incresed performance from a 0-300

[roger]

Question is ,for as many years as the 0-300 has been flying and given the numbers built someone must have designed and tested some performance modifications that were sucessful, could they be in the seaplane arena? Does anyone know of a 0-300 being turbo-charged? were they ever used as helicopter engines? or hardcharged,We know the IO-360 crank fits the d model 0-300 is this crank drilled for a constant speed prop,? lots of ideas have any of them been blessed by the FAA?how about NASA archives? just food for thought, Geno

[GAHorn]

I don't know where that "360 crank fits" came from, but TCM certainly tried to increase the output of the O-300 when they created the GO-300 (giving it a claimed 25 hp increase), but that engine was never very successful and was discontinued after only a few years.
The demise if the O-300 came about as the result of the introduction of the Cessna Cardinal/177 with the (underpowered) Lyc O-360 (150 hp). Cessna purchased 5,000 engines for the new airplane and immediately ran into resistance to the airplane, partially because of it's underpower status. Sitting on top of all those engines, already in inventory, Cessna installed them into the 172 (which had been planned for extinction) and the Skyhawk continued production (and the Cardinal eventually went the way of the dodo, despite it's improvements with more horsepower and other mods. I always liked the Cardinal, mostly because of inflight visibility, but it never handled as nicely as a 172 or performed as nicely for the same cost as a 182 or 210 even.)
In any case, the O-300 no longer had an airframe mfr installing it as new equipment and the engine fell out of production despite it's reputation as one of gen-aviation's most reliable engines. (Lycoming always marketed their engines as high-reliability, but when the O-300 was in production and being re-mfr'd it had the lowest inflight shut-down rate of any reciprocating civil engine in history....a fact not much appreciated anymore with so many engines running on older, high-cycle and aftermarket parts. Not knocking all the aftermarket parts...it's just that for a while they suffered developmental issues.)
Things look good for the engine still except for some crankshaft availability issues on older cranks.

[Joe Moilanen]

Rumor has it that C-85 pistons will up the power a tad. Not approved however but tried and true.

Joe Moilanen
4518C

[Bruce Fenstermacher]

George I'm sure it was a typo but the Lycoming 150 hp is an 0-320 unless they severally derated the 0-360 for the Cardinal/172 which is normally 180/200 hp.

BTW running MMO and MOGAS increases performance.

[n3833v]

Bruce, Watch what you say. You might start some severe discussion.
John

[blueldr]

The O-300 series is rated to run continuously at 2700 RPM. If you want a little more power, thin your prop pitch down and run it at a few more turns. Of course, if you pull more power you will burn more fuel. (MMO too)... I have my prop skinnied down to 50 inches and I cruise at 2600 at 115 MPH and my fuel burn is almost exactly the same as it was with a 53 incher at 2450. However, it does get off and climb much better, especially at high elevations such as up in the mountains in Idaho.
I kind of wonder about the story of the IO-360 crank fitting in the O-300. If that was the case, guys would bootleg them in and save engines for experimentals rather than junking them for lack of a serviceable crank. As far as the crank being drilled for a constant speed prop, the cases aren't drilled and there is no accessory pad to accept a governor and drive it.
On the O-300 the B&S is4.1 & 3.9. On the IO-360 it is 4.44 & 3.88.
So the IO-360 has .340" more bore and .020 less stroke, and the compression ratio is upped from 7 to 1 on the O300 to 8 1/2 to 1 on the IO-360. I do not know if the bearing and journal sizes are compatible.
On a standard day at sea level the IO-360 makes 210 HP at 2800 turns where the O-300 makes 145 at 2700.
Some models of the IO-360 are restricted to 2600 max rpm and are rated at 195 HP.
Installing an IO-360 in a C-170 is really expensive, but it sure makes one hell of a performer.

[blueldr]

Maybe I should explain about my above comments. I am now flying a stock engined "55 model (my spare) because I screwed up and busted my '52 model with the IO-360.
I cry a lot at night.

[Jr.CubBuilder]

blueldr, I hope this doesn't sound like a stupid question, but where did you get the motor for your 52, or was it already in it when you bought it? I'd like to do this conversion in a couple of years, but I don't see any of these motors out there for sale. I've seen Lycoming 360s, but I haven't found any Cont. IO360s.

[N1277D]

I am sure the FAA would not like this but it might be within the fine interpertations of the regs. I never have seen this done but I wonder if this would be possible, perhaps if an owner produced or spec-ed out or participated in the design a replacement piston with a 10% higher compression ratio using the same materials, tolerances as the orginal part - Would it or should it fall within the guidleines of being an acceptable owner manufactured replacement part. I believe 10% is the tolerance you are allowed by the manufacturer/FAA for engine hp?? The hp is directly porportional to the compression ratio, stroke, cylinder volume and rpm. Increasing the compression ratio increases power, lowers EGT and fuel consumption, but increases the stress on the cylinder, rods, crank, bearing and thrust pads.

You could also adjust the mag timing some to get some additional hp, or run a flatter prop to get the additional rpm, use an air filter with less pressure drop - all these could help but you can't exceed 1.10 of the rated hp rating of the engine and still be within the type certificate.

I have heard of C85 pistons being used in experimental O300 engines, the pistons need to be machined some so that the upper edge does not contact the region where the cylinder head and barrel mate up.

There are a couple of manufacturers who produce experimental pistons for the 0200. One is Lycon who has a range of compression ratios, the other is a well know "Reno" engine component rebuild shop. They run about $175 each plus require special rings.

[FredM]

I do not think altering the design of your pistons for the purpose of creating more horsepower, is anywhere close to being "within the fine interpretation of the regs". The owner can produce their own parts, if they are exactly as the original parts. Where are you going to get the the specs needed to produce the part. Not the manufacturer, They won't give you the time of day, when you are trying to reproduce their parts and take business away from them. Since your part could only be considered altered you would have to prove the design to the FAA. Not an easy task for something like critical engine components. Even if you did this you will still end up with a modified engine and no basis of approal to have that engine installed on your aircraft. Don't forget that a higher hp engine would exceed the horsepower rating of your prop which is 165 hp or be so close as not to give you any safety margin.

[blueldr]

blueldr, I hope this doesn't sound like a stupid question, but where did you get the motor for your 52, or was it already in it when you bought it? I'd like to do this conversion in a couple of years, but I don't see any of these motors out there for sale. I've seen Lycoming 360s, but I haven't found any Cont. IO360s.

You're right. They're very hard to find. I watched TAP and all the other publications for a long time. I bought mine from Don George Aircraft in Florida, and I had been looking for over a year. You have to be careful because a lot of junk is offered, and you need to be sure it has a VAR crank or you have to buy a new one. TCM Continental has good records of their engines and are very helpful.

[lowNslow]

There are 6-10.5 compression pistons (i.e.you can specify a compression ratio anywhere in that range) available for the O300, but these are for experimental use only.

[zero.one.victor]

The ideal mod to me would be to take a set of IO-360 cylinders, screw a set of O-300 heads on them, bolt them onto your existing lower end,then you'd have a (carberated) O-360 which should be good for 180 horse or so. Same case, same mount, same carb, same baffling, etc, just maybe re-pitch the prop & reset the timing and away you go.
Of course, there ain't no way you'd ever get anything like this approved. But it's fun to daydream.

Eric