just wondering what peoples thoughts were on the subject of a 20b engine conversion. i hear alot about the 13b but never on the 20b in to the mighty datto ute/coupe. does anybody have any info on the degree of difficulty compared to doing the 13b, or even if someone has already done it before. any thoughts would be appreciated?????

If you can't get enough power out of a 13B then you're just nuts! I don't see any advantage of putting a 20B into such a light car. 13B should be enough to void any traction you can dream up with a 1200. Hell, there's a 12A powered 1200 out there running 8s! It would definitely be cool though, don't get me wrong... just on a wank-based scale.

I wouldnt really know much about this conversion. But I would think that the 20b would be a bit long to fit in the standard engine bay. But it wouldnt be impossible to fit in a modified bay. I am sure someone who has a 13b or any rotor in their datto will shed some better light on the subject. You might even be lucky and find that someone has dont this same swap or contemplated it.

i think a 20b would be good option as u wouldnt need to do much work to it if any to make the same power of a 13b, u would have to put it in a coupe as a guy i talked to said his fj20t standard cracked his ute chassis, i think 20b would be tuff as.

Hy. The 20B would not be that much more trouble, because, if you see the engine, it is basically a 13B motor with an added rotor housing, not much larger, yet a lot more powerfull. That is a posibility I am looking into for one of my cars. If going for a 13B, why not the 20B? The only obstacle would be the price of a 20B motor.I talked to the guys at Mazdatrix(experts in rota's)and if I go that avenue, to save money I can make it a carburetor 20B(saving on all the computer/electronics/turbo or EFI system), and still, lots a power.As said before by another member, it will be a lot of power to handle by the mighty 1200, so, make sure you have rubber on the pavement, I mean, real rubber, not 17 X 5 inch wheels with 205 tires, that is looks, not performance,you need real rubber, or else you might end pasted on the corner wall! (a friend of mine did that a few years ago, still his car is "pasted " on that wall, big motor, wimpy tires/wheels , tremendous understeering)
later._____________________

Hmmmm..... NA 20B.... that would be soooo pissed off sounding. I like it.

the 20B is the size of a 6gal drum, so making it fit is as easy as pie. it's actually not much longer than an A15 block - but the mounting points are all wrong. you should run with a 12A style timing cover, and use modified RX3/7 mounts to mount it over your swaybar as per most of Mazda's arrangements.

a ported NA 20B would see you filling up at every servo on the way to your destination. and of course, there's the rebuild cost.
you could make it carby, but then, you'd need to make all new manifolds to suit and then get the carbies on top of that.
the 20B has one of the best flowing inlet manifolds around, so why ditch it? hook up an LTX12 microtech onto all the std manifolds and injectors for $AU1395 and SAVE yourself money by going EFI.

the 20B doesn't need to be revved as hard to make the same power as a 13B, hence why they have the tag of being more reliable. but don't be fooled, the very early engines are known for eccentric shaft failure and rear rotor shifting. this problem was quickly rectified though, i think the problem engines were 1991 and early 92.

you could use a std FC3S RX7 5 speed behind a 20B with no turbos, with a good 13B clutch and flywheel and the 20B counterweight.

the sump might need mods though, although if it does foul, use a 180B / stanza crossmember and be done with it.

it's certainly a conversion i was considering, but trying to get a "4.0L" engine (mazda quotes it at 1998cc - so double that) engineered into a 1200 would see you on a mission from god.

but if it's not going to be street legal, then take it away. it's certainly not an overly complicated conversion.

good luck

If you were posessed enough to do it you would have to modify the fire wall, seam weld the body, fully cage out the car. It would need big tubs to fit tyres anything like big enough to put the power on the ground.
Its not impossible , but unless you are rich I wouldnt try it.

you won't have to touch the firewall at all.

but yeas, you will need lots of rubber for traction!

You would have to enlarge the tunnel , or you might sneak in with a shell that was a factory auto. (bigger tunnel)