Is a V4 the same as the I4?

The V4 engine is basically obsolete. The I4 is the standard, like Honda and others use. The V4 was evidently pretty powerful for its size. Used in some sports models, but appears to have been largely left to outboard motors and BIG motorcycles. The V4 is hard to work on under the hood because the cars where it was used were typically compact cars. Long story short - no, they are not the same.

V-4 is an engine in a "V" configuration, 2 cylinders on each side of the "V". I-4 for is an "inline" engine with the cylinders all in line.