I've been thinking a lot about engine swaps lately, and I thought to make a thread asking about everyone's dream powertrain swap, and why.
For my Insight, I have the following contenders:
1) Honda Civic Hybrid (1st gen) LDA engine + 5MT
-This is basically the Insight's stock engine, only with a 50% larger electric motor and an extra cylinder. It's so smooth and quiet, you'd almost think it's full electric, and I feel there's a certain elegance to the swap, because most of the wiring would be compatible, including for the hybrid system, and the batteries use the same cells. In the HCH1, which has a much larger frontal area, higher drag, and weighs 50% more, this engine is still good for 60mpg cruising at ~55, so I can't see it being significantly lower than the Insight's stock engine, but with gobs more power. With an aftermarket controller, the electric motor in this engine might actually be enough to power the car while cruising entirely by itself. Best of all, these are cheap and abundant, and I'll probably have a spare engine in a few years once the salt claims the all-steel HCH1 my wife drives.
2) 2016 Honda Civic 1.5T + CVT
-Getting rid of the hybrid battery would greatly increase storage area in the rear hatch. The engine + transmission weigh close enough to the Insight's engine + tranny + battery that it wouldn't much affect the total mass of the car, though weight distribution would be shifted forward a bit. This engine looks marvelous on paper, able to deliver 174-hp/162-lb-ft while also delivering nearly 65mpg cruising in the significantly heavier and less aerodynamic Civic it came from.
3) 2017 Accord Hybrid drivetrain
-This car's drivetrain is fascinating to me. Honda touts the 2.0L Atkinson engine as the most efficient in the world, at something like 42-43%. It's mostly a series hybrid, with the ~140HP engine generating electricity for the ~200HP electric motor, which can take the 3600lb Accord to 60 in under 7 seconds. When cruising at certain speeds, there's a clutched single-speed transmission which connects the gasoline engine directly to the wheels. It has no belts or accessories, and like the Insight, has heat-recovery systems that aren't found in any other Honda. The car it comes from is rated 49 city / 47 highway, and I'd be curious what kind of economy I could get in a car literally half the size and weight. The previous generation Accord hybrid came in a plug-in variant, with a 13 mile range with its 6.7kwh battery. I would be surprised if I couldn't get 25 miles or more out of it.
4) As fascinating as the above 3 engines are, I can't help but feel that gasoline engines are on their way out. With cheap Nissan Leaf motors and batteries on the market, and the Bolt about to bring 200 mile EVs "mainstream", it makes me wonder if it's a good idea at all to put a gas engine into this car. The Leaf battery's range would probably be at least 50% better in the Insight at modest cruising speeds, and I expect 150-300 miles would really suit my needs. An EV conversion might even end up being cheaper, all said and done, because of the fabrication and special parts required for the above swaps.