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)