Could someone give me a breif description fo the FD twin ingition system please.
I know basically that there are two spark plugs per rotor, and that these can be fired at seperate times but I have a few questions.
1) Does the spark timing close up (ie no1 fires closer to no2) as RPM increases.
2) Other than emissions purposes does this provide any benefits (obviously cleaner combustion also makes better power) ?
3) Do they both follow ignition adavnce at the same rate (ie as ignition advance increases do they stay the same distance part)?
4) Are they completely timed by ECU or does it follow a CPS or similar.
Do a search on Rx7club.com on split timing, there is a whole thread on Split timing and how it works, some people run 0 split for power, some people disconnect the trailing altogether, for economy you should run some split
it\'s very much like the Twin Spark system Alfa romeo used to have on the 90\'s engines.
Basic idea is to have the leading sparkplugs to ignite the air/fuel mixture and to initiate the powerstroke, the trailing sparks will fire a certein amount of degrees (crackshaftrotation that is) later to ignite the remaining unburned air/fuel mixture in the combustion chamber.
Purpose is to maximize the energy that is in the mixture, burn the mixture as clean as possible and by lengthening the \'flame front\' over a wider band (degrees on the crankshaft) to have a longer powerstroke on the crackshaft.
The rotary benefits from this as it has 3 burning cycles on one crankshaft rotation instead of a normal piston engine (fe 4 cylinder engine has 2 cycles (2 pistons up/burn/2 pistons down)
This togehter with the roatary concept makes that it is so vibration free and it feels so smooth..
More or less :D
Quote from: Speedworks;544504This togehter with the roatary concept makes that it is so vibration free and it feels so smooth..
More or less :D
IE Fine until you chip a rotor tip! :Giggle
Try rebuilding a Porsche (or any other sports car for that matter) engine with thesame power output and fun factor as a rotary for the money you can rebuild a rotary ;-)
power and fun come at a price... ;-)