I think it goes better, but it`s probably psychological.
I read somewhere in a BMW magazine, that the full engine power of the 315bhp M5 (1989-90 model year) is only generated with no cat and leaded petrol 5 star which is I believe 99ron.
Before you shout me down, remember;
No cat was compulsory in the UK until AFTER 1st Jan 1990, the car was developed before that. Not all countries worldwide require a cat.
A power loss is inevitable with a cat.
99ron 5 star leaded burns smoother than 97ron unleaded.
Leaded petrol is not banned! The UK law states that no more than 0.5% of all petrol sales may be unleaded. There are several petrol stations that sell it, I saw a list somewhere on the web, they all appear to be in the UK midlands. The stuff is sold mainly to classic car owners who can`t take leaded, and rumour had it, to motor manufacturers to produce their figures. Its something like £3 a litre !!
__________________
"Never enter Karussell when on the brakes! I have gone round there on the roof, I know what I'm talking about." ~ Sabine Schmitz
Last edited by IvanDias; 19th October 2001 at 15:31.
Optimax gets my vote.
Was running 97 super unleaded, as std 95 is no good for mine (have tried it but power and response was down, compared to normal), but have recently returned from France, and have been using the Super 98 over there, what a difference it made!!
So now back in the UK, I've started to use Optimax, and the car is so much more responsive, no pinking (which was happening sometimes with the 97 S/UL) and is now a smoother running engine.
(I have a E36 M3 3.0)
AG
Originally posted by IvanDias
[b]
No cat was compulsory in the UK until AFTER 1st Jan 1990, the car was developed before that. Not all countries worldwide require a cat.B]
If your car came with a cat then it is compulsory to have one fitted when it comes to the MOT. You can put a free-flow sports cat on though.
I tried it on my old VW and it only added 10bhp, but robbed about 10lb/ft! Then at a track day the scrutineer told me that even though the compulsory FITTING of them came into force in 1990, if the manufacturer fitted one before then it is still compulsory - unless you happen to have a model from a changeover year where some had the cat and others don't as this confuses them a little.
__________________ "If you're not producing skidmarks you're not trying hard enough"
Cheers Mmm-five I'll get some when I find a Shell garage with some. Just checked out thier web site where they acknowledge it's only produced at one refinary at present.
So, what exactly is Optimax? I don't think we have that in the U.S., but you never know. What are the properties of it? Just higher octane rating? Why not just use a can of octane boost or go get actual racing fuel when you take it to the track? Please help the foreigner understand.
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