99 RON!!

[SimonExtreme]

With Tesco now offering 99 RON, will it actually make a difference to an RS. I don't know how the ecu is set up in this regard. It would be worth reprogramming a decent ecu (MOTEC) but I am not sure if its any use for the standard ecu

 

[Laurence Gibbs]

The car is set up for use with 98ron fuel. The motronic ecu has the ability to retard the ignition to cope with lower grade fuels but not afaik the ability to adavance or map for higher grade, there is a perfomance limit if you like. That said higher grade (ron) fuel de-grade's with age i.e. sitting in your tank or even in the forecourts tank, additives go off etc and what was 98 becomes 97 etc. so using 99 ron may well help ensure you get the full 98 and therefore max efficiency from the motronic.
again afaik it's possible to remap the standard ecu and take advantage of whatever fuel you are running.

 

[SimonExtreme]

I had guessed that might be the case. Most ECU's do work like that.

I have seen many debates about whether octane rating degrades in tanks (either forecourt or car) and while it can given enough time, it won't given the time it is in the various tanks. One particular point to note with this is that if it says a particular RON on the pump, what goes into your car must be at least that or the garage is in breach of trading standards. I cannot be certain of the figures but IIRC, Optimax is actually 98.4 when it leaves the refinery and will remain above 98 for up to one year ( could have been 3 months)

 

[Melv]

I had my old chipped and hot filmed 964 C4 set up to run on 95 octane -it was worse on 98!!

So may not work....but is 1 RON negligible? -will anybody notice?

Anybody tried Miller's octane boosters?

 

[RSR]

ORIGINAL: Melv
Anybody tried Miller's octane boosters?

What as an energy drink? [8D]

On a more serious note do you guys actually notice any difference between 95 or 98 in your RS, or do you think its 4/5ths of naffall?

 

[Yoda]

I use Optimax most of the time and try to use SuperPlus (97 Octane) the rest. I remember refilling with having 95 Octane in once and I thought there was a perceptible difference in performance - small but better in every area. I use Optimax in my bike on my regular trip to work and back and as well as more perky performance, I consistently get at least 10% better fuel economy.

I've seen a mk1 GT3 dyno print out that that showed a 40bhp drop due to poor quality fuel.

 

[Yoda]

Just read this month's EVO and they seem to have liberal splattering of pictures of our very own Allan's Weltmeister garage in the mag. Great place and great publicity for the business (well done Allan!!).

I digress .............. in one of the articles it actully said they gained 20 bhp (on a 380 bhp car) by swapping to a premium super plus type fuel. Yes petrol is expensive but that has to be the cheapest 20 bhp you will ever buy.

I am convinced.

 

[SimonExtreme]

Yoda

Sorry to burst your bubble but....................

When optimax first came out, I was involved with some back to back tests with Ralliart UK on 2 Evo's. One car had 340 bhp on 97 RON fuel and then 343 on optimax while the other car was 373 before and 377 after. The curves had moved by similar anounts. However, the gain is within the margin for error of the RR.

The only way I can see gaining 20bhp is if the ecu has some way of knowing the fuel is better quality and therefore the map changes. This is possible with a good knock sensor if you map for 99 RON and allow the knock sensor to adjust for lower grade fuel. However, the Porsche doesn't work like that. The other way would be to remap specifically for that fuel.

 

[Yoda]

Have a read of the rest of the article as I think it suggests that you get more consistent fuel qulaity as well as the higher rating. The difference between a bad batch of fuel and a good batch could easily be of the magnitude of 20 bhp. I was at G-Force a few years back and they said they had a customer car in (GT3 mentioned above) for a dyno run which was consistently showing down on power by a considerable margin (40bhp). They kept tweaking and trying things until the car's fuel warning light came on, ran it to the petrol station and put in some new fuel (I think it was Optimax) and hey presto, majority of power restored.

Not suggesting that Optimax will give you 20 bhp but I think there is a good argument to use it to make sure the car is running at its best. I think there is an appreciable difference between 95 RON and the 97/98 RON fuels - not 97 vs 98 as you pointed out when you were a EVO max power boy []. I bet the second EVO was producing more power because it had a bigger spoiler and more stickers on it [][]

Regards