engine sizes

[Bobfish]

Science paper coming up...

im sorry, but your all wrong! in a way anyway...haha.

our engines are two voids with a capacity of 654cc. That makes 1308cc, or a 1.3 litre.  By design, a 4 piston engine car fires two of four cylinders in two full revoloutions of the crankshaft; i.e the crank has to turn four times to fire all four cylinders or to draw in the full capacity of the engine (eg 2.0 litres)

WIth a rotary engine, each combustion event lasts through 90 degrees of the rotors rotation, and because the eccentric shaft spins at 3 times the speed of the rotors, this is equal to 270 degrees of the shafts rotation. So in effect a single rotor engine produces power for three quarters of each revoloution of the output shaft.  Compare this to a single piston engine where power is only provided for 180 degrees out of every TWO revoloutions of the crank shaft, or on average a quarter of every revoloution.

so with a rotary providing power through 3/4 of a revoloution, and a piston engine providing power through 1/4 of a revoloution, obviously the rotary is going to push out more power as not as much is wasted.

The shaft on a rotary engine has to spin 3 times for the engine to take in 1.3 litres of a/f mix. The crank on a 4 piston engine has to spin 4 times to take in 1.3 litres of air (if the pison engine is a 1.3)

So in effect, a rotary has 6 combustion cycles lasting through 270 degrees for every 3 turns of the shaft. A piston engine has 4 combustion cycles lasting through 180 degrees for every four revoloutions of the crank.

in every 12 turns of a rotary shaft, the rotors turn through all 6 faces (3 facesx2 rotors) 4 times, so you have 24 combustion cycles and power provided for 3240 degrees of the shafts movement out of a possible 4320

in every 12 turns of a piston crankshaft you have 12 combustion cycles providing power through 2160 degrees of rotation out of a possible 4320 degrees of the cranks movement

So a rotary engine provides power for 1.5 times the length of time a piston engine does. There is also a 90 degree overlap of each rotor (i.e rotor 1 face 1 is providing power 90 degrees before rotor 2 face 1 finishes providing its 270 degrees of power)  This means that a twin rotor rotary engine provides power for a full 360 degree\'s of rotation; as opposed to a piston engines 180 degrees of power.

This is why the rotary engine is classed as a 2.6 litre, because it provides power for twice as long as a piston engine per revoloution.  There is no other reason for this...

In reality, you cannot look at it like this - due to the fact that there is not enough fuel intake to last a full combustion cycle, and also that there is a lot of power loss to heat and friction in a rotary.

It was agreed in motorsport that the 13b would be classed as a 2354cc engine, as it clearly could not be classed as a 1.3 and it simply ISNT a 2.6 engine. Calculations were done on losses and in the end, it was agreed on a 2354.

Since the rotary started its life as a motorsport development engine, this rule has stuck - and insurance companies have taken it on too.

The rotary engine is simply TOO different to analyse and calculate its size in comparison to a piston engine.  There are too many unmeasureables and uncalculables.

In short, the rotary engine has a capacity of 1308cc, NO MORE, NO LESS. Anyone who says its a 2.6, or a 2354cc is simply wrong.  The only reason it is considered to be a 2.6 is because it provides power throughout 360 degrees as opposed to 180, and the reason it is said to be a 2354 is because this is what it is classed as in motorsport.

ALthough neither theories are strictly wrong in their workings, as i say - the rotary is a 1308cc engine and always will be.  It still draws in on average the same as a piston engine. 3 revoloutions of the crank draw in 1.3 litres of air. With a piston engine, 3 revoloutions of the crank draw in 1.3 litres of air - however, the rotary would have fully burnt this 1.3 litres of air in 3 cycles, the piston engine needs 4 crank rotations to draw in AND burn 1.3 litres of air.

[Bobfish]

and for your guys info, im currently 20 and insured with adrian flux - 3300 third party fire and theft.

Got a quote from firebond, based on being 21 with 3 yrs NCB (im 21 in april, current policy expires feb) for 1422 fully comp

oh what a difference!

[Ricco_04]

Engine\'s are deffinately 1308cc
My V5c (or whatever it\'s called) has 2616cc
And insurance insist that its a 2354cc  (They insisted this is all fine and above board, so I have to trust them)

Just can\'t win!  

