Olli Snellman

Octane figures seems to be low in the States.Is it RON/ROZ/MON figures? The lowest we can get is 95.

Olli
'88 951

Danno

"Octane figures seems to be low in the States.Is it RON/ROZ/MON figures? The lowest we can get is 95."

Yeah, U.S. gasoline tend to have very low octane compared to the rest of the whole. The standard at the pump is (RON+MON)/2 . Typical aromatic content is around 19% while in Europe it's 29%. California law forbids anything above 25%. Must some sort of political maneuver or tax structure. You remember the gas-tax/toluene scenario in Australia a while back?

Not all's lost however. You CAN tune your car to take advantage of higher-octane fuels. By getting a custom-chip burned with extra ignition advance across the board, you can make the most of higher-octane gas. Then when you put normal gas back in, turn the FQS switch to retard spark say... 4.2 degrees and everyone's happy!

I've actually seen a DME with an external rotary **** for the FQS switch. Anyone know about these?

Olli Snellman

[quote]Then when you put normal gas back in, turn the FQS switch to retard spark say... 4.2 degrees and everyone's happy! I've actually seen a DME with an external rotary **** for the FQS switch. Anyone know about these?<hr></blockquote>

That's sounds interesting.Maybe Guru Racing can burn custom chips for me when i have enough money to buy your MAP conversion
I usually use 95 octane, but when i know i have some "action" i use 98 octane pump gas.

Olli
'88 951

Levish

FYI your 95 octane is probably equivalten in knock resitance to our 92-93 Octane and your 98 octane is about 94-95 octane here (due to the differences in ratings)

the difference isn't that big (1-2 octane) but yes we do have higher aromatics

in most states (CA excepted) we can get 93-94 octane at every pump, and in some there are pumps that sell straight 100 octane unleaded or better (by your method it'd be about 104 if not more)

100+ octane = very happy car running lots of boost

jim968

Ok, I'll stick my nose into this & see if I can get it bloodied... AFAIK, the S2 has either one or two knock sensors (the 968 has two). Higher octane is beneficial _if_ it keeps the DME from retarding timing due to knock. This does not apply to cars without knock sensors. Normally, with proper octane, the DME runs whatever maximum advance the chip is programmed for at WOT; when knock is sensed, it retards timing to prevent engine damage. So, too little octane= less power; the right octane = max power; more octane = no gain, wasted $$.

OK, Danno, is this anywhere near right?

Jim, old & easily confused...;-)

Levish

[quote]Originally posted by jim968:
<strong>OK, Danno, is this anywhere near right?

Jim, old & easily confused...;-)</strong><hr></blockquote>

you got it spot on

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Ceenit

Now that we've got the octane question as clear as it's going to get....I'm curious what everyone thinks about gasoline 'Brands'. It looked like there were some guru's on this thread that might have some insight.

Are they all the same? Is 'Petro Express 93 octane just as good as BP 93 Octane, and what about Amoco Ultimate 93? And what about these SAM's club and BJ's gas stations. I've been getting the 93 octane there for years, but am I really buying less than the best gas for the car?

OK I'm ranting, but I'm curious if GAS is really just a commodity and pretty much the same thing (other than octane ratings) no matter where you get it?

Levish

ideally yes it should be the same thing but in practice no

sometimes gas isn't as good at some locations as others.

It can be due to many factors like:

tanker just refilled the station and the sediments aren't deposited at the bottom but rather mixed up

Oxygenated gas
(winter mixes sometimes called)

Poor tank maintenance

and so on

Find a station you like and the car responds well to and stick to it <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

streck-fu

[quote]Originally posted by Brian McCoy:
<strong>FWIW - higher octane just means the fuel burns slower... less explosive (less power if you use higher octane than the car needs). On motorcycles, it's easy to tune - you just run the lowest octane you can, and if it pings you go up in levels till it stops. a Little more difficult with a car that has a brain w/knock sensor.

My 87 Honda VFR puts down 90.3HP with regular (this was Arizona in the summer, not sure if they run METB/additives). My numbers dropped to 86.7HP with 'premium' on the same day (after an extended lunch-break - heh), same dyno. Even armed with this info, there are lots of listers on my VFR list who still insit upon premium/higher octane and 'swear' that 110 race fuel boosts the power even more. A testiment for the imagination and 'seeing/feeling' things just because you believe in it enough.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> </strong><hr></blockquote>

Brian, what are you doing over here?
I never imagine you'd socialize with the cage drivers......

By the way, it's Streck from the VFR list..


<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

FormulaOne10

One thing I will have to call you on though Danno.

[quote] There's no such physical material called 'octane', it's simply a rating number. <hr></blockquote>

There actually is a physical material called octane, C8H18 I believe. However, this doesn't pertain to the octane ratings we were talking about.

Now as for gasoline brands, there is a big difference outside of octane ratings. When you pay for upgraded gasoline you are also paying for special detergents that keep your engine clean. These detergents vary by producer and change constantly but I still believe that Amoco Ultimate, Chevron Premium and Shell Premium are at the top of the list.

ClassJ

I tend to dissagree with the fact that octane boost does nothing. I have built more than a couple engines. One of which is a poniac 400 pushing 500 horse at 11:1 + comp. On pump gas the car will ping. Dump in the super 104 and the detonation dissapears. I have read numerous publications on the stuff and actually have a freind that is a Phd chemist that verified my theory that the stuff works. It raises the octane of the fuel it is added to.

Brian S.

Danno for President!!!!!


He may or may not know what the hell he's talking about (and I think he does)............
but I believe him!!!


<img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />

Levish

[quote]Originally posted by ClassJ:
<strong>I tend to dissagree with the fact that octane boost does nothing. I have built more than a couple engines. One of which is a poniac 400 pushing 500 horse at 11:1 + comp. On pump gas the car will ping. Dump in the super 104 and the detonation dissapears.</strong><hr></blockquote>

then for that particular car the Octane was borderline and the 104 boost (.5-.7 octane improvement was sufficient)

but the point made was that unless the car calls for more octane you would see little to no benefit from higher octane

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />