Re: Need some guess. I'm putting the euro 3.8L in my E30 and wo Yes the engine will fit in the engine bay and you can keep your AC. But whatever you do DO NOT KEEP THE GEARBOX. The E30s were designed to have 5 speeds and a relatively tiny engine coupled to it. What you are doing in essence is Taking away the 400lb weight at the top of a 400lb support and replacing it with an 800lb weight. You WILL break the car. Go on ahead and pair the Euro engine with a 6 speed from a current M5. The gearing mechanisms will fit into the E30 with a little bit of work and custom fittings. The results are shocking. For a car that can get 0-60 in 6.5 seconds out of a six cyl engine, you will pump out low 4 to even mid 3 second 0-60s. Traction will be an issue also, so put a wide body kit and widen the tires. If you wanted to go even further, turbo charging would increase the power of the car to a silly extent. Whoever said turbo charging a BMW is wrong is incorrect themselves. BMW did not emerge as a force to be reckoned with within the racing communtiy until the 2002tii TURBOs came onto the scene. They swept the races becasue of turbos. That is why this more evolved BMW deserves to be turbo charged. Just be responsible and not be too crazy with the psi of the turbo.