Usually ... since the ignition temperature of premium fuel is lower than the lower octane rating fuel, the engine runs a bit cooler. I have a VW Jetta Mk IV 1.8L Turbo vehicle and it uses premium fuel - at an average of 20 cents higher than the lowest octane fuel price, it only adds another $2.50 to my total fill up at the pump ... no big deal, really, especially considering the expert performance I get from that engine.
Ther is no egr valve on the 2.2 turbo engines. With FI and turbo, there was no need. Some of the earlier carb engines did have egr.
Turbo Shaft Engines?
You need to use premium fuel
if you have a turbo engine you need premium gas, look inside your gas tank door and it will tell you what octane your car requires.
No, It will run just fine on 87. But higher octane won't hurt it. If you have the MazdaSpeed 6 it does require premium due to the turbo.
Computer is set for premium,and it performs much better on premium.I have a supra turbo tried both, went back to premium better mileage and performance.
all engines hesitate when cold they need to get to proper running temp
You don't need it, A 4cyl turbo engines like in eclipses have different pistons(low compression ratio/ forged)/rods/etc. that make them able to withstand more boost/hp. N/A engines "usually" are recommended to run 7psi or less.
Yes it will make your life much easier to have the turbo ecu and harness. The turbo injectors have a resistor pack that the non-turbo engines do not use. So that would have to be manually wired in to use stock turbo injectors and ecu.
A whole lot. You'll need to replace the intake, redo the exhaust, replace the injectors... there has to be a precise fuel/air mixture in these engines.
You have problems. You need to locate the source of the leaks and determine the cause.
The best place to look for a certain engine is summitracing.com. They carry a line of engines and can help you to get the specific one you need.