Gas burn fraction tuning

Hi every body,

I am currently seeking to better measure the impact of my tuning changes by data analyses instead of using a dyno or my "road feelings" only. As a lot of us, I use HPtuners to log every data and then cross analyses the results.

I recently discover the parameter "Gas burn fraction inverse" in the HPtuners tracable parameters (see attached screen capture).

A quick digging on the net gave me some explanation about this method of gas combustion efficiency measuring (Rassweiler and Withrow developed this technique in 1938...).

I am thinking to use it for timing calibration in complement of detonation noise dectection. Is there anybody having tried this approach? Could I expect some real benefits and is there any trap that I should prevent?

This isn't something that I've personally looked into so I can't offer too much advice here. I'm interested to know what that parameter actually delivers though? As I understand it, an accurate understanding of mass fraction burned will require in cylinder pressure monitoring which you're not going to have access to without expensive test equipment. My best guess is that whatever that parameter delivers is modelled rather than being directly measured. Whether or not that proves useful I couldn't say though sorry.

The price of "affordable" pressure transducers incorporated into spark plugs has come down massively, but even then you need to know what you're doing.

I suspect the application may be best used for theoretical development and, IMO, the final tuning should be done on the dyno' or track.

As Andre mentioned, this is modeled,. If you have significantly altered the mechanical system, and don't have the extensive data required to correct the tables involved in the model, the result monitored values aren't likely to match reality. You can certainly observe comparative changes, but I would take modeled values with a grain of salt.

Thanks to all,

It seems I was dreaming...