Twin Spark Offset ?

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
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ignitionautosport
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Re: Twin Spark Offset ?

Post by ignitionautosport »

There is an option in the main setup page to use Advance Map 2 for Twin spark offset - ie trailing degrees.

And no, I wouldn't expect any gain except maybe at light loads/idle. Even rotaries make good power at zero trailing split.
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VR6Turbo
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Re: Twin Spark Offset ?

Post by VR6Turbo »

DTA's definition of "twin spark" may mean something else but the manual does state it can run 2 plugs per cylinder :D
DTA Manual wrote:
TWIN SPARK?
S60PRO and above. Only use this when the engine has 2 spark plugs per cylinder. First spark plug coil outputs coil 1 to coil (number of cylinders), second plug outputs are coil (number of cylinders) to coil (number of cylinders x 2), that is cylinder 1 first plug is on coil output 1, second spark plug on cylinder 1 is coil output (number of cylinders + 1).
DTA Manual wrote: This ability to run twin spark mode can be very useful for an engine which has individual coils but no cam sensor. Wire the coils as you would for running them with a cam sensor fitted and select twin spark on.
This is how I run my COPs. I didn't want the added complication of COP firing angles, just straight forward wasted spark 8-)
DTA Manual wrote: TWIN SPARK OFFSET
S60PRO and above. Allows small delay (in degrees) between 2 sparks on the same cylinder. If 0 then both sparks are at the same time. If 10 then the second spark occurs ten degrees later. Note that all advance figures relate to the first spark.
69alfa
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Re: Twin Spark Offset ?

Post by 69alfa »

Next question , why do rotary engines use twin spark ?
VR6Turbo
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Re: Twin Spark Offset ?

Post by VR6Turbo »

Good question!

Looking at this diagram, I'd say it's either to help push the rotor round (staggered firing) or just to give a bigger burn area?

Image
Simon P.
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Re: Twin Spark Offset ?

Post by Simon P. »

Twin spark is simply because the combustion chamber is very long. Using 2 spark plugs solves bad flame front propagation speed issues. Rotaries run pig rich to start with which is hard to ignite at low RPM/load and this helps.
As stated above, they run split from the fatory to help with emmisions and low load conditions but many tuners running stanalones will run them sync'd to simplify things.
There are actually some race engines (Mazda 787B Lemans car) running a third plug right in between the 2 seen in the diagram above. No idea about the timing split on those...
Cheers!
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