Has anybody had one of these engines on the dyno?

Here are the facts I know:

The 0-200 crank does give more throw.
The O-200 pistons are shorter than the C-85 (less compression)


So the question is....

How do you get 15 more hp without adding more fuel? They are adding cubic inchs to the engine, but not putting more fuel in the combustion chamber? Seems like you would need a cam and carb jetting change for that much of an increase.


still looking for a C-75 or C-85 case to turn into a C-90.
Tim

[Redbaron180]

I did the O200 conversion to an 85 I had in a Luscombe. It did seem to have more go, but they don't allow you to turn it up to O200 rpm's so you don't get 100 hp.

Ron

[brown bear]

As I remember it the c85 and c90 cam shafts have the same valve timing which I think have less valve overlap than the 0200, 10 dec. less I think.
The c85 cam has less valve lift . the c90 and 0200 have the same lift but differ in valve over lap which is why you can swing a large dia. prop on the c90 but not the o200.
DW