unleaded or v power

i use v power, but the cars meant to run on 98 ron min.
i find that it runs badly and feels more laggy - unresponsive. ive also eun diagnositc after running on both standard unleaded and v power. difference was around 10bhp and 12 ftlb. but like i said its supposed to be run on it as a minimum.
cost wise your only looking at £2.50 a tank bsed on 50ltr ( 11 gallon )

its good stuff to use a couple of weeks before an MOT and give it a good blasts when its warmed up
 
think it helps when your booting it, as in when i said getting it ready for MOTs. wouldnt believe everything they say.
driving it hard occasionally - WHEN WARMED UP - will keep the injectors cleared
 
Only really worth running if your car has a knock sensor (dont know if the clio rsi does or not?) , if its a jap import or if you are running high compression ratios.

If your car doesnt have a knock sensor it cant adjust timing to suit and you wont see any more power/better fuel economy
 
The higher octane rating only means its more resistant to detonation...something you get with too much ignition advance or too high a compression ratio...on a standard engine you will get neither of these things...but if your car has a knock sensor the ecu will advance the timing for more power
 
higher octane petrol is not necessarily beneficial unless your car is set up to use the stuff. However, such fuels will nearly always have better detergent packs than std fuel. Supermarket fuels, which are a lot better than they were in the early 1990s when such filling stations started to appear, are still generally at the lower end of the quality spectrum

Using 99RON fuel in a car that only requires 95 RON is largely pointless. Apart from, and this is the biggie, it's likely to have a better additive package.

You can fill a car that demands 98 RON fuel with 95 RON fuel and it will still work.

The knock sensing is pot by pot in most 4 cyl petrols so you won't damage the car, but the performance will be compromised.

Much as the supermarkets have cleaned up their image with car fuel, it's possibly still better to source the stuff from the likes of BP, Esso, etc.

And do you really want to eat supermarket meat anyway, card points or not?

I choose to not do so.
 
i heard a rumour, not sure if its true or not, that some investigation had been made into the likes of shell and their supposed claims on superunleaded fuels but the findings were (as they are allowed tolerances on the actual rating according to standards) that sometimes their is very little difference in the RON value despite what is written on the pump. Previously my brother had a Jap spec Scooby RA and as well as Superunleaded he had to put in additional something or other everytime he filled up. An extra gbp5 a shot. Bloody expensive but it need this.
 
I've been to a fair few Subaru specialists and they recommend using Shell V-Power for Impreza's. Scooby clinic swear by this and I won't argue with them seeing as they use it in all their TOTB cars.
I don't use super in the focus cause it's just not worth the extra money. I did try it and found no difference whatsoever in performance so I just use normal fuel.
 
Munday said:
...but if your car has a knock sensor the ecu will advance the timing for more power
Click to expand...

Nah, not correct.

Most PCM's or ECM's on modern (OBD-2) cars that have Knock Sensors fitted have both a High and a Low Octane Table. These cannot be adjusted without the proper software tuning package.
These cars also (mainstream production) usually have just one or two knock sensors on the cylinder block. Only particular high end of the market (read expensive) cars have individual KR control to each cylinder, such as the BMW M-Division, high output turbo-charged cars, etc.

All of these cars regardless, are capable of running 91 RON ULP. The ECM/PCM simply senses KR events because of the lower octane rating and retards the timing towards the Low Octane Table.
If KR events are regular enough it will adjust fully to the Low Octane Table either until all events stop and no KR is detected in a certain period or the tank is filled with better fuel. It will then re-adjust back towards the HOT as long as there is no further KR.

Cheaper fuels have higher sulphur content, not good for clean running and can cause carbon build-up.

If a car is validated to run on 98 RON it will still run safely on 95 or even 91. It just won't make the advertised power output. As the timing will be scaled below the High Octane table values.

Conversely running higher octane fuel than the car is actually mapped for will do squat for any power increase as the High Octane Table is set at the factory and KR control only retards timing from the HOT it cannot advance it to a value above it.

http://www.powerchipgroup.com/articles/PET0605.pdf
 
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v power is better you can easily feel the difference especially with the subarus.
 
I only use V-Power or BP Ultimate. I definitely feel the difference on the throttle. It also seems to last longer than regular as well. I will never use supermarket fuel unless I am desperate... it's poor quality and runs straight through my tank.
 
I pretty much alawys use V-Power if I can get hold of it. My car was supposed to run on 98RON from factory. With a remap and exhaust, 95 is starting to push my luck a little.
 
You certainly won't get the best from it on 95 RON.

I've not tried V Power unleaded petrol as I don't have a suitable car to put it in.

I used to rate Optimax, which was Shell's earlier high octane fuel.

I'm not overly fond of V-Power diesel, preferring BP Ultimate diesel over it.
 
HDi fun said:
You certainly won't get the best from it on 95 RON.

I've not tried V Power unleaded petrol as I don't have a suitable car to put it in.

I used to rate Optimax, which was Shell's earlier high octane fuel.

I'm not overly fond of V-Power diesel, preferring BP Ultimate diesel over it.
Click to expand...

My FreeLander Td4 (has been remapped) turned into a smoke machine on V-Power Diesel. I'm back to cheap-crap - it seems to like it.
 
It's funny how different engines prefer different fuels. Mine hates basic diesel with the remap but it's no happier on V Power. But Ultimate sees it happy.
 
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