95 vs 99 octane fuel

Also worth noting is tesco 99 has a high methnol rating compared to shell
It's the ethanol content of Tesco Momentum that is higher. Neither fuel contains methanol. Momentum is an e5 fuel (5% ethanol) iirc. :)

On a related note. I dabbled with a 5% methanol mix with V-Power for a while. It certainly made a difference to how the engine behaved. :devil:

Paul
 
when the engine knocks it means the fuel is basically not "explosive" enough for the engine, it's wanting more oooomph from the ignition stroke of the combustion cycle, so the engine starts knocking or pinking.
That's not correct either. The higher the RON value of a fuel, the better its ability to resist igniting. If a car pinks/ knocks the fuel/ air mixture pre ignites before the optimal moment, before the piston is at the top of its compression stroke. This is caused by too much pressure and heat in the combustion chamber and possibly poor quality fuel or lack of fuel (fuel can he used to act as a coolant for the combustion chamber).

Using the high RON/ MON fuel will reduce the risk of this happening as the fuel is more resistant to igniting, meaning greater ignition advance can be used, smoothing out power delivery and increasing power and torque.

Paul
 
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It's the ethanol content of Tesco Momentum that is higher. Neither fuel contains methanol. Momentum is an e5 fuel (5% ethanol) iirc. :)

On a related note. I dabbled with a 5% methanol mix with V-Power for a while. It certainly made a difference to how the engine behaved. :devil:

Paul

Thats what I meant ethanol, lol

Been known to be as high as 6.5 %

All I know is my m3 used to kangroo like a mother with that tesco 99.
 
I always use Shell V Power, the odd times I've put Tesco 99 in the car has felt coarser and done slightly less mpg.
On one of the Saab forums Im on some owners with tuned Saabs put a certain amount of thinners in as well which is supposed to put power up.
 
On one of the Saab forums Im on some owners with tuned Saabs put a certain amount of thinners in as well which is supposed to put power up.
The thinners will contain toluene which is used in off the shelf 'octane' boosters and has a high RON value itself. Using pure methanol is a good and cheaper alternative (60p odd a litre) it's also more readily available with the boom of homebrew bio-diesel. As with all these things though, handling and storage need to be carefully considered.

Paul
 
Still early days, but I can see a small increase in MPGs even after one tank

OyNetBo.jpg
 
That could be anything though!

Slightly warmer temperature, so the car warms up quicker. Might have done more 50/60mph journeys than town stop/start driving. Getting stuck in traffic, less often.

Its going to take a few tanks, over a few weeks, to see if you a real increase in MPG. :smashin:
 
Yes, I know. That's why I said it's still early days, but it is the highest MPG I've seen in this car yet, to date. So I got a bit carried away ;)

As I said earlier, my main reason for going for another tank of Tesco's 99 Momentum, is the 5p off coupon. So what have I done? I was running out of time (busy day yesterday) and petrol, I got to the the petrol station, pour the whole tank, got to the till and.. forgot about the coupon. Bloody typical :facepalm:
 
If you want to say that on low power naturally aspirated cars the difference in power is non existent, than that is exactly what I have ;) 1.6 petrol car with just 105 BHP.

Edit: it's a Mazda 3 Sport 1.6 petrol 2009 (1st generation) hatchback

Also it says on my filler cap "min 95 octane", so I take it means the higher the better

EDIT2: I just checked my manual and the tank cap and it says on both "Unleaded premium fuel, 95 octane or above"

I have the Mazda 3 Skyactive which is naturally aspirated.
So Are you saying 99 Ron won't benefit me?

Edit...
Oops, just realized this thread is old lol
 
I have the Mazda 3 Skyactive which is naturally aspirated.
So Are you saying 99 Ron won't benefit me?

Edit...
Oops, just realized this thread is old lol
Yes, that is an old thread :)

How big is your engine? I have used 99 ron for quite a few months non stop, and then went back to 95 which I'm still on. I can say pretty confidently that I have not noticed any difference. Not in power, not in MPG, nothing.
 
[rian=, post: 24757989, member: 203756"]Yes, that is an old thread :)

How big is your engine? I have used 99 ron for quite a few months non stop, and then went back to 95 which I'm still on. I can say pretty confidently that I have not noticed any difference. Not in power, not in MPG, nothing.[/QUOTE]
Thanks for the reply.
My engine is 2 litre
Must admit, I did try V Power in my previous 2litre (turbo) and didn't really notice any improvement.
I think it's probably phscological with most :D
 

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