Using 98 vs 95 octane in a roadsport

[BrendonJ]

Guys a quick question, the manual says to use 95 octane in my 1.6 Roadsport (supersport 130). Will using 98/99 octane petrol make any difference hp-wise?

Many thanks

[Piers917]

I'm pretty sure it won't as the Supersport upgrade was mapped on 95 fuel.

[Chris71]

Very few road engines actually need the detonation protection that you get from higher octane fuel. What might be of interest is that I've always found I get measurably worse MPG from Supermarket fuel. In theory it shouldn't happen, but it doesn't seem to return the same mileage as standard pump fuel from the Shell station down the road.

[BrendonJ]

Hmm suspected it wouldnt make any difference, thankyou.

[BrendonJ]

Hmm suspected it wouldnt make any difference, thankyou.

[sjmmarsh]

It can help your engine run a bit cooler on trackdays, even though there is no more bhp available.

Steve

[Scotty996T]

Asked the same question of the guys at Caterham when I picked upo my Supersport and they said not to bother with higher octane. 95 is fine.

[thinfourth2]

You might get less power as when the octane rating goes up the calorific value goes down.

[The Wookie]

Having raced on both I can confirm there is knob all difference. Only useful if the car has been mapped to run on higher octane fuel, and even then only turbo engines are particularly sensitive

[Epimetheus]

thinfourth2 said:

You might get less power as when the octane rating goes up the calorific value goes down.

Indeed . .. . I heard one of the Graduate racers (1.6 K series) dynoed his car with both fuels and found it was marninally more powerful with UL.

As the standard Caterham 1.6 K ECU doesn't use a knock sensor, I don't see how it take advantage of higher octane fuels without being mapped specifically for them.

[allen l]

I have an 1.8 vvc 160 bhp. I assume I have wasted my money by using 98 all the time?
If it does absolutely nothing, not even on fuel consumption, I'll opt for 95 from now on...

[Finchy172]

Branded fuels such as V-Power and BP Ultimate certainly reduce the Exhaust gas temps, increase MPG and have a marginal 1% MAX increase in power.

For me i run V-Power in my road car as i can collect more air miles, generally get 30-40 more miles per tank than supermarket stuff and the idle and part throttle on my turbo megane is much nicer to drive.

[Spingo]

I own 3 cars, two of which I run on either Shell Vpower or Tesco 99 octane from time to time.

My Caterham (a 1.4 Supersport) seems to run smoother on the higher octane brew compared with 95 but with probably only a marginal increase in power - hardly noticeable really.

My other car - a Skoda Octavia VRS loves the higher brew fuel - much smoother and eager to accelerate. In fact when I use 95 in it, it feels a bit strangled.

Edited by Spingo on Wednesday 1st July 15:31

[BadgerBill]

my 1.4 supersport definately runs better on the v-power stuff. Especially noticeable on motorways in 5th, it pulls much cleaner and stonger. Also when the revs get up around the 7k+ in teh lowers gears it seems to get through the last few 100 rpm just that bit quicker. Perhaps it's a placebo effect, but as I'm not a big tart and don't thrash the legs off teh car most of the time, it lives off shell std stuff, but if I know that I am out on a run for pleasure rather than a commute, I'll bob a tank of v-power in.

BB