Has anyone here specificaly measured the effects of compression ratio alone in relation to HP on a Dyno?
I tried to search Lyc. for information and have not found anything proven specificaly.
In a seperate thread Malon seems to indicate a 5 hp increase in the 360 engines when going from 8.5 to 9.2:1 ratio but that seems like a general figure.
If I divide 5hp by 180 hp we get a 2.78% increase in that particular ratio increase.
If we use the angle valve engine with 200 hp. 5hp by 200 hp we get 2.5% increase.
can these figures then be expected when raising the C/R of the 540 engines?
Kevin? Dan? Thomas? you guys seem to have checked out a lot of these details that I am interested in.
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Weasel
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Weasel,
I have not done a piston swap (compression ratio change), then a dyno pull to get data results yet. However, I plan on freshening up the top on this O-360-A4A (peanut drone engine) and if the pistons are lower than 8.5, I plan on changing them to that, since I have extras. Should produce some good comparison data.
When my 0-320 E2A was rebuilt I went with 9:1 pistons. It wasnt dyno'd but with the 160 club installed it pulled 75 more static rpm than a 160hp engine. I dont know how to determine Hp from RPM.
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C-GVMK
RV9a Slow(ly) built
Flying as of July 2012
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Weasel
RV-4 715hr Sold
RV-10 "School Bus"
I have changed my User Name to the correct spelling as it became availible. Please direct all correspondence to Weasel
When my 0-320 E2A was rebuilt I went with 9:1 pistons. It wasnt dyno'd but with the 160 club installed it pulled 75 more static rpm than a 160hp engine. I dont know how to determine Hp from RPM.
Well, you do need RPM and TORQUE but once you have those two you can calculate HP. Here is the formula:
2π(T)(RPM)
----------- = HP
33000
where:
π = 3.14157 (pi)
T = Torque
If you know the TORQUE at a specific RPM you can determine the HP at that specific "power" setting. The documents for your specific engine should have a power curve graph where you can extrapolate these numbers for your engine at any given power setting.
Well after running the supercharged 540, the O-360 drone motor received the name of peanut. Because it just look small? The final numbers of the last dyno run before it came off last weekend were. Un-corrected @ 8218 density alt. 2650rpm: Torq. 657ft-lbs // 331.37hp. Installation in process, will be flying to KOSH.
SWEEEEEETTTT! I am planning to make it. Work dependant
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Weasel
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RV-10 "School Bus"
I have changed my User Name to the correct spelling as it became availible. Please direct all correspondence to Weasel
If you increase compression ratio above 8.7:1 it is recommended that the timing be retarded by 5 degrees from standard so it is likely that some of the power increase from the higher CR will be lost by retarding the timing.
Have a look at this thread I started some time ago. Also in Post #6 Kevin gives the CR HP formula.
Effects of compression ratio to HP
Linear Mode
