Rx7TyreBurna

iTrader: (1)

Just curious to know how many people would be interested in buying this product.

I am going to be working on some circuitry that will basically cut off the fuel flowing to one of the rotors, but will keep the OMP active to keep the rotor oiled. Fuel cut off will mostly happen on highways when load is low. When accelerator is pressed, the fuel will kick back on and then it will be normal. I also plan on an LED to show when system is active, also a toggle switch to turn on or off the module.

Trying to figure out if I should plan on making more then one, or just one.

This is first going to be avaliable for the S4 seeing as how that is what I have, so that is what I can test on.

Just let me know. Throw me some additional ideas. Thanks guys!

Icemark

well since the fuel is part of the lubrication process, cutting the fuel equals cutting the lubrication.

See not all the seal lubrication comes from the MOP, but rather the fuel itself.

And remember that the fuel also disperses the oil from the MOP to all corners of the combustion chamber.

And this is not really 2nd gen RX-7 technical section post; now is it???

ussprinceton2004

I don't go anywhere due to high gas prices, but like Icemark said, it is part of the lubrication

classicauto

iTrader: (3)

Ive had a long time working-theory that the reason rear rotors are more prone to losing compression first is because its the rotor that experiences the most fuel cutting, in decel and in fuel cut.

Gas might be expensive, but I suppose rebuilding isn't that cheap either......not a terrible thought I suppose. But IMHO - I wouldn't EVER waste a dime on something that will wear out my engine faster and save a very marginal amount of fuel.


Did you know that according to statistics, that fuel consumption varies by as much as 33% depending on MOOD??......just a thought, I usually listen to soothing orchestra music while I drive!!! j/k

HOZZMANRX7

iTrader: (43)

I read that at least one of the new Chrysler V8 models are designed work along the same lines as Rx7TyreBurna is proposing. At freeway cruising the V8 will run on only 4 cylinders and kick back to 8 under load conditions.

So, is this a fundamental difference between a piston and wakle engine? Or, perhaps the cylinders in the V8 that are turned off are still receiving some minimal amount of fuel to address the issue Icemark brings up?

Aside to Icemark. I asked one last question regarding the Standard and AE stock head units. Knowing you have particular expertise in car sterio work, can I talk you into dialing into my thread with your thoughts?

Icemark

actually GM had that same tech back in the late 70's

actually the fundimental difference between a piston engine and a rotary as far as this concept is that the piston rings are not lubricated by the mixture, but rather from underneith with oil jets in in the crank that spray the bottom of the pistons and cyl walls.

The only way this concept would work on a Rotary, is if you could spray (at high pressure) the apex seals/housings. But of course we all know that the MOP only trikles oil in, and would hardly be up to the task...So the other approach would be small high pressure jets in the rotor itself, that is forced into place by the E shaft, that would shoot the oil out on the apex seals and combustion walls (a simular design is sometimes used in other manufactures rotary engines, except the oil is shot into the apex seal groove with the apex seal and it ozzes out around the seal... but that does nothing for the combustion walls of the housing.

And then what do you do with all the oil, you have just spray'ed to lubricate???

Pm me the link, I'll look again

Rx7TyreBurna

iTrader: (1)

Bummer. Wishful thinking I guess.

Oh well. Thanks for the info Icemark.

RotaryEvolution

iTrader: (30)

not only that, the engine would suffer drastically in mileage because of having to drag the rest of the motor along with it. i had a customer who put one of my rebuilds in his car and it had always had trouble starting and had low power, after several months of driving the car like that he finally had a chance to bring it by my shop. long story short the injector clip to the rear rotor primary injector was not getting contact with the injector so literally he was driving for several months on only one rotor.

his observation was that the mileage was pure crap and so would this be a result of this idea as well.

coldfire

iTrader: (1)

people are better off keeping their cars tuned up nicely. having some way to control fuel delivery, such as an SAFC or standalone would help a bunch.

i have leaned out my cruise to the point that the engine is almost at the point it starts stumbling. my wideband reads around 15.0 at cruise, and i usually manage between 350 to 400 miles a tank (if i were to only cruise under perfect conditions, i might even be able to push close to 450 miles a tank).

but hey, don't let us nay-sayers get you down! experimenting is always good, just don't blow up an engine or anything

Icemark

How Mazda R&D is looking at it, is to bypass one combustion event, per rotor at light load.

Since there are normally 3 events per rotation, dropping one event allows the fuel and oil mixture still to be distributed on the other two rotor faces and events. This rotates around through the cycle (such as if face 1 is killed on the first cycle, face two is killed on the 2nd cycle and face three on the third cycle, face 4 (rotor#2 face 1) on the 4th cycle, face 5 (rotor#2 face 2) on the the 5th, etc.

