A late model car that is tuned to run on ULP , would its performance be better if you filled it up with PULP?
I was speaking to this guy who reckons it would, but I don't believe it would make any difference on it's performance and could make it worse unless the EEC is tweaked to use PULP.
Anyone else agree or disagree?
I've tried to get a definitive answer on this area and there doesn't seem to be a unanimous opinion.
PULP is denser, i.e. more molecules of fuel than ULP in the same volume, so theoretically you get more bang and more power.
But I spoke to Shell technical people about Optimax and they say it doesn't really produce more power (so much for the advertising) but just makes the car more responsive on the throttle, but it doesn't really go any harder.
Originally posted by (\/)ADXF I was reading an article from an old street machine mag where they were saying that higher octane actually gives less power cause it burns slower.
But this is contrary to everything I have ever heard.
 my XF has a knock sensor...i think it was only for ULP efi engines.
In my case it was true. I had a Mustang, rebuild the donk (302W) and it pinged on Super under load due to high compression, ran it on PULP for a test, slightly less pinging, so tried Avgas - ran like shit, is was hard to start and clearly lost power - stopped pinging completely though !!
I ended up running it on roughly 50% Avgas 50% Super and it ran sweet.
Originally posted by EF_Falcon_GuY Ok for cars that have a knock sensor as in EF's onwards running the car on PULP or 98 RON fuel will give the car abit more power as timing will advance as a result of increased RON.
IF however you own a car with no-knock sensor say an XF it would run abit smoother but won't really benefit much.
Have noticed it with my EF, you feel the difference running on PULP compared to normal, whilst in our TBi EB it didn't really feel any different.
I get slight pinging under load/hot days from the EF XR6 using ULP, I have now been running it on PULP (BP Ultimate) for about a month and have not noticed any performance or economy gain, it does run smoother, especially at idle and it pulls away smoother + pinging has gone.
Higher octane of course has a higher flash point (ie harder to set fire to), which allows you to advance the timing and it allows you to run higher compression, this is where the slight power gains can be made. So if you run a standard donk, it can potentially reduce power - see the post in this thread about my 'Stang.
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