Originally Posted by Sal@Evolve
Leaning out AFR is a huge misconception and a generalisation.
Yes, if you have a car that runs from somewhere in the 10's-high 11's, leaning that out to anywhere between say 12.2-13.0 will increase power.
This is used to be the case with much older cars and some modern cars.
Here we are going leaner but we are going from silly rich to AFR for best power.
The lambda target @ WOT for an MSS60 is set as from 13.6 (1000rpm) making it's way towards 12.5 (8500rpm).
Now that's very good for achieving best safe power already and more importantly, consistently.
Leaning out at the higher rpm will only give you a temporary increase in power and even then it will not be much. Even if there was a genuine power increase it's so small that it's just not worth doing.
Ignition timing of course always gives power but the MSS60 already has some pretty radical ignition targets for a stock car. You can see from a recent dyno day that we don't actually run much ignition timing over stock at all. I mean, the ECU is already targeting 32 degrees at WOT high rpm! How much more do you want!
On another post I have shown the full throttle target for ignition (stock). So you can make your own mind up from there if you want to add, or if it's even possible to gain, massive power from ignition.
You can set the targets to what ever you want, does not mean they will be achieved but it's not the best idea in the world to raise them too much.
A combination of CAM timing, ignition timing and changing the allowable maximum torque (these are calculations) gives a very nice safe power increase.
Just going back to the ignition timing again. Even though the targets are set pretty good in the first place, it does not mean that the targets will be met. To make more power more of the time you can 'force' the timing. You have probably seen one other tuner mention this also. This is done by increasing the preset ignition maps.
Some say it's a bad thing, some say it's fine but it all depends on where these maps are preset to. If it's very close to the targets then you already know what's going to happen!
Well said, there are also some #'s floating around that are a little 'inflated' for these NA cars. When all is said and done you will be able to feel a difference from a properly tuned S65 motor.