If you know the horse power you can calculate the torque. If the hp is 37 at 6500 rpm you would use the following formula.
((37*5252)/6500) or 37HP times 5252 divided by 6500 RPM. This would give you 29.9 ft lbs. of torque. The engineers also use a correction factor for tempature, humidity, and barometer but this will give you a number good enough for us consumers.
You can use this any place you know the horsepower at a given RPM.
Hope this helps.

 

That only gives you the torque figure at the peak hp rpm. Peak torque will occur at a lower rpm, and that's the number most people are usually interested in. Try doing a search for dyno numbers or charts.