Quick question
 

For the ones who've recalibrated their tune. When you have to replace the engine, do you have to switch back to one of the older tunes or just tweak the latest one you've developed?

being that every rotary is hand built and no two are the same i would say a retune would be the way to go. are you tuning with a cobb? did mm tune it? if so i would go back to his base tune and go from there but im sure someone will have more info for you

I would personally go back to a stock tune. Then run through calibration for MAF/injectors. That's what Kane preached, because you don't really know what your sensors are doing. The calibration for your individual sensors will be different, not so much the tune(assuming stock-ish engine).

There are particular AFRs that produce best torque/power under different circumstances. Most people who aren't super into tuning/FI/porting shoot for Rich Best Torque because it's an optimal point that's considered "safe". If you can get your sensors and injectors calibrated so that the ECU can hit it's target AFRs, it's really just a matter of setting the targets for the AFR. That would be the part that is the "tune", and I wouldn't expect it to have nearly as much variation as the calibration between engines since the RBT point doesn't actually change that much per engine.

I think RBT is somewhere around 12.2 or something. A search will get you the actual value.

Disclaimer: I'm a hobby tuner, not a professional. This is not my day job, and I only do very little modifications to my own vehicle. I don't want to mislead anyone, so if anyone sees information that is wrong, or would like to clarify anything please let me know and I'll correct it.

The VE of the new engine will be different, a new tune is definitely needed. Or just go back to the stock tune.

9k, does the VE of a stock engine really change that much?

it's well within the adjustment parameters of the stock ECU 😎