Is it worth trying a petrol additive?

[Bellow]

That's not quite accurate. In Direct Injection engines the fuel (and additives) doesn't flow through the intake valves, true, but it does flow through the piston crowns and combustion chambers, and crucially also through the exhaust valves - the latter being far more prone to carbon deposits (leading to leaks and burnt exahust valves) than the intake valves.

Assuming it survives combustion....

(And, some Direct Injection engines have an additional fuel injector in the intake manifold, precisely for this purpose i.e. allowing the intake valves to be washed by fuel)

More for more complete fuel atomisation than consideration of inlet valve well-being.

 

[markjay]

Assuming it survives combustion....

Fair point, but it will still clean the injectors.....

 

[Deleted member 166430]

My friend Dave tried one of the petrol additives for cleaning cats and exhaust sensors. It made no difference to the EML coming on with associated NOx sensor fault codes. Fuel consumption has improved, although that may be because of other things that he’s had done.

 

[grober]

The thing that kills NOx SENSORS is moisture/water-exhaust treatments are unlikely to help

 

[E55BOF]

Liqui Moly..... I also sometimes use their Speed-TEC gasoline additive. It's not an octane booster but increases the ability of your fuel to atomise by increasing its surface area. Definitely not snake oil or placebo,...

Maybe I have a nasty suspicious nature, but "increases the ability of your fuel to atomise by increasing its surface area" sounds remarkably like some kind of snake oil to me. Is there anybody on here with the relevant expertise who can comment on this claim?

 

[GeeJayW]

Maybe I have a nasty suspicious nature, but "increases the ability of your fuel to atomise by increasing its surface area" sounds remarkably like some kind of snake oil to me. Is there anybody on here with the relevant expertise who can comment on this claim?

Well, surface area usually relates to droplet size. Bigger droplets with increased surface are will have more fuel mass and need more energy and/or time to vapourise than smaller droplets. They will also have a tendency to stick on the cylinder/combustion chamber walls, contributing to engine oil dilution and unburned hydrocarbons (liquid fuel doesn’t burn). So as far as I know, big droplets are not thought of as being good in either diesel (cause increase in ignition delay and combustion noise) or gasoline engines.

I’m not getting how increasing surface area* helps with atomisation, which is usually a feature of fuel pressure, surface tension and injector nozzle geometry. Fuel viscosity has a secondary effect on atomisation that reduces as fuel pressure increases. With modern high pressure fuel injection systems, viscosity effects (within the range specified in the relevant fuel standards) are minor.

*maybe they mean surface tension?

 

[PunkyB]

Do your own research on the product, might not be around forever because I know there are concerns about naptha/naphthalene. I'd say Liqui Moly is one of the more reputable brands and if I was going to believe anyone I'd believe them. If you think about my particular case, a M266 engine which isn't the height of sophistication, 8v and SOHC. Don't know how you would describe the fuel delivery, the injectors are attached to a rail so I'm just going to say port injection. If speed tec does what it says and that fuel goes in as a finer mist with more surface area then the results would indeed be positive. I've tried it in higher concentrations than recommended and defiantly it has a result. Additives will be debated forever but its the one I swear by.

 

[DSM10000]

Do your own research on the product, might not be around forever because I know there are concerns about naptha/naphthalene. I'd say Liqui Moly is one of the more reputable brands and if I was going to believe anyone I'd believe them. If you think about my particular case, a M266 engine which isn't the height of sophistication, 8v and SOHC. Don't know how you would describe the fuel delivery, the injectors are attached to a rail so I'm just going to say port injection. If speed tec does what it says and that fuel goes in as a finer mist with more surface area then the results would indeed be positive. I've tried it in higher concentrations than recommended and defiantly it has a result. Additives will be debated forever but its the one I swear by.

Are there any Peer reviewed papers on the efficacy of this product?

 

[geoffus]

fuel goes in as a finer mist with more surface area then the results would indeed be positive. I've tried it in higher concentrations than recommended and defiantly it has a result.

So your saying this product actually alters the viscosity of fuel, this then helps to provide a more efficient spray regardless of injector pressure or pattern. Wouldn’t you think manufacturers would have already designed injections systems to produce optimal results anyway ?

 

[Bellow]

What is meant by 'atomisation'?
The pulverisation into droplets or the vaporisation into the gaseous phase?

 

[E55BOF]

Strictly speaking, conversion into fine droplets, but if as I suspect the product is actually a snake oil with little if any real benefit, who can say?

