Premium gas in 1.8L TSI?!

[buyingconstant7]

So my 1.8t has 16,500kms on it now, I've been strictly running Shell 87 octane. I'm satisfied with performance and fuel economy, but does anyone have experience or firsthand knowledge of putting 91 octane in the new 1.8t? Does it benefit fuel economy and performance by a big margin? Or should I stick to regular? I know in the 2.0t, premium fuel makes a big difference, so I don't know if the same would apply to the 1.8t. Please help!

 

[plat]

According to the VW.ca website, the MK7 Golf's 1.8L TFSI Engine run on Regular Unleaded fuel.

However, the VW self study guide for the EA888 1.8L TFSI 118kW Engine found here: http://vwts.ru/engine/byt/byt_bzb_1_8_tsfi_eng.pdf

says on Page 5, that the engine 98 to 95 Octane fuel but it is possible to use 91 Octane with a loss of output power. Keep in mind that this self study guide is the European version which means those fuel octane numbers translate to 93 to 90 AKI as optimum and 87 AKI as possible but with loss of power. AKI or Anti Knock Index is how North America rates fuel octane.

Also, keep in mind that this manual is for the EA888 engine with 118kW output and not 125kW which is the one fitted in North American MK7 Golf models. But, both are the same EA888 type engine.

So, to answer your question, it may be possible that using 91 AKI fuel will make your engine output more power. Go try a couple of tanks and see how it feels. There's certainly no harm in doing so.

 

[raimo_81]

Running a tank of 87 as we speak, had the car 1 week. Gonna run some 91 and report findings


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[Sexysoxy]

I'm running American 93 grade and it's a good power difference from 87, I get up to 40mpg with 93. But I've only ran 87 2 times so I'm not sure a out the mpg gains.

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[monochrome]

When switching between different fuel grades (87, 91, 93, 91 ethanol free, etc.), does the ECU adjust immediately or does it take a couple tanks before you would notice MPG/performance increase?

 

[raimo_81]

I would be surprised that it would adjust at all. My u understanding is that the engine is tuned to work optimally with a certain fuel grade and performs better or worse with different grades. At some point, a low octane fuel will make the engine underperform and maybe even give problems. But on the other spectrum, there may not be a point in using gas with overly high octane if the engine is not tuned to take advantage of it, however unless you put jet fuel you shouldn't be harming the engine either. I suppose that finding the right octane fuel is best, without any overkill. For a 1.8t, I have been recommended 91 octane (in Canada). Supposed to actually make a little more power than 87, while even reducing the minimal lag at takeoff from stop. Can't wait to burn through this tank and try. However, I have been told that there is a slight adjustment period until you actually notice a difference, need to fully burn out the older fuel and clean up the system with the higher octane fuel before you can see a difference.


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[nprofitt]

I'm currently running a tank of Shell 93, I had been running 87 up until this point (for about 8,000 miles and often Speedway rather than Shell).

I have noticeably smoother idle with the Shell 93 at least. Not sure about any perceivable increase in power.

 

[xPETEZx]

Not this shit again.....
You won't tell the difference.
On a GTi it's at best 7bhp... On a 1.8t probably nothing at all.

Hell, I can't tell in my R...

Wait for everyone to jump in and tell you putting 87 is like putting piss in the tank and you are but a tank away from engine failure.

Take a look at the other topic when this came up last week.
Posted a video test in there showing the f all difference it makes.

Keeping filling 87 and save a few dollars.

Of try 91/93 and see if you can tell.
I ran 10 consecutive tanks of premium and got exactly the same miles to a tank and the same mpg. Also didn't notice any difference at All in power.

 

[raimo_81]

I think it will be harder to tell in a 2.0t since it is already tuned to take advantage of the higher octane. You would be doing your engine a great dissatisfaction by using 87 octane and also going against manufacturer recommendation. In a 1.8t, I can see how a slight increase in octane would justify slight gains in power and consumption. Slight. Like as slight as better idle or slightly reduced lag. I wouldn't expect the change to improve 0-60 times noticeably


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[PLF8593]

Yeah if you have the 1.8, stick to 87. It's not a "high output" motor anyway. If you're sticking with Shell 87, then it'll be quality fuel so you won't need to worry.

 

[raimo_81]

There is also a school of thought that would tell you never use 87 on a turbo engine, since it's already higher compression than naturally aspirated.


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[PLF8593]

There is also a school of thought that would tell you never use 87 on a turbo engine, since it's already higher compression than naturally aspirated.


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Yes, but the relatively "high output" 2.0L GTI engine says ON THE FUEL CAP "87 required, 91 recommended." If the higher output GTI engine can take 87 (bc ECU copes with lower octane), the already-lower output 1.8L, smaller turbo engine can definitely take 87 with no problem. It's an everyday commuter car, not a performance car (the Golf, not the GTI). They designed it to run on regular just fine, but if you WANT to use premium it OBVIOUSLY won't hurt it.

 

[nprofitt]

I stand by my comments regarding smoother idle with Shell 93.

I will try Shell 87 next time and see if it's just the difference between Top tier fuel vs. Speedway rather than the octane difference...

 

[scott091981]

Owning a 1.8 and trying them all you do notice a difference in power with 93. I have found shell 93 best, Chevron 2nd best.

 

[monochrome]

At this point, I've run about 12 - 13 tanks total with 3 tanks on 91 ethanol free. I actually returned one of my worst tanks with the 91 e0 (~30mpg) and it was 75% highway driving. Didn't notice any power increase on the butt dyno with the 91 tanks, and it seemed to stutter more than usual at idle.

At this point, I honestly think the more important factor for performance is buying quality gas when available. My most recent 87 e10 tank was from Mobil, so I'm hoping to see a slight increase in MPG with Top Tier.