Regular VS Premium Gas - Page 3 - Club Touareg Forums
Club Touareg Forums  

Go Back   Club Touareg Forums > Club Touareg Community Forums > Touareg Reviews

Join Forest River Forums Today


Reply
 
Thread Tools Display Modes
Old 03-22-2012   #21
Moderator
 
nickm's Avatar
 
Touareg: 2013 V6 TDI
Join Date: Oct 2006
Location: North of the 45th
Second Vehicle: too many to list
Posts: 8,689
Quote:
Originally Posted by smallblock View Post
This. ECU knock control strategies pull timing and may even add fuel. This increases net fuel consumption. It is at best a wash, possibly an increase in total fuel cost. Run the minimum the manufacturer specifies, unless you're chipped (generally advanced timing, leaner mixtures) and/or running higher boost on a turbo car (non-issue for gas Touaregs, but my Scooby FXT never sees less than 93, since it's far from stock).
Good point on the ECU adding fuel to prevent knock, it does this to richen the mixture making it more difficult to combust - preventing knock.

__________________
-------------------------------------------------
2013 Touareg TDI Black Pearl / Titan Black
--PREVIOUS TOUAREGS:
'09 TDI, '07 V8 FSI, '04 V10 TDI, '04 VR6
nickm is offline   Reply With Quote Quick reply to this message
Old 03-22-2012   #22
Touareg Guru
 
Touareg: Still looking
Join Date: Apr 2009
Location: Qc, Canada
Second Vehicle: too many to list
Posts: 7,172
Quote:
Originally Posted by smallblock View Post
This. ECU knock control strategies pull timing and may even add fuel. This increases net fuel consumption. It is at best a wash, possibly an increase in total fuel cost. Run the minimum the manufacturer specifies, unless you're chipped (generally advanced timing, leaner mixtures) and/or running higher boost on a turbo car (non-issue for gas Touaregs, but my Scooby FXT never sees less than 93, since it's far from stock).
I have to be quite honest, there is but one thing that I have never quite entirely understood.
Let's take my AXQ V8 engine as the example. In stock form, 91 AKI(95 RON for you Europeans) is required to make full use of the documented stock 310HP. When chipping this engine with any of the reputable off the shelf chip makers out there, average peak HP is usually bumped up to 330HP, basically a 20HP increase. Timing is advanced at partial throttle maps, fuel is enriched as well at WOT along with timing advance. The recommended fuel by the chip manufacturers still remains the same as the stock factory fuel octane requirement at 91 AKI (95 RON). Why does the fuel requirement stay the same on these off the shelf "Stage 1" tunes? Now I'm no expert, hence why I'm asking, although I have my theory. Anyone want to take a stab at this and explain it to me?

__________________
volkswagendude is offline   Reply With Quote Quick reply to this message
Old 03-22-2012   #23
Moderator
 
nickm's Avatar
 
Touareg: 2013 V6 TDI
Join Date: Oct 2006
Location: North of the 45th
Second Vehicle: too many to list
Posts: 8,689
Because octane measures a fuels resistance to combustion...the octane need comes from compression ratio, piston crown design and head design. If you do modifications such as running a thinner head gasket, milling your head, or installing high compression pistons you are raising your compression ratio and hence increasing your octane need.

as you know diesels ignite their fuel mixture via heat of compression, in the old diesel days that was done via compression ratios of 22:1, with modern CRDs (that atomize the fuel) its more like 16:1....take a modern gas engine, a high output one will run a 12:1 compression ratio, it needs 91 octane such that it doesn't knock (which is really dieseling, its the mixture lighting up before the spark)...

tuning an engine via software changes nothing when it comes to heat of compression - so no need to change octane rating...all it does is richen the fuel mixture and messes with the timing a bit. Rich mixture = bad for emmissions, which is why most vehicles are tuned super lean (lotsa air, not so much fuel). Since a rich mixture will resist ignition more than a lean mixture (more fuel to ignite, the mixture is "wetter") your octane requirement should technically drop - not increase.

