Hmm, don't see a problem here, neither any grave

Raising ignition for better octane. Knocking somewhere, maf readings are dropping there.

Raising fuel, knocking prevented, maf readings raising.
More torque on that specific engine point. Not touching cams.


That worked in my two decades of non-pro calibration in my spare time for most of the cars including that with M272 3.5
Im talking for getting max torque, for which this engine is designed. Not others including the ones you mentioned.


In my opinion you could respect that there are other possibilities than a dyno to make a car owner happy. What if you have a nice looking curve on dyno but owner is not happy with the real feel?

I totally agree that you only make best graph and real numbers with a dyno. But if that is not the goal, then there are other possibilities for improvement.

Call that retarded, call it not knowing anything, call it what ever you want.

Why not wait what thread creator reports about richer or leaner Lambda? Sure he will not have good looking graph, maybe less power. But a smile each time he accelerates his car. Maybe some day he will go to a dyno to make it even better.

See, you think that is the truth. I doubt that it is true under any circumstances. Two opinions.

Here is my contrary opinion:

Bad combustion efficiency due to knock retard leads to less energy moving the engine inertia. This meaning slower engine rpm increase under similar load conditions. resulting in less air in the NA engine at a given point in acceleration phase. since the airflow is correlated to engine speed on NA engine very much.

This results in less torque at a specific point during acceleration and the feeling of a weaker car/engine.

I mainly work on forced induction engines, right. And my expertise is embedded software development.

What i observed on non-pro calibration on NA engines was what i posted. My explanation is written above. Might be wrong explanation, but the observed and the approach derived from it stands from my side. Going richer with increased ignition using higher octane fuel in rational steps might help and helped me on that specific engine. Helped me on many Volvo B5254S, B6304S and B8444S. Helped on LS3... 0,85 is the point of highest possible torque. Need to discuss this too? Surprisingly on all these engines including M272 it was the value for best acceleration and MAF readings during acceleration.

That's why watching MAF readings during that process helped me to find the "sweet spot" of best acceleration.

Again, im not talking about highest power at high rpm. Not about the prettiest curve. im talking about peak torque in an acceleration run. I have the impression, you intentionally mix that up?

Don't know why. To call me out? Do that.
To justify your Dyno? No need, it has its eligibility.
Not spilling any poison here.
Giving information about what worked for me to others - that's what a forum is for. And can be for in parallel to your usage of it to advertise your business

Luckily it is up to everyone by itself decide to use that approach, or go to your shop or do something completely different

Ok, as i said. My opinion / explanation for the observed might be wrong.

I double checked some recent logs. On an LS3 V8, not realy that close to an M272, i know, i had a rise of the mean airflow by 3,5% when dialing Lambda from 0,92 to 0,84..0,81 while increasing ignition some degrees.

How can that be explained? The process was two or more runs with same software, same gear, same evening, same people in car. Minutes after each run. Mean value of Maf readings over rpm, mean of the runs.

Same approach gave nearly no changed MAF values on an SLK 55 AMG NA, but still a faster time 0..100 Km/h measured with V-box.


So where is the error in my explanation? Engine speeded up by energy from combustion. The more energy, the faster speeding up per time. Is that agreed or an error already in your opinion?


I realy would like to understand instead of throwing stuff at each other.

Yes, that sounds like e better explanation which i didn't thought of so far. Thanks.

Makes even more sense since the exhaust of the LS3 Crate Engine seems to be very restrictive. Should have 525 Hp with factory Dataset, on dyno it only had around 470 Hp.

Same goes for the Volvo exhaust on 5 and 6 Cylinder.

SLK 55 AMG has obviously a good exhaust.

So maybe this method only leads to identify a very restrictive exhaust, which a dyno can do probably faster than driving around all night full accelerating (which is fun too).


What is left are sometimes (not always) faster acceleration times on some NA engines with Lambda around 0,85 in mid rpm range instead of 1,00. Probably in cases where factory Dataset is very "emission friendly".


I still need to find out why my explanation / opinion is so much "bullshit", but no need to flood this thread even more.

Yes, 0.85 will probably make more power than 1.00 on most engines.
But maybe 0.9 will make more. Or in case of overstroke engines they often need 0.8 or lower.

You have no way to find that out without a well repeated power measurement. Certainly not by looking at measured airmass or anything else.