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What are the torque ratings for aircraft engines?

For some reason it is not written in any manual that I know of. Why I don't know. :read2:
 
Can that all ways be figured out? Per say a diesel makes a lot of torque not as much horse power. Where gas motors the horsepower are different.
 
Yes is the short answer. The diesels turn slower in general and need more torque to produce the same power if that makes sense.

The Horse power ratings are usually quoted at the max hp rpm. That is probably not the max torque rpm, but the torque can be calculated at that rpm with the formula. You would need the hp at the max torque rpm to calculate that and that is usually not available unless you have the curve.

jim
 
HP = [torque x RPM]/5252

So if an engine makes 500 ft pounds @ 3000 RPM then

[500 x 3000]/5252 = 285.6 HP

From this it is easy to see that HP is just a mathematical figure and if you don't know what RPM, it is no more useful than the torque figure. I prefer torque figures but most of the world runs on HP figures.

On a side note, just because the engine is operating at that RPM does NOT mean it is always making that HP (or torque). It will only make max power at WOT, and assuming the air/fuel mixture is the same and the operating temperature is the same.
 
So to tie that back into Boblee's question, they make a LOT of torque. This is by nature if their displacement.

The average aircraft motor seems to make between .9 and 1.02 foot-pound per cubic inch if you are to believe their HP ratings and provided these are achieved at 2850 RPM

That's not a lot of torque per cubic inch, but they have a lot of cubic inches. In the automotive world, a 360 is a mid sized V8; A/C does it with a 4 cylinder!

Also, like Jim said, their max HP RPM might not be their max torque RPM, so they could be making more torque per cube at a lower RPM
 
The torque figures I calculated may not be the max torque for that engine. They are just the torque at the max hp rpm which could be less than max torque.

jim
 
We need to find a MFG (or an individual) that we can encourage to do some dyno testing on AC engines.

I think it would benefit a lot of folks to have better data about what these engines are putting out and where.
 
aircraftman":8odyvrp5 said:
I just got dyno numbers for a IO-540 and it made 685 lbs at 2765 RPM and 363 HP.

good lord.

EDIT - found the formula for calcualting torque as

(HP x 5252) / RPM = Torque so that would mean my 160hp 0-320 makes 311
 
It ought to be more than a caddy 500, Its got more ci's and more than likely a longer stroke. Seems like an ac motor combines the responsiveness of a gasoline engine with the torque and longevity of a diesel
 
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