W and Z Engine

what is the difference between a 91 Z engine and a 92 W engine? for an s-10 blazer

The Z engine is a 4.3 T.B.I

the W engine is a 4.3 C.P.I.

I need to know how you can tell the difference. Is there something I can look for that will determine this?

Look in your VIN #. Its the eighth letter/number.

Look in your VIN #. Its the eighth letter/number.
or look on the eng if it kinda looks like a carb its a t.b.i if it has a manfold that says "vortec" its a w the w is 200 hp the z is 160 or 165 i can't recall for that year but the z is more dependable

91 TBI is the 4x4 was 165 hp, 92 W CPI was 195 hp.... 8th letter of your vin will identify your engine. CPI has both different fuel injection and cam size than TBI. CPI was available from 92-95, both CPI and TBI ended in 95... Both W and X motors from 96 to current use CSFI. Differences are ecm programming and the X engine has a smaller cam..

If you are thinking abuot a swap out it could be a lot of changing. doing one as we type.