CA Horsepower

Don't know every detail of it, but like the similar engine the 226, More RPMs, and, extra Fuel were the two key reasons the 226 climbed in HP over the years.  

According to TractorData, the C turns at 1500, CA at 1650.   C Compression 4:25x1, Ca  6:25X1 plus the CA has the 4 speed

Gary(MO) wrote: Max ia  Where did the CA's get the extra compression? Different pistons or was it in the HEAD? I always thought C's and CA's were identical engines but, with the different comp. ratios something was different. Thanks Gary

Different pistons

wfmurray wrote:  Tracor cranks and run good  but speed flucates  when not pulling . When it pulls it level out . Think it is a little richer than the B carb was. IT don,t have adj.

Raw Horsepower is Torque x RPM x constant. Typically Torque curves have a peak before they reach highest design RPM - somewhere I think I have typical AC torque curves and I think they peak early - so More RPM may or may not equal more HP by itself.

But if you add compression and tweak timing or camshafts, the torque curves and peaks can be changed - or if you improve combustion like the 226 Power Crater design did. And of course displacement makes more torque so the CE engines made more power than the BE.

As to drawbar HP, that does include factors like tire size, transmission gearing, and rear end ratios - hence the need to also look at Belt HP which is more straightforward.

But I think the simple answer is CR was increased to take advantage of higher octane gas as it became available and torque increased. RPM increase x increased torque = increased HP.

Only variation significant to CR were Pistons and Head Gaskets - yes Head Gaskets. On early engines - mostly the 116 CI BE, but also used for the earliest 125 CI variant in the R tractor - they used 2 head gaskets to lower CR for Low Octane (Distillate) fuel.

And the differences in the pistons - as pointed out by another poster would be height from piston pin to top of piston and possibly piston top geometry.

Pistons for early CE Low Octane were 4.7:1 Cast Iron - these would be CE engines with K suffix

Pistons for early CE Low Octane High Altitude were 5.2:1 with both CI and AL variants
Pistons

Pistons for early CE gasoline engines in B & C tractors up to early 1950 were 5.7:1 Cast Iron - presumably these would be the G suffix engines

Pistons for CE gasoline engines in mid 1950 up to s/n CE153961/CR47264 were 5.7:1 Aluminum - presumably the GA suffix engines in early CA and some B tractors

Pistons for late CE gas engines beginning mid-1950 at CE153962/CR47265 were 6.2:1 Aluminum - presumably the PA suffix engines in late CA and B tractors

ACEd2010,  That is an outstanding explanation of the genealogy of  the B-C-CA engine pistons. 
Working with B-C engines I did not know the technical terms or the proper wordage but it always seemed that you could get more power in a B-C-CA engine by putting in a new engine kit.  Pistons and sleeves seemed to add horsepower.  In fact when we did an overhaul to an older unit we always told them to expect more horsepower but cold not explain it as completely.
Thanks again for clarifying the reason.
Good Luck!
Bill Long

There were both Aluminum and Cast Iron pistons in 5.2:1 and 5.7:1 range depending on year. The 6.2:1 were only in Aluminum. As to telling the 5.2:1 or 5.7:1 Al vs the 6.2:1 Al I think you would have to have a Part Number or have the 2 side by side and measure height from pin to top.

You could infer the higher 6.2:1 compression if Alum pistons are coming from a PA suffix engine, but since others may have been rebuilt over time - who knows?

Stock "CA" has more HP (26.7hp) than a stock "C".

CTucker    I got my carb off of a parts CA  ,. IT was still on the tractor . Seems AC made a lot of varations along the way.