also, i'm wondering if using 99 ron fuel with decent booster will be enough to stop any pinking and allow the timing to be upped. reason ithought about widening the lsa before a mapping seshwas A) to lower the effective comp and B) because Jez didn't seem too keen on cam gear tuning etc unfortunately
i'm also gonna make some det headphones for if i messs with owt lol
Well widening the LSA will lower your dynamic compression, and reduce pinking.
But on its own, all it will do is make the engine feel flatter in the midrange, on the plus side the power should hold on longer, right upto 8krpm.
Advancing the ignition timing also effects cylinder pressures, by making the mixture ignite sooner during the compression stroke, the burning/expanding gas and heat will cause the cylinder pressure to increase... the trick is to harness the combustion process and use that energy to push the piston down at just the right time.
Over advanced timing will therefore cause the pressure to peak too soon, and end up trying to push the piston down while its still on its way up the bore....and you end up with detonation.
Its also definatley worth mentioning that becuase you are burning oil, you are effectively lowering the octane of your fuel.
So anyway, you'll be bleeding out pressure by widening the LSA, then increasing cylinder pressure by advancing the ignition timing.
Ultimately, widening the LSA is just going to be a compromise to run more ignition advance.
Really the best option for you to make more area under the curve is higher octane fuel to support the ignition timing tweaks.
also dale, as above you've said the knock could be worse and therefore ignition will neeed retarding more on the low lobes, and this is something i've read on the web too - but can you explain why please? lol, cos i'd have thought it was under heavy load etc in high end that knock could be just as bad?
The easiest way to put it in context is to imagine trying to compress the mixture with the intake valve still open. Its a leak. The sooner the intake valve closes on the compression stroke, the more time there is to effectively compress the mixture.
Basically the low duration of the low lobes means less valve overlap, and that means LESS cylinder pressure is bled off, so your cylinder pressure is high.
On the mother lobes however, there is lots of intake valve overlap, so much more pressure is bled off, so cylinder compression figures would be lower.
Have a read up on dynamic compression ratio.
Anyway, stop asking me complicated questions !!:winkiss:Took me ages to write that crap...
