Experiencing 100 RON fuel in my Skoda Kodiaq : Is it just mind tricks?

Given that the recommended RON was 98, I was not sure if the perceived increase in performance at RON 100 was just my mind playing tricks.

BHPian phi recently shared this with other enthusiasts:

A bear filled with 100 RON

I was on my monthly trip to Bangalore and it was time to return to Cochin. I had splurged on HP Power 100 petrol from Bangalore a couple of times before, when I was not expecting much traffic on the return journey. Both times, I felt that the engine was smoother, faster to respond, and had less turbo lag than when I was running at RON 98. Given that the recommended RON was 98, I was not sure if the perceived increase in performance at RON 100 was just my mind playing tricks.

It was a beautiful Friday morning, and traffic was not expected to be heavy on my drive back to Cochin. I thought I would try to add some objectivity to my perception, so I filled up Power 100 again, put the car in Sport mode, and drove in a semi-spirited manner, taking it as a challenge to be not as rough as to disturb my wife who was sitting alongside, working on her laptop. It was such a pleasure, the car was responding extremely quickly to every input, as I was struggling to plan ahead and adjust to avoid sharp speed changes, and it was gliding with almost imperceptible vibration across the great new highway via Rayakottai, that I was reminded of a brand new Gillette razor driving smoothly over my freshly lathered cheek.

It was awesome until Dharmapuri, when a couple of braking incidents (a scooter that veered on to my path, and a suicidal dog that wanted to bolt right across the highway) jolted my wife off her concentration. The joyride continued, and as much as I could, I was closely keeping track of turbo lag and vibration, committing the experiences into memory quite consciously. By mid afternoon, as we crossed Salem, wife wanted to take a nap, and asked if I would miss her chatter. My dad had forbid her from sleeping while travelling with me, chiding her lovingly about the need to keep the driver alert with good company, just like he would do unfailingly on every family trip that we took. So it was our private secret that she would indulge in her privilege of getting rocked gently to sleep once in a while. She gently suggested my choice of music to keep me engaged. I refused amiably, too polite to tell her that our bear of a car was talking to me, and me to him, and that was all the joy I needed while she slept.

And so we drove on, and as I crossed Coimbatore bypass, on towards and beyond Palakkad, the sky decided to bring on drama with a beautiful sunset, wispy silver winter clouds spread as flakes illuminated among the orange light. It lasted for a glorious thirty minutes, and the bear and I were still chatting in mirth when my wife woke up finally. She asked me if I was swerving and braking more than usual - probably I was, but how would she know when she was sleeping so soundly, so I told her that she might have dreamt it, while I winked at the bear.

A quick bio-break and tea later, my refreshed wife and I were conversing in earnest about small things as we love to do, and the bear hummed along smoothly on straights, accelerated lightning-fast out of clutters, and overtook cleanly upon my slightest whisper, keeping a steady pace even as traffic picked up beyond Thrissur. Finally, we reached the Indane COCO pump at Pongam, which is where I ensure that the bear has his fill before we reach home. True to my experiment, I filled up XP100 and XP95 in part quantities to true up to approx RON 98 and resumed my journey, still in Sport mode.

And there it was, the bear was grunting in protest, my legs and mind which were tuned to the instant response through the day were left waiting, not just once, but again and again, until I decided to turn off Sport mode and started driving more sedately, till I reached home at Cochin. After a good night's sleep, I took the bear out the next day on a short trip, and with my muscle memory partly reset, it felt much better than the previous evening after that refueling.

Now that I had a pretty clear idea that the better performance with RON 100 was not a fluke, I set out to dig into the theory of how this could happen. Spent a pleasurable Saturday afternoon revising my understanding of Otto and Atkinson cycles, learned about Miller cycle and how it worked great when paired with turbochargers and superchargers. Then, got a little insight into the EA888 Evo4 DNNA engine used in my Kodiaq, read about how it used Budack cycle, and variable valve timing to shift between Budack and Otto cycles by adjusting camshaft phases to boost efficiency during low-power operation and deliver power at load. Finally reached the conclusion that the turbo lag itself does not reduce with RON 100, but the higher RON probably causes the ECU to adjust (advance) ignition timing and boost pressure more aggressively, leading to faster power delivery, creating an impression of lower lag. Apparently, one of the steps that engine remaps do is to adjust settings such that ignition timing is advanced and boost pressure in the turbo is increased, leading to faster power delivery (which is why they often insist on higher octane fuel after remapping). My daughter, with her budding interest in cars (or as I sometimes like to believe, her feigned interest in cars so that she can get me to spend more time with her), then distracted me to discuss interesting trivia - that Otto, Daimler and Maybach collaborated on the development of Otto cycle engines, that L&K was the original name of the company that was renamed Skoda after its founder, that Skoda means "pity" or "shame" in Czech (urghh!, that spoiled the name for me), that the original Superb was released in 1930s in beautiful art-deco form, and that Volkswagen was started as a Nazi company and was directly complicit in Nazi war crimes. We ended the day discussing whether our bear was a Nazi too, and concluding that he was too gentle to be one, and anyway, it was impossible for him to be one, since Skoda was acquired by Volkswagen many years after the latter was cleaned of its Naz(t)iness.

As the Sunday rolls down its curtains, the bear is back to being happy with his RON 98 diet, and the two of us are back to having fun feigning class and etiquette on the road. But I know that our tryst with 100 RON petrol is gnawing at us, and we will be back at our expensive hobby pretty soon, as soon as we get a chance.

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