95 vs 98 Octane

[DrYazz]

Can a chemical engineer explain what the benefits of feeding a car with 98 rated petrol over normal 95 is?
Are there genuine and noticeable performance gains with the 98 stuff?

[SoapyShowerBoy]

Why don't you give them 5 mins to answer your other thread! 3posts, 2 threads and 1 willy wave!

[krallicious]

SoapyShowerBoy said:

Why don't you give them 5 mins to answer your other thread! 3posts, 2 threads and 1 willy wave!

Use the search fuction. This topic creeps up fairly often

[300bhp/ton]

DrYazz said:

Can a chemical engineer explain what the benefits of feeding a car with 98 rated petrol over normal 95 is?
Are there genuine and noticeable performance gains with the 98 stuff?

octane is a rating of combustibility (or so I'm told) the higher octane fuel contains more potential energy. This allows you to run more aggressive tunes and with turbo cars more boost and make more power.

With many modern cars with "knock sensors" the ECU can automatically run a more aggressive tune (to a limit) on the higher octane fuel. Gains maybe minimal though and turbo cars see the best results.

[Orangecurry]

300bhp/ton said:

DrYazz said:

Can a chemical engineer explain what the benefits of feeding a car with 98 rated petrol over normal 95 is?
Are there genuine and noticeable performance gains with the 98 stuff?

octane is a rating of combustibility (or so I'm told) the higher octane fuel contains more potential energy.

No no no.

Octane rating does not relate to the energy content of the fuel. It is only a measure of the fuel's tendency to burn rather than explode.

Hang on I'll find a decent website....

[Orangecurry]

Decent websites are thin on the ground.

But here's some bedtime reading.

http://www.rxp.com/Octane.htm

[GravelBen]

DrYazz said:

Are there genuine and noticeable performance gains with the 98 stuff?

Depends on the car but with turbos most definitely - I notice 10-15% better fuel economy on 98 as well as significantly more power.

[Coq au Vin]

This bloke explains everything quite well:

http://www.fuelsaving.info/fuels.htm

[Jimbeaux]

It is nice not to have to be re-explaining how U.S. octane ratings are equivelent to European ones even though the numbers are different. I suppose folks are finally over that one.

[Orangecurry]

Coq au Vin said:

This bloke explains everything quite well:

http://www.fuelsaving.info/fuels.htm

Quite well, but in the UK (and most other countries) RON 98 and RON 95 start off as EXACTLY the same fuel, and have EXACTLY the same amount of energy; the increase in octane rating is achieved by chemical additives, usually added at the distribution depots.

[JJCW]

Member since yesterday and how many threads? Use the search function ffs.

[blueg33]

GravelBen said:

DrYazz said:

Are there genuine and noticeable performance gains with the 98 stuff?

Depends on the car but with turbos most definitely - I notice 10-15% better fuel economy on 98 as well as significantly more power.

It allowed me to advance the ignition timing on the G33 which was worth 2bhp on the rollers.

[ChapppeRS]

I'd like to think my Focus RS runs better on V-Power than normal shell, but since i'm too chicken to try anything else, I can't prove it. It specifically says "97+" on the fuel cap, so i'd like to think there's a reason for it.

Does anyone know if normal shell is 95 or 97 ron? I'm assuming it's 95.

[leon_t]

Orangecurry said:

Coq au Vin said:

This bloke explains everything quite well:

http://www.fuelsaving.info/fuels.htm

Quite well, but in the UK (and most other countries) RON 98 and RON 95 start off as EXACTLY the same fuel, and have EXACTLY the same amount of energy; the increase in octane rating is achieved by chemical additives, usually added at the distribution depots.

Usually, but not always, as we blend 95 and 98 differently at the refinery I work at.

[Orangecurry]

leon_t said:

Orangecurry said:

Coq au Vin said:

This bloke explains everything quite well:

http://www.fuelsaving.info/fuels.htm

Quite well, but in the UK (and most other countries) RON 98 and RON 95 start off as EXACTLY the same fuel, and have EXACTLY the same amount of energy; the increase in octane rating is achieved by chemical additives, usually added at the distribution depots.

Usually, but not always, as we blend 95 and 98 differently at the refinery I work at.

Who's that then? And could you explain why? (genuine question)

[stigmundfreud]

I sell octane boosters, red power bands and magic beans. Let me cut you a deal on some snake oil

[off_again]

According to the manufacturer, my car shouldnt get any more MPG on 98 vs 95. It does, but its only a small amount, say 2-3MPG over a full tank. Its something, but there is a difference. Better than having to run a car on 98 only, can't always get it!

[youngsyr]

Orangecurry said:

leon_t said:

Orangecurry said:

Coq au Vin said:

This bloke explains everything quite well:

http://www.fuelsaving.info/fuels.htm

Quite well, but in the UK (and most other countries) RON 98 and RON 95 start off as EXACTLY the same fuel, and have EXACTLY the same amount of energy; the increase in octane rating is achieved by chemical additives, usually added at the distribution depots.

Usually, but not always, as we blend 95 and 98 differently at the refinery I work at.

Who's that then? And could you explain why? (genuine question)

Interesting, I understand that Tesco 99 Ron is an (ethanol?) blended fuel, but I thought V-Power was just a higher octane gasoline fuel?

Can anyone explain the difference in make-up of these two fuels in particular?

[The Wookie]

DrYazz said:

Can a chemical engineer explain what the benefits of feeding a car with 98 rated petrol over normal 95 is?
Are there genuine and noticeable performance gains with the 98 stuff?

No performance gains if your car isn't set up for it. If your car IS set up for it, then depending on the engine you either lose performance and/or risk damaging the engine.

As said there is no worthwhile difference in energy content, it is purely based on the way it allows the engine to ignite the fuel, and thus the efficiency of combustion. Long story short, lower octane fuel must be ignited later in the cycle, which means more of the energy is wasted as heat in the exhaust, and less of it goes into driving the piston.

[Orangecurry]

youngsyr said:

Orangecurry said:

leon_t said:

Orangecurry said:

Coq au Vin said:

This bloke explains everything quite well:

http://www.fuelsaving.info/fuels.htm

Quite well, but in the UK (and most other countries) RON 98 and RON 95 start off as EXACTLY the same fuel, and have EXACTLY the same amount of energy; the increase in octane rating is achieved by chemical additives, usually added at the distribution depots.

Usually, but not always, as we blend 95 and 98 differently at the refinery I work at.

Who's that then? And could you explain why? (genuine question)

Interesting, I understand that Tesco 99 Ron is an (ethanol?) blended fuel, but I thought V-Power was just a higher octane gasoline fuel?

Can anyone explain the difference in make-up of these two fuels in particular?

Tescos99 comes from Greenergy who get it from europe - we were talking about 'normal' 98 don't forget

Tescos99 has 5% bioethanol
http://www.greenergy.com/tesco_99_octane/FAQs.html

V-power - who knows, Shell seem to want to keep it secret
http://www.shell.co.uk/home/content/gbr/products_s...

ETA I found this - this implies that ordinary v-power does NOT have any (bio)ethanol

wikipedia about v-power said:

The higher the Octane rating, the more the fuel resists premature ignition (see petrol for more detail). V-Power also contains higher concentrations of detergents and other additives to clean the engine and smooth its operation. In Australia, the previously obtainable higher grade V-Power Racing which contained 5% ethanol to boost V-Power's octane rating to 100 RON has now been phased out by Shell due to a "changing market".

Edited by Orangecurry on Tuesday 12th May 11:43