Ron

[dj_davo]

so you put some octane booster in with your 97 super or 98 optimax and suddenly your jap import is happy cos its at the 100 RON mark it likes,...

BUT

if you use the unichip (or other) to alter the fuelling and map the car to run on say 98 optimax (making the car now think that 98 is it's magic figure) would adding an octane booster now not have any effect as the ecu doesn't see a higher octane rating as desired.

or am i off target here?

does octane work in the combustion chamber and effect the pistons etc. - not dependant on the ecu.

any suggestions peeps

[boundsw]

Im sure the RON of a fuel has something to do with the ignition timing.

A lower RON fuel needs an earlier spark

A higer RON fuel a latter spark is ok, and it ignites better !

Jap cars run on 100 RON fuel 'back home' so as close to that as possible is advised as the ECU is mapped and timing set for 100 RON.

If a car is mapped to 98 RON on an ECU, then it will run fine with 98 RON now.

But as for adding octane booster now (after mapping), Im unsure of the effects...it cant do any damage, as UK cars are setup to run on 95 RON fuel, and they sell 97, and 98 RON, and UK car owners put that in their cars..so its cant do any damage. But tuned turbo UK cars may benifit from Higer RON fuel to help / Stop Det.

Basically, im a bit unsue, as you are, as to the effects of using a higger ocatne fuel than mapped on the ECU.

Im sur eits better than using a lower RON though !

Any Help ??

[mikeb]

A lower RON fuel needs a later spark (assuming pinking is occuring). The knock sensor detects it and the ECU retards the ignition accordingly (and limits boost on a tubby?).

There is no advantage to using a higher octane fuel than your ECU is mapped for. As the standard tubby is mapped for 100 RON, the closer you can get to 100 the better the engine will run. But there's no point going higher than 100 unless the engine is tuned to take advantage of it (higher compression/more boost/more ignition advance).

I don't understand exactly what you are asking, does the above answer it?

[dj_davo]

sort of?,.......erm,....no :D

i know what you're on about, my main question was would it be worth mapping the car for 98 with a unichip thus making it happy putting up with all this country can offer at the pump, but in the process possibly negating the effect that an octane booster could give on say a track or rolling road day - if mapping this way would deem the octane booster redundant.

from what i can tell by the responses is that the octane booster would be pointless if the car was mapped for 98 as the car wouldn't recognise the higher octane available?

however, if this is so, why would octane booster be sold at all then cos surely everyones car that is ecu controlled would also not recognise any more octane.

blimey,..alright in a nutshell, i want to fit a unichip and map my car for 97 super as this is what i use all the time and i dont like the fact that im 3 octane points lower than my car wants. i assume this will !Removed! my timing and affect the boost, but the unichip will tweak my timing and increase my boost to overcome this (with the help of a tuner of course).

but then would i feel any benefit from adding an octane booster?

hth

[mikeb]

sort of?,.......erm,....no  :D

i know what you're on about, my main question was would it be worth mapping the car for 98 with a unichip thus making it happy putting up with all this country can offer at the pump, but in the process possibly negating the effect that an octane booster could give on say a track or rolling road day - if mapping this way would deem the octane booster redundant.

from what i can tell by the responses is that the octane booster would be pointless if the car was mapped for 98 as the car wouldn't recognise the higher octane available?

←

Correct. BUT, the Unichip is a piggyback ecu, so you could map it for 100 RON fuel, then when the main ECU detects knock from 98 (or lower), it will !Removed! the ignition timing before the unichip modifies it. At least, I think that's how it works.

however, if this is so, why would octane booster be sold at all then cos surely everyones car that is ecu controlled would also not recognise any more octane.

←

Some people run octane booster/race fuel all the time, and their aftermarket ECU is mapped for the higher octane. Some people have JDM cars that are set up for 100 RON fuel (like yours), and they run octance booster to maximise performance.

blimey,..alright in a nutshell, i want to fit a unichip and map my car for 97 super as this is what i use all the time and i dont like the fact that im 3 octane points lower than my car wants. i assume this will !Removed! my timing and affect the boost, but the unichip will tweak my timing and increase my boost to overcome this (with the help of a tuner of course).

but then would i feel any benefit from adding an octane booster?

hth 

←

Yes, you can fit a unichip, and 'tune' it for 97 octane, but it won't intrinsically offer any power gain over the stock ECU. And it won't benefit from the occasional addition of octane booster (you could map it separately for each fuel and download a new map when you change).

I would say you are best to run with octane booster all the time, and get the unichip setup for 100 RON fuel.

[ae111sr]

A link to all you need to know abour octane ratings here

Get the Unichip mapped for the fuel you will use. The mapping is done on a rolling road dyno and the tuner should map it so the engine gives most power without pinking/knock - this depends on the fuel in your tank. If you want to continually use Optimax then make sure your tank is full of Optimax when you take it to be mapped.

[Skeete]

Basically the RON rating is gained from where the boiled crude oil re-condenses in the tower. Diesel is just the same as petrol, but it is the element of the oil that condensed earlier. Aeroplane fuel is the highest I think with red diesel or something at the bottom.

The lower the RON rating the less it needs to be compressed before ignition, hence if you run your 10:1 tubby on 95 ron fuel you get pre-ignition (pinking/knocking), the lower the compression ratio of the engine the crappier the fuel you can use.

by using 100 Ron fuel you can increase the compression ratio of the engine and get more fuel in the cylinder to make a bigger bang for the same capacity (just like a turbo does with compressing air).

If you up the RON rating to 100+ it shouldnt (?) make any difference in power unless you increase the fuel pump rate and put more in and turn your boost right up.

This is a fairly simple explanation, and I am sure there are better ones out there, but for your purposes it should do..

Hope it helped anyway.

Skeete.

[Skeete]

Out of interest as well, this is why the US tubby runs at 200bhp as they have changed it to run on their crappy 87 ron fuel !!!