My Exige is 190 upgrade with the cat replacement pipe. I have noticed on the track that Optimax gives better performance than other grades of Super Unleaded and unless I am cracking up gets better (lower) readings on sound tests particularly Goodwood where I am over the 98db limit.
Question is can I get even more benefit by running on 4 Star as I have no cat or does this muck something else up?
Hi FarnhamFox,
Stick to Optimax or super un-leaded if you can’t get Optimax. Your engine will not like being run on 4 Star, (internal components will suffer if you run leaded petrol,
Steve.
I could be wrong … but I always understood that super unleaded had a higher octane than normal 4 star anyhow …
I always use Optimax and also add a little octane booster , the octane booster may be a placebo as I’m told it will not work so well with current fuels ( toluene is better ) and yes I know the K series cannot give any performance advantage from it - but it does mean that your engine is less prone to detination.
Equally having a good cold air supply to the engine ( air intake to vent ) will have a larger effect as you get denser air …
Optimax every time IMHO
I have experimented with octane boosters, but the best bet is to get your engine management sorted - e.g. Emerald
Optimax here.
I don’t really notice any extra power with any fuel. I notice though that Optimax makes it run freeer and avoids pinking.
BP super unleaded if not.
Uldis
Farnham Fox,
Hello from another Farnham based exige nut.
Is yours the yellow one that I only ever see when I’m out in the company hack ?
I’m with the other guys. Optimax every time. The car just seems to pick up and rev so much better with it.
Con McL
Hi FarnhamFox,
Stick to Optimax or super un-leaded if you can’t get Optimax. Your engine will not like being run on 4 Star, (internal components will suffer if you run leaded petrol,
Steve.
Ponit of order…
Lead has no detrimental effects on the engine whatsoever, it’s the Cat that will not stand it (and before somebody starts on about the Lambda sensor, you would need a shed load of lead to harm that ALA. 1960 levels).
4* at 99.9% of pumps these days is NOT Leaded, it’s LRP which is basically super UL with some added potasium (at a VERY low level). it’s often cheaper than SUL for some daft reason, it’s octane rating is 97, (as was 4*).
Optimax is just SUL but at 98+ octane (as it what it used to be before 1st Oct 2000 when BS7800 specified 98 as the min for SUL).
That’s what I meant to say…