The International Cessna^® 170 Association

With your new cylinders you should be good for a lot of good flying. Don't baby that engine however. Its made to run anywhere up to 2700 rpm's.

I have wondered what, if anything, was/is different in C-145/O-300 engines vs GO-300 engines. I realize the GO has the propeller reduction gearing, but otherwise is there anything different to permit 3200 rpm's? I understand the recommended tbo is lower on the GO.

The GO engine's cylinders required better cooling and a heavier head-casting. It's cylinders could be used on the C145/O300 but not the reverse...and so it didn't take long before the mfr's wised up and only made the heavy cylinders (which is what you buy these days when buying new.)

The GO300 had a shorter TBO because the engine ran around at 3400 RPM or thereabouts and it simply wore them out. It'd be like running your car downt he highway in second gear all the time... Lots of get-up-and-go... but not much durability.... and that gearbox was not built for high gyroscopic manuevers or rapid power changes...so the engine didn't enjoy nearly the durability-reputation of the C145/O300...which is loafing at 2700 RPM or less.

Your right the O300 is a tuff engine to beat, the GO300 fail because people lugged them back and wouldn't run them where they were designed to fly, my gearbox held up but I broke a piston contaminated the oil with pieces of rings & piston . In 1990 it cost $32000.00 to overhaul the GO300, which I didn't have , and wouldn't borrow so I took a break until my kid got of college. I put them through school but I'm flying their inheritance now. I think TBO is 1200 hrs on the GO.

DoubleOught wrote:Your right the O300 is a tuff engine to beat, the GO300 fail because people lugged them back and wouldn't run them where they were designed to fly, my gearbox held up but I broke a piston contaminated the oil with pieces of rings & piston . In 1990 it cost $32000.00 to overhaul the GO300, which I didn't have , and wouldn't borrow so I took a break until my kid got of college. I put them through school but I'm flying their inheritance now. I think TBO is 1200 hrs on the GO.

"Lugging" them (running them below recommended RPM) was indeed hard on them ...but not for the reasons commonly thought. It wasn't hard for the same "lugging" reasons implied as in automobile engines (where "lugging" implied running the engine at high Manifold pressure in too high-gear, resulting in detonation. Except for the GO-300-E engine which used a constant speed propeller...it was difficult to "lug" a fixed pitch engine because low RPM naturally was the result of low manifold pressure/reduced throttle settings.
The low-speed operation resulted in a high-angle of attack during cruise and overheated the engines (which, since installed in simple-instrumented airplanes) were rarely equipped with a CHT gauge and, even if so equipped, the releatively in-experienced pilots operating them in rental fleets and flight schools didn't know how to operate either the CHT gauge OR the geared engine...which requires that the engine drive the prop....and never the prop driving the engine from sudden power-reductions. (Old WW-2 aviators knew better because they'd been operating radials which were often geared.)

The GO-300 installation in the 175/Powermatic Cessna's had a tachometer which indicated ENGINE RPM. If Cessna had tied the RPM indication to the PROPELLER...then pilots wouldn't have been so inclined to operate it slowly. In any case, it was a small engine with big-engine complexity and served no useful purpose in the C-175 when a significantly better airplane, the C-182 was only a few bucks more.