93octane vs. 91 octane

[element256]

Ive run 91oct. with my APR 93oct. program and really didnt notice a difference at all performance wise. I guess the advantage is for us EastCoast guys!!

WHAT ?? There's no advantage to living out there
I'll take L.A. and 91oct AND the CHP over anyplace east with vp109 at the pump for $3.00\gal

[lsc2g]

we have 91 and 94 (at some stations) here in Calgary Alberta Canada..with my APR 93.. on 94.. i can tell a HUGE difference between the 91..
its easily 15HP or more could be my butt dyno tho haha

[1997gtx]

You'll gain about 20 crank HP from the "Two Points" ... Yes, we're all aware that thread is old, but it's a good topic that hasn't been discussed in a while ... I have VP109 at a gas station in Newington ... $7.00 a gallon last I checked.
--Adam

[txaudifan]

OK, to bring this one back from the dead again... I was searching so I don't get burned... not even looking for this subject might I add, looking for apr vs giac chip answers... anyways, so does it hurt our cars to use octane booster? I live in Tx and they have 91... I have yet to locate 93 but still looking!!

[The_Jerbel]

People people....haha

Higher octane DOES not make the gas burn slower! It makes it more resistant to ignition. Harder to ignite, but doesn't burn slower. In fact, by the time there is sufficient energy to ignite it, it burns quicker than low octane fuel because the mixture is denser and higher in energy. High octane fuel has higher potential energy than lower octane fuel because it has more hydrogen bonds to break (which release energy)

2ndly,
When you go up in altitude, you are decreasing the density of the O2 in the air, which makes the mixture leaner and hotter. Lower octane fuel will pre-detonate earlier up high because of that fact. You need higher octane in order to combust the same as lower octane at lower elevation.

Now 3rdly,
You can run down to 87 octane fuel in our cars but as it states in the manual, you will feel a power loss and there will be some fuel consumption increase (maybe noticeable maybe not). You can run 91 on your 93 program, the knock sensor will help the ECU compensate for it and you will get power loss compared to if you were running 93 oct. Go ahead and use octane boost, it won't harm the engine.

[woofster]

What do you guys think of the idea of better fuel economy running 94 octane vs. 91 octane?

Reason I ask is because I typically fill up 91 octane in my neck of the woods (91 is the most common octane for premium in Ontario) but just this holiday weekend I was in Quebec and filled up 94 octane before my drive back home. Instead of 9.8L/100km (24.0 mpg) which I achieved on the way there, I achieved 7.7L/100km (30.5 mpg) on the drive back! Any thoughts?

[The_Jerbel]

You're car makes slightly more power on 94 oct, or in other words, uses less fuel to make the same power. Example, if it takes 268 hp (random number) to go 130 mph on the highway, your engine will make that hp figure with less throttle on 94 than on 91, giving you better mileage numbers.

The problem is, people usually drive harder with more power, so they lose the benefit in fuel economy of the power increase.

[qwks4]

I only run on 94!

[Bimmer2Audi]

Shell Vpower 93 FTW. Stock chip.

[Das General]

east coast owns the west coast.


/thread.

[Go_S4]

Yes Im being an idiot, bringing a thread so old back, but I just wanna get a straight answer from what i just read:

Its technically ok to run 91 on a 93 program, and could cause loss of power, but is it going to cause problems in the long run???

[Caddy7]

I have been running a 93 APR chip with 91 gas for 6 months. I have had no knocking or problem what so ever.

However, there would be more power in the car if I ran it on higher octane.

[Boris]

Ive run 91oct. with my APR 93oct. program and really didnt notice a difference at all performance wise. I guess the advantage is for us EastCoast guys!!

+1, I used to run a 93 octane program, stage 3 at that, on 91..

Ran fine. Yeah CA 91 is shit, no doubt about it.

It may retard timing, but it will run fine. I would really avoid getting a 93 program though if you can get a 91 one. I only ran that way for a few weeks...

[AWD87]

what if you run 92 octane on a 93 program?

[NOTORIOUS VR]

Just to clear up a misconception in here... The difference between 91 and 93 octance is 20 (twenty) points, not 2 (two) points. 2 points = 0.2 octane or two points on 91 octance = 91.2.

Which is why 'most' off the shelf octane boosters are a waste of money, they only raise the octane level by approx 6 points which would turn 91 into 91.6.

[Renegades]

Just to clear up a misconception in here... The difference between 91 and 93 octance is 20 (twenty) points, not 2 (two) points. 2 points = 0.2 octane or two points on 91 octance = 91.2.

Which is why 'most' off the shelf octane boosters are a waste of money, they only raise the octane level by approx 6 points which would turn 91 into 91.6.

Exactly. Thank you for clearing that up, I was going to post this until I read your response... There is a TON of misunderstanding in this thread..


And guys,
It's not a good idea to run 91 on a 93 file, there is a REASON why they make two different files - think about it..

