# 89 Octane in V8 Touareg?



## Strictly-European (Mar 4, 2003)

With gas prices going crazy especially here in Hawaii and some other states $3.07+ for 92 here.. is it safe going down a notch? anyone have any experience with it?
Not to compare but a friend of mine owns an Armada and uses 87 don't know if I would do that but just curious, if any ill affects.

Thanks http://****************.com/smile/emthup.gif


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## LeBlanc. (Jul 15, 2003)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

although i strongly advise against it, the ECU will retard the timing
to run even regular 87 octane gas. i went ballistic in another thread
a few months ago regarding this topic, but i have since experimented
with different octanes, and have used 87 without any pinging under
normal driving conditions. high load conditions may be a different
story.


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## garibaldo (Jul 10, 2004)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

I've tryed 89 octane just last week when the numbnut gas attendie filed in 'Plus' when I said 'Super', yes in NJ everywhere's full service. 
Although I was very upset when I left, I felt no noticeable changes in performance in mainly highway driving conditions.


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## spockcat (Jun 5, 2003)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

I always used 89 in my V8. Never had any issue. Hard driving or not.


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## joeofthemountain (Jan 9, 2005)

*Re: 89 Octane in V8 Touareg? (spockcat)*

I ran 89 last week en route from Philly to DC. Didn't notice a thing. By wy of comparison, my Audi 100 with the 2.8 V6, performance drops noticably on regular gas.


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## jakbqik (Mar 24, 2004)

*Re: 89 Octane in V8 Touareg? (joeofthemountain)*

I live near denver colorado and have actually noticed better performance running 89...


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## ryangambrill (Aug 1, 2005)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

My advice is to use gas that at least meets the minimum octane rating for your vehicle.. I am picking up my V8 Touareg tomorrow. 
Currently I have an A4 1.8T. The minimum rating for the Audi is 91. My wife did not know any better and filled it up with 87. The hesitation and lack of performance was felt immediately. 
My assumption is that the higher the compression in the engine, the more important the octane of the fuel.


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## wjpeace (Aug 3, 2005)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

I have used 89 once in a while and never had a problem or noticed a lack of performance. When I used 87 on the other hand my mpg dropped like a stone.


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## 4x4s (Dec 18, 2003)

*Re: 89 Octane in V8 Touareg? (ryangambrill)*

I would agree with ryan, but there are obviously many opinions and factors to consider. 
This subject has been discussed a bazillion times or so here - try doing a search in this forum for "octane" in post bodies, archived content, and read for a few hours to see all of the previous discussions.


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## MiguelT (Oct 12, 2000)

*Re: 89 Octane in V8 Touareg? (4x4s)*

There really isn't that much of a savings. You're saving $2 or $3 on average. I'm thinking of giving up the Touareg to MrsTouareg and getting myself the new Passat. I have a longer commute and a quarter of it is Newark traffic.


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## LeBlanc. (Jul 15, 2003)

*Re: 89 Octane in V8 Touareg? (MiguelT)*


_Quote, originally posted by *MiguelT* »_There really isn't that much of a savings. You're saving $2 or $3 on average. I'm thinking of giving up the Touareg to MrsTouareg and getting myself the new Passat. I have a longer commute and a quarter of it is Newark traffic.

Funny you mention this... I recently had the pleasure of a 2.0T Passat
for a weekend for use in a car show. I beat on it to see how economical
the new 2.0T is. 21.4MPG, in sport mode, driven hard only, over two 
days. My 1.8T GTI would have seen 18MPG or so. Three







for FSI.


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## chrisj428 (Feb 26, 2005)

*Re: 89 Octane in V8 Touareg? (jakbqik)*


_Quote, originally posted by *jakbqik* »_I live near denver colorado and have actually noticed better performance running 89...









89 in Denver is the equivalent of 91 or 92 in the flatlands. Altiutde is a factor in the octane equation. For example, our regular unleaded is 87 and yours is 85. (Lived in CO for seven years). The octane requirements listed in the manual are at sea level. You wouldn't be able to find a 92 (or 94 for those of you lucky enough to have a Sunoco nearby) rating at 5200 feet.


