Why do people buy high octane petrol?

[FnG]magnolia;20547044 said:
Whether an engine can 'adjust' and whether there is any point are two different things, aren't they? I don't think snowdog will see any performance increase in his volvo (is he still in that?) running 98 over 95, if, as he says, it was tuned for 95.

Keen to hear your thoughts on what 'adjust' means given the nature of the thread.
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Mitsubishi galant...

I'm asking more or less, if fueling my Galant (2.5 v6) with 97 or 98 has any point...
 
I use 97RON, Because my Supra is a JDM (Yo!) import and that's what it was designed for. Its pretty comical when new owners come onto the Supra forums banging on about how they use octane booster in their fuel because they read on some yank forum somewhere that all JDM cars are mapped for 100RON cos that's what they use over there :P
 
ubersonic said:
I use 97RON, Because my Supra is a JDM (Yo!) import and that's what it was designed for. Its pretty comical when new owners come onto the Supra forums banging on about how they use octane booster in their fuel because they read on some yank forum somewhere that all JDM cars are mapped for 100RON cos that's what they use over there :P
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Erm, they do use 100RON, and have done for some considerable time.
 
ubersonic said:
I use 97RON, Because my Supra is a JDM (Yo!) import and that's what it was designed for. Its pretty comical when new owners come onto the Supra forums banging on about how they use octane booster in their fuel because they read on some yank forum somewhere that all JDM cars are mapped for 100RON cos that's what they use over there :P
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Is it as comical as pretty much everything you post?
 
Mine says Super Unleaded Only 98 (95).

Why argue with what the manufacturer designed the engine for? Also my ECU has been tuned (remapped) for V-power hence it only gets that (and only ever has since I bought it brand new).
 
Clarkey said:
Erm, they do use 100RON, and have done for some considerable time.
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They do now but they didn't start selling it until the very end of the nineties and it didn't became widespread until this century either, no JDM Supra ever left the factory mapped for more than 97RON, however because some Americans imported JDM cars mapped for race gas and killed them up on their premium gas it spread round the internet like wildfire that Japan uses 100RON, always has, and every performance JDM car needs 100RON, its like saying every British performance car ever made is designed for Tesco 99, hence comical.
 
At a recent rolling road I went too, we had 2 Megane's, mine a 225 cup, and one an R26. Both the same age, similar miles, similar history etc etc. Mine made 223.6, his made 216. Whether it's coincidence or not but I've always ran mine on Vpower, he's always used cheap 95 tesco. His being the 230 was 14 bhp down, mine 1.4bhp down, go figure!

I reckon that says quite a lot, personally, unless there was something else drastically blunting performance!
 
Never trust a rolling road. Ask a tester, if he says its accurate hes such a liar ;)

Bench Dyno is accurate if done properly

More Octane > Less Octane Its better quality fuel. More controlled explosion.

Like any computer.. its worthless without being setup for it though. Modern ECUs will have some self learn and appear faster/smoother.
 
Defcon5 said:
The 1.4 AUB 100bhp Polo engine is actually designed to run 98ron :p
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Defcon5 said:
Yep, in the fuel cap sticker too!
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Says that for a 1.2 Honda Jazz engine. Its only SOHC but I presume it'd change things slightly, it has the sad version of vtec :(

Its possible it might raise MPG slightly anyway but I think at least some of the higher RON fuels have a lower calorific content.

A bit like LPG is rated for well over 100 RON, will run in most petrol engines but in fact has 80% of the energy as petrol making the lower prices you see slightly deceptive.
However if it was tuned well for that higher RON its possible it might make up the loss of energy
 
Ghostdog said:
Never trust a rolling road. Ask a tester, if he says its accurate hes such a liar ;)

Bench Dyno is accurate if done properly

More Octane > Less Octane Its better quality fuel. More controlled explosion.

Like any computer.. its worthless without being setup for it though. Modern ECUs will have some self learn and appear faster/smoother.
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agreed
 
I'm getting mixed answers as to whether it would benefit my car.

In the manual it says use no less than 95Ron. Other websites are saying that with the Abarth version of my engine you should run it on 97+. I have the same engine, near enough, as the abarth just different injectors and turbo.

I might try it and see what happens. If I have anything done to it in future I will be getting it mapped to run on V-Power anyway.
 
near enough the same, but its the ecu software that will make the most difference

also, engines with particularly high static compression 11:1 vtec territory also benefit from higher octane
 
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