OC_

and done with a peripheral port. I find 6000 rpm quite streetable. I thought PP engines dident make any power untill you got to the big rpms. So what gives?

http://powersportaviation.com/Home/Engines/engines.htm

yes, its a 4-port 13b done up for aircraft use. but why cant we do this for our cars?

Mark S

iTrader: (1)

Check the price, it's 16 grand.

Mark S

iTrader: (1)

Check the price, it's 16 grand --and it's only available if you buy the prop reduction gear.

banzaitoyota

For one thing, (PLEASE CORRECT ME IF I AM WRONG!!!) Aircraft engines are tuned to run at a specific narrow RPM band. Therefore the tuning, timing, carberation is optimized for this range. It does not make a very drivable engine

OC_

well.. kind of. that 215 hp is "take off" rpm. they usually throttle down when crusing.

if you look at the dyno chart, you can see it looks like the engine stops making power after 6000rpm!

yes.. its 16 grand, but why hasent any of us done a port job like this?

Phu5ion

yeah the power curve looks very usable but i wonder how it looks closer to idle.

Also, Mazdatrix makes custom PP engines for about half the price and could probably have it tailored to look similar to Powersport's dyno graph.

mazdaspeed7

Its an aviation engine, theyre tuned way differently than auto engines. Besides, most PP's for auto applications are designed for racing, where big rpms's and big hp's are the norm.

Aircraft PP's use a smaller PP, and its located a little higher on the housing than an auto PP. It also has a long intake manifold tuned for peak power at 6000 rpm. But keep in mine aircraft dont use mufflers. The exhaust is less restrictive than anything feasible on a car, unless youre dumping off the headers.

I im agine the drivability would be great from that motor, but if you take into account the 17% or so driveline loss of an FC, youre looking at a motor that would make less hp then most street ported 6 ports with full intake and exhaust.

mazdaspeed7

The reason that engine is so expensive is because it has to be built to satisfy FAA regulations. And trust me, there are a lot of them.

OC_

Excellent points. I wonder what they are doing for the Rx-8 too, since thats a PP intake.

I heard mazda went to see what Power Sport did with their engine...

i know this engine isnt realistic, i just wanted to let people know whats going on out there, and what can be done.

I think the 6000 rpm drop off with this engine wouldnt be so great for our cars, i would like for it to pull untill the 8 grand redline... ill sacrifice a lot of my low end, i have no problem with that

but again, is the stock ports in a NA engine the bottle neck, or is it the intake manifold? whats currently causing the bog after 7000?
id like to read up on porting and port timing on these engines. Got any good resources?

mazdaspeed7

The rx8 has NO peripheral ports. Both the intake and exhaust are side ports.

The intake ports are not the primary restriction on n/a's. Everything bolted to the motor is. The AFM, TB, intake manifold, exhaust, etc. Im not going into the specifics of each here, but it you want me to elaborate on any of them, I will.

Port timing for what motors? 6 port, or the above PP motor?

Links
mazdatrix on porting
rotary engine illustrated
yaw power

OC_

with the expermental aircraft program, you can run any engine in your aircraft. This engine has a lot of R&D, especially with its gear reduction unit and finding which props will work with it. thats why its so expensive. Also, its targeted at people who can afford to own and run an airplane...
Atkins sells a rotary engine kit to go on the same aircraft (RV-6, which is a home built) and it costs a lot less, but its totally rinkey dink compaired to the powersport setup and it only makes 160 hp.

OC_

was going to make a post, but then realized you ment rx8 not 7.

bingoboy

look for the pics of the renesis engine OC, you can see the side ports for the intake.

Scott 89t2

a car 13b PP engine will make 300hp...

mazdaspeed7

At 9000 or so rpm

neo_omega

they do have 300hps NA in Japan. Can't remember it's tuned by FEED or some other shop. Will post it when i come across it again.

Jimmy325i

Also keep in mind that aircraft insurance is based on engine HP. It takes another rating to fly a plane that has engines exceeding 210HP. They made that engine to sneek under that provision.

Another thing is that not all aircraft run fixed speed props. That engine is tailored for them because they're more popular. They're more efficient because you can tune the engine for a narrow powerband to make a certain fuel consumption and power at that RPM and then adjust the pitch of the prop to accomodate the load you want to see on the VAC gauge and speed you want to fly at.

Apples to oranges here people.....

blue87

iTrader: (2)

215 HP sneaks right uner 210 eh...? hmm..

787B

would anyone else feel a bit nervous flying a plane w/ a rotary? Im sure they break them in a crapload before letting them up in the air, but what if they didn't and you got the one rotary that wasnt assembled to perfection? And we're at 20,000 feet......KABOOOMM.....APEX SEAL DISASTER! AHHHHHHHHHHHHHHHH

Jimmy325i

Sorry, thought that it was rated at 210. Pretty dumb to make an engine just barely into the "performance engine" rating if you ask me.

Aircraft engines are required to under go overhauls at specific intervals. Depends on the engine type and size and all that nonsense. I'd look up the FAR's on it but I really don't care to go into it that deep.

I'd have just as much confidence in a rotary as I would a boinger. Rods break just as often as apex seals do.

kristopher_d

Rotary engines are the engines of choice for private aircraft due to the reduced maintenance required in fewer moving parts. Yes, we do have apex seals to break. Name something else that might break. The apex seals are not much of a concern because the engines are constant speed (for the most part) and only run richer (on carb'd units) as the plain goes higher. Piston engines, however, have lots of things to check before every flight and lots of things to fail in flight. The reason most people lose apex seals has to be modifications. I have over 207k mi on my 7, and she still pulls hard all the way past redline.