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## Bigtop (Jan 8, 2004)

Spoke with a buddy of mine hogh up in BP, and altitude makes a large difference in octane requirements. I live at 9,600 ft and you can run 87 octane and for some strange reason get more mpg than running 91 octane. He said that most modern engine management systems will compensate for a lower rating octane, although if you are not at a higher altitude you should probably keep to the manufacturer's recommendations. It they could say that you only need to use Regular or Mid Level grade fuel they would do so as it is in their interests to do so and not have to force you to use the expensive stuff!!!


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## shinlegion (Aug 27, 2005)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

Well, maybe you can get away with it, but the mauals and VW themselves state that premium only is the proper fuel...and given that VW can be a little tempermental, I wouldn't mess with it to save $20-$40 a month. It may void the warranty


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## Strictly-European (Mar 4, 2003)

*Re: 89 Octane in V8 Touareg? (shinlegion)*

Thanks for the input fella's.. sounds like it's split... I'll see what happens here and try it out... I have read the past discussions just wanted to get an updated feel of how everyone is feeling about the jump in gas prices.. like I said one day here it was at $2.61 and next few weeks I'm seeing $3.07.. and I do commute alot







.
I use to be a very firm believer in using strictly 92+ but when I started commuting alot more with my MKIV VR6 I used 89 with no problem, of course I changed my oil every 3k with Royal Purple oil and kept the engine bay clean and fluids flushed every year. 
Now, me and my wife own the Touareg got rid of the MKIV VR.. wish I had it still on the side instead of driving the Touareg everyday







, MKIV was a workhorse at *118k miles *for a 4yr. old car gave no problems, maintenance is key... Maybe I will have to take my 97 VR6 out of storage and start driving that...









Peace Out 
Thanks Again


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## DANBURY VW-PASSAT (Jun 17, 2003)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

Your gas milage and performance will drop like a rock - Do not do it. you have been warned


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## Dominik (Jan 7, 2004)

IMO, The savings of going to a lower octane fuel are only psychologically relevant. How much do you really save? like 20c/gal? For a full tank thats around $5. Logically, it doesn't make sense to save a few bucks and risk damage to a horrendously expensive engine.
I mean, if you HAVE to save $5 per fill up, you better get rid of the vehicle alltogether and straighten out your finances!!!


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## Strictly-European (Mar 4, 2003)

*Re: (Dominik)*


_Quote, originally posted by *Dominik* »_IMO, The savings of going to a lower octane fuel are only psychologically relevant. How much do you really save? like 20c/gal? For a full tank thats around $5. Logically, it doesn't make sense to save a few bucks and risk damage to a horrendously expensive engine.
*I mean, if you HAVE to save $5 per fill up, you better get rid of the vehicle alltogether and straighten out your finances!!!*


*OK Lee Iacocca *


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## LeBlanc. (Jul 15, 2003)

*Re: (Strictly-European)*


_Quote, originally posted by *Strictly-European* »_
*OK Lee Iacocca *









LMAO http://****************.com/smile/emthup.gif


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## ramco2212 (Jun 17, 2004)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

I talked to a VW service tech who said the computer will compensate. I've used 87, 89 and 91 and can't really find any difference in performance of mileage. It won't kill the truck. Try it and see how it works.


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## 1stTREG (Aug 18, 2005)

Most people don't understand octane. Higher octane fuel simply does not ignite as easily as lower octane fuel. Lower octane fuel will not damage these motors. Lower octane fuel "could" pre-ignite and create a knock condition but the motor has knock sensors and will immediately work to pull back timing etc. to protect from this normally harmful condition. No danger in using lesser octane fuels, it "could" result in diminished performance because of the retarded timing. But there is no real danger of any damage.


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## Devoman (Aug 3, 2003)

*gas prices*

Lets just see what happens to gas prices after this hurricane.What does every think might happen?Another 30 to 60 cent addition or will it stay the same.Makes you kind of wonder.


