| [ Total Views: 1285 | Total Replies: 14 | Thread Id: 61431 ] |
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 flashman
A.k.a.: Hans Eiberschlong
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| posted on March 28th, 2007 at 06:59 PM |
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Victoria - Rotaries competing in under 2l sports sedan
I have seen a few cars recently competing in sports sedan class under 2l in Victoria using 12A rotary engines 'resized'. Can any one shed some light
on this, swept capacity is well over 2l for a 12A [2290ml i think], please explain....
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Flintstones
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| posted on March 28th, 2007 at 08:11 PM |
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Back in the day, Mazda classed the 12A engine as a 1.2L, 13B's as 1.3L
Maybe that's how they are getting around the "under 2L" classification......... not saying that this is the reason, but mearly a suggestion...
Hope you find out
Cheers
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westi
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| posted on March 29th, 2007 at 12:24 AM |
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what is a resized 12a,do you mean that it has 13 b housings with 12a stamps.please explain how you got 2290ml.
a 12a is a 1.2 litre.
it's mutiplucation factor for sports sedan is 1.75 so the total is 2.1 litre and there is a certain percentage of cubes that are alowed over the 2L
capacity and still be legal for it's class.
so theoretically you can run the same cubes for a vw.
i think it is 15%.so a 2.3 vw should be allowed.
down sharon.
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amazeer
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| posted on March 30th, 2007 at 02:27 PM |
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Rotary equivalence factors were played around with at the beginning of last year.
It started out at 1.8. It went to 1.5 and then it varied between classes 1.5, 1.75 & 1.8 and then sanity prevailed and it went back to a flat 1.8. So
an 1146cc 12A comes in at 2062cc and a 1310cc 13B comes in at 2358cc. Accordingly neither are under 2 litre in standard form. Turbocharging adds
another factor of 1.7.
How you would resize one, I dont know. I wouldnt know how to calculate the capacity in the first place! I'm not aware of any fudge factor, but a race
organiser can choose their own way of dealing with these things and apply different classing and factors if they so feel. Eg WSCC shuns the CAMS
manual and the NSW speed event guidlelines by combining types 1 & 2.
I found this: http://www.ipravic.com.au/bulletin/B06-069_20Rotary_20Equivalence_20Factor.pdf
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Euro_67
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| posted on March 30th, 2007 at 02:59 PM |
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Pardon my complete ignorance here ! Why is there a multiplication factor added to a rotary engine's swept capacity for competitioon classes ? It
seems like a deliberate class handicap to me.
Wayne
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flashman
A.k.a.: Hans Eiberschlong
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| posted on March 30th, 2007 at 08:53 PM |
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Hey guys thanks for the replys. The engines I am talking about are apparently classed as 'restricted 12A's'. I know the actual capacity [like550ml x 2 for a 12A] is way less then swept capacity, but no matter which way I look at it I can't for the life of me work out how to reduce the
capacity of a 12a, or a 13b engine for that matter. I mean volumetric efficiency isn't taken into consideration, and porting size doesn't make an
appreciable difference to actual capacity. And its not like a piston engine where you could change barrell size, head space etc
as to why there is a multiplication factor I think it has to do with envy, can't catch them make them heavier/slower/different class etc. uh-hum I
mean parity.
Amazer, i know that individual officals can interpret things differently, but as far as i can work out there are a couple of cars that compete at
different circuits on a state level with under 2l rotary engines.
anybody?
Mick
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 helbus
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| posted on March 30th, 2007 at 09:12 PM |
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Rotary is similar to a two stroke in the way that it fires every revolution. A standard piston four stroke/ cam/ valve engine fires every two
revolutions.
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amazeer
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| posted on March 31st, 2007 at 05:54 PM |
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| Quote: | Originally
posted by 1964_Notch
Pardon my complete ignorance here ! Why is there a multiplication factor added to a rotary engine's swept capacity for competitioon classes ? It
seems like a deliberate class handicap to me.
Wayne
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Thats exactly what it is. No secret. While the swept volume may only be small, the engines exhaust and intake ports are open at the same time. One
side of the rotor you're on an intake cycle while the opposite side is on an exhaust cycle. On the third side of the rotor you are half way through a
combustion cycle. A piston engine can only do one thing at a time. The multiplication factor levels the playing field. Same as the 1.7 factor levels
the playing field for turbo/supercharged engines.
If you used a larger rotor that would make a difference to the swept volume wouldnt it? By larger I mean less triangulated. Would that make a
difference? Is it possible? I dunno. They sound shithouse. ive never had any interest in them at all. Even after working on an RX7 at Bathurst... no
interest. And I was lucky enough to be on the opposite side to the exhaust.
 
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flashman
A.k.a.: Hans Eiberschlong
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| posted on April 3rd, 2007 at 10:31 PM |
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that may be it - the distance seal to seal would have to be the same but the meat on each surface could theoretically be made fatter, as in more
revolving mass. I have made a few inquiries elsewhere and got no joy. i just wonder how it is effecting the Under 2l guys running vw.s, it may be the
field is bigger so that is good, or is the rule dodging causing problems.
There was a reason rotaries were outsized in the first place, they were too competative in the smaller engine capacities.
Mick
[ Edited on 3/4/2007 by flashman ]
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Flintstones
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| posted on April 3rd, 2007 at 11:49 PM |
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| Quote: |
There was a reason rotaries were outsized in the first place, they were too competative
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That's why they were banned from the Le Mans 24 hour after they won it back in the day.....
Cheers
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76bug
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| posted on April 4th, 2007 at 11:50 AM |
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there are people running in sports sedans using a 13b motor that has the housing's machined narrower(12a capacity), so basically the motor has 13b
housings and 12a rotor's, mazprep engineering builds them in canberra
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1303Steve
A.k.a.: Steve Carter
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| posted on April 4th, 2007 at 03:17 PM |
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Hi
Wasn't there a 10A in the early models? They might come in under 2L.
Steve
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Flintstones
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| posted on April 4th, 2007 at 11:13 PM |
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Hiya Steve,
Yeah there is the 10A engine but try getting parts for them, hehe
Good luck if your going racing, just hope you don't blow it up and damage the rotors or crank!!
Cheers
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1303Steve
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| posted on April 5th, 2007 at 08:20 AM |
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Hi Deano
What about a rotary from a NSU, they used whale bone rotor seals, imagine trying to buy them, maybe in Japan if your doing research.
The RTA also rates rotaries at a higher capacity. Quote "The engine capacity to be used for rotary engines is the displacement of all rotors x 2."
So a 12A would be 2.4 litre and so on.
Steve
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bigrudi
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| posted on April 18th, 2007 at 08:39 PM |
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rotary capacity
capacity cann be reduced by machining rotors and rotor housings makiing them narower and therefore less capacity
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