Gains from higher octain fuel ?

[Ianmcurtis]

Apart from the often huge price difference at the pumps, is there any benefit in using any of the \'better\' petrol\'s in my 8 (optimax? or equivelant) OR, is it just worth putting some in the tank once in a while?

Anyone please............ :cheers

[gsb876]

Our rx7\'s use Optimax as per most of the time the cars have been used to running higher ron fuel in Japan, also Optimax has more minerals introduced which keep the engine cleaner abd less suspectible to detonation.

However the RX-8 has been developed to run as a normal car so i would think you are ok putting in normal unleaded, but there was a thought that every 4th tank fill with Optimax to keep the engine clean and responsive.

You will feel the car to be a little quicker using Optimax and will be more responsive, i dont think its a neccesity on RX-8\'s but maybe others have more experience ?

Hope that helps a little Ian,

Gurj

[TRex]

Ian I look at it this way mate,
 The difference in price between the 2 grades(octane) is 4 pence (avg)
 
 To fill the Rex from empty with normal gas (95 unleaded) is £60
 To fill the Rex from empty with Optimax or other 99 unleaded is £62.40

 Â£2.40........ \'WoW\'.  

 And if like some that only put £20 at a time... thats only 80 bleeding PENCE more at a time!

 Personally there is nothing to even think about, I will put the higher grade in everyone of my cars...
 If someone has to think about an extra £2.40 for every 200+ miles, then their Rex should be sold and a 1.1 micra or similar should be invested in!

[TRex]

Sorry just to add,,,,,
 Not a swipe at anyone but,
 Anyone that says they can feel a difference in performance between 95 and 98 Octane........ well ........

[webrx8]

Ian

There are no reported performance or mpg gains from using optimax or similar in the RX8. If you want to use a tankful every now and then to help clean the combustion chamber then this may help, otherwise it is a waste of the extra cash, Unless of course you go F.I.

Chris.

[gsb876]

Sorry just to add,,,,,
 Not a swipe at anyone but,
 Anyone that says they can feel a difference in performance between 95 and 98 Octane........ well ........

I said responsiveness not power gain  :rolleyes:

[asp]

i take it every 1 lives next to the optimax pump,
optimax is 20 odd mile away,£2.40 i wish,

good old super goes in my car

[asp]

Sorry just to add,,,,,
 Not a swipe at anyone but,
 Anyone that says they can feel a difference in performance between 95 and 98 Octane........ well ........

and this means what???

[Jono FD3]

If you want a niticable differance in responce, a mate of mine recomended some Denzo iridium plugs? He put them in his Mk1 MR2 and GT4 and aparantly felt an increase from the loud peddle!! Don\'t know if it was psycological or what??

Jono

[robedwards99]

I think the final answer is that if you want improvements on the loud peddle you have to upgrade performance parts on the car.
Cars will respond a little better with higher octane fuel but it will hardly ever be a great improvement that you will notice in day to day use.
If you can afford it (as has been pointed out) it doesn\'t cost much more to put super in your tank
Just my opinion

[Ianmcurtis]

Wow! A great and varied response, many thanks to all  :yes .

I seems to be that, as it\'s been pointed out to me here, rx8\'s are designed to run on bog standard un-leaded but at the same time, filling up once in a while with super \'aint going to do any damage so that\'s what I\'ll be doing.

Once again, thanks for the response.

Ian.  :cheers

[MikeLMR]

Unless the rx8 is holding back its ignition advance or changing other perameters to prevent detonation then using a higher octane fuel will have no advantage (thats assuming the only difference in the two fuels is its octane value)

remember the octane number is only an indication of how well a fuel can resist detonation. A car running exactly the same map with two fuels of differing octane numbers only should produce the same power on both fuels.

[oldone]

On my REX we did the test by running 98,(on the dyno),then draining and running 102.....1/2 kw diff on the wheels !!!!!!!!!!!!!!,,,personally i think tht cos the rotor is a low comp motor,you will have no signif gain, obvios it was a n\\a motor but still put out 245bhp on the wheels....

[Trevrx]

On my REX we did the test by running 98,(on the dyno),then draining and running 102.....1/2 kw diff on the wheels !!!!!!!!!!!!!!,,,personally i think tht cos the rotor is a low comp motor,you will have no signif gain, obvios it was a n\\a motor but still put out 245bhp on the wheels....

What fuel was the 102?
On another thread we talked about this, the calorific value = energy, the octane rating is insignificant in terms of power gains (on the same map) as Mike has said. Higher RON fuel can be compressed to a greater amount to give power gains.

[oldone]

What fuel was the 102?
On another thread we talked about this, the calorific value = energy, the octane rating is insignificant in terms of power gains (on the same map) as Mike has said. Higher RON fuel can be compressed to a greater amount to give power gains.

It was a fuel manufactured by SASOL (sponsors of Jordan F1 team a few years back),basically a race fuel that was prchased at the circuits...out of a normal fuel pump rig like you would get at TESCOS,s...technical can be sourced if you need it.