RotaryRyan

Okay im not stupid, books, people, and webpages all say different stuff. I have a 12a in my 84 gs Ive read that its a 1.1L. Then a machanic told me it was a 1.2. I have read on many websites about the engine, and some say1.1 and some say 1.2. What is it? Its annoying when you can never get strait info.

WanKeL FD RX-7

iTrader: (7)

1.1

mcinnes

are you sure.....becasue my carfax report said 1.2...

RotaryRyan

thats the thing, i always thought it was a 1.1. but then i start hearing 1.2.

rhinor61

Mazda naming convention, at least early on used the displacement in Liters as there engine model number, the letter had to do with the various of design.

10A '67 cosmo 491 x 2 = 982cc
12A 79-85 RX-7 573 x 2 = 1146cc
13B 84-85 RX-7 (GSL-SE) 654 x 2 = 1308

1000cc is equal to 1 liter

So what mazda did was round up on the 12a engine, was to round up to name it although it is 1.146 liters displacement.

Hope this helps.

John

K-Tune

iTrader: (26)

it's 1146cc. which way do you round? i call it a 1.1

Aviator 902S

Actual displacement for the 12A is 1146cc's. Traditionally this would be rounded down to 1100 (hence the 1.1L claim), but Mazda thought it would sound better if the engine were called a 12A rather than an 11A.

If the engine dispaced a mere 4 more cubic centimeters it could legitimately be considered a 1.2 liter since the number 5 and above is rounded up rather than down.

The 13B rotary displaces 1308cc's, so there's no arguement there. (Unless you want to open the "actual-displacement-is-twice-what-Mazda-claims" can of worms. Oops, too late...).

The_Dude

it's most definatly a 1.1 ... it's just not EXACTLY 1.1 .. it's a bit bigger . so some "idiots" round it up to 1.2 :P

Aviator 902S

Double post...

RotaryRyan

alright. thats interesting. Now i finally know whats goin on.

vipernicus42

iTrader: (4)

Eric (The_Dude)

Idiots, like MAZDA?!?

Listen guys, you're always going to have people sit on the fence for this one.

The *correct* way to round 1146 is 1.1

The *mazda* way to round 1146 is 1.2

Mazda calls it the "12a" because it's "roughly" 1.2 litre engine, revision a. So Mazda rounded up incorrectly.

The 13b is *actually* 1.3L

So depending on your parts store, your insurance, your shop manual etc.. etc... it can be quoted as either a 1.1 OR a 1.2.

Jon

Pele

iTrader: (28)

Nah.. It's the double round up...

1146cc...

round up to 1150cc...

that rounds up to 1200cc... 1.2L

It's a 12A, so I call it 1.2 Liters...

Whenever I'm in the parts store, I always say the carbureted, smaller of the two engines... Or I say 1985 Mazda RX-7 and let them say "Which engine 1.1 (or 1.2) or 1.3?"

85rotarypower

EVERY parts book I have read (exhaust, various parts from parts stores) all say that its 1.1L. I will stick with 1.1L becuase its the CORRECT way to round it off. Heck, if I could rename the engine the 11A I would, just becuase it would indicate the correct displacement. Even my Haynes says its 1.1L or 1146cc. The 13 in 13B is correct, but it sure isn't revision B. There was no 13A production engine. So in reality, each engine name except the 10A is incorrect in some way, if Mazda's naming stratagy was followed.

mcinnes

alright ic

Pele

iTrader: (28)

I thought the A or B in the engine designation was for the eccentricity or something in the rotation of the rotors about the eccentric shaft.

hornbm

Yes there was a 13A engine. Instead of wider rotors, mazda made bigger rotors to get to 1.3L. This allowed for a shorter engine. It had to be done this way, because mazda used it for a few years in the "Luce" in japan, for the only front wheel drive rotary car mazda ever made.

However I'm sure there isnt a 20A engine, so I dont know what thats all about.

peejay

Indeed.

Mazda might have done two things:

First, they might have considered the 13G to be the "20A". Second, they might have called it a 20B so it could have name recognition with the 13B. Remember that technically the '74-85 1146cc engine is a "12B" because it was so much different from the '73-earlier version, but Mazda continued to call it "12A" for name recognition reasons...

85rotarypower

I wasn't aware that there was a 13A engine. Sorry for my mistake. But I did forget about the 20B engine, so my post is still lagitamate (sp?). I have read about a lot of different rotary engines, and NEVER have come across a 20A engine.

Now that I think about it, I do remember reading about a 13A engine a long time ago (about a year ago). I just forgot about it untill you mentioned it.

thricerx7

hooray for clearing that up. i was wondering it myself. i go on like partsamerica.com and they ask what kind of engine and i say 1.2 because thats the only selection, when i know mine is 1.1 L. that's not the only website that is mistaken

hiboost7

i say its actually a 1.2 technically...but when i race a competitor i tell them 1.1 because it sounds better, win or loose you can just say "hey, its a 1.1 liter"

85rotarypower

Like I said, everything I have read says 1.1L for the 12A engine, with the exception of a few posts asking this same question or something related. I have never heard 1.2L outside of this forum, and I have read A LOT of stuff online and looked for many parts at various parts stores. EVERYTHING says 1.1L.

peejay

I usually say it's equivalent to a 2.3. Save the hassle of saying "it's about 1.1 but that is rated per revolution instead of per two revolutions like a piston engine, blah blah" half hour later they have that glaxed look in their eyes.

85rotarypower

Its not looking like this is going to get resolved I don't think. Some say 1.2L. Others 1.1L. I still say the technically correct way to say 1146cc in liters is 1.1L. Its just the rules of rounding. I should know that too since I just finished Math for college technology in school. You do a lot of rounding in that class, and if you do something stupid like mazda did and not round something properly, you get the question marked wrong.