4.3 TBI vrs CPI 4.3?

The 1992 to 1994 Engines the differences are: Intake manifolds, fuel injection type, cam grind, valve covers, throttle body type.

TBI is Throttle Body Injection. This means the Fuel Injectors reside in the Throttle Body (like a carburetor with fuel injectors inside instead of venturis or "barrels"). This type fuel injection uses a intake manifold similar to a Carbureted engine. On 1990's TBI 454's they are Carburetor intake manifolds with a adapter plate for the TBI unit.

CPI is Central Port Injected. The Throttle Body handles no fuel, just air. The Injector(s) sit in the middle of the lower intake manifold with plastic fuel lines that run to the head port. The lines carry the atomized fuel, and it mixes with the air at the head port when the intake vales open. similar to GM Multi-Port Fuel Injection, except the Injector(s) are remote mounted, with feed tubes running to each cylinder instead of a injector at each cylinder. CPI injection units are known as "Fuel Spider".

CPI engines use composite plastic valve covers, TBI engines use stamped steel. The cams are supposed to be different grinds. Yet are close enough if you convert a TBI to CPI, or CPI to TBI, they run just fine.

Later 1995 up CPI engines have a Balance shaft, that is above the cam galley, running threw the lifter valley.

Charles

Thanks Charles for the info.I just bought a 93 S-10 Blazer 4.3 CPI engine and was wondering what parts where interchangeable with my 88 S-10 Blazer 4.3 tbi.So below the heads everthing is pretty much the same.Also the CPI engine is dumping gas into the oil pan?i just gave a couple hundred bucks for it ..I'm mainly just gonna use it for parts.It ran long enough to get it on the trailer...now it cranks but won't run..hopefully the trans. is good.....Bobby

You can use the whole CPI engine with the TBI Intake & distributor. The wiring harness under the hood will be different and the ECM will be as well.

The transmission is where you need to watch out. If it is a 4l60-E it will not interchange. If it's the older style I will.

If you need to change the rear end, and want to keep the ABS you may have to switch parts. Some 1993 & 1994 blazers are 3 sensor ABS some are

4 Sensor. 4 sensor trucks have wires coming out of brake backing plates, with a abs wheel on the axle, 3 sensor trucks have no wires coming out of the brake backing plates. 88's use the old style grill. The 93 uses the new style, to swap with out headaches swap the core support as headlamp adjusters are in different locations.

Other then a few items, 84 to 94 S-10 blazers are pretty interchangeable. Charles

How cheap? I have a 94 here that could be looking for a new home. It's a 4.3 Vin W 4 door. Needs one exhaust manifold, front fenders, fuel lines (those will probably be replaced real soon). Door bottoms are rusty but still solid.

Are you near SE Pa. ?

I'll pull the upper plentium tommorrow..I appreciate all the info.It's a

93 S-10 CPI Vortec W code 200,500 on the odometer,4 door.It does have ABS on it ...I'm stripping a lot of stuff off of it....had a lot of rust in the cooling system.I took the radiator off..ran water through it....and I never seen so much rust..like muddy water.Checked antifreeze..only floated 1 ball..rust probably floated that.How can I tell what kind of automatic Trans. is in it?Thanks! for the help! Bobby

When you took the plenum off and fixed the cracked hoses with regular fuel hose for 8 bucks,didn't you have to replace the gasket that sells for about 14 bucks?Just wondering....haven't taken it apart yet and checked site at advance auto..and got the price on the plenum gasket.Thanks! Bobby

Middle of Upstate NY.

4 hour drive from Cabelas in Hamburg

Look on the glove box sticker if it is still there. It probably has the same trans as my 94. The 4L60 AKA 700R4.

The gasket was brittle & baked fell apart. Has to be replaced.When I get the fuel regulator...and install it then i'll look for leaks again ...before I put the penum back.Did you install the larger hoses(inlet...outlet)If so how do they connect on the back where they come through the lower manifold?I'll bet those smaller poppet line clips are easy to break.The junk yard here wouldn't let anyone take parts off engines.Take Care! Bobby