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## LeBlanc. (Jul 15, 2003)

*Re: 89 Octane in V8 Touareg? (ramco2212)*


_Quote, originally posted by *ramco2212* »_I talked to a VW service tech who said the computer will compensate. I've used 87, 89 and 91 and can't really find any difference in performance of mileage. It won't kill the truck. Try it and see how it works.

We used 87 octane in our recent trip to Plymouth, MI from Chicago.
Perfect distance to perform an experiment:
It's around 290 miles. With 87 octane, we averaged 16.4MPG at 
an average speed of 59 MPH. With 93 octane on the way back
we averaged 19.4 at an average speed of 57 MPH.


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## jgkptreg (Apr 7, 2004)

*Re: 89 Octane in V8 Touareg? (N2N)*


_Quote, originally posted by *N2N* »_
We used 87 octane in our recent trip to Plymouth, MI from Chicago.
Perfect distance to perform an experiment:
It's around 290 miles. With 87 octane, we averaged 16.4MPG at 
an average speed of 59 MPH. 
With 93 octane on the way back
we averaged 19.4 at an average speed of 57 MPH. 








Tail wind . . .


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## mfriedman (Sep 27, 2003)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

You can run the T-reg on the lower Octane rated fuels and it will run just fine and not have any long term impacts. Octane rating does only one thing. It increases the fuel's resistance to auto-ignition (i.e. knocking). 
Auto-ignition occurs when the pressure of the fuel air mixture gets so high that the corresponding temperature causes the mixture to ignite on it's own, rather than being ignited by the sparkplug. When this happens the "knocks". 
Most modern engine management systems have knock sensors that listen for this "knocking". If they hear it they will retard the timing to prevent the auto-ignition from occuring. When the timing is retarded the engine runs in a less efficicent mode (safe, but inefficient)
The reason that the smaller turbo charged engines will see a significant drop off in mpg and performance is because the compression ratio is higher (also the turbo charger pressurizes the cyclinder before any compression even occurs) thus the auto-ignition is much more likely to occur, thus the retarding of the spark is more likely to occur. Compound this with the fact that one will notice a significant drop off of performance on a small engine.
All in all, I am not surprised that one would see a significant drop off of performance on the smaller turbo charged engines, and not on the Touareg. So go ahead and use the cheaper fuel.


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## Caribmon71 (Apr 22, 2005)

At the rate that fuel prices are increasing (seems daily) is it safe to say that it is more economical to put fuel in your car every day? Too bad no one has come up with some sort of "pre paid" gas card in which you prepay for a specific amount of gallons at the current price. Then you fuel up and gallons are just deducted from your card. Price increases wouldn't affect you untill your 1000 or 2000 gallons run out. Imagine. Gas today at last years prices... Bliss!. Wait, did I already post this? Sorry if I did. I haven't been keeping up as much lately. The less I'm here, the more I tend to like my Touareg.


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## cybulman (Dec 18, 2003)

So why have some of you SOB's been filling up with 89 for years and not told us???
Why did you let us waste all this money on 93???
Tch...tch...tch...scweinhunds!
Cy


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## spockcat (Jun 5, 2003)

*Re: (cybulman)*


_Quote, originally posted by *cybulman* »_So why have some of you SOB's been filling up with 89 for years and not told us???
Why did you let us waste all this money on 93???
Tch...tch...tch...scweinhunds!
Cy 

I have stated my prior 89 usage in the past. Just go back and check my posts.


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## cybulman (Dec 18, 2003)

*Re: (spockcat)*

Spock my dear man, you are soooo predictable...I knew you would respond wrt your numerous other posts. You never came out openly and told us to go 89!!!






















You are the undisputed "Leader of the VWhoretex Board" and not just in numbers of posts - but intellectually (on Egg issues only)...so you could have saved us all thousands of $'s and helped the oil import strategy of the USA.








Better late than never!








Cy


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## LeBlanc. (Jul 15, 2003)

*Re: 89 Octane in V8 Touareg? (mfriedman)*


_Quote, originally posted by *mfriedman* »_
The reason that the smaller turbo charged engines will see a significant drop off in mpg and performance is because the compression ratio is higher (also the turbo charger pressurizes the cyclinder before any compression even occurs) thus the auto-ignition is much more likely to occur, thus the retarding of the spark is more likely to occur. 