And is a $250 charge (or whatever it costs) really a big deal in the grand scheme of things? Tuning and timing are things you do NOT want to skimp out on. Get rep wheels, or whatever else, to save money, but don't get the WRONG tune for your ENGINE just to save some money - get the 91 file and be safe. All it takes is some poor timing for a very short period of time and you could cause some major engine damage...

[saucys4]

just remember that the ecu will adapt to different octane fuel. if it senses knock, it will retard the timing. when i first got my car, some f*cker put my car in race mode while i had 91 craptane in it. luckily i soon found out but it really didnt feel any different and there was no knock though my cfs were probably sky high haha

[S4 in_lowplaces]

Wow this is old. and no its not big deal, thats what the knock sensor is there for. The ecu is smart and will adapt to what ever octane is in there., Think about it if your running a stock s4 on the east coast at 93 octane and you move to west coast its going to have to adapt to the 91.

I ran the 93 apr with 91 octane for a year, no issues here. And for anyone wondering, The APR 93 program i had adapted VERY well to 100 octane :-). If you decide to go any higher on the octane scale i would recomend the race gas program. But the apr 91 and 93 prgams can adapt to the 100 octane no problem.

[Go_S4]

Im more confused now, ppl say the ecu is smart enough to correct it if you put 91 on 93 octane, but some say its not...Im just going to get a 91 octane program and save myself the confusion..

[Evilevo]

Technically the ECU is "smart" enough to adapt. But what happens if something fails. or you get a REALLY bad tank of gas. Is $100 really worth a 5k motor?

[Renegades]

Technically the ECU is "smart" enough to adapt. But what happens if something fails. or you get a REALLY bad tank of gas. Is $100 really worth a 5k motor?

That's my point exactly...All it takes is one bad time.

Do the right thing and get the file suited for YOUR car, not some car that was on the east coast. There is a reason why they have 91 files and 93 files...

The ECU will pull timing... But it's set to run timing at 93, so it'll constantly be working to keep the timing right for 91, instead of going fine with 93.

Not worth the possible damages. Seriously.

[Jayco88]

Here we go again, this is the thread's third revival.. don't flame me because I SEARCHED and have a genuine question.

So say I get a Stage3 kit for 93 octane, and decide to use it with 91 craptane here in Cali.. I know the ecu will retard timing on its own, and will sort it out to make it work, but will constantly be expecting to burn 93 octane (which could be potentially catastrophic for my engine)... BUT, would it be ok if I retarded the timing with Lemmiwinks?

if so, this is were I need a small clarification.. lemmiwinks has either "-" or "+". Which symbol represents advancing/ retarding, or pulling, or adding/reducing timing? I get these terms mixed up to the point that the plus and minus signs lose their meaning.

merci beaucoup

[The_Jerbel]

Yes, you could pull some timing and log the car to make sure everything is as it should be.

+ means advancing, - means retarding the timing.

[Shenanigans]

I have been running a 93 APR chip with 91 gas for 6 months. I have had no knocking or problem what so ever.

However, there would be more power in the car if I ran it on higher octane.

x2

[viceprp]

I know I wouldn't 91 oct with a 93 program but what about the opposite? I have 91 oct programming and I fill with 91,93 and 94 oct. Is there any cons? My year 1.8 doesn't have 93 programming..

[Rated S]

I know I wouldn't 91 oct with a 93 program but what about the opposite? I have 91 oct programming and I fill with 91,93 and 94 oct. Is there any cons? My year 1.8 doesn't have 93 programming..

Wrong car, but no. There is no foul play when running a higher grade octane.

[Audi S4 Turbo]

This is why I'm switching to E85. (With a 91 tune just in case).

[B1TuRBO]

I can't remember exactly as its been awhile since I researched it, but it deals with the lower airpressure/oxygen content decreasing the nead for octane. It also might not really apply to forced iduction vehicles, although considering it takes just over 3psi of boost to make-up for the altitude it still could. Basically, in Denver area (or similar altitude) you aren't really running a full 20psi when you're set at 20psi because of the lack of outside air pressure. This also has a greater effect on NA cars because they are relying on that outside air pressure to feed them.

Don't get me wrong, I'm not saying we can make more power with crappier fuel. I'd say it more along the lines of, "We can't make shit for power up here anyways, whats crappy fuel going to hurt?"

I will research this again as my fascination is resparked.

it does not affect turbos only NA cars

[BMCINSD1]

This is why I'm switching to E85. (With a 91 tune just in case).

I'm doing the same... Good thing Pearson Fuels with E85 is only two miles away!

[Jayco88]

I like simple answers.. Thanks Jerbel!

[The_Jerbel]

No problem

[Audi S4 Turbo]

Ya, I'm north county so I have to drive about 5-7 to Carlsbad for E85. Supposedly, in the next year, there will be a 50% increase in E85 stations...