We know that SCCA racer Dave Patten's A15 made 156hp at the wheels, that's the night figure I've seen for an A15. Benny's motor isn't particularly radical.

D at the risk of being contrary; people have been developing A-series engines long after Nissan stopped. There are people in Japan and the U.S. that are getting more than the factory did 45 years ago. This applies to most manufacturers whether it's A-series L-series or BMC A-series or whatever. Take a look at what guys are doing with flat head Ford V8s.

I don't have the Dyno sheets to back it up but I do know that guys here in the U.S. using A13s in D-Sports Racers we're getting quite a bit more than Nissan did. This is because they were not constrained by sedan rule sets. I know this because I was told so by someone at Nissan Motorsports. These guys went to E15ET heads on the A13 block and that got them 168whp (remember they are mid-engine cars using a Hewland box) I was told E head was worth 10% over the A head on these motors, so that makes an A13 putting out 150ish at the wheels.

One thing to note on the D-Sports engines is they were rebuilt after every race; at the end of every day they'd inspect the oil filters (metal screen sandwich type) for signs of deteriorating bearings. I saw more than one changing things like valve springs and bearings overnight. Once they went to motorcycle engines the A-series became even more obsolete, not necessarily because of power but because the bike engines ,are the same power and went several races before needing anything more than an oil change.