Just wanted to clarify that in T/C motors, the *cylinder pressure* is higher, not static compression ratio. Turbo motors generally run *lower* static CRs to reduce cylinder pressure, usually CRs of 8:1 to 9.5:1 (DI engines can run higher due to greater fuel stratification).
The high cylinder pressure is what makes T/C motor succeptible to *pre-ignition*. Pre-ignition is where fuel ignites before the spark plug fires. Pre-ignition is the cause of *knock* which is the audible result of pre-ignition. Auto-ignition refers to the spontaneous combustion of a fuel at a specific temperature.
Just wanted to clarify so that we don't get confused.
The TReg ECU will retard timing, making less power, making the engine less efficient, but will not allow pre-ignition to occur.


_Modified by N2N at 9:32 AM 8-31-2005_


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## YllwTRB (Feb 15, 2004)

*Re: 89 Octane in V8 Touareg? (N2N)*


_Quote, originally posted by *N2N* »_
We used 87 octane in our recent trip to Plymouth, MI from Chicago.
Perfect distance to perform an experiment:
It's around 290 miles. With 87 octane, we averaged 16.4MPG at 
an average speed of 59 MPH. With 93 octane on the way back
we averaged 19.4 at an average speed of 57 MPH. 

This is what I wanted to see. 93 Octane overall will give better fuel efficiency in the hightway. I will run tests to see what kind of MPG i get in city driving using 89 and 93.


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## rflor (Apr 11, 2000)

*Re: 89 Octane in V8 Touareg? (N2N)*


_Quote, originally posted by *N2N* »_It's around 290 miles. With 87 octane, we averaged 16.4MPG at 
an average speed of 59 MPH. With 93 octane on the way back
we averaged 19.4 at an average speed of 57 MPH. 

More importantly, how the $%$#$ did you manage 59 MPH on I-294/I80-90 leaving Chicago? Did you leave at 2AM on a Sunday morning to avoid the inevitable traffic?








Or did you average 90-100MPH once you got past the Indiana border?








Rik (who lives in Round Lake and has endured the full-brunt of I-294 traffic on a Friday afternoon)


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## YllwTRB (Feb 15, 2004)

*Re: 89 Octane in V8 Touareg? (rflor)*

I got caught on 80 West coming back from Michigan on Sat and let me tell ya. that was horrible. Driving in the middle of the night would be a much better option. It was stop and go for over 15 miles.
Horrible, horrible, horrible


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## NMoore (Jun 11, 2003)

*Re: 89 Octane in V8 Touareg? (mfriedman)*


_Quote, originally posted by *mfriedman* »_
Auto-ignition occurs when the pressure of the fuel air mixture gets so high that the corresponding temperature causes the mixture to ignite on it's own, rather than being ignited by the sparkplug. When this happens the "knocks". 
Most modern engine management systems have knock sensors that listen for this "knocking". If they hear it they will retard the timing to prevent the auto-ignition from occuring. When the timing is retarded the engine runs in a less efficicent mode (safe, but inefficient)


This is true, but is a _lot_ less than modern engine management systems do. There are a surprising number of temperature sensors that among other things measure the difference between the air temp at the intake and at the radiator.
When this is high, at low or no speed for example, the engine also richens the fuel mix considerably as well as retarding the spark to protect from pre-ignition. This combination of more gas and "less" spark at high temperatures (or specifically high underhood temps) can result in very rough running and/or stalling.
There is no question you lose performance and fuel _mileage_ for every step below 93 you go, including the 91 octane gunk we get out here. Figure 6-10hp for dropping into the 87-89 range on a V8. Since fuel _economy_ is the price differential times the mileage differential, it is not impossible that it pays to give up some power and reliability.