[anthony]

and for your guys info, im currently 20 and insured with adrian flux - 3300 third party fire and theft.

Got a quote from firebond, based on being 21 with 3 yrs NCB (im 21 in april, current policy expires feb) for 1422 fully comp

oh what a difference!

see i got a decent quote from firebond but that was for the 2356 engine! that was a similar price to what your paying.. since then ive got them to change ti to 2.6 and it went up to 1980. which is serious money, but im just going to have to lump it for another year and see how the insurance pans out next year, when maybe all this 2354/2600 confusion gets sorted out

[Ricco_04]

I wouldnt count on it being sorted out - it\'s been like it for years!  :mad:

[Bobfish]

Antony - INSIST they insure you as a 1.3, because thats what size the engine is. THERE IS NO WAY IN ANY SHAPE OR FORM THAT OUR ENGINES ARE 2.6 LITRES.

The capacity of our engines is 1.3 litres, simple as that. If they try and tell you anything diferent, you are best off insuring the car as a 1.3, not a 2.6, because the car ISNT a 2.6, and it has a capacity of 1.3 litres.

they cant moan if you insure it as a 1.3.

[GeckoGareth]

This is a nightmare and I wouldn\'t advise anyone insuring as a 2354cc as the insurers will use any and every excuse they can possibly find to worm their way out of paying out in the event of an accident. Yes it gets you a better quote but in the long run I think it would be a false economy if you had an accident. Plus getting done after an accident with technically invalid insurance wouldn\'t be nice either!

I\'ve a UK FD and because of the messed up database that the insurers use there is no UK FD listed, the only one that comes close is the 2626cc Auto that you\'ve mentioned. In the end I got insured througha  company who specialise in track day cars, they really don\'t care about these sort of details.

To be honest I think that £2k at 21 in an FD is about right. I paid £1600 at 24 last year!

cheers

G

[Bobfish]

false economy?!

A ROTARY ENGINE IS NOT A 2600cc, a 2616cc OR a 2354CC, IT IS A 1308CC, ALWAYS HAS BEEN ALWAYS WILL BE AND WILL NEVER CHANGE, INSURING YOUR RX7 AS ANY OTHER ENGINE SIZE IS A FALSE ECONOMY AND A WASTE OF MONEY. INSURERS WILL NOT HAVE A LEG TO STAND ON AS THE PHYSICAL CAPACITY OF A ROTARY ENGINE IS 1308CC, END OF!!!!!!!!!!!!!!!!!!!!!

[Bobfish]

Im not saying insurers will not contest it by the way, but at the end of the day, they ask you what size engine the car is. The car has a 1308cc engine; so the engine size is 1308cc.

What can be more black and white?

[FD3UK]

GeckoGareth, I think that the list does show a UK spec car although it\'s not very clear. "Mazda RX7 (turbo inj) manufactured 1992-1995 2354cc

Bobfish, I don\'t think anybody is trying to disagree with what you are saying, but insurance companys nearly always look at the list and as we can see that is a right mess.

[Bobfish]

this is true, but at the end of the day - if they say its invalid, you take them to court.  The engine size IS a 1.3 litre - so whats the issue?

Its their error, not yours

[Ricco_04]

Problem is though the V5 will still say 2616cc (for most) even though we all know it\'s a 1308cc.  So again there is a discrepancy!

And it\'s not simple to change V5c to 1308cc.  Remember the age old thread......
http://www.mazdarotaryclub.com/forums/showthread.php?t=4041&highlight=2616

Ho hum  :rolleyes:

[FD3UK]

They will not acknowledge a 1308cc, however I would insure as 2354cc for a more realistic quote. My V5 states my car is a 1308cc so I would defend myself if they refused to pay. Some V5s show cc as 2616cc so that would be more difficult to defend.

At the end of the day this does not really affect me as mine is highly modified so is insured on a classic policy based on value and horsepower.

[Bobfish]

I told my insurer it was a 1300cc and they just did it?

I agree, if its REGISTERED as a 2.6 then it will be harder, but at the end of the day - its still a 1.3 by capacity. You could argue the logbook is incorrect.

[Jono FD3]

whos that with ?

Firebond classic insurance with limited mileage (3000)!!
Jono