Finally piecing things together, have some questions...

[bigburb]

Skip to the bottom if you wanna get down to brass tax, otherwise read on.

I think I've decided to go with the 6.0, the extra power and flexibility of this setup more than makes up for the 1 or 2 MPG difference from the 5.3. I'm looking into the LQ4 because it'll run regular gas, and from what I can tell I need to get and 05+ because they have stonger rods. I'm looking to make this into a reliable daily driver with GOOD gas mileage.

Here's the question, I want to find a donor vehicle to pull EVERYTHING out of, down to the climate control and gauges, the only hitch is I don't want the 4L80E (which is all that came with the LQ4 if IIRC). I know some of you will contend me on this, but hear me out. The 4L65E has a better 1st and 2nd gear, it is also cheaper, has less drivetrain loss (better MPG), and I don't plan on getting any more than 400 crank HP for a long time anyway, if ever. I might have plans for a head/cam swap in the future, but for at least a couple of years I'll be running it bone stock.

Can I pull the ECM, TAC, BCM and transmission out of an LQ9 and have it run a LQ4 engine with no tuning needed?

[GasGuzzler]

You'll have to have the security stuff pulled by a tuner unless you have a GM buddy that will do a theft relearn. Not sure if the 4L65 PCM will control the 80. Someone else probably knows. Seems like you'd have to have the tune changed for the trans type....plus the wiring will have to be redone.

[bigburb]

but see that's why i wanted to pull the ECM out of a 4L65E truck, so I won't have to change any wiring or tuning. My question was if the LQ9/4L65E computer would control the LQ4 just fine.

[GasGuzzler]

OIC. Yes, shouldn't matter. The timing and fuel may be a little different considering the compression difference but some of the experienced tuners here could tell you that for sure.Why not use an LQ9/4L65E/harness/PCM all out of the same truck? BTW, the 80 doesn't eat that much MPG.

[bigburb]

I like the LQ4 for the compression, gives me flexibility if I change my mind and want to go forced induction one day. Plus I can run it on 87 octane, at least until I do a head/cam.

Any evidence on how much mpg the 80e eats? I've heard its like 28% loss compared to the 60/65e is 15-20% loss.

[GasGuzzler]

You'll never see 8% difference if the trans is the only thing that changes....much less 13%.