Originally Posted by MattRS1600i
ps. Yamaha, jointly designed the Sigma engines
with ford, its not all their own work
Interestingly, have a look at, and take some measurements from a 1.6 twincam from the mk1 toyota mr2
and compare to the sigma
Toyota basically copied the BDA for their 4A-GE engine (in the Mk1 MR2's), same bore and stroke, same size valves and similar port shapes/size. They also make similar power at similar revs. I can't find out much about the Sigma engines, whats the same/similar? They aren't regarded as being as good as a BDA or 4A-GE.
Yahama designed the 20v head on my 4A-GE engine, good bit of kit.
