The 1500 has inlet (carburettor) and exhaust on the same side (left side in direction of driving) while the 1600 has the inlet on the right side and exhaust on the left (hence crossflow).

Manifolds and most other parts for the 1600 are available from BurtonPower (www.burtonpower.com). Parts for the pre-crossflow are more difficult to find. Lotus specialists are sometimes a source.

Frank

1967 4/4 1500 Comp.
1935 Super Sports Barrelback