There was a typically huge arguement on 4 v 6 cylinder tractor engines in the power bracket on another forum. The usual tales of poor performance from the 4 clyinder engine was brough to the table. A poster posted the torque curve from the market leaders 6 cylinder engine and compared it to a competitors 4 cylinder. The 4 cylinder was generating more torque than the 6 all the way down to something like 1,100 rpm by which time the 6 had fallen flat on its face.

PACCAR have been putting a 4 cylinder 200hp engine in their DAF LF's for years http://www.daf.co.uk/en-gb/trucks/the-new-lf they're using a 3.8 litre now.

Here's Massey's English website and a link to the 6718S http://www.masseyferguson.co.uk/mf6700s.aspx the max torque is the same as the 6 cylinder engines of the same power. If you look at the broucher, you'll see pictres of it doing pretty hard graft. It's a 200hp tractor doing the work you'd expect a 200hp tractor to do, not a ride on lawn mower.