BobB

Everything I read via Mazda talks of a cc size of 1.3 litres - taking the capacity of each rotor (653) and multiplying by 2. This makes sense to me.

However, my vehicle registration document came in the post yesterday and this states the cc to be 2616.
Also, when insuring the car (via Esure) they insisted that the cc was 2.6 litres. I actually asked them to confirm this is writing as (and maybe I'm being paranoid here) I can forsee a problem in the future should a write-off occur.

Can anyone explain this to me please?

RobDickinson

Its a 1.3 litre 2 rotor engine.

Which is equivelant to a 2.6litre piston engine. And its judjed as so by the goverment, insurance, and was for the international engine of the year.

Why gets complicated, but mainly because for each rotation of the output shaft each rotor fires once, whearas in a piston engine each piston only fires ever other revolution.

Why it gets complicated is :

Each rotor is equivelant to 3 cylinders (3 combustion chambers etc) and as it fires every revolution, but as a 1-3 setup to the output shaft, at 9000rpm (output) the rotor is turning at 3000rpm, but firing every turn, which equates to 6000rpm in a 3 cylinder engine (same number of compression/fire cycles). But thats equivelant cc, so I dont realy understand 100% why its a 2.6, its more similar to a 1.3 2 stroke 6 cylinder, but its not 2 stroke.

rael

Norwich show it as a 2.6 too. I have spoken to them about this and they are discussing the size with the Insurance regulatosr or the like. I think its just the nearest tax bracket.

rael

BigGrin

I am happy for it to be classed as a 2.6 on the V5.

Why? Well that way the tax man can't agrue when I claim 14p per mile from my employer. If it was a 1.3 then I would only get 12p and with less than 23mpg I would not be happy.

BigGrin

fishadr

The DVLA, Inland Revenue and Insurance companies all base their systems around piston engines.

It has been established that to compare the rotary engine to that of a piston you double it's cc. That is why it is classed as a 2.6 Ltr piston engine

ChrisW

2.6L is definitely the correct figure. After all, just think about why you actually want to know the capacity of an engine. Is it because you actually care about the size and number of the combustion chambers? The important thing is its capacity to suck in and burn fuel to power the vehicle. At a given engine speed, a larger capacity engine will burn more fuel and in the process produce more power.

The Renesis will combust the same volume of air/fuel mixture as a 2.6L piston engine when both engines are running at the same crankshaft speed. So its capacity (i.e. its capacity to burn fuel) is equivalent to 2.6L. As has been mentioned above, this is because rotary engines undergo one combustion cycle for every crankshaft (actually eccentric shft) rotation versus one combustion cycle for every two rotations for a piston engine.

Torpedo

That is until it is to their advantage that it's classed as a 1.3

druck

The number of combustion chambers is important. With cylinders, the more the better, as you get a greater overlap in the power cycles, for a smoother power delivery and freer reving due to less fly wheel inertia.

A twin rotor has more overlap than a V6, making it very smooth, and has a very lite fly wheel, and you know how eager it is to rev.

Cheers
---Dave