 

[Bellow]

Strictly speaking, conversion into fine droplets, but if as I suspect the product is actually a snake oil with little if any real benefit, who can say?

As you alluded earlier, then maybe a slight change in surface tension could create smaller droplets sooner with greater overall surface area exposed to heat.
Without any additives, there isn't AFAIK any problem in fully atomising and vaporising petrol in a hot port injected 4 stroke engine, the final vaporisation being accomplished during the compression stroke with heat from the hot piston crown and the fuel adequately atomised by then if the fueling system (injectors and pressure) are functioning as they should, and air motion. With direct injection it is different hence the need for particulate traps but with port injection the luxury of time sees fuel fully prepared before the spark is introduced. Without a problem - how can there be a solution?

 

[PunkyB]

What is there to be measured, it does not increase horsepower or torque remember. Read the reviews for the product, which are very positive . Have a look how it works;

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Don't forget Alfa Romeo used the twinspark system so they could run with AFR's not usually workable because being able to cleanly burn all of the fuel injected has many benefits performance and emissions wise. Don't some Mercedes-Benz have twin plugs too. Building a bigger and better flame front is a good thing

 

[DSM10000]

What is there to be measured, it does not increase horsepower or torque remember. Read the reviews for the product, which are very positive . Have a look how it works;

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Don't forget Alfa Romeo used the twinspark system so they could run with AFR's not usually workable because being able to cleanly burn all of the fuel injected has many benefits performance and emissions wise. Don't some Mercedes-Benz have twin plugs too. Building a bigger and better flame front is a good thing

The salient point regarding any review is who carries out the review.

Are they adequately qualified to do so and have full independence from the manufacturer of the product being reviewed?

 

[PunkyB]

Rated 4.5 out of 5.0 on Amazon from a source of 507 Global ratings. Rated very high with Google but only from a sample of 11. Don't forget this is a product that could benefit someone much more than someone else. If you have a brand new Mercedes with direct injection and amazing technology then I doubt that Stuttgart's finest haven't already got the fuel delivery/swirl patterns etc about as perfect as they can be. Some less sophisticated units though or older engines like mine, where the injectors have been cycled countlessly for over 90,000 miles then I say the potential for benefit is there.

It's like how in the news all these VW owners complaining about how their cars run like crap on this new E10 when all along they should have been using high octane fuel for the FSI system to stratify properly

 

[GeeJayW]

Rated 4.5 out of 5.0 on Amazon from a source of 507 Global ratings. Rated very high with Google but only from a sample of 11. Don't forget this is a product that could benefit someone much more than someone else. If you have a brand new Mercedes with direct injection and amazing technology then I doubt that Stuttgart's finest haven't already got the fuel delivery/swirl patterns etc about as perfect as they can be. Some less sophisticated units though or older engines like mine, where the injectors have been cycled countlessly for over 90,000 miles then I say the potential for benefit is there.

It's like how in the news all these VW owners complaining about how their cars run like crap on this new E10 when all along they should have been using high octane fuel for the FSI system to stratify properly

How are YOU qualified to be making recommendations about fuel additives?

 

[Bellow]

What we do know about Liqui Moly is they are spending shed loads of money on advertising. Banners displayed at F1 meetings aint cheap. Worked for Mobil now it's Liqui Moly's chance to do the same. The best lubricants come from companies that spend their money on research, product development, the best 'ingredients' and the manufacturing processes.

 

[PunkyB]

Have been using two w169's one an A160 for a little while and then an an A150 both with the same M266.920 engine. Have driven thousands of miles under different temperatures, driving conditions etc. Very used to how the engine feels and operates, it's response to throttle etc.

Then felt a really good difference when I used the product. That's all I can say really. Fuel additives are as debatable as re-mapping n/a engines or manuals vs auto's. It's just a never ending debate but if some benefits from something or it works for them then that's a positive thing. If you ever have a tenner lying around try it for yourself and see if it does any good for you or not......

 

[E55BOF]

Fuel additives are as debatable as re-mapping n/a engines or manuals vs auto's.

Not really; you can measure the differences there.

If it gives no more power or torque, then there are no measurable benefits, so what does it actually do? You stated that it "gives great extra mid range shove"; now that's something that could be measured, so have LiquiMoly published dyno results on a before and after test with a car? If not, why not?

If you're convinced, fine, but I'm afraid I'm not.

 

[GeeJayW]

Edit - Nevermind, can’t be Rsed…