Considering a Slant 6 swap into a Mitsubishi Starion...

Sorry it's taken so long to get back to you guys. I do appreciate the interest in the thread and I'd like to explain how I prioritized the Slant 6 as my first alternative choice to the 6G72TT.

First, a little history about what has happened in the StarQuest community over the years...

1) The first V8 swaps were typically 302 Fords. Someone mentioned checking steering box clearance up the board, and that was indeed the primary concern with the 302. Custom exhaust headers had to be fashioned, usually on both sides, but definitely on the driver's side of the car. However, once in the car, this swap proved to be a highly reliable and straightforward conversion. For that matter, the EFI system that goes on the 302 is one of the options if you want to convert a G54B from throttle-body injection to EFI.

2) In more recent years, GM's ubiquitous LS V8 from a Corvette or Pontiac GTO has been the go-to for V8 swaps because of the better power capabilities. There is also less work to do under the hood, at least left-to-right. There is some front-to-back clearance concerns, but another advantage to this swap is it seems to be easier to seat a manual transmission (compared to the 302) if you so choose. Again, these cars are highly reliable after such a swap. The primary concerns with the G54B are (1) fuel control and (2) the maddening inability of this motor to get consistent lean-rich readings across the four cylinders, which often leads to head gasket issues at the rear of the motor.

3) As for a straight Mopar swap, we've seen a couple of LA swaps in our group, typically 318s and up. They are rare and I'm not really sure why, compared to the 302 and LS.

4) The first engine swaps done on these cars was to pull the G54B and hook up a Mitsubishi 4G63 out of the DiamondStar cars (Eclipse/Laser/Talon). You could make incredible power from them, there were a lot of parts that could be reused (the earliest power-adding mod to the StarQuest was arguably the 1G MAS from the 4G63) and the motor fit with room to spare. At one of the earliest national StarQuest meets, a streetable Conquest that was primarily a drag car showed up with this swap; his 1/4-mile times were well down into the 9s. If you want to take the "easy" way out even today, this is your swap.

5) The most common swap now is the 1JZ/2JZ Toyota/Lexus motors. The power these things make is downright insane. Getting 600 rwhp is common with the right mods, and the car is still completely streetable well over the 400 rwhp mark. In a car that weighs about 3,000 pounds, with some of the best handling characteristics ever put on a road, you have just created for yourself an autocross demon. But there are downsides. Chief among them is the necessity to relocate (and perhaps downsize) the radiator forward of the front core support, which necessitates moving and/or downsizing the A/C condenser (if you can even figure out how to retain it in the first place). Also, the front sway bar has to be removed from the car entirely. I am afraid this would also be a consideration with the Slant 6.

Now, having said all that, why am I interested in a Slant 6?

I am a big believer in retaining the soul of a car, even when you modify one. I have long been involved with old Jaguars as well, and yet I refuse to consider a GM LS swap to either of my current old Jags even though it's pretty much a bolt-in mod (most Jaguars older than 1988 already come with GM transmissions anyway if you want to retain them). In my view, once you pull the Jaguar mill, you don't have a Jaguar anymore. You have a GM heart in a Jag body.

To that end, I feel I have two choices with the StarQuest: another Mitsubishi motor, or something from its adoptive parent, Chrysler Corp. I also really want to retain a turbocharger, as that is almost equally a base characteristic of this car. If a turbo wasn't important, I could pull the Mitsubishi 6G75 out of the last-generation Eclipse coupe and be done with it. Switching over to the Mopar side, there are a handful of 4-cyl options I'm not crazy about (2.2 from a Daytona, 2.4 EDV/EDT). Beyond that, I would be looking for some kind of 6-cyl engine I could use some kind of forced induction on. The Slant 6 seems to like the addition of a turbo very much; the M112 AMG out of a Crossfire would be supercharged (but given no manual transmission was ever mated to the supercharged version of that motor, I'm unclear on what my options are there).

So if there's a more modern Mopar V6 that could be turbocharged and get up over those power numbers, I'd be open to it.