RE: Tesco launches high octane fuel

[nisman]

This is 95% petrol, 5% bioethanol. See what's been done at le Mans and BTCC with 95% bioethanol in Energy Efficient Motor Sport at www.eemsonline.co.uk/

[redvanman1964]

I've been running my ZS 180 on this since August and the car is much smoother at low revs around the town.

[Tripps]

Good to see that on a performance car (the Scooby) that the horsepower and torque gains in percentage terms outweighed the higher price of the Optimax - I'll be sticking to that from now on, as my car has never got on with any 97 fuels too well.

Mind you '95 is louder on the overrun I find

Just a shame they didn't include Tesco's 99 octan stuff - hopefully EVO will though.

[aceparts_com]

I can leave my house and go left to Tesco's and pay 96p for unleaded or go right and pay the same for Optimax.

[vixpy1]

One of my mappers stuck this in a rally car running a race fuel map and there was no knock.

Its good stuff, plus cheaper than optimax round here

[lap_time]

Japan have been using 100-octane fuel for quite some time now.

[dcb]

lap_time said:

Japan have been using 100-octane fuel for quite some time now.

As have the Germans.

In fact, I was chatting with a petrol station attendant near Nurnberg, and
he says most of the major German chains of petrol stations have
stopped sellimg 98 octane, and now sell 100 octane.

Just as 98 octane gets popular in UK.

[Chris71]

Ok, I'm confused.....

Is the only benefit of a higher octane rating the resistance to auto-igntion?

If so, it strikes me that any car without a knock sensor should see no improvement. Surely you'll have fixed AFR and spark timing for a given engine speed and load based on what the manufacturer or tuner belived was safe. If you've got a closed loop knock sensor then you can advance it to the point where detonation starts to occur, but if not you're stuck with fixed values intended to be safe for that speed and load under all conditions (maybe the ECUs have an open-loop knock strategy which adapts for coolant temperature, MAP etc, but this still would have to have a 'safety factor' to guarantee stable combustion, unless you've got a knock sensor of some description)

If you've got a very high (geometric) compression ratio or forced induction it might be that your car is better off running with higher octane fuel, but again without a knock sensor, the car cannot adapt to it. Maybe the answer is that more modern cars have knock sensors than I thought (a far cry from my carburettor/distributor 80s lump!). Or maybe the fuels have other performance benefits (greater calorific value, better atomisation)?

[pallison]

I watched Fifth Gear last night - with the comparison of different petrol brands. The used 3 cars and 3 types of petrol...

Cars: Renault Clio (1.2/1.4?)
Golf GTI (2.0 Turbo)
Impreza WRX STI

Fuels: Normal Unleaded (95 RON - brand not specified?)
BP Ultimate Unleaded (97 RON)
Shell Optimax (98 RON)

Mearuring BHP figures on a chassis dynamometer (bolted to the 2 or 4 driven hubs) they found the following....

Renault Clio - gave the same bhp on all 3 fuels (82bhp IIRC)

Golf GTI - Shell gave 5bhp more than UL, BP gave 2bhp more than UL.

WRX STI - Shell gave 15bhp more than UL, BP gave 8bhp more than UL.

Finally they tested the torque figures of the WRX. Shell was 15 Nm(IIRC) ahead of BP, which was a minor increase over normal.

Their conclusion was that higher RON fuels are only worth the money if your car can adapt to it (knock sensors etc). Probably only worth it for high performance cars - economy cars better sticking to normal UL.

NOTE: I had a 2 year old jumping on me for half the programme - so my figures will not be 100% exact - but good enough for comparison!





>> Edited by pallison on Tuesday 15th November 12:41

[pallison]

<Removed duplicate post - original post above was added OK>


>> Edited by pallison on Tuesday 15th November 17:48

[cyrus1971]

" The conclusion you’d have to draw is that a high performance car will experience less improvement using Tesco 99 "

... is the opposite of what 5th Gear said last night !

Personally I like this stuff in my 996TT.

C

[Nuggs]

Hmmmm... seems the PH test was about as unscientific as they come - 'we thrashed four (non-identical) cars around a track with no measuring devices and came to a conclusion'...

The 5th Gear test last night was interesting (and a bit more scientific), shame it didn't include Tesco 99 in the comparison.

Does the Tesco stuff have engine-cleaning properties as claimed by Optimax (and proved to some degree in an evo test some time ago)?

[dieseljohn]

Nuggs said:

Does the Tesco stuff have engine-cleaning properties as claimed by Optimax (and proved to some degree in an evo test some time ago)?

This is what I want to know as well.

[moose1978]

Dam blast those Southeners who get all the good stuff first!!

When do all us Northeners get it!!! (please deliver to Barnsley first ;-)

[Nuggs]

dieseljohn said:

Nuggs said: Does the Tesco stuff have engine-cleaning properties as claimed by Optimax (and proved to some degree in an evo test some time ago)? This is what I want to know as well.

Anyone???

[pallison]

I can't get to a phone just now, but I'm sure the Tesco press office will be able to give more details on the 99 RON fuel.

Their telephone number is 01992 644 645. I got it from the following petrol press release (about 99 RON and bioethanol)

www.tescocorporate.com/page.aspx?pointerid=6CAE6067F10C4171B40512BC9F0454E8

[bjwoods]

Its cheaper than 95 unleaded at my local texaco, EVEN cheaper if you spend £50 in the shop, you then get an extra 5p/L off. SO 84.9p a liter potentially. My leon likes it as well.

B

[remal]

going to try it and see if its makes any difference in ny s turbo forester.

anyone know of the tesco in bristol that sell it. or will they all soon?

[cptsideways]

Looks like I might be doing some research on this soon, give me a few weeks my car was designed to run on 100 octane fuel & it definately goes better on this stuff. Will wait to see what the figures are.

[dazren]

My local Tesco 99 has recently stopped supplying it.

DAZ