jbl

Hypothetical question.

Two identical cars, same mods etc, both run super unleaded (97/98 ron) in standard oem trim. Both have , for sake of argument, oem 250bhp.

Both remapped.
Car 1 mapped to 97/8 ron and now gives 300bhp. Not an extreme map, just realistic.
Car 2 mapped to 'ordinary' unleaded 95ron ( I am assuming that this is possible ??? ) Identical type of remap, not extreme. SO.... what would be the bhp for this, how much of a loss over Car 1 ?

Remember...hypothetical !

Cheers

jbl

Ed-EG

I don't think it's a proportional loss between the fuels, my understanding is the lower RON fuel will cause detonation and pinking under higher boost levels, so really you'd be restricted to lower levels of boost regardless of the components and the quality of the map.

Of course I'm not 100% on this, so someone correct me if I'm wrong!

dan-lincs

Your quite right there Ed, you CAN be mapped on lower quality fuel however there will be reduced boost level and the timing will not be advanced as far resulting in a power loss compared to higher octane fuel. I'm not sure how much in BHP will be lost as every car is different but as a good example:

A standard WRX vs remapped with supporting mods start to detonate at around 280 bhp on 99ron fuel (decat, fuel pump, 18psi boost, free flowing filter). More can be achieved with bigger turbo and more supporting mods. So that's close to a 40bhp gain over standard mapping which on a WRX supports a min of 95 ron (altho recommends 98, and I have seen det on my standard map with 95 ron fuel on a hot day).

tubbytommy

iTrader: (20)

Hypothetical answer.


dont be such a pikey and run the car on the correct fuel.
if you want to save money on fuel get a diesel

Andy Stevens

You will only know for a particular car by trying it.

You would be able to run the same boost levels with both, and in my experience, retarding the ignition by one degree will cost ITRO 4bhp at peak torque. When I twin mapped my car for 99 and 95 I saw a 5 degree drop in ignition, so in the region of a 20bhp deficit.

The fuel consumption seemed slightly worse on the lower RON fuel, but that is subject to so many variables that it isn't exactly a scientific conclusion.

With a twin map system you could use one fuel for everyday driving and another for the track/dragstrip/etc.

Slightly off topic, I added 20% methanol to 99 and gained 9 degrees over straight 99! As meth is cheaper than SUL I think that qualifies as the only mod that will gain power and save money.

jbl

Thanks all, I hadn't realised about the effect on the timing and boost issues. I will add those into the 'deliberations' at the appropriate time.

Cheers
Brian.