Putting RON98/99 in a car optimised for RON95 will not see appreciable gains in output or economy.
Putting RON99 fuel in a RON95 optimised car may result in a marginally less efficient burn because the fuel is nowhere near the threshold for self detonation. You end up with a slightly less energetic fuel/air mix at the point of spark induced ignition. The differences are small and won't make much difference.
Some of the cars that Evo did the test on basically had "95RON" on the fuel filler caps.....& the MR2 in the above Thorney motorsports test isn't exactly a "98Ron only" candidate... unlike the BMW M3 CSL
& please explain why my MK7 Golf "95Ron" 1.4lt which should have 140ps (138bhp) & 250Nm actually has 167bhp & 267Nm....from Shell vpower & a drop in ITG tri layer foam air filter....if the fuel will do nothing??
There are a number of reasons for your power/torque increase over book:
1. VW are notorious for Conservative power/torque values. Most are over book from the get-go and improve more when running in.
2. Many dynos over-read to flatter the client- it's the difference between the before and after (remaps etc.) that counts).
3. Do you think your filter is doing anything for your output? It's a contributory factor. You can't attribute gains to one variable.when there are multiple variables to consider, unless you've eliminated one at a.time.
Even though.VW outputs are Conservative, I'm dubious that your car is outputting 21% more power over spec, but correspondingly only 7% more torque. More likely putting out 150- 155ps and that dyno is drastically over-reading for the rest.
To quantify your gains that you attribute to the fuel and filter, you should dyno stock with 95RON fuel, then dyno with new filter and 95RON fuel, then dyno again with 98/99RON fuel on the same dyno and note the differences between them.
By your reckoning, there's no need to buy a TCR, just put your filter in a 245ps GTI performance, fill up with Shell V Power and you'll get 296ps.
Not buying it.
Cars set up for RON98/99 can retard timing to run on the lesser stuff at reduced output. Cars set up for RON95 don't advance timing to gain meaningful amounts of power using RON98/99 fuel, which means the extra compressibility of the higher octane fuel is not being utilised.
