stupid question - which fuel ?

[arabian]

i have been told only to put super unleaded in. That was until the other day when someone else said i didnt need to.

So, 95, 97 or 99 RON ? or doesnt it really matter ?

[snuffy]

What ever you put in it, just make sure it's not diesel !

[hoyin]

It is all debatable whether it makes that much difference and whether you can really notice it.

I just use super as it cleans the engine.

[JLSELAN]

Extra octane is wasted unless ECU is specifically tuned for it since there is no detonation sensor.

[GC1]

I tend to swap around with fuel depending how much money I've got and where I'm going.Cheap stuff most of the time and long run's gets the BP extra stuff so to put back the additives and clean the injectors abit.Once every 3k I but some millers injector cleaner additive in their also.

[arabian]

thanks guys, should save me a few quid on general running around. The company that sold me the car told me specifically that i should use super, and if i put 95RON in it, the car would seize. I couldnt believe that the extra bits in super would make that much difference except maybe on track days, but didnt want to risk it.

Where has all that sun gone ??? I am due to get my car back from the garage soon and need some dry days !

[JLSELAN]

But just a word of caution--if you do not know exactly what ECU map is in the car you should make an effort to find out before changing the fuel you have been using. Very bad things can happen very quickly if detonation occurs since the ECU has no way of adjusting fuel/spark to compensate.

[AMG Merc]

Lee Noble stated 95RON here.

[2.5bluenob]

In the owners manual it says 95. But your car could have been mapped for 97 by a previous owner.

[hoyin]

JLSELAN said:

But just a word of caution--if you do not know exactly what ECU map is in the car you should make an effort to find out before changing the fuel you have been using. Very bad things can happen very quickly if detonation occurs since the ECU has no way of adjusting fuel/spark to compensate.

So is it bad that I use V-power? If my ecu is unchanged and mapped for 95Ron?

I am not really concerned about performance I just want a clean engine.

[Adrian W]

hoyin said:

JLSELAN said:

But just a word of caution--if you do not know exactly what ECU map is in the car you should make an effort to find out before changing the fuel you have been using. Very bad things can happen very quickly if detonation occurs since the ECU has no way of adjusting fuel/spark to compensate.

So is it bad that I use V-power? If my ecu is unchanged and mapped for 95Ron?

I am not really concerned about performance I just want a clean engine.

It won't do any harm,other than the high detergent content you are just wasting money

[arabian]

somehow i knew there wouldnt be a straightforward answer !!!! I'll ask Dave at jetstream since he's been tinkering with it recently, he'll probably know what the ECU/engine is set up for.

[sundance02]

As long as the car is not pinking in low revs 95 is fine but for the sake of 10p a litre use 97 its cleaner and cheaper in the long run.

Edited by sundance02 on Tuesday 4th May 17:19

[hoyin]

JLSELAN said:

But just a word of caution--if you do not know exactly what ECU map is in the car you should make an effort to find out before changing the fuel you have been using. Very bad things can happen very quickly if detonation occurs since the ECU has no way of adjusting fuel/spark to compensate.

In other more modern cars would ht eECU know and be able to adjust accordingly?

Otherwise is performance only going to be noticeable in a car that has been specifically mapped for 99 RON?

[ThatPhilBrettGuy]

sundance02 said:

As long as the car is not pinking in low revs 95 is fine

For Christs sake don't take that as a good test! Not pinking at low revs doesn't mean that when there's the slightest amount of boost your pistons aren't being melted.

hoyin said:

JLSELAN said:

But just a word of caution--if you do not know exactly what ECU map is in the car you should make an effort to find out before changing the fuel you have been using. Very bad things can happen very quickly if detonation occurs since the ECU has no way of adjusting fuel/spark to compensate.

In other more modern cars would ht eECU know and be able to adjust accordingly?

Otherwise is performance only going to be noticeable in a car that has been specifically mapped for 99 RON?

Some do some don't. Most very high performance engines don't seem to (the Ford GT doesn't have knock sensors because it's really hard to make them work reliably).

There's probably a bit of power to be had mapping for higher RON, but why take the risk? Mine's mapped for 95. I can always get it. The 30bhp or so I'll leave for the convenience of always being able to fill up thanks.

[JLSELAN]

+1--the only reliable test for detonation is under high load--especially in higher gears. For example, going on to full throttle in 4th or 5th while climbing a long hill will tell you right away if you have a detonation problem.

And yes, there is quite a bit of extra power available when the car is tuned for significantly higher octane. You can get unleaded race fuel in this part of the world (at race circuits) with octane up to 110. Boost/timing can be safely increased using that fuel (and appropriate injectors) to produce an extra 75 to 100 BHP.

Edited by JLSELAN on Wednesday 5th May 00:00