So how does it work

I get the impression on a modifed car at peak revs and power you want as much as possible without causing detonation? is this right?

Not planning on doing any mapping just comparing say the OEM map and the evocars maps, the evocars runs alot more advance.

No I don't think so.

Peak engine power is achieved when peak cylinder pressure is achieved around 12-14 deg after TDC.

In order to achieve this you need the spark to ignite the mixture sometime before this point, and depending on how much fuel/air is in the chamber this point varies.

Imagine this.
200cc N/A cylinder filled with perfect AFR @ atmos pressure. Spark plug ignites it and its burns for 5 miliseconds.
200cc turbo cylinder filled with perfect AFR @ 1 bar pressure. Spark plug ignites it and it burns for 8 miliseconds.

In order for them to both get to max cylinder pressure they need to be ignited at different times in order to arrive at 12-14 after TDC.

Similarly the same turbo or N/A engine ignition advance is affected by time. So at 2000rpm the engine needs to x degrees of advance, however at 10000rpm it needs a lot more advance to reach the same point as the engine speed is so much faster yet the burn time doesn't speed up in comparison.

There are a few other factors that affect advance too including throttle position and fuel type used.

Chris

First you set the fuelling up typically 0.88 lambda for performance.

Then you advance the ignition until it starts to det for that rpm/load point. (MAP/RPM mapping strategy) Then retard it 2 degrees for engine safety and fuel compensation (street cars). Repeat this process until all the relevant load sites are complete. It must then be corrected for WOT.

You will find the faster the rpm the less advance you can run. This is only due to the fact of engine knock. The highest advance will be at peak torque and if your engine is good you should hit BMEP. The same is for injector pulse width.

Peak pulse width and peak advance should be at BMEP (max torque) so about 3000rpm depending on the engine.

TurboJ your sounds like what I thought that you run as much advance as possible till you get detonation then back it off "half a turn"

Nobby, I get this bit "Similarly the same turbo or N/A engine ignition advance is affected by time. So at 2000rpm the engine needs to x degrees of advance, however at 10000rpm it needs a lot more advance to reach the same point as the engine speed is so much faster yet the burn time doesn't speed up in comparison."

But need to do my home work on 12-14tdc

Thanks for the info

Paul, check the grale EVO2 advance maps. As Xav. told me (and from my experience) it's got decent advance curves not as harsh as the EVOCARs one
I've scrapped EVOCARs maps couple of months ago and I'm just using them for comparison only

V.

Why did you scrap them V, too much advance

mostly yes, imho evocars maps are fine if you want to push a standard setup. If you go for a larger turbo, hi-lift cams, headwork, 3inch dp, other injectors, etc, there's nothing left from the original map tbh

So I'm sorting out fueling duration map (by feeding a constant "stoich" signal to the ecu and reading the wideband values )
Then I have to check advance and go a bit back and forth.
Haven't sourced a decent detonation system that I can use whilst driving though...

I'll email you the evo2 bin later on tonight or tomorrow Paul.

V.

You advance the ignition to reach one of two points first:

1. MBT
2. Detonation

If you reach MBT first then there is no reason to advance any further as you have now reached optimum torque and fuel economy for the setup. If you start to reach detonation first then you cannot reach MBT without changing the fuel octane or the combustion dynamics. Most boosted cars will reach #2 first, however it is a dynamic process at each load point and as Nobby says ignition timing will advance as you reach higher loads as a requirement to burn the fuel before BTDC.

When you're talking about the maps you have lying on your pc's... How do you alter the chips you have? I take it you would need some hardware to write the chip, and some software?
Do you have some links where i can read up on it?

Can anyone give me a list of all these abbreviations? BTDC and MBT and the rest. I got Wide Open Throttle though

BTDC - Before top dead centre
MBT - Minimum Best Timing
BMEP - Brake Mean Effective Pressure

Thanks Nobby