hammerhead, you might be right on with your experience with Isuzu diesels. But, I personally know that when I engage the well on the big blocks, I have to slowly engage the clutch as not to kill the motor, the Isuzu's, they are being put on with-out a clutch...direct drive, that kind of power comes from somewhere..and it's not from a lawnmower engine. Of course economy is only based on use, but a close friend of mine that farms 5 miles west of me bought 11 new Isuzu motors, $139k for the batch, they where payed for already this season by what he saved on the natural gas/big block expense, of course he had gotten lucky and contracted 50k gallons of farm diesel at .80 last winter, that helps a little.