Mazda B series (aka Miata, Mazda 323, Mercury Capri,Kia), and the Mazda ZL-VE with an alloy block, VVT and a decent factory hp out of 1.5l
Although I'm not directly experienced with any Japanese powertrains, I've heard good things about a few. Some Mazdas being one. The B series Mazda you mention was of particular interest to early (Mk1) Fiesta owners as a direct bolt-in swap for a serious performance upgrade in a very light car (even lighter than the X). With that body being similar styling to a Mk1 Uno, I considered making a project of it. However it seemed the B series engines were not as easy to get as I would have imagined (very likely I wasn't knowledgeable enough about them to know what models to look for though). And this ZL-VE you speak of sounds quite interesting; alloy block and head would be one of the mandatory criteria on my list of possible swaps. Why go through all the effort and not use the lightest powertrain you can? And you say it is smaller plus VVT. What models was it used in? Are they readily available and affordable as complete donor cars?
Another Japanese powertrain you mention is Suzuki. If I'm not mistaken they were designed by Yamaha - something of the Japanese equivalent to Cosworth (both being designers of things like F1 engines)? Which might explain the low torque; engines from those designers tend to be high revving "top end" performers (more on that in a moment). Adding a turbo to anything is MUCH easier, more reliable, and affordable that it was in the past. I'm with "ricar" about not feeling comfortable with them...or at least I was. Recently I decided to take another look at the possibility of a turbocharged engine; it had been many years since I had and they did not impress me back then. But I was amazed at how much things have developed and improved with them. One of the biggest factors being the use of a aftermarket ECU to manage it, and MegaSquirt has provided a very affordable and doable option for that. So a small and lightweight turbo'ed Suzuki would be a good one to look closer into. But are there many of them available (I honestly don't know)?
Karl, two things you have mentioned a couple of times bring questions to me. One is the desire for a high revving engine. I'm not sure if that is something to do with wanting to mimic the nature of the SOHC or ?? But in my opinion high RPM screaming top-end engines are not at all street friendly (I'm only referring to non-track use). I'll take an engine with lots of torque over a top end HP one every time. I'd even consider a diesel for that very reason (but I simply won't touch any diesels, so that's definitely out for me). In fact one of the reasons I'd consider doing a powertrain swap into the X is to get away from the nature of the SOHC (no offense to all of our devotees).
The other item you've mentioned is the loss of trunk space. That one I completely understand. However according to what I've read, the amount of intrusion the Honda B intake causes is miniscule and only toward the top edge of half the bulkhead. Going back to a earlier post by Odie, "The rear trunk divider will have to be trimmed up to allow the intake to poke through. It can just be trimmed and the trunk will be 99.6% the same size as before." I have to ask, does that really break the deal for you (no sarcasm intended)? I think it could be done cleanly with a little custom metalwork over that small section to make it insignificant as far as trunk utilization is concerned. But I'm even more intrigued by this comment from Tom, "I watched a video last week, of a guy who put a Honda B motor in his X. IIRC, he said by rotating the engine slightly, he was able to fit it in the engine bay with NO cutting of any of the frame rails or having to modify any of the interior bay panels." Sounds like there may be the possibility of virtually
no trunk intrusion? Might be worth a closer look.
A VR6 in an x would be a pretty fast car but even with it's tight angled heads, would it still not be too wide?
I believe there is no way to get a VR6 into the X's engine bay - even with significant cutting. They are rather large, and heavy. Honestly they aren't one of VW's more reliable engines either. I've considered the VW 4-cylinder engines as possible swaps into the X. I have a couple of built engines available - 1.6 and 1.8 liter 8-valve from the Mk1 and 2 VW's. They are about the smallest VW powerplant you can easily get in the US. And frankly even those are a bit large/wide (and heavy) to make good swaps. Which goes back to my earlier comment of wanting a all aluminum engine if I'm going to make the effort. That rather limits many of the affordable, easy to get options unfortunately.
Another possible swap choice that was discussed in a earlier thread is the Toyota (don't recall the specific model of it). I believe it was Steve Hoelscher that gave a lot of info about it? And there have been a couple installed into X's using the mid-engine trans from the MR2.