So in therory (and I have not seen actual figures) there would be about a 15% increase in gas mileage at light load situations (about 3.6 MPG increase at light highway speeds based on 25 MPG (Mazda RX-8 Renesis claimed Highway Mileage) at highway speeds).

Of course the emissions issues are what is really holding up that. See there is still air being pumped through, as well as exhaust still being recirculated. Normally a light loads, there is not any air being pumped into the cats, but with that bypass there is an increase of 16.5 % of the air being pumped into the exhaust stream, causing cat problems.

RETed

It's a stupid idea.


-Ted

90WhiteVrt

Gas has dropped .50 cents a gallon here in the past month

kungfuroy

iTrader: (6)

cutting the fuel to the rotor isnt enough. you would need to cut the airflow into the rotor(cylinder even) to keep it from sapping power with its compression stroke

j9fd3s

iTrader: (3)

you cant do that, because then that rotor draws a vacuum, and the power it takes to do that, is almost the same amount of power that the other rotor is making.....

HOZZMANRX7

iTrader: (43)

Ah Ted. Surely as a technical advisor you can provide better input than just ...

RETed

The information is out there.
I'm not going to hold your hand, and I'm not your babysitter.

Mercedes Benz has been using it on their V-12's for a while now.
This technology has transferred over to Chrysler, since Mercedes now owns Chrysler.

That should give you a good starting point on where to start looking...


-Ted

HOZZMANRX7

iTrader: (43)

Much better.

vaughnc

So best bet would be to heavily lean the fuel mixture at light highweigh loads, and light lean with moderate acceleration (requires fast aftermarket ECU with ODB-2/3 specs) which would still offer lubrication with fuel savings and clean emissions.

My5ABaby

iTrader: (7)

Soooo..... use an aftermarket controller such as Megasquirt and tune it properly. Gotcha.

jackhild59

iTrader: (7)

Each of you gentlemen are describing half of what is called pumping loss.

In boinger tech, they close off both the intake and exhaust valves, therefore trapping (substantially) the air that is inside the shut down cylinder. By doing this, the energy spent compressing the air is recovered as the piston travels back down the cylinder. This is pretty much a net cancellation of energy used (except for the friction of the compression and oil-control rings) within that cylinder. If they did not shut off the valves, the cylinder would become an airpump and would add a huge drag to the engine and would kill fuel economy not help it.

The only difference between the 1970's tech and the 2006 tech is the computer control of the process to minimize the effect of the shutdown and startups on the driving experience and to maximize economy.

BTW, Honda does this on the Accord V6 Hybrid and it is speculated that most of the increased fuel economy is achieved from the cylinder deactivation, not the electrical hybrid portion of the powerplant.

I think if you deactivate one rotor without controlling the air, you will be very dissapointed by losing much power and fuel economy.

SureShot

Fuel economy is a monster issue.
All the easy ways have been done years ago.
When it comes down to power per $ of fuel in a practical car, the hybrids are showing the way.
When it comes to power per displacement or per weight, the Wankel shows the way.

RETed

There's also another trick...
Negative split.

There's a thread in one of the other sections which talks about this.
The results are promising.
Of course, you'd need to run an aftermarket EMS that can do this...

Why don't you just run 5psi more pressure in the tires?


-Ted

ericgrau

iTrader: (1)

I don't suppose you'll englighten us with a quick definition of negative split?

Leaning out the mixture too much risks detonation, which will blow your engine.

That Mazda R&D trick sounds pretty cool. Maybe those of you without cats could try it and tell us how it goes.

RETed

Normally, the leadings fire before the trailings or at the most - at the same time.
If the trailings fire before the leadings, some will call this "negative split".

Mazda started doing this with the RX-8.

You CANNOT do this when the engine is under load - i.e. under boost for turbo'd or close to "0" for NA.
This will quickly kill the engine!

Under vacuum, it allows you to run leaner than normal mixtures, which brings up the mpg.

There was a recent thread in here talking about this - try searching in this section for keyword "split"?

Leaning out the fuel under vacuum only induces lean surge which makes the car undriveable.
At really high RPM's, it will cause the EGT's to get really hot - not good.
You really cannot cause detonation if the engine isn't in heavy load.


-Ted

vaughnc

Yeah MIT's been running with that idea & 21:1 compression with dual tank gas (87 octane & ethanol):
http://www.technologyreview.com/read...727&ch=biztech