First a recap. In the November 2021 issue I tested three different Pinto 4-2-1 exhaust manifolds: a cheap small-bore; a big bore three-piece; and an all-out, race five-piece manifold on two different spec engines (one just under 140 bhp and a second, higher-revving unit making a little over 150 bhp). There was little difference between them, and I surmised it was because I didn’t have a high-enough spec engine.
Last week I dyno tested a 2.1 Pinto fitted with a big-valve head, 10.6:1 compression ratio (CR), Kent Cams RL31 camshaft and