As I prepare to swap into my 1986 Jeep CJ a 5.3 I am performing the required preparation in reading many forums to lear as much as possible prior to diving in. Thanks to the many who have taken time to enlighten us all. Your kindness keeps us all energised to supplies the safety blanket to "give it a try".

In that light, I'm stuck with a question. If needing to choose between a Gen III 5.3 (2004 Silverado LR4) and a 2007 Silverado LY5, both with roughly the same milage, which engine would be best for the swap. I'm not looking for killer horsepower, just a cruiser so to speak. The "Active Fuel Management" is the heart of the confusion. I'm old school and I admit I am being dragged into a new geration of engines which sound awesome. The AFM of the Gen IV engines sound great in theory but I am concerned will be over my head if issues arise and I need to diagnose problems.

Please give me Pro's and Con's of both engines so I can get off the fence. Any help here will be greatly appreciated

 

The LR4 RPO is for a 4.8L BTW.

The LY5 should be AL block and have AFM

Pros: is the Gen III will be easier and cheaper and has one PCM for the trans and engine.

Cons: not as much power as a Gen IV 5.3L

Pros: for the Gen IV is it will have better 243/799 heads on it little more power.

Cons: for Gen IV Newer and most times more expensive cost for the motor. And AFM could cause problems even if just tuned out. Also need a TCM for an auto trans.

 

The LR4 RPO is for a 4.8L BTW.
The LY5 should be AL block and have AFM
Pros: is the Gen III will be easier and cheaper and has one PCM for the trans and engine.
Cons: not as much power as a Gen IV 5.3L
Pros: for the Gen IV is it will have better 243/799 heads on it little more power.
Cons: for Gen IV Newer and most times more expensive cost for the motor. And AFM could cause problems even if just tuned out. Also need a TCM for an auto trans.

Thanks BO185.. As you are probably aware I indicated the wrong RPO. The Silverado 5.3 is a LM7. Thanks for the catch. My research indicates the LY5 has an iron block though. I am leaning towards the GENIII due to expense and technical aspects of the GENIV.

 

If you are building a cruiser go for the easiest route; cruising should be fun not a headache. I suspect a gen III would be more than adequate.

 

There's a lot of information on the GEN III swaps, so I would be inclinded to go that direction seeing that you'd rather avoid complexity (or keep it to a minimum; can't say I wouldn't do the same). The LM7's can be bought cheap with low miles, and parts are plentiful.

Andy1

 

I did some trading on a gen IV motor and i am pretty much converting it back to gen III cause of all the headaches with d.o.d. and 58x reluctor etc... as with the cost. I'd stick with the gen III.

 

I have done a few swaps with the DOD stuff still enabled, and I was not real fond of it. It is very odd in a non-OE setup, and most people (even with factory vehicles) don't really like the sound it makes through aftermarket exhaust when the 4 cyls turn off. Also, we have noticed very little gas mileage improvement with it.