Premium fuels. Hidden benefit

Simon

Simon

Simon

Caporegime
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Another fuel thread reminded me of this.

Took these photos at Geneva motorshow this year. The car is an Audi S4 with two fuel systems

One half is premium fuel with extra cleaning. The other is EN228 minimum spec fuel.

Car was bought on 50k km and run an additional 5k km after the fuel system modification. Endoscope in each half of the engine:

2E5A8ABF-0DB3-4B92-94FE-5BD46D90C4E5_zpsugfmadyn.jpg


55FFF20B-1D74-4B94-9E34-1EEE9D8C3A46_zps3cegi3jo.jpg


7C8D73C4-E4B2-4405-9049-D4E4E01DD490_zpscdfabu83.jpg
 
We can't actually see any results?

From afar the results are the same in both?

edit:

Or are the first and second supposed to be alternate systems?
 
The thing is that the first one isn't actually that bad. Just a thin layer of carbon after 50k which probably doesn't make a difference to performance.

Also I'd like to see the before pic before they ran minimum spec fuel.
 
Diddums said:
Top photo = premium fuel.

Bottom photo = cheapo stuff.

And I don't believe one ounce of it.
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I've seen first hand the difference between two examples of the same engine (Rover T16 Turbo) ran on standard fuel (prior to my ownership) and another running on V-Power (40k miles in my ownership). I've also sent off sets of injectors for cleaning and flow testing, one set from each of the aforementioned engines.

The difference between the carbon build up of the engines and flow rate of the injectors was substantial.
 
muon said:
The thing is that the first one isn't actually that bad. Just a thin layer of carbon after 50k which probably doesn't make a difference to performance.

Also I'd like to see the before pic before they ran minimum spec fuel.
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It's all gunked up with deposits on the inlet valves
 
They never show the inside of the cylinder where they are probably exactly the same. I don't see how limited carbon buildup outside is a problem. What you see above is probably an equilibrium state.
 
Direct injection is worse for carbon buildup issues :/

Suburu have actually gone back to using port injection alongside direct injection on their current engine, to prevent buildup.
 
Last edited:
Nasher said:
Direct injection is worse for carbon issues :/

Suburu have actually gone back to using port injection alongside direct injection on their current engine, to prevent buildup.
Click to expand...

It is worse because fuel is unable to clean the inlet valves. So how will expensives fuels with lots of additives help?
 
Simon said:
By keeping the injectors clean
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So it doesn't actively clean anything other than the injectors and cylinder?

Whilst cleaner combustion if true, is great, that doesn't reconcile with the pictures above. Also getting absolutely zero carbon buildup?
 
Jonnycoupe said:
Cos that's where the air goes into the cylinder...
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But you would need to present evidence it causes air/fuel ratio problems. Not that it looks ugly.

Brakes look terrible after a while and yet perform fine.

I think engineering explained presented the evidence on this. I'll find it to show here.
 
muon said:
So it doesn't actively clean anything other than the injectors and cylinder?

Whilst cleaner combustion if true, is great, that doesn't reconcile with the pictures above. Also getting absolutely zero carbon buildup?
Click to expand...
The Audi is one issue.

You have started talking about another so I replied to your question about what additives do.
 
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