Im confused

[R1 GTR]

Ok this is probably very simple but, what is the difference between a
1) In-line 6
2) Straight 6
3) Flat 6

V6 I know (who the hell doesnt?) but the others are really satrting to bug me.
Help please

[R1 GTR]

Alex@POD said:

In a flat 6, there are two banks of 3 cylinders either side of the crankshaft, think of it as a 180° V6, flattened.

Like a subaru boxer engine?

[R1 GTR]

Cheers guys