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Volkswagen GTI Engine Problems

82 messages,  Last post on Jun 08, 2011 at 10:34 AM

You are in the Volkswagen GTI Forum.

What is this discussion about? Volkswagen GTI, Engine, Hatchback

Messages Page 7 of 9

#53 of 82 Re: 2007 GTI - Fuel Requirements [eneko] by eldaino

Jun 13, 2007 (6:10 am)

Replying to: eneko (Jun 13, 2007 12:21 am)
this is what i thought it was.

#54 of 82 Re: 2007 GTI - Fuel Requirements [eneko] by geeteeeye

Jun 13, 2007 (12:07 pm)

Replying to: eneko (Jun 13, 2007 12:21 am)
You're way off. The only thing you got right is that octane is a hydrocarbon. Don't think of gasoline as a pure substance. It is a blend of many hydrocarbons that are produced through many different processes in an oil refinery plus other synthesized flammable chemicals that are partly petroleum based. The straight, pure, hydrocarbon component of gasoline that you're referring to is usually less than 50% (of which iso-octane is only one example of).
 
Iso-octane (and other anti-knock chemicals) is considered an additive because it is added such that a specific "octane rating" is acheived, unlike the base blend of gasoline in which the specific blend of hydrocarbons is not as crucial.
 
The octane rating of gasoline doesn't mean that the only anti-knock component is iso-octane, just that it has the same anti-knock characteristics of a reference blend of, say, 87% iso-octane and 13% heptane (to refer to an "87 octane" gasoline). This is what you were getting at when you said the octane rate was a reference to the proportion of different octanes in the fuel (but this is incorrect).
 
Also, all gasolines in a high performance engine will "burn at the right moment." But a fuel with the proper octane rating for the engine means that it will combust when the cylinder is at its highest pressure. That's where you get your engine performance. Lower octane-rating gasolines will work fine, because the engine's computer will alter the timing so that it prevents any knocking.

#55 of 82 Re: 2007 GTI - Fuel Requirements [600kgolfgt] by vvk

Jun 14, 2007 (11:26 am)

Replying to: 600kgolfgt (Jun 08, 2007 7:05 pm)
Every car I have owned got 1-2 mpg better mileage on regular vs. premium.
 
I still use premium because a) my BMW requires premium and b) my SAAB engine runs a lot smoother and quieter on premium.

#56 of 82 Re: 2007 GTI - Fuel Requirements [geeteeeye] by 600kgolfgt

Jun 17, 2007 (6:38 am)

Replying to: geeteeeye (Jun 13, 2007 12:07 pm)
Just saw this little blurb on Consumer Guide's evaluation of the Passat:
 
"VW requires premium-grade fuel for the 2.0T and recommends it for the V6."
 
F.Y.I.

#57 of 82 Re: 2007 GTI - Fuel Requirements [600kgolfgt] by geeteeeye

Jun 18, 2007 (3:34 pm)

Replying to: 600kgolfgt (Jun 17, 2007 6:38 am)
Hop on over to the GTI section of Consumer Guide and it says:
 
"Test GTIs averaged 16.8-19.1 mpg with manual transmission, 23.6 with SMT, both in slightly more highway travel vs. city driving. VW recommends premium-grade fuel."

#58 of 82 Re: 2007 GTI - Fuel Requirements [geeteeeye] by fasterthanyou

Jun 18, 2007 (6:40 pm)

Replying to: geeteeeye (Jun 18, 2007 3:34 pm)
Test GTIs averaged 16.8-19.1 mpg with manual transmission, 23.6 with SMT, both in slightly more highway travel vs. city driving. VW recommends premium-grade fuel."
 
That is a complete aberration. I drive my GTI hard at 4-5000 rpm every day. I get 25-26 mpg with manual transmission mixed city and highway. EPA figures are 32 highway and 24 city. The FSI technology used in the GTI makes for the most fuel efficient engines in present time. It is the most fuel efficient car in its segment

#59 of 82 Re: 2007 GTI - Fuel Requirements [fasterthanyou] by eldaino

Jun 20, 2007 (7:03 am)

Replying to: fasterthanyou (Jun 18, 2007 6:40 pm)
it is one of the more fuel efficient cars in its class, but driving that hard sounds a little hopeful for your mpg.
 
just because your numbers and their numbers are slightly off doesn't mean its an 'aberration'. its not a diesel you know.

#60 of 82 Re: 2007 GTI - Fuel Requirements [geeteeeye] by 600kgolfgt

Jun 20, 2007 (1:50 pm)

Replying to: geeteeeye (Jun 18, 2007 3:34 pm)
Hop on over to the GTI section of Consumer Guide and it says:
  
"Test GTIs averaged 16.8-19.1 mpg with manual transmission, 23.6 with SMT, both in slightly more highway travel vs. city driving. VW recommends premium-grade fuel."
 
Check out this AutoChannel.com road test of the GTI:
 
http://www.theautochannel.com/news/2006/07/07/014005.html
Fuel Requirement 91 octane unleaded premium gasoline
 
And from VW's own technical specifications:
 
http://media.vw.com/press_files/text/GTIT.S..pdf
 
Check the Fuel Requirement section: It will say 95 RON Premium for Maximum Performance & 91 RON for a slight reduction in performance.
 
Most VW mechanics I've talked to said that using anything other than premium (91 RON or above) in a forced-induction engine is asking for trouble ($$$$)...

#61 of 82 Re: 2007 GTI - Fuel Requirements [600kgolfgt] by geeteeeye

Jun 20, 2007 (5:41 pm)

Replying to: 600kgolfgt (Jun 20, 2007 1:50 pm)
We're talking about requirements vs. recommendations. All the technical data you've pointed to has put the requirement at 87 octane gas (91 RON). Everyone understands that you will get better performance with higher octane gas. But until I hear otherwise from some official document, I won't believe that I'm damaging the engine if I use 87 octane gas.
 
Also, VW is technically saying that Mid Grade (91 (R+M)/2, not 91 RON) is the recommendation.
 
Lastly, if you crunch the numbers, you're still saving money by using 87 octane even if you get lower gas mileage using 87 octane. You'll have to get better than 2 mpg better using 93 octane gas to break even.

#62 of 82 Re: 2007 GTI - Fuel Requirements [geeteeeye] by 600kgolfgt

Jun 21, 2007 (5:10 am)

Replying to: geeteeeye (Jun 20, 2007 5:41 pm)
But until I hear otherwise from some official document, I won't believe that I'm damaging the engine if I use 87 octane gas.
 
Ok. It's your money and your car. Ben Franklin has a saying about money, too. All I have to say is I wish you well...

Messages Page 7 of 9

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