So recap octane measures a fuel's resistance to ignite - that's it. It doesn't mean 94 octane is more powerful than 87, or that its cleaner, or that its better, it just means that 94 will be more resistant to igniting under heat of compression than 87 will.

heat of compression is how a diesel engine runs, it is also what can destroy a gas engine.
__________________
-------------------------------------------------
2013 Touareg TDI Black Pearl / Titan Black
--PREVIOUS TOUAREGS:
'09 TDI, '07 V8 FSI, '04 V10 TDI, '04 VR6
nickm is offline   Reply With Quote Quick reply to this message
Old 03-22-2012   #24
Touareg Guru
 
Touareg: Still looking
Join Date: Apr 2009
Location: Qc, Canada
Second Vehicle: too many to list
Posts: 7,172
Ok. I understood and agree. But perhaps I should have thrown this example in the mix as well. A 87-91 BMW with a low by today's standards of 8.8:1 compression with its inline 2.5L six, is required per mother ship to take min 87AKI regular unleaded fuel. However, when you chip it with either of the most popular choices(comforti or dsylva) to gain a measly 15-16 peak HP at best, 91 octane is suddenly required, otherwise it will ping, and trust me that it will. Those Motronic units also had no knock sensors might as well point that out if it means anything as far as the final answer to my question might be concerned.

It is really the above known example versus the Touareg example I threw in the previous post, that the question was really being based on.
__________________
2005 Touareg V8: Sold but not forgotten.
volkswagendude is offline   Reply With Quote Quick reply to this message
Old 03-22-2012   #25
Touareg Enthusiast
 
zosocane's Avatar
 
Touareg: 2012 V6 TDI
Join Date: Jan 2012
Location: Florida USA
Second Vehicle: Still looking
Posts: 228
I will stir the pot some more ...

Consumer Energy Center - Information for the consumer about Saving Energy from the California Energy Commission / transportation / consumer tips / REGULAR VS PREMIUM

REGULAR VERSUS PREMIUM GASOLINE
Regular Gasoline Has As Much Merit As Premium Gasoline
"Put a tiger in your tank," says a classic advertising tagline. In today's motoring world, what kind of fuel grade will have the power to place a beast in your gas tank?

The answer, according to experts who study fuel efficiency in detail, is both regular and premium gasoline. And it would be a waste of money to favor premium over regular, especially in these times when gasoline prices are high, according to the experts.

Virtually nothing is gained by filling up with a premium or more expensive grade of fuel than the vehicle manufacturer has recommended, the experts say. And many of the same experts explain that drivers may not lose much performance from their cars by using a lower grade of fuel than recommended by the car manufacturer.

There is little difference in energy content of regular versus premium gasoline. They both contain about 111,400 British Thermal Units of energy per gallon.

The price difference, however, between the fuel grades is anywhere from 20 cents to 40 cents, depending on where you live in the United States. The experts' consensus goes against the long-held belief by thousand of drivers who fill up with premium only, or on every third or fourth trip to the pump. The idea is to fill up with premium every so often to clean out the engines or rev up the performance of older engines.

But according to the experts, this practice is like tossing quarters in a wishing well, since most engines are designed to operate on relatively low-octane regular unleaded gasoline.

Octane is defined as a fuel's resistance to knocking. There is no benefit if the octane is higher than what the engine needs. Engine knock occurs when fuel in a combustion chamber ignites before it should. This disrupts the engine's operation. But electronic knock sensors are now common and have nearly eliminated engine disruption.

The American Petroleum Institute says if you find that your car runs fine on a lower grade, there is no sense switching to premium. The Institute recommends following manufacturer's recommendation, but even those manufacturers say that it is more of a suggestion than a command.


For more about this subject, see the excellent article "Fact or Fiction?: Premium Gasoline Delivers Premium Benefits to Your Car Exploding the myth that premium gasoline delivers better performance in the average automobile" by David Biello on Scientific American's website at: Fact or Fiction?: Premium Gasoline Delivers Premium Benefits to Your Car: Scientific American ("But for standard cars on the road today, purchasing premium gasoline is simply paying a premium for a fuel that delivers no added benefits. "If you think you need it," Green says, "you're being very eccentric.")
__________________
2012 Volkswagen Touareg TDI Lux
2003 Infiniti Qx4 (retired)
2000 Nissan Pathfinder (retired)
1996 Nissan 240SX (retired)
1993 Nissan Pathfinder (retired)
1979 Toyota Celica (retired)
zosocane is offline   Reply With Quote Quick reply to this message
Old 03-22-2012   #26
Touareg Guru
 
Touareg: Still looking
Join Date: Apr 2009
Location: Qc, Canada
Second Vehicle: too many to list
Posts: 7,172
To the above post^^^^^, yes you will not really feel (average Joe butt dyno) the decrease in HP by adding lower octane fuel than stated on your fuel filler door, but do be clear, that if you were to put your vehicle on a dyno, the HP would be less than the HP figure listed in the owners manual, due to timing retard by the knock sensors, to compensate for the lowering of standards by the end user, for what the product was initially designed around.

