Warbird Information Exchange

The Fifi thread got me wondering about engine torque for the large piston engines; we all know the hp the various engines are rated at, but what are the <general> torque ratings for engines like a -2800,-3350, -4360, Merlin, Allison, etc...

John the Nerd....

The KC-97 with R-4360-59B was limited to 247 torque psi (3,500 hp).

The C-130 with a T-56-15 was limited to 19,600 inch pounds

The P-3 with a T-56-? was measured in horse power

FiFi with R-3350-B29 will be limited to 129 torque psi (2,200 hp.) We will need to build some charts with various power settings to use in flight.

On a cold day you can easily exceed these limits.

And it depends on where the readings are taken. Meaning is it direct from the crankshaft or through a gear set like the reduction gear unit.
Engine HP is derived from the torque, as determined by a dynamometer.
If it is a R-4360 and the given HP is 3250 at 2700 rpm's the torque is
6321 lb ft.

A way to figure out BMEP is shown on this site:

http://www.tsrsoftware.com/bmep.htm

-Chaz

http://www.epi-eng.com/piston_engine_te ... dstick.htm

These people seem to have lot's on this subject as well.

b29flteng, you are going to run FiFi L.O.P. I assume?

-Chaz

Simple formula is:

HP = (Torque x RPM)/5252

or to use Engguy's example, 3250 = (6321 x 2700)/ 5252. Have any two and you can get the third.

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[quote=b29flteng, you are going to run FiFi L.O.P. I assume?

-Chaz[/quote]

I'm not sure about running LOP yet, we may just run it in Auto Lean.

I talked to a P-3 engineer and the max Hp on a T-56-14 engine used in a P-3 is 4,600 hp (indicated).

Don't forget that engine torque at the crankshaft is much lower than the actual torque on the airframe from the prop due to the gear reduction in the engine nosecase. None of these large piston engines are direct drive (except P-39/P-63 with remote mounted nosecases).

Well...ahh, I'll leave this one alone...

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