Clio 172 mk2
BenR said:Ignition timing is a tricky game, its much much more complex than fueling as thats simply a case of more of less, withing the start/stop perameters you dictate.
The old skool and relatively useless method of advancing till you pink (dont even get near det, true det or auto ignition will damage a piston in a single event and ruin an engine build in several) then retarding is practically useless. Firstoff, listning to det is the hard part, you wont be able to notice it accurately enough on a RR with all the ambient noise at about 110db, people who tell you they can are fooling themselves. You need a quality set of det cans, and even then its going to be hard even with an amplifier, you really need to have your ears honed to the particular freqency for that engine (ever engine will have a different natural frequency when pinking/knock/det occurs).
You HAVE to watch egt on every cylinder, and more importantly, you HAVE to know what egt your looking for inconjunction with the AFR your engine likes best and that all depends on how you built it and its mechanical octane. Its a game of constant fiddling between afr, egt and the torque output.
You could piddle all day with ignition timing. MBT and peak torque is what your looking for, but if egt's dont agree, then say goodbye to your exhaust valves, unless your running inconel. Advance too much and you might step over peak torque but still not get any abnormal combustion, but egt's will drop, you think your safe, sudden radiator temps increase because the piston is absorbing more heat than it wants and you end up with either a melt of seizure.
This is why chamber, piston crown, mixture control (not necessarily homegenous) has been pushed to the forefront of engine design reseach at the moment. You can put all the air and fuel you want in there, but if you cant burn it properly, then there is no point having it there at all.
Interesting stuff....I learn't a bit about mapping etc from my Subaru days but have no desire to do anything involving ecu changes etc with my Renault.....I think if it comes to me wanting something more full on a car change would be on the cards again