Tim, The power and torque vs. rpm info for the Subaru 2.5 litre engine I got from Subaru sales literature and Road & Track test data. Even though the 2.5 litre is a DOHC, 4-valve engine it appears to be an inherently high-torque motor. Torque peaks at 162 ft/lbs @ 4000 rpm - on my 4-speed Vanagon 4000 rpm in 4th gear is approx. 70 mph. This is a very normal Interstate speed and you've got max torque to ensure that you don't slow down too much on that next hill! Since I can't transmit the graph to you I'll give you some torque vs rpm figures: 900 rpm (idle) 128 ft/lbs (thats more torque at idle than the Wasser's max!) 2000 rpm 148 ft/lbs 3000 rpm 158 ft/lbs 4000 rpm 162 ft/lbs 5000 rpm 159 ft/lbs 6000 rpm 143 ft/lbs That's about as flat a torque curve as I've seen outside of a Chevy truck engine. The horsepower vs rpm curve is somewhat more steep and it peaks-out at 160 to 170 hp (depending on whose data you use) @ 5600 rpm. The data is as follows: 900 rpm (idle) 19 hp 2000 rpm 58 hp 3000 rpm 90 hp 4000 rpm 123 hp 5000 rpm 152 hp 6000 rpm 162 hp (from Subaru data) The redline is 7000 rpm (try taking a Wasserboxer to that !) Over a normal road speed range of 50 to 70 mph with the 4-speed gearbox, you would have optimal torque available and approx. 50 - 60 % horsepower. That combination should yeild a quite good efficiency. In a single-engined light aircraft that would be an ideal cruise power and deliver the lowest fuel burn. I'm looking at these engines now anticipating an engine replacement in about 3 years. Hopefully by then there will be a somewhat reasonably-priced supply of them in the used market. Safety Fast Sam Bateman '87 Vanagon GL (122k) |
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