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## Caribmon71 (Apr 22, 2005)

I know this is an old thread, but I was bored and just wanted to chip in. Touareg states 91 octane minimum. If your engine is clean and working normal, then adding 93 over 91 won't do didley squat for you or your car. Only wastes your money. It won't give you better mileage or power, unless you do something else, like raise the compression or advance the timing some. The octane rating - as has already been established here - is only a quantitative measure of a gasoline's ability to resist spontaneous combustion caused by hight temperatures.
There really are about 5 things that determine whether your car will knock or not:
-Cylinder pressure (compression) (lower prevents)
-Cylinder Temperature (affected by compression, due to boyle's law) (lower prevents)
-Fuel Mix ratio (richer prevents)
-Timing (retarded prevents)
-Octane rating (higher prevents)
You may be able to get away with lower octanes, like 90 or 89, but as you go lower, you risk knocking. The sensors in these cars (as far as I know) only act when they "hear" knocking occuring. Not before it happens. So even if your engine compensates for knocking by retarding the timing, your engine has already knocked. That's never a good thing.
To the person who stated that only pre-ignition causes knock, that's not entirely correct either. Knock can be caused by pre-ignition or auto ignition. Preignition does not usually occur due to high cylinder preassure alone. Something else (usually a very dirty engine with a lot of deposits acting like hot coals or spark plugs of the incorrect temperature range) is usually present to increase the temperature further than just the high pressure itself.
As is the case with auto ignition. The fuel mix doesn't just auto ignite due to the high pressure alone. If that were the case, retarding the timing wouldn't help any. In fact, it would be pointless. What raises the temperature high enough to contribute to auto ignition is the heat generated by the advancing flame front from the mixture that has already been ignited by the spark plug (which in turn increases the pressure further). Combustion occurs from around the sparkplug to the rest of the cylinder. Imagine making a line with gunpowder. When you light one end with a match, the flame travels along the line. The gunpowder at the end will only ignite once the flame reaches it. That's what happens inside the cylinder. If it got hot enough, then the rest of the line might spontaneously ignite. Inside a cylinder, this causes an uncontrolled explosion. In other words, you have two explosions and a violent shockwave. That's what you hear as knocking.
Ideally, the entire fuel mixture would all ignite at once upon the spark going off, thus allowing the spark to go off right at TDC, which is where we'd get the most power. That is not the case, and that is why timing is advanced slightly (at the factory), in order to allow the entire mixture to have ignited by the time the piston reaches TDC. 
When you retard the timing, since the piston is already on a downwards travel when the spark goes off, the cylinder pressure has decreased, thereby eliminating the chance of auto ignition. I assume that pre-ignition is harder on engines because the piston is racing towards the explosion that just occured, where as in auto ignition, the piston is practically at the top. I guess there's more chance of bending rods and stuff like that with a pre-ignition situation.
As our Touaregs get older, they will probably require higher octane ratings to compensate for deposits in the engine and other factors, I assume. But right now, 91 is just right and I guess that 89 or 90 won't hurt much either. Yes, lower performance, but as long as it don't knock, it should be ok. I don't know about 87 or stuff lower than that at sea level. Live up way high? Then put rat piss in it if you can get it to ignite. You should be ok.
Who knows, maybe I'm completely way off. Heck, I was with the over steer - under steer issue. Maybe I got this backwards also!

_Modified by Caribmon71 at 2:37 AM 9-28-2005_

_Modified by Caribmon71 at 2:46 AM 9-28-2005_


_Modified by Caribmon71 at 2:54 AM 9-28-2005_


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## chessmck (Dec 22, 2003)

*Re: (Caribmon71)*

Here is my 2 cents from days of long ago when I actually adjusted my own timing. By the way, the timing changes all the time to match engine speed as the explosion of the gas is more of a fixed time, so the faster the engine runs, the earlier the spark needs to occur...
The higher the octane the slower the gas burns giving you a smoother and longer power "moment" and more energy transfer. Therefore you need the spark to occur a little before TDC - just before the piston completes its compression cycle to take advantage of the full burn. (BTC - before top dead center)
Regular gas burns faster and has less energy which means you need to fire the spark "later" than when using premium to prevent the resulting explosion from occurring while the piston is still compressing the gas. Otherwise you have the knock which is basically the piston being driven back while it is still trying to go up.
As long as the engine computer adjusts the timing correctly, using regular should give you less power and less MPG. In cars that do not have the higher compression or wide computer timing adjustment range - they may not be able to change the spark enough to take advantage of the higher octane - meaning if you put premium in, your wasting your money.
So don't put premium in something that is mostly manual spark and set up to use regular - like an older lawn mower or you may actually have less power than with regular.....


