UK vs US Fuel Octane Ratings

Dave-R · Post by **Dave-R** » Wed Jul 11, 12 11:22 am

I was talking to someone the other day about an engine build in a US magazine article and he thought the fuel they built the engine to use was the same as our Premium pump fuel here in the UK.

Just to remind anyone thinking of copying a build to US spec that when they say the engine runs OK on "94 Octane" they are talking about a fuel that would be rated at 98-99 Octane here in the UK.

Here is a comparrison for reference;

UK rating 95 RON = 90-91 in the USA

97 RON over here = 92-93 in the USA

98 RON here = about 93-94 there.

John · Post by **John** » Wed Jul 11, 12 12:17 pm

Yeah it all makes things very confusing, There is so much that goes in to fuel its a bit of a mine field and as you say Dave, its a bit mis-leading

Adrian Worman · Post by **Adrian Worman** » Wed Jul 11, 12 12:37 pm

What about the so called special fuels like the one that you can get from Shell, is the octane rating any higher? Or does it have less detergent or something?

Dave81 · Post by **Dave81** » Wed Jul 11, 12 1:32 pm

Adrian Worman wrote:What about the so called special fuels like the one that you can get from Shell, is the octane rating any higher? Or does it have less detergent or something?

V power is 99RON i think!

I'm sure BP do a 100RON unleaded at the pump. Ultimate used to be 98!

VGVIP · Post by **VGVIP** » Mon Jul 23, 12 10:29 am

Good info on the comparison of ratings Dave

From what I know
Shell V power = 99 RON
Tesco do a 99 RON as well
Understand that Morrisons sell E85 not close to one to know for sure though.

E85 raises the subject of Ethanol blends and higher compression engines, anyone have any experience or knowledge on the subject?

In Oz, I used to use avgas in the Monaro at times.
Back in the day one mate used to drive his car into a remote airport, clamp the earth strap onto the bumper then fill up with avgas at the airport pumps.
Those days are loooong gone now!

Steve · Post by **Steve** » Mon Jul 23, 12 11:28 am

Anyone Ive spoken to, with all types of pld cars, say that our cars, in stockish spec, should run fine on V power. I use castrol valvemaster plus in the fuel but have been told I dont need to. I put it in every other tank cos it helps me sleep better at night....

Cheers Steve

Dave-R · Post by **Dave-R** » Mon Jul 23, 12 11:37 am

Unless you have a high compression engine (over 9.5:1) our cars can run fine on normal Premium fuel either.

Steve · Post by **Steve** » Mon Jul 23, 12 9:36 pm

Mine is 10.0:1 so hoping that the valvemaster plus helps out a bit.

Cheers Steve