For Sale: Mazda 13B Rotary

[majic79]

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0639851201

a reasonable offer will be considered - was going to be used in an old skool project, but since I can't use it for Road Rallying, I'm going with something more conventional

[Renrut]

What sort of size is it? I've never seen a 13B for real. I've heard they're quite small. How small is quite small?

[majic79]

Hmmm, I reckon the gearbox for my Polo is about the same size.

Imagine a 1ft cube, make the top face rounded (downwards) and elongate it an inch or two and you're there. I'll measure it up properly on Saturday when I'm back in the garage. It's light weight, probably less than a K-Series

I was hoping I could use it in a road rally car, but MSA says no (Specifically, the rule says "One wankel unit will be classified as three cylinders." and as there's two of them to make up the complete engine, the engine is banned under the "no more than 4 cylinders allowed" rule)

[Renrut]

So pretty compact then. What sort of weight is it?

I'm considering my options for Salami as this V-twin is such an awkward shape to fit in to anything except a motorbike. The 13B is about 150bhp isn't it?

[majic79]

It really depends on the engine - the turbo'd lumps made astronomical power, the N/A's are a bit more conservative. The early cars are around 130hp and it just goes up from there

I think bridge and peripheral ported engines can rev astronomically and make in excess of 200hp in N/A guise

http://www.rx7club.com/showthread.php?t=809124 - claims of 280hp at the wheels with a 9600rpm limit. There's also a dyno plot of a 210 hp engine with some additional pictures

[majic79]

Weight of the engine: 180lbs for the core engine, the ancillaries will add weight naturally

http://www.rotaryaviation.com/faq.html#weight

[Relentless Rob]

N/A 13B's love superchargers. The nature of the progressive boost suits the characteristic smoothness of the power output.

Just in case Will needs any further convincing.

[Renrut]

Just read that thread on rx7club - there are some crazy people on there.

I was under the impression they could rev a lot higher than that so I'm surprised that people don't have them revving into motorbike engine territory.

[majic79]

there's a few limiting factors, but I suppose you could take it to 10k easily on carbs, they lack torque low down though, with staged fuel injection and peripheral porting you could overcome the limitations and get the thing to go to 16k or so!

If I could have used it for road rallying I'd be doing just that (MSA says no )

[Renrut]

I confuses me that they don't run a set of slide throttles at the ports to give low down torque and high rev performance.

[majic79]

they do have slide ports - it's called the rotor!

Measured it up in the garage: 19" long x 16" tall x 15" wide

[Renrut]

No. From what I've seen 'camming' the wankel effectively raises the power peak rpm at the detriment of low rev power. This is done by opening up the size of the ports in the housing - bigger gives higher RPM performance. What I'm suggesting is a slide throttle over the ports changing the size of the opening depending upon the rev range in which you're operating.

That's a pretty tiny engine! Does it have a fairly standard gearbox mounting face?

[majic79]

No. From what I've seen 'camming' the wankel effectively raises the power peak rpm at the detriment of low rev power. This is done by opening up the size of the ports in the housing - bigger gives higher RPM performance. What I'm suggesting is a slide throttle over the ports changing the size of the opening depending upon the rev range in which you're operating.

Ok, I've not really looked at it, my plans got scuppered when I learnt that the MSA had banned them from road rallying, so I stopped looking into it.

That's a pretty tiny engine! Does it have a fairly standard gearbox mounting face?

Yes - I forgot to have a look for the original gearbox this weekend, but I'm back in there tonight, I've been assured that it's in there somewhere, probably under a pile of metal/tools/rags!

[majic79]

Yep, it's definitely in there - I'll drag it out this evening while we're in there - no garauntees on condition, but it'll be bundled with the engine to the winning bidder

[majic79]

Well, foudn the gearbox - it's fine, still got oil in it (no water!) and turns over nice and clean (couldn't feel any backlash in it)

Didn't meet the reserve on ebay (£100) so I guess it's not as valuable as I thought. I need a car to put it in, I wonder if I can convince my mate with the Datsun 120Y that that'd make a good car....