Scottish Elises

my car had been running a bit rich lately and is fouling the plugs, i've been running standard unleaded petrol and i'm thinking this was a mistake! so....

ninja

Can we have the option for Std non supermarket petrol with one in 5 optimax ?

I voted optimax, purely 'cos my car is mapped for it (reprogrammable ECU)

There is NO power benefit (won't run leaner, or richer, that's not what octane refers to) with a standard engine as it doesn't have a knock sensor to account for octane levels. There is some argument about it's detergent additives, however, and some cars can pink a bit as standard ('cos there's probably something else the matter) Optimax will cover that up.

I go standard(but never supermarket), and about 1 in 3 is optimax.

My car is mapped for standard 95 octane unleaded, so it doesn't matter what I use - I may as well use the cheapest petrol I can find, which is what I do.

Simon

Shug wrote:I voted optimax, purely 'cos my car is mapped for it (reprogrammable ECU)

There is NO power benefit (won't run leaner, or richer, that's not what octane refers to) with a standard engine as it doesn't have a knock sensor to account for octane levels. There is some argument about it's detergent additives, however, and some cars can pink a bit as standard ('cos there's probably something else the matter) Optimax will cover that up.

pink?

can you explain for the hard of thinking please.

ninja

petrolprices.com's cheapest is what goes in my tank (although nothing went in last night as Mac, Sanj & tom will tell you )

After reading Evo this month, I'll be putting some optimax in purely for the cleaning additives.

Be worth having a poll to say manually added cleaner or stump up for a tank of opti.

ninja wrote:

Shug wrote:I voted optimax, purely 'cos my car is mapped for it (reprogrammable ECU)

There is NO power benefit (won't run leaner, or richer, that's not what octane refers to) with a standard engine as it doesn't have a knock sensor to account for octane levels. There is some argument about it's detergent additives, however, and some cars can pink a bit as standard ('cos there's probably something else the matter) Optimax will cover that up.

pink?

can you explain for the hard of thinking please.

ninja

The short explanation is that the ignition timing is out (too advanced) and you'll hear a tinkling sort of sound from the engine. Sometimes more prone to happen when it's hot.

Basically the spark is being fired slightly early for the octane of fuel (this is what octane refers to - resistance to pre-ignition & detonation, the extereme form of pinking) The sound is a resonance from that pressure wave being in the wrong place (not the piston rattling, as some would say!)

Shouldn't happen in a standard engine (and can be difficult to spot, unless you know what you're listening for) but it can, if it's very hot, or the fuel is a bit crappy - that's even if the timing is spot on for normal running.

Not fatal in itself, but saps a little power and is not great for the engine to be constantly doing it.

More fatal forms are Knock (as in knock sensor) which sounds like a more pronounced rattle and detonation, which will kill the engine very, very quickly....

I use petrol. Whatever is nearest when I run out.

It's a rover FFS. It doesn't care.

If I'm feeling flush (Which is fairly rare) I might go for a tank of ultimate/optimax, I was going to yesterday but it was £1.04/lire and my Yorkshire heritage caused me to twitch to the cheaper stuff. Still 98.8 robbing barstewards.

I'm with Rich, and as shug says no knock sensor so no point in the K engined cars - maybe once every so often for its cleaning properties. What did Evo say Greg?

The_Rossatron wrote:I'm with Rich, and as shug says no knock sensor so no point in the K engined cars - maybe once every so often for its cleaning properties. What did Evo say Greg?

IIRC it was a very informative advertising piece

Then again 99% of the content of Evo could be accused of that. I just look at the pretty pictures

"The short explanation is that the ignition timing is out (too advanced) and you'll hear a tinkling sort of sound from the engine. Sometimes more prone to happen when it's hot. "

I was trying to find a rattle on my engine yesterday when I started it from cold . Sounded like two bits of metal rubbing together. Took it out for a short run and when I got back it had gone. If it was pinking would it be more prone to do it at start up as they mixture is richer ?

tenkfeet wrote:"The short explanation is that the ignition timing is out (too advanced) and you'll hear a tinkling sort of sound from the engine. Sometimes more prone to happen when it's hot. "

I was trying to find a rattle on my engine yesterday when I started it from cold . Sounded like two bits of metal rubbing together. Took it out for a short run and when I got back it had gone. If it was pinking would it be more prone to do it at start up as they mixture is richer ?

Erm, IIRC no - it's more likely to pink when leaner... Pretty sure that was my personal findings when tw@tting about with mine.... Leaner mixture burns quicker than richer one, as there's more oxygen. Please someone tell me I'm talking pish, if I am!

The rattle was probably just a dry tappet - as soon as the oil had thinned and filled it, it would quieten down.

Won't be long before that tescos 100 octane stuff spreads north. All the novas and corsas will be running on it as it's dead good. Got bigger numbers so it must be good and the BP Ultimate stand at goodwood said I could get 30 more miles to a tank, the exhust is friedly to Wales and Whales and fluffy bunnies and I'd gain up 50 bhp*

















*if you rebuild and remap your engine specificaly for this. Accuracy cannot be guaranteed and is +/- 60 bhp....