hooleyboy

Man my car is loving the race fuel i just put in, but my wallet is not. The car just feels better when i run race fuel. At 7.99 gal. its not the most cost effective fuel out there. I have to say Its nice to treat the car to some 100 oct. race gas from time to time. Headed back to the drags on Friday so when i dump in 105oct I should get a better mix. Rather than 91oct mixed with 105oct. I wish it was like $5.99gal and more available I would have a new fuel map made and run 100oct all the time

bumpnzx3

unless you've got some unusually high compression, nitrous, or agressive timing- i'm not real sure you are gaining anything by the higher octane gas. if your computer isn't tuned for it- there isn't much of anything to gain.

over the long, long run- you are actually doing your car more harm than good. higher octane gas, when not needed, adds to carbon buildup. again- this is something that happens over a long period of time if the car isn't meant to run it.

this coming from the ford and chevy camp that i am used to. the computers are more or less the same.

c32AMG-DTM

Beware the dreaded "placebo effect" that occurs with some mods...

Kidding aside, this likely isn't doing much for you, but there's probably a slight benefit since you've tuned the ECU. Didn't you have a dyno-run with some race gas added, and it gave a modest gain?

e1000

also keep in mind guys, we only get 91 octane out here in AZ.

hooleyboy

A few months ago when i was on the dyno we added so race fuel and i picked up 12whp from it. I got the dyno chart somewhere i will try to find it. This 91oct gas out here in AZ is crap. I am a firm believer that 10hp or so is almost impossible to feel, but i do know that the car as a whole just feels better with race fuel, It just seems to respond better to my right foot.

bumpnzx3

to each their own- i like my sprint booster that i blew $250 on, even though it doesn't do much for real performance. it's all about the experience to me

e1000

yeah, I used to live in Chicago and all the places have 93 there, some places in Indiana even have 94. You wouldn't think it makes a difference but I know what you're talking about.

cruzinquick

The 100 octane we get at the track is Torco 100 MACH UNL, it has a motor octane of 100. See what fuel you are using and check the motor octane. Some are much lower than 100. Plus it's $6.50 at the track.

hooleyboy

When I was over at dyno comp in Scottsdale I was told a story that BMW reps came in to the shop and showed them an octane rating for Arizona's gas and 91oct was not even reading 87 in their finding. I dont have any proof to that story as its just what someone told me, but i can find it believable.

e1000

whoa. yeah the gas around here sucks. I used to use BP/Amoco in my car but Arco is the only station that carries BP gas, and they're ghetto.

Hey I was thinking about getting a small meet together sometime soon, you down?

jturkel

i hate arizona gas. im gonna start mixing in 100 octane when i go to the track to make what i believe to be 93 octane, assuming 91 octane actually is 91 octane

hooleyboy

I'm down for sure! and i know some others in the phoenix area who are game too. maybe we could do it at a drag strip

hooleyboy

i'm headed out to speedworld Friday if you want to roll up. Always cool to have AMG's out there.

SRTpowa

I'm ordering a 5 gallon drum of VP MS109 to mix and test at the track. It's oxygenated and proven dyno gains. Bad news is it's gonna cost me $60-70 for 5 gallons.

bumpnzx3

and i've got a used car i'll sell ya

MRAMG1

+1

Also keep in mind that you will actually LOOSE HP due to higher octane fuels as the flame propogation is slower, aka it burns slower so you loose efficientcy. Anyway to each his own, but if your car isn't tuned, or doesn't require it, bumpnzx3 is right and your just burning up your wallet.

See yeah

ohlord

run it on a steady diet of it,simply because of the cost in Arizona.But to the above post.
First LOSE Power in Arizona in most likely is not going happen to at 100 octane.Have you ever raced there?The altitude density of the air on a 100 degree day is about equal to Denver mile high.So you need to take that into account.Planes taking off from airports need to compensate for it,race cars adjust fuel for it,tuners adjust nitro for it.Burns slower yes.Use it all the time in some areas of the country waste of money,yes.Trip you check engine light with O2 sensor codes ,yes.Certain altitudes and high temp conditions More power,Yes.Although for $60 bucks a can he can find 10 h.p. which is only a tenth of a second for far leass money.

e1000

This is true for cars without a knock sensor, but our cars dynamically adjust for knock and advance timing as better fuels are used. Now, at a certain point there are diminishing returns, but since the fuel is so bad and the air is so damn hot and dry (thanks ohlord), better gas can make a difference.

Newzchspy

I run the 100 from Road Pilot (now Marathon) and yes it does make a difference. It allows the timing to advance and if you have the LET tune like I do, you CAN feel the difference. Our std "premium" is 93 in Illinois. I can't tell the diff between the 91 and the 93, BUT the 100 does make a difference.

The Marathon near me has it for 6.00 per gallon, which for race fuel is not that bad. You can also get it where I race at Joliet at the AutoBahn as well as RTE 66 and Union Grove. I think over 100 its all low leaded though?? The 100 I run is NO lead.

loungn14

Agree with you...i have put race gas in for a dyno and it did make a difference.

But, I also have many tunes ready to go, and have one especially setup for the 100 oct at the track to maximize maps for it.

So, both point previously made are correct....

donjuan45i

haha like how your "member status" under your name says outta control

haha same here in Ia, like 90% of the BP's are run down little gas station, kinda makes me think twice before filling up. Matter a fact the BP closest to me JUST got self serve pumps before they had the ones where you had to lift that wand up and around with the rolling numbers.

I go to Quick Trip they gaurantee their gas, and claim that Toyota and BMW recommend it? But mainly because of the guarantee. a few months ago i wasnt paying attention and thier pump pumped like $90 worth of gas into a half tank on my car. Called manager and he was willing to pay for any damages. all i had tho was a stuck floater I think that eventually unstuck itself.

If I could I would go for the higher octane, I get a nice warm feeling inside every time i fill er up

cruzinquick

I don't use the fuel for hp gains. I bracket race every weekend and use it because it keeps my engine cooler. My engine cools down in 10 minutes versus 25 to 30 mins on regular premium gas. It is unleaded because I have my stock exhaust with cats. Running leaded with cats will ruin them. Now I'm not going to deny that the car feels stronger with running race fuel, but it also could the mind factor. Even the fuel guy selling the fuel said unless I have the 100 octane tune, it's just for cooling purposes. Which for SC motor is very important. I win alot so something is working. 12.02 is not too shabby either.

hooleyboy

I can attest to that. He does win alot. His Srt-6 blows my c55 off the road.

timdf

is that it only really comes into its own on forced injection engines which have a specific map for it.

EG my 911 twin turbo loves it :-) but only when I select race fuel map and of course I'm at practically sea level.

For a normally aspirated engine at elevation and or hot temps - it makes little to no difference as the engine will already be running at effectively a lower compression ratio due to the thinner air.

Higher octane fuel is only required to prevent detonation in higher compression engines and where ambient air pressure merits it.

As a data point Formula 1 race cars were mandated to use regular pump gas some years back as the 'special mix race fuel' for Formula 1 was getting too volatile !

Newzchspy

Couldn't have said it better myself. There's a reason other than profit why they make it. On the weekends at this particular station, you will see the P Cars, the Ferraris and the Vipers all buying this gas to the tune of $150 or more per tankful. Other than throwing money away, these guys who are also gearheads have to know something we don't.