The_7

please forgive the newbie question, but what is the exact displacement of the 12A?

MikeLMR

Mazda quote it as 1146cc's

The_7

thanks. i needed it for some calculations im doing having to do with ram air. ill post it when i figure it out.

MikeLMR

don't forget that a rotary has an intake event every crank rev instead of every 2 rev's like a 4 stroke piston engine

Mike

MarkPerez

thats 70 cubic inch's (CID),,,, tiny ! is the litre size 1.1 ?

Manntis

Don't forget that ram-air is impossible with the intake manifold configuration. The best you'll get is cool, clean air.

The_7

lol, manntis i have an idea, i dunno if it would work but its an idea....say you figure out how many cc's of air the engine takes in at high rpms 5k-7k in one minute and then say your going 60mph, you figure out how many cm the car moves in a minute. then you figure out the area of a circle ( a cone around the air filter) that would take in more air than the engine uses at that rpm and therefore pressure would build up, and since that is for a high rpms you will have even more pressure in the lower rpms. so at highway speeds and up it would give you a low end boost.....what do ya think?

The_7

mark p, yea rotary engines make so much more power than a piston engine of the same size, they didnt need to give them a very big displacement.

Manntis

The shape of the FB actually creates a negative-pressure area above the bumper that extends back to the last third of the hood.

In addition, even if you do manage to create a pressure wave going into the air cleaner, the filter would block any noticeable increase.

So let's say you circumvent that problem and have a 1-2psi increase - you then have a right-angle down into the carb, and a few more hard angles through the intake manifold and down into the engine.

There's no way that forward velocity of the car would create an intake pressure greater than the air draw of the engine that would be so much greater than the resistance caused by all these changes in direction of the airflow as to measurably increase the pressure of the air charge going into the engine.

To maintain a pressurized system you need a one-way valve system similar to a turbo - and once you get into such moving parts, you may as well just turbocharge or supercharge your car.

The_7

oh yea, well what if you were going 1000000mph lol....hmm...you said there is a negative pressure area ABOVE the bumper. i was gonna mount them right in the bumper radiator opening. also, you mentioned the resistance of the bends in the hoses/pipes. yea that would slow the air down but the car isnt gonna slow down and once the air goes in it cant come back out so.... if more air went in than the engine was using you would get a little bit of pressure.....your move

Manntis

You're not really getting significantly more pressure into the engine. Before the first bend in the pipe you may get an increase in pressure as the gas presses against the back wall of the bend, but that just reduces the amount of air going into the pipe - other air coming in and meeting the increasing pressure before the pipe will simply slip around it and find another, easier, path.

The_7

yea thats true but still, no matter what way the pressure builds, or what areas get pressure first, it would still get pressurzied because, like i said before, more are goes in than the engine uses and the air obviously cant slow the car down and the air isnt going to go backwards, so there will be pressure

REVHED

For doing any sort of calculations using formulas for piston engines you need to double the rotaries displacement. So a 12A would be 2.3 litres.

Manntis

the air won't go backwards, but it can stop on the atmosphoere side of the filter (assuming the pressure wave even makes it that far) while the engine only draws what it needs through the filter and down into the carb.

If you get pressure just from 'ramming' air through a multi-bend pipe strictly by car's velocity, and this pressure is enough to push through the filter and still have a pressure increase, I'll be greatly surprised.

The_7

i see what your saying about the filter...do you think having two would help at all? well when i can get togther the cash ill put it together and get a boost gauge and ill post the results...if there are any. lol

Manntis

First, read up on fluid dynamics and gas pressurization.