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## Caribmon71 (Apr 22, 2005)

If what you are saying were completely correct, the engine would know the difference between one octane rating and another to adjust the timing. They don't know the difference. Timing is retarded when the sensors (microphone type) "hears" knock occur.
Knock can, theoretically, occur at any point in the piston's travel. The sound you hear is not the piston. The sound you hear is the sound of the pressure wave created by the uncontrolled explosion characteristic of knock, either due to preignition or detonation.


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## chessmck (Dec 22, 2003)

*Re: (Caribmon71)*

Thanks for the comments - I agree that the engine does not "know" the Octane, and uses its knock sensors to change timing. I also did not add that higher octane fuel requires a higher temp to self ignite. And I also left out that suggested octane rating is normally tied to the compression ratio of the engine as a higher compression creates higher temp in the cylinder. I believe what I originaly said will hold true in the cases where the octane rating ranges your dealing with is high enough that self ignite will not occur - say in the case you used 100 octane, you may want to advance the spark.
This also relates to why you can run a lower octane at high altitude - air is thinner creating less preassure in the cylinder (even though the compression ratio is always the same) as you start with a lower air pressure.
As to the sound - I think there are 2 levels of knock - a weak knock and a strong knock - when it sounds like pieces are flying out of the engine. That strong knock is more than just the uncontrolled explosion. However I must admit, I have not heard that sound in a few years as the computer systems do a great job. I guess last time I heard it was on my old 1970 Road Runner when I set the timing wrong....


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## anthem1 (Oct 3, 2005)

*Re: 89 Octane in V8 Touareg? (Strictly-European)*

I have been using 87 oct in my V-8 Touareg for sometime see no differance but i ad a bottle of a $2.00 octane boost you dont really save that much but a couple of dollars not worth it.. Just hate paying these prices...


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## Caribmon71 (Apr 22, 2005)

*Re: (chessmck)*

I just know the theory. I was just an engineering student for some time, I'm no mechanic. I wouldn't know knock if it knocked me over the head.


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## matthewsjl (Mar 23, 2004)

*Re: 89 Octane in V8 Touareg? (anthem1)*

The cost issues put aside for a moment, the car is continually varying the ignition timing based on multiple factors. Get your VAG-COM out and look at the measurement blocks for the engine. Each cylinder is monitored and the ignition timing controlled independently.
I'm sure that the engine doesn't know as such what octane has been put in the tank but it does make adjustments to the engine running on the fly based on the numerous sensors. I'm pretty sure that the engine would know something isn't right and try and adjust before the knock sensors.
Anyway, I've been running my Golf VR6 and Touareg V6 on regular 87 for a while. There is a slight drop in performance but mileage seems to have remained the same.
Meatster said a while ago that he tried running his V8 on 87 and scanned it with a VAG-COM. He found a 'Knock sensor - limit exceeded' code for the engine with no dash or warning notification for the driver. As for me, I've scanned both cars and not had any codes thrown on the regular gas.
If you're running on regular and have a VAG-COM, it may be wise to scan








John.


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## spockcat (Jun 5, 2003)

*Re: 89 Octane in V8 Touareg? (matthewsjl)*


_Quote, originally posted by *matthewsjl* »_The cost issues put aside for a moment, the car is continually varying the ignition timing based on multiple factors. Get your VAG-COM out and look at the measurement blocks for the engine. Each cylinder is monitored and the ignition timing controlled independently.
John.

I can't find my ignition timing or my knock snesor?


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## matthewsjl (Mar 23, 2004)

*Re: 89 Octane in V8 Touareg? (spockcat)*

There's always one ;-)
Still, this late, I did have to read it twice








See you in NH.
John.


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