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good luck tring to keep the handling even close to stock, I noticed a difference, with the added weight of a turbo and intercooler. and even the lightest of the common v6s available, has a fair bit of weight behind it, it will be an expensive exercise, by the time you fit a rwd gearbox, and the tunnel will need modifying, as well as a larger diff and brakes

Smallest or one of the smallest V6's is Mazdas V6 in the Astina V6/Eunos 30X. It's a 1.8L V6 & the Astina also had a 4cylinder variant with the B6/BP engine so maybe those V6's wouldn't be too difficult to swap in to an MX-5. Considering that the 2.5L V6 in the MX-6 is commonly enough swapped into the Astina/30X that mightn't be too difficult either. I know it has been done already in the US on the Miata forums.

A couple have tried the KL swap. Here are a couple of examples:

http://majica.net/JNR/here.htm%20

http://forum.miata.net/vb/showthread.ph ... t=mx6+swap

I have also seen a couple of cars over here in the US with the Buick 3.8L V6 (the old VN/VP Commodore engine over there). This is apparently quite an easy swap but I can't speak from experience.

In truth, if you want <300rwhp, just build a nice strong BP and turbocharge it. It will be cheaper, and easier to engineer too. Consider that the first KL swap discussed above made 180rwhp. There is basically no room for turbos in there, and a supercharger would be a fun install too due to clearance issues with the TBs - so that is about the limit unless you want to cut the bonnet open. For the trouble, why bother? It is stupidly easy to get 180 rwhp out of a BP - even a B6 has little trouble producing 200-220 rwhp in stock form with the right boost option.

If you want more than 300rwhp, just do an LS swap. It will probably cost less than a V6 swap because there are mass-produced kits available to do it and you won't have to custom-make a whole bunch of parts. Your handling will suffer but that is to be expected.

If you want to retain your handling with >300rwhp, expect to spend HUGE $$$ - either building a super BP, or doing something with an exotic powerplant.