garyevs

Active Member
Aug 28, 2015
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I had my new Cupra yesterday, it is awesome and I love the DSG.

Just wondering if there is a noticeable difference in performance between the 95 octane fuel and the 98, and is the Momentum fuel any good ?


Cheers
 
I had my new Cupra yesterday, it is awesome and I love the DSG.

Just wondering if there is a noticeable difference in performance between the 95 octane fuel and the 98, and is the Momentum fuel any good ?


Cheers

95RON is ok but will not be best. Generally you should be running it on 99RON Shell V Power or Tesco Momentum.


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Momentum is decent and probably the cheapest of the supermarket fuels.

on a car such as a cupra you will want to run it on premium fuels will get the most performance out of the engine, more so if you remap it
 
On my MK2 Cupra R I only filled up using V-Power 99 ron and kept the receipts to prove it when I sold it on lol I don't have Tesco Momentum near me otherwise I would of probably used that.

I think the main difference between the 95/97 ron and 99 is 99 has extra ethanol in it I think for better performance but I may be completely wrong haha
 
I had a golf R which said minimum 98 RON. Now I have the cupra it says 98 RON, but minimum 95. Suggesting you can run it on 95 if you want. I've been using momentum entirely for 2+ years now. You may not notice the extra performance or mpg figures, but it's better for the car. It's only if you go stage1+ where you actually need to run on 99. But for the extra cost of momentum (maybe 6-8p/litre), I do it. If you buy a performance car, seems only logical to try and get the best out of it.
 
I used to use V power 99 Regularly but now I use momentum 99 it’s weird but I get louder pops and bangs when using it so stuck with it. Maybe every 4th fill I put some V power in agains to add some of its additives in.
 
If your fuel cap says 98/99 RON, then the engine is designed to run on that. If it says you can use 95, it will run on 95 but retard ignition timing accordingly (and therefore power). It's mainly a get out of jail when your stuck in a traffic jam South of Devon, 330 miles from home with 1/4 of a tank of fuel and only Jonas Brothers petrol and tomatoes available (ask me how I know).
 
Run the car on 95 if you like but you may have well purchased a slower car because that's what your going to get by doing so. As said before lower octane fuel will induce knock and timing retard.
 
I never understood why it says 98RON for UK markets when 98 RON is not avaliable. I know in countries where the best fuel is 95RON, it only says 95 RON and possibly tuned accordingly. I would say pump Vpower 99 or Momentum 99. Else Esso/Texaco/BP 97RON. Seeing that in most cases Vpower 99 is not that much difference price than Esso or BP, just pump Vpower. My personal experience in a non Cupra, was that Vpower gave best mpg, Esso 97 gave the smoothest engine, Momentum 99 gave me nothing that I could discern except a cheaper price. Had only a 1.0TSI though...so no discernable power gains!
 
Up to you but some info so you're better informed:

The best way to explain RON isn't how powerful the petrol is, it doesn't produce a bigger bang. Its better to understand it as how 'stable' it is. So higher RON, higher stability. F1 cars will run on 100+ RON with other additives.

So the more stable the fuel, the more the engine can be pushed.

If you put crap (lower RON) fuel in the engine, then there is more chance of detonation or pre-ignition, the fuel igniting too soon.

Imagine as your piston is being forced up, the petrol ignites and the force is trying to push the piston down. This happens because the fuel has ignited off of the hotter parts of the engine, instead of the spark of the plug.

At worst this can involve in broken piston and engine blocks.

When the ECU detects this, it can do a number of things. Adjust the ignition, reducing power, and (believe it or not) stick extra fuel in to cool it down. Although there is more fuel there is still only a certain amount of oxygen that can be used to burn it.

So crap fuel in an engine tuned for a higher RON will be less economical AND less powerful.

Now the ECU on the Golf R/Cupra is designed to fit the Irish market as well, where 98+ just isn't available. So it will run on 95, but at a reduced power. I'm happy to be told otherwise, but from memory a Cupra 290 runs closer to 265-270.
 
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Many (many) years ago my wife worked in a garage that had Esso pumps, the boss asked why I didn’t buy my fuel there, I explained I could buy supermarket fuel cheaper, he explained that whilst all fuels were advertised all fuels were sold as the rating on the pump supermarket fuel would be say 95 ron the Esso fuel would be minimum 95 ron a s usually a couple of points higher. He also put me on staff fuel rates, that convinced me haha.
 
Also really depends what your using the car for, if your literally pottering about in it 95 isn't going to do any harm as long as use 99/fuel additives every now and again. if your driving it hard all the time it needs 99.
 
As previously stated RON (Research Octane Number) is the amount of pressure the fuel vapour can withstand before exploding without the need for a spark. 99 RON can be squeezed more than 95 RON. If 95 is used in an engine designed for higher RON values the risk is that under full load (lots of boost and piston compression) the fuel will ignite before the spark. Should this happen say on the upward stroke of the piston your in trouble.
Luckily were not driving 1990 massive turbo supras and r34 skylines, were driving modern cars with knock sensors. A knock is when the fuel ignites before the spark and the knock sensor detects these very quickly. The ECU will aim to eliminate knock but retarding timing, making the fuel mixture leaner to cool the mixture,and lower boost.

This is all happening so fast you wouldn't even detect it the only result to the end user is a lack of power.

Now 99 Vpower or momentum is another discussion but they should be similar on performance.

Don't use 95 unless you have to and if you do don't drive aggressively.