Actually - there might be a logical explanation to this, most people I know don't know what mild knocking even is. The clakclakclak that they hear has always been there and they think it's normal. Once 97 comes in the knocking is gone and hence the thinking that it's smoother. Yes it's smoother, only because you've been living with knocking since day 1.
The other possibility is the additives in 97 is different from 95 for whatever reason. I don't know for sure but it's likely the additives are different. *shrugs*
Kancil carb - mechanical engine no knock sensor or anything. How you're able to get 30km more is beyond me. Consistently? Or one off? Or did you fiddle with the carb to utilize the fuel? Or was it originally tuned that way and you've been having pinging for a while but never noticed it since it and suddenly the introduction to 97 improved things overall?
As for the Kelisa experiencing something different - that's damn weird. 100km is a lot. There's too many factors that could attribute to your cars inability to reach 150km/h easily.
There's a few reasons your car does that. A normal wira doesn't vibrate and shake violently after speed bumps. Mine didn't before and after modding it. So to say the fuel helped reduce the vibration means there's a potential problem with your engine - either at the ignition portion, or something. I'd consider having that looked at soon.
A lot is hearsay until proven properly otherwise. The logic and science behind the octane number is there but there's too many feedback from people saying different things. A few things need to be considered before anything conclusive can be said.
- Engine and car overall condition. Any failing component will definitely affect the performance the car which might get covered by the RON difference (early detonation, weak ignition, misfiring, etc). Dirty air filter at the point of time will affect performance and mileage too. The condition of your petrol tank too will dictate the quality of petrol. Sand, water, additives you bought from Tesco that never dissolved properly, old worn fuel lines, clogged injectors, etc.
- Environmental factors. On a cool humid but dry day, the cars will generally work better compared to a hot humid day. Dusty roads, lack of tyre grip due to road conditions, etc.
- Weight of the car during the tests. Highway running means you might have bags and passengers. Or not. FC will definitely be affected as well as acceleration.
- Quality of petrol pumped. Not all kiosks get a fresh supply of petrol everyday. Some refill weekly and a rare few bi-weekly. If it just so happens you get petrol from a kiosk that might have a contaminated storage tank, or perhaps an old tank that has sediments, rust, or whatever inside then the quality of the petrol will be tainted. Having said that Esso / Mobil in the past had a regulation that the storage tank had to be replaced every 10 years. I wonder how it works for other companies and whether kiosk operators actually adhered to these rules since it's not exactly cheap to replace underground storage tanks.
So many possibilities that could directly or indirectly affect your cars performance which would contribute to your RON95/97 tests.
Having said that I'm offering a challenge to anyone interested to try. Offer up your car for a complete service and inspection, run on RON95 for 2 weeks, go dyno, run RON97 for 2 weeks then dyno again.
Conditions that must be met :
1. Inspection must be done by a independent party. Eg - me or anyone who might be interested. Service must be complete - GB, EO, brakes, etc
2. The car must be driven exactly the same way at the same route everyday (almost is fine, doesn't have to be precise)
3. The exact same petrol pump and kiosk and petrol brand must be used
4. The same dyno machine must be used.
Anyone interested? I'll document the whole process and post it up as a ZTH article.