Just realized that is one long sentence , the heck with editing.
__________________
2005 Touareg V8: Sold but not forgotten.
volkswagendude is offline   Reply With Quote Quick reply to this message
Old 03-22-2012   #27
Touareg Mechanic
 
Perry01's Avatar
 
Touareg: 2008 V8
Join Date: Jan 2011
Location: Hawaii and Utah
Second Vehicle: is not a VW
Posts: 1,133
Images: 9
Bottom line is that the the manufacturer of the gasoline Touareg (VW) recommends PREMIUM fuel. If you want to go against the manufacturer's recommendation, go right ahead.

When you get a tune, one of the things done to increase performance is to advance the timing. To prevent detonation, high octane fuel is needed.
__________________
----------------------------
2008 V8 CAMPANELLA WHITE
NAV, 4 ZONE CLIMATE, DYNAUDIO, BI-XENON
KEYLESS ENTRY/PUSH BUTTON START
LEISTUNG CUSTOM EXHAUST AND CAT BYPASS
----------------------------
2008 AUDI A4 S-LINE
----------------------------
2004 TOUAREG V8 (SOLD)
Perry01 is offline   Reply With Quote Quick reply to this message
Old 03-23-2012   #28
BANNED
 
Touareg: 2004 V8
Join Date: Jun 2006
Location: SW Missouri
Second Vehicle: Other
Posts: 2,818
I just traded my V8 for a Hummer H2. Everybody asks how much gas does it use.
I say about 11.5 mpg on a gallon of 87 octane.
I also add that I used to have a midsize VW with V8 that consumed 14 mpg but requires 91 octane.
I you do the math it does not make much of a difference anymore in the cost per mile in the end.
With the VW I never was questioned, with the H2 I get questioned on a regular basis. I think about putting a hybrid emblem on my Hummer and say it does 20 mpg (downhill)
__________________
nltomba is offline   Reply With Quote Quick reply to this message
Old 03-23-2012   #29
Touareg Enthusiast
 
Touareg: 2006 V8
Join Date: Sep 2006
Location: Wytheville VA
Posts: 190
2006 V8. Here is my comparison. YMMV. Ethanol free gas is hard to find.

93 no ethanol - runs great.
87 no ethanol - runs ok. 10% less mpg.
93 w/ ethanol - runs ok. 10% less mpg.
87 w/ ethanol - runs poor. 15% less mpg.
__________________
nickyt is online now   Reply With Quote Quick reply to this message
Old 06-13-2012   #30
Touareg Enthusiast
 
Touareg: 2004 V8
Join Date: May 2006
Location: Markham, Ontatio
Posts: 103
Quote:
Originally Posted by pardesi View Post
In reality, I can tell you I have a 2004 V8 and have always run premium and done maintenance by the book. Never had an issue with the engine although once in a blue moon it will do somehitng that will make my heart stop and then go away. So far it has 145,000 km's on it. My Uncle however has putting regular in his 2004 V8 since he bought it. He has 260,000 Km's on it. It pulls just as good as mine, but you can tell when you drive it there something different. I dont know if its the age, the gas or the fact he drives it harder, but in terms of things breaking.. so far nothing. His maintenance isnt by the book like mine, but I guess you could says he gets it done.
An update to the regular versus premium gas "experiment" that I talked about before about my uncles 2004 V8. The engine died last night at 265,000 km's. The shop looking at the Treg said it was related to low oil pressure.

__________________
'04 V8 - Air Suspention - Alpine - Dynaudio - Soundstream - Fully Loaded
'06 Toyota Highlander - Panoramic Moonroof
'03 BMW X5 V6 - SOLD
'03 Nissan 350Z - SOLD
'95 Ford Mustang - SOLD (Sorely Missed)
pardesi is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Club Touareg Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Regular gas in 2006 Touareg V6 AKHDZ General Maintenance & Repair 4 09-02-2010 07:42 AM
premium vs regular salvo82 General Maintenance & Repair 6 02-09-2009 05:42 PM
Regular gas on an 08 V6 siberian General Maintenance & Repair 24 09-12-2008 11:20 PM
Premium vs. Regular Gas routertyty General Maintenance & Repair 1 09-25-2004 10:11 PM
Regular gas Vs Premium jmontoro General Maintenance & Repair 1 03-23-2004 09:04 AM




Upgrade your Account

» Featured Product
» Auto Insurance


All times are GMT -6. The time now is 05:27 PM.


Social Knowledge Networks
Volkswagen Touareg is copyrighted and trademarked to Volkswagen AG.
ClubTouareg.com is not in any way associated with the Volkswagen AG.

VW Touareg News Delivered to your Email!

Stay up-to-date with Touareg news in your inbox.

unsusbcribe at anytime with one click

Close [X]