ive heard of high 70s! Its all about a well balanced bottom end and head work coupled with well set up fueling
I built a NA 1600 that had 85bhp... would've had more with a better exhaust and some bigger carbs, and poss big valve heads I've heard of a NA 1600 making about 140bhp it's a high revving beast from what I understand, totally unsuitable for a van though
Make it bigger then? Mine goes like stink and still does the same 28 mpg as the 1600 SP beetle engine it used to have. I didn't expect that.