General Octane question
07-31-2017, 02:10 PM
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General Octane question
So the 2.0 recommends 91. So, we'll just call it Premium.
I assume my motor is also the GTI motor. Anyone know if all older Dubs take Premium? Or does the 1.8 just need 87?
Yes, I know they will all run on 87. I don't like how mine runs on 87 and I follow the book anyways.
I really enjoy the power of the 2.0, enough so that I'd consider getting a GTI if one came along for the right price. Only Jetta I ever owned was an '85 NA diesel. After being very dissapointed in the fuel mileage, a nice condition gasser seems just as tempting. Even a 1.8 would be fine, I heard they get in the 30's mpg-wise thus my octane question.
I assume my motor is also the GTI motor. Anyone know if all older Dubs take Premium? Or does the 1.8 just need 87?
Yes, I know they will all run on 87. I don't like how mine runs on 87 and I follow the book anyways.
I really enjoy the power of the 2.0, enough so that I'd consider getting a GTI if one came along for the right price. Only Jetta I ever owned was an '85 NA diesel. After being very dissapointed in the fuel mileage, a nice condition gasser seems just as tempting. Even a 1.8 would be fine, I heard they get in the 30's mpg-wise thus my octane question.
08-02-2017, 06:25 AM
#2
VWs and Audi four cylinder engines with CIS fuel injection have an 8.5:1 compression ratio and vacuum/mechanical ignition advance, 87 octane is fine, adequate, no gains available by running higher octane
Later VWs 1.8 and 2.0 are entirely different and have digifant fuel injection. These 2H and ABA engines have a significantly higher compression ratio at 10.0:1, they also have knock sensing ignition and completely electronically controlled ignition advance. These engines need and preform better with 91+ octane fuel.
So if your engine has a knock sensor then you have digifant fuel injection and a high compression engine. You need the higher octane fuel and the "base" ignition timing is set with a very exact prescribed ritual with a timing light. Once that is set correctly fuel economy is very good..maybe 30mpg is possible.
I have attached a PFD on page two and three it talks about how to set the timing correctly.
Later VWs 1.8 and 2.0 are entirely different and have digifant fuel injection. These 2H and ABA engines have a significantly higher compression ratio at 10.0:1, they also have knock sensing ignition and completely electronically controlled ignition advance. These engines need and preform better with 91+ octane fuel.
So if your engine has a knock sensor then you have digifant fuel injection and a high compression engine. You need the higher octane fuel and the "base" ignition timing is set with a very exact prescribed ritual with a timing light. Once that is set correctly fuel economy is very good..maybe 30mpg is possible.
I have attached a PFD on page two and three it talks about how to set the timing correctly.
08-03-2017, 05:58 PM
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Word.
Thanks! You Sir are the definition of Precision.
I do indeed have a knock sensor. So I suppose that explains why an 88 2.0 prefers Premium.
Well technically 'I' don't have one as of today; The gentleman who posted new awhile back now officially owns my car.
The 'wife' and I found out we could afford a 2011 Volvo meaning I no longer had justification to own a 30yo Audi.
It was fun while it lasted.
I'll read through that stuff as I still have interest in these motors. Maybe I'll start getting some and fixing them up for some actual profit. Just need to turn off my 'new car-GO NUTS- instinct.
Thanks! You Sir are the definition of Precision.
I do indeed have a knock sensor. So I suppose that explains why an 88 2.0 prefers Premium.
Well technically 'I' don't have one as of today; The gentleman who posted new awhile back now officially owns my car.
The 'wife' and I found out we could afford a 2011 Volvo meaning I no longer had justification to own a 30yo Audi.
It was fun while it lasted.
I'll read through that stuff as I still have interest in these motors. Maybe I'll start getting some and fixing them up for some actual profit. Just need to turn off my 'new car-GO NUTS- instinct.
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