Shell Optimax or BP Ultimate???

[Tom]

It does have a slightly higher calorific value.

You don't need a knock sensor for an engine to use a certain grade of fuel.

And yes, the bravo/a/mareas have knock sensors. But this does not mean they can run to optimum on higher octane fuel. The knock sensor is there for a much more boring reason.

 

[Buzz]

BP Ultimate is 97 ron (as is sainsburys super)
Shell Optimax is 98 ron, and probably cheaper too.
thats why Shell wins for me
i dont care what any of you who 'know' say, my car, a naturally aspirated 1.8 prefers optimax to regular unleaded...

Buzz (formerly LightWarrior)
The champion of the Bravo 1.4
Owner of the Bravo 1.8
Member Page

 

[Steve]

OK, didn't know about the knock sensor. Doesn't seem much point in it considering the ECU pretty much optimised to run on standard unleaded.

I suppose it would have it's uses if you went to eastern Europe and were running on some of the crap they call petrol over there.

The calorific content increase is so minimal it can be discounted.

In summary - total waste of time in a Bravo/a/Marea, although the placebo effect may fool some into thinking there's a difference.

 

[Tom]

Its going to make very little difference in ANY car setup to run 95. The knock sensor is purely there to take into account minor variations in fuel quality, fuel temperature, air temp, engine temp etc..

If you want to make a car perform best on super UL then raise the CR to 12:1 or even 13:1 and tweak the ignition forward a good few degrees. Just never ever run it on normal fuel, even with a knock sensor. (as they only work at low revs)

 

[RR]

I can only speak as I find - I ran my 145 1.8 on Optimax for a year or so, without fail. It nearly ran dry (my own fault) and I filled it up with "ordinary" Fina - none supermarket before you ask. The difference was huge - it felt like my handbrake was on. Back to Optimax and there was teh added zap back again.

Cant say that I have noticed in the difference in either 145 Cloverleaf or the 147 1.6, but in mt Focus 172 it makes quite a difference in terms of acceleration.

No doubt different vehicle owners from with different manufactureres have different opinions and experience?

 

[Danny]

I had my Dastek Unichip fitted and tuned with a full tank of Optimax, if I dare put 95 Ron unleaded in her now she doesnt want to go at all! BP makes it alot better but as soon as I stick in a few quids worth of Optimax she flys again...big difference in my opinion...1.8 HLX.

 

[Dan]

my car does run slightly better on higher octane fuel just like nige and andy said, after I had my remap done

Dan

Skate2create/D-Unit: Angeltuned Fiat Bravo 1.2 16v......LostInMyOwnWorld......

 

[Tommy L]

Would u have to empty your fuel tank completely before filling up with optimax? Or just let it run low and then refill with the good stuff?

 

[Anonymous]

to all you turkeys who say there aint no difference shut up and dont buy it cuz we that do know there is a difference in performance ie accelleration/ top speed.

Amen/End of!!!!

 

[Tom]

English?

 

[Anonymous]

ok i need something explaining

wont the ecu counter act the higher ron fuel, in the same way the ecu counter acts the ebay resistor. thus the performance would be noticable for a little while but once it has learnt it would run like it did on normal fuel. then when u put normal fuel in it feels underpowered? and if the ecu doesnt learn. then y does an ecu reset do anything cos its only gonna go back to the settings it was before the reset?

thats how i see it i think im wrong tho

Smee

http://www.visionstyling.co.uk for ALL your car needs!!!

 

[Tom]

The ECU won't/can't advance the timing enough to make use of the higher RON fuel. If it was constantly trying to advance the timing just incase you had filled up with super the engine would not last very long.

 

[Stu R]

Have not got a clue what you have just said Smee???

@Tom - Does using this fuel make any difference in

i) Performance
ii) Fuel Economy
iii) Throttle Response

If yes is the effect perminent???

Can you make it simple answers please Tom because this thread is getting really confusing now.

"Old enough to know better, Young enough not to care"

 

[Anonymous]

Whilst I agree with the general consensus on the
superior quality of Shell Optimax, Shell don't acually guarantee that it will be 98 octane. Apparently it goes off quite quickly, 2-3 weeks if left in the tank.
BP on the other hand reportedly guarantees it's Ultimate at 98 octane, hence the price. I think Evo car did a little test not long ago. Not a fan of BP a)too expensive and b)never rated their fuel.

Shell diesel seems to be far better then rival brands for power and miles per tank.

 

[Tom]

i) Performance
Tiny
ii) Fuel Economy
Tiny
iii) Throttle Response
Tiny

Super UL is sometimes a better grade of fuel than normal stuff and burns a bit better, this is why people say their engine runs smoother.

If you build an engine specifically to run super UL you could expect to gain 10-15% power or more over the same engine built for normal fuel.

You may get a couple of % by using super in a normal engine.

 

[Stu R]

I new the increase wouldnt be massive but in your opinion Tom, do you it would be worth paying the extra money to put in my HGT.

What would/do you put in your car???

"Old enough to know better, Young enough not to care"

 

[Tom]

I run normal UL Engine is as sweet as a nut after 100k miles.

 

[JOSH aka Wonderinglad]

i used to use optimax a lot but it reached £1.03 a litre down here in oxford way at one point so give up.

the biggest reason the higher ron petrol was brought over is becasue of import/Jap company cars. Japan's fuel is standard 98ron commpared to our 95ron and as was said earlier about TVR's being built around the fuel as such so are nearly all JAP models.

Sorry just my bit of info...

 

[SteveH]

If you build an engine specifically to run super UL you could expect to gain 10-15% power or more over the same engine built for normal fuel.


Are you one of these people who believes an Ecotek gives you '10 percent across the range'?

If you really could get that much of a boost from a small increase in octane, don't you think everyone would do it?

 

[Anonymous]

the point i think he's trying to make is..

if you build an engine with a CR of 12:1 against our 10ish:1 the engine is far more prone to pre-ignition,
so it needs an higher octane fuel which is more resistant to pre-ignition.

even then, i think the power increase comes from the higher CR instead of the fuel octane.

could be wrong