SleepersRock

I took a longer route home the other day through San Jose and need to fill up my tank. I stopped at a 76 Station on Foxworthy and Alamden. While I was fueling up I noticed that my pump had a seperate nozzle for 100 Octane Racing Gas!! They did not have the price on the pump, so I asked the attendant and he said it was $5.59 a gallon.

#1) What would be the pros and cons of putting in 100 Octance in the NA 55 Motor?

#2) How much of a performance gain would I see?

#3) Is $5.59 a lot for this gas?

I really want to try this gas "just to see" . I think I will do it in a few weeks, but would like some info or previous experience if anybody has it.

Nocturnal-G

Basically from what I know, it's a cleaner burning fuel... but you will see a big difference IMO. I only fill up 91 in my girl. I guess it's worth the price, since it's rare.

E55 Estate Fan

Good question. I've been wondering if there is a worthwhile difference. Think Palmer3914 runs only on the high octane stuff and has improved hp & torque but he has had his ECU modified to run on the higher octane juice.

karl.w

higher octane gas will let you run more advanced timing with out the risk of pre detonation in the cylinders.

Your ecu will advance the timing once it detects that it is able to safely through adaption.

But to get the best out of it you will need to use it all the time and get your ecu reprogrammed/remapped

E55 Estate Fan

Thanks Karl. So do you run your car on the high octane fuel? I've always run mine on Shell 95 octane regular unleaded. Is it worthwhile switching long term to a 99/100 octane product?

karl.w

yes i have always run mine on 98 octane and it feels a lot better using 98 octane than normal 95 petrol.

for normal everyday driving 95 octane is fine and wont harm it at all.
But 98-100 octane will always be better ie more power and better for your engine.

give it a go and see what you think. but wait a while for your ecu to advance the timing slightly (1/2 tank or so) for the higher octane fuel.

the higher the timing is advanced, the bigger the bang in the cylinders will be, and the more power and torque it will make

45acp

i used to run 100 oct VP fuel in my old bmw all the time. as stated before, the ecu will advance the timing accordingly. after the 2nd tank, man the car woke up. but then again, the engine was running abit leaner, so i had to change plugs abit more often. tho i haven't tried it in the w210 yet.

E55 Estate Fan

Thanks guys, I'm persuaded. I'll fill up tomorrow. If I try & drive in the same manner as before, would running a higher octane actually improve fuel consumption? Wondering if the extra cost of high octane is offset by improved fuel economy?

SleepersRock

This is good info. Basically, I have to use it regulary (or at least 2 tanks) to get the best results? I was thinking I could put it in every now and then and get good results, but it seems that is not the case.

Will there be engine longevity issues due to "the bigger bang?" I would think every now and then would be OK.

BTW. At 5.59/gallon it would cost about $110 for a tank vs. about $60 at $3.19/gallon. Assuming 20mpg the fuel would have to basically double your MPG for it to offset the added cost. I doubt this will happen.

In the UK with GREATLY higher gas prices (in some ways I'm glad I don't live there anymore!) you may need to see even higher MPG to break even.

palmer3914

minw made 381bhp and 428lbft on 98 Ron fuel... mine however has been mapped for only 98 RON + fuel... its fine on UK's 95 RON untill you put your foot down then it PINKS/DETS

so it does help but thats only due to the fact we squeezed every last bhp out of it we could..... bareing in mind car it mech standard.... not even filters.......!!!!

higher aint the word!!!!

98Ron fuel is £1.04p a litre ..... or roughly £4.70 gallon which means its about $9.20 a gallon!!!!!!!

while normal is a snip at only £4.30 gallon - $8.60

ENGLANDS GREAT!!!!!!!!!!!!!!!!!! NOT!!

E55 Estate Fan

Sorry don't agree. In the UK the price differential between for regular 95 octane & super 98/99 octane, is much smaller e.g. Shell regular 95 octane at 95.9 pence per litre versus Shell Super 99 octane at 102.9 pence per litre. This is a price difference of 7%. So if the 99 octane gives me improved fuel consumption of 7%, the extra cost of 99 octane should pay for itself.

palmer3914

yes its cleaner burning and more efficient.. BUT.. from what i have worked out it does NOT improve MPG at all........... or if it does its so small i have not noticed it!!!!

E55 Estate Fan

Interesting test on regular vs. super fuel was carried out by Thorney Motorsport recently:

http://www.thorneymotorsport.co.uk/t..._Results.shtml

Conclusion: Definite & significant power increase (+10% for a BMW M3 CSL) & an improvement in fuel consumption.

Tesco's 99 was found to be the best fuel.

Blk04cobra1

On a N/A 55 motor, you probably will not see much of a gain...you will however foul your O2 sensors (eventually) if you continue to use it. $5.59/ga is actually not a bad deal on 100 octane.

E55 Estate Fan

I'd call 381hp on 347hp for a N/A E55, a pretty good gain (see Palmer3914's earlier post).

karl.w

why would he foul his o2 sensors

the only difference in higher octane fuel is that it is harder to ignite!!
(meaning that more advanced timing can be run)

its also cleaner burning so there would be more chance of fouling o2 sensors on lower octane fuel.

most of Europe has been using 97-100 octane gas for years.

That may be why most European companies can get over 380bhp at the crank from simply chipping the ECU on an otherwise stock car

JamE55

Unless your ECU has been modified with aftermarket mapping, running higher octane wont do you anygood.

I'm running a custom ECU along with VP 109 and noticed and marginal improvement.

ProjectC55

only if you are using leaded fuel will you mess up the O2's I understand.

E55 Estate Fan

Not sure if I agree.

The quote below is from the recent Thorney Motorsport fuel test I mentioned previously. I interpret it as saying a car's ECU has the ability to recognise different octane levels in fuel & adjust the ignition timing accordingly i.e. no need for aftermarket mapping:

"This apparent gain in power is due to the ECU of the car’s ability to advance the ignition timing to take advantage of the extra power the higher octane offers. Looking at the air/fuel ratio on the charts does show that the higher octane fuel allows a more efficient burn creating more power.

The chart shows the car’s ECU when running on 95 Octane fuel enriches the fuel mixture (adds fuel) to compensate for the less efficient burn and to avoid early detonation. This extra fuel robs power as the air/fuel mix is less efficient. By changing this fuel to a higher octane the car is able to advance the ignition (essentially using less fuel at higher rpm’s) to create more power"

machz990

So with everyone postulating on what gains there are running higher octane fuel how about the other end of the pendulum. Suppose you buy premium locally and it isn't premium or doesn't have the actual octane level as advertised. I assume the ECU makes an adjustment for the low octane fuel but how long does it take for the ECU to get back to normal numbers once you put some more good fuel in the tank. I wonder how many E55 owners down on performance have been hit with this scenario? There was a 20/20 type show on a couple years ago that tested gas and found many pumps, especially in big cities, that were all pumping regular out of all 3 grades.

JamE55

That quote is probably for Euro cars only.

karl.w

if you fill up with 100 octane gas. Then yes your ecu will advance the timing which will result in more power.

But there will be a set limit to how far your ecu will advance the timing on it's one with out being reprogrammed.

you will defiantly see gains in performance but the only way to fine out how much is to try it

palmer3914

mysticblu999

i get 110 in kentucky for 4.95/GA

karl.w

110 is almost alcohol

the higher the octane the slower it burns and if you go to high, the gas will not have enough time to fully burn in the cylinders which is bad news for your engine

pure methanol is 110-114 octane