Anyone tried firing leading and trailing plugs at the same time, PFC or other ECU?

[BlitzBoy]

. I\'m concerned that the guys who have just run leading plug are all short duration drag cars so completely different to my needs. Do you know anyone that is running just leading plug in any circuit cars?

James Willaday has been running leading only on the road for the last year, so I think your assumption they are only in short duration drag cars is incorrect.
Trailing spark is for economy to be more efficent and make full use of the charge. for example the Lemans 24 hour car run three sparks per rotor I believe correct me if im wrong though

[royal]

Road still isn\'t anything like circuit though, regardless of how much of a hooligan James is
 Wouldn\'t the Lemans car be running 3 sparks more for ignition control or something rather than economy? this is an area where my noviceness comes to the fore lol!

[BlitzBoy]

well in a Lemans car you need to be fuel effcient less stops for fuel = better pace for the race

[BlitzBoy]

Quoted from an article about the Lemans car
 
"The R26B Wankel engine benefited from a variable intake system, optimizing air intake for certain vehicle speeds. Two periscope-shaped air intakes were mounted ahead of the rear wing. Each intake assembly was mated to a telescoping-pulley system which was able to vary the height of the protruding periscopes through a stroke of approximately six inches. The extension and retraction of the intakes was governed by the car’s ECU computer depending on vehicle speed. At high speed, the intakes were retracted to decrease drag and smooth airflow over the rear wing, and to reduce the restrictions on the air flow into the engine. At lower speeds, the intakes were extended in order to provide maximum positive pressure to the charge entering the rotors. Also, it benefited from an extra spark plug on each rotor from the 767’s two, making the car more economical and improving combustion. An oil cooler was mounted at the front and the car’s aerodynamics was improved at the sides and top of the bodywork. Like all previous engine, it featured Peripheral Porting in order to achieve the high levels of power from a naturally aspirated motor."

[royal]

The \'improving combustion\' bit stands out to me! surely having the trailing plug missing would lead to only part of the mixture being ignited and the rest being kicked out the back? loss of power,etc?

[BlitzBoy]

This is where you need a dyno to experiment, in terms of pure power you shouldnt see any loss of power if your spark is powerfull enough, reread Profs post its quite good as to why there is two spark plugs per rotor.
I think the reason why some people run without trailing as not to risk the trailing firing before the leading on boost

[royal]

I think thats a Haltech timing myth that was going around Rx7club. The Haltech timing isn\'t very accurate so people were worried about it. Someone checked with Haltech and they said the trailing firing time is based on the primary so impossible for it to fire before the leading plug. There maybe other issues as I\'ve only been looking at this stuff for a few days.

[royal]

Repeat question from earlier but want to make sure of some detail, do the primaries deffo swap to the secondary injectors or do the secondary injectors come on AS WELL AS the primaries?

[BlitzBoy]

They come online as well as the primaries all four injectors are working past 3800rpm normally, you can tweek transition to smooth it when they come online

[royal]

Ah right nice one , thanks.

[Prof]

This is where you need a dyno to experiment, in terms of pure power you shouldnt see any loss of power if your spark is powerfull enough, reread Profs post its quite good as to why there is two spark plugs per rotor.
I think the reason why some people run without trailing as not to risk the trailing firing before the leading on boost

If you think about the shape of the housing and the rotor - there is a \'pinch off\' of the combusiton chamber as the rotor face sweeps past the \'inny\' bit of th figure of 8 trochoid.  If you look at a model fo the rotary engine - you will see that this is pretty much in the combustion phase - all the charge on the top side of that pinch off would suddenly be reintroduced to all it\'s happily burning friends on the other side
 
Probably very oversimplistic - but I tend to think from their upwards.

[antnicuk]

James car may be running leading only as a safety precaution,  if you run trailing and the leading spark/coil fails you will not know and as the engine will still run but it is likely to kill the engine, if you only run leading and it fails, the engine cuts and causes no damage.  I was chatting to a tuner who said he was looking to map cars with no trailing after full boost.


Royal,   surely you had an ecu in the yellow car?

[royal]

Yes mate, I have an Apexi PFC and commander. I want to really learn how it all works and really like the idea of a DIY system like the VEMS or Megasquirt rather than a solution in a box so to speak. Just me in tinker mode I suppose. If I\'m going to map the PFC myself I need to buy a wideband and datalogit and for a similar price I can buy the full VEMs system which includes a wideband anyway. The only problem is there doesn\'t seem to be many people who\'ve done it with the VEMS. There\'s a guy with a 3 rotor turbo called bcool on rx7club who I\'m trying to get in touch with. I\'m pretty sure he\'s just using leading plug, but don\'t know how far he\'s got to getting it running.

If I could just confirm if doing leading only is ok then alls well but until then I can\'t make a decision and will have to use what I have. The VEMs guys were talking about adding in a split spark feature but I don\'t know how long that would take.

[BenLewisMav]

Isn\'t there a piggyback unit you could use to duplicate/modify the ign. signal for the trailing plugs?
I know with the Apexi AFC(Air flow convertor) you can take the fuelling signals and increase/decrease them (then potentially pass them on to additional injectors, scaled up or down).
Theoretically you could do the same but with an ignition controlling unit, adding a couple of degrees low down, and 10-15deg up top/under boost?
Personally I\'d prefer a compatible ecu, but it could be an option, if such a thing does exist?!

[Hayward North]

Cleaned as requested