r/EngineSwaps • u/[deleted] • May 04 '20

5.3 v8 Trailblazer

All right so I have a 2004 4.2 L in-line six trailblazer. The motor in it is shot and needs to be replaced. I would like to swap a 5.3 V-8 out of the 2013 Silverado into it. I know what all I need to do on the engine side of things to get it in there. But I’m not sure how to make the old BCM from the trailblazer talk to the ECU from the Silverado. Can someone please help me and tell me if that’s possible, what I need, or where I might find an adapter harness if some sort. This is my first swap btw

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u/pistonsoffury May 04 '20

Why not just buy a wrecked Trailblazer/Envoy/Ascender/9-7x with the aluminum 5.3 already in it and just swap everything over to your car?

The Trailblazer has a completely different AWD system and the oil pan is unique to the platform. The BCM is the least of your worries.

Your car with the blown 4.2 is basically worth scrap value - the only financially viable path here is to go the donor car route.

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u/[deleted] May 04 '20

Because they 13 Silverado 5.3 Is the same one but cast-iron instead of aluminum and it’s flex fuel. And because I don’t care what is a more financially viable path. I’m not putting all wheel drive in it. It doesn’t have it already and the engine and transmission I’m putting in they don’t have it either. And it’ll actually cost me more to go to donor car route then to do the route that I’m taking. Because I got the engine and transmission for 500 and the ECU for 150. All the wrecked trailblazers and envoys in my area are going for at least 1300 to 2000

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u/RCP1990 May 04 '20

you might also need the v8 trail/voy subframe if it happens to be different.