rotary megajolt

[orangepeel]

hey guys, newbie here, im about to turbo my 12a rotary powered hillman imp and and im hoping that megajolt can be programmed for rotarys.
can they? a friend of mine has a megajolt that he says i can use.
thanks
niall

[BRUCEROE]

The MJLJ-EDIS can operate engines with a 90, 120, or 180 degrees crank rotation between power strokes, or multiples of these. That doesn't usually work on a radial with an odd number of cylinders. If you don't have 2 cylinders reaching TDC at the same time, it would take twice as many coils. Bruce Roe

[orangepeel]

so thats a no?:(
out of interest i run two coils at the moment, one for the leading plugs and one for the leading plugs.
cheers
niall

[BRUCEROE]

Even with dual plugs per cylinder, you can't use the same coil to fire them. An EDIS coil drives 2 plugs which reach TDC at the same time. But the expectation is that one is a compression stroke needing a lot of spark energy, and the other is an exhaust stroke needing minimal energy. 2 plugs on the same cylinder would need more total energy on the compression stroke, than the coil is designed to deliver. Bruce Roe

[orangepeel]

thanks, looks like im looking for an other management system
oh well, thanks for your help
niall

[NITROPIXIE]

Is the engine equivalent to a 3 cylinder engine????

[BRUCEROE]

I may be entirely off track here, thinking of a radial engine. A 3 cylinder engine will have firing intervals at multiples of 120 degrees,
won't it? Then you may have a possibiity. Just what it the firing interval, will the engine work with waste fire? Bruce Roe

[bossie]

Please read the information on this site about the ignition: http://www.megamanual.com/v22manual/rotary.htm

It seems to be possible to use an EDIS module. So that might make it possible to use a MegaJolt.

[NITROPIXIE]

It looks highly possible to megajolt an engine to me. By looking at http://en.wikipedia.org/wiki/Internal_c ... ine#Wankel on the flash film to the right. The crankshaft (B) is always in the same position when the ignition event takes place which is exactly what an edis does. Both spark plugs fire at the same time, which again is the same as a wasted spark system.

So an edis 4 with standard ford coil pack would be fine to run a wankel engine. The only thing i dont know is if there is more than one rotor, which i'm guessing there are two, so you can use both sides of the coil pack with an EDIS 4 or just one side of the coil pack if there is just one rotor.

Hope this helps

Ryan

[dr.occa]

to help with understanding the rotary through the MJs lense here's some info borrowed from the megamanual article originally here.

To understand how a rotary engine works with MegaSquirt® EFI Controller, we need to figure out how MegaSquirt® will 'see' the rotary in terms of injection cycles.

In 720° of crank rotation, a four-stroke cycle piston engine (two revolutions = 4 strokes) ingests its rated displacement (ignoring volumetric efficiency issues and the like) of air. In the same 720°, the rotary swallows twice its rated displacement (somewhat like a 2 stroke cycle engine).

To understand this, recall that a Wankel rotary engine has three faces on each rotor, evenly spaced at 120° apart. The rotors rotate at 1/3 the eccentric shaft speed, so we see an ignition event every 120°×3 = 360 degrees, and all three faces require 3×360° = 1080° of eccentric shaft rotation.

(Note that all of these factors are determined by the geometry of the case, housing, and gears, and are the same for all Wankel rotary engines.)

In the 13B, there are two rotors, however, and they are phased 180° apart, giving an ignition event every 180°, alternating between the rotors.

Crank Degrees Piston Engine
Cylinder Firing Wankel
Rotor Firing
0° 1 1 (face 1)
180° 3 2 (face 1)
360° 4 1 (face 2)
540° 2 2 (face 2)
720° 1 - back where we started 1 (face 3)
900° 3 2 (face 3)
1080° 4 1 (face 1) - back where we started

So to MegaSquirt® EFI Controller, the Mazda 13B rotary looks just like a 4 cylinder engine, except for having a 2nd set of plugs delayed by a few degrees. Each rotor has 3 chambers and executes an Otto cycle (intake-compression-power-exhaust) in 1080° of eccentric shaft rotation.

Therefore, setting up a rotary as a 4 stroke cycle, 4-cylinder (since it gives 4 tach pulses per 720°), and 2600cc (displacement x 2), works out fine. The number of squirts per cycle may need some experimentation for your specific installation, as with any MegaSquirt® installation...

i've also been reading and trying to get up to speed on it.

[BRUCEROE]

Agreed, disregard my comments about radial aircraft (not rotary) engines. Bruce Roe

[dr.occa]

I know it's been a few months but I wanted to run this by some of your electrical geniuses:

If I were to run CPPs (Coils Per Plug since the coils aren't directly "on" the plugs - RX8 Coils) and 2 EDIS modules in parallel (Leading Spark handled by EDIS 1 & Trailing by EDIS2) could a resistor be installed inline on the VR sensor leads to the Trailing spark EDIS module to delay the firing enough to be comparable to that of the factory Trailing spark?

[NITROPIXIE]

A simple resistor wouldn't be enough. What you require would be more complicated than that. All a resistor would do is reduce the voltage to the second EDIS.

What you would require to do that is a calculated time delay event by a processor as the timing between these 2 events would change with rpm and load (possibly).

This may require an altogether different make up/proramming of ignition system which is currently beyond the capability of a megjolt, I believe.

Ryan

[dr.occa]

Thanks Ryan. Yeah, I was thinking about my suggestion and realized it was an idiotic suggestion on my part. Goes to show you my lack of understanding the electrical engineering arena.

I've got another option I'm looking at that an RX7Club member is generously lending me a hand involving a CAS from an 86-91 FC (NA/Turbo II) and a 72 tooth gear setup similar to that of Dean924. Thanks for not besmirching my obviously novice understanding of these things.

Joe Nuts

[BRUCEROE]

You could do it with one trigger wheel driving 2 VR pickups and 2 ignition systems. Since you couldn't locate the pickups only 4 degrees apart, space them 120 + 4 = 124 degrees apart. You will also need to change the coil driver wiring to get back the 120 degrees. I see it as a pair of 6 cylinder ignitions, the second wire on each coil is grounded as 6 plugs are driven. Both ignitions use the same curves. Bruce Roe