Hey now... You leave Nissan alone.
Anyway if Nissan told me to put premium in my Rogue I would do it... and that car only cost me $25k.

 

Good points but pre-ignition will kill a motor, it will blow holes in the top of your pistons after a while. Very dangerous scenario!! This piston is approaching TDC (top dead center) and the explosion occurs (with spark or not) and the piston continues to move towards TDC with no release of pressure (valves closed) very hard on motor. Car retards timing automatically for optimum performance end of scenario.um performance end of story.

Please elaborate or explain your point? I do have a little experience with motors, I run compression and timing advances never seen on street cars and I have to rebuild my motor about every 20hrs of racing, if the motor lasts that long. But I also use these same motors for recreation, same build same quality parts, everything. You know How they will last forever? Drop the compression and timing to run pump gas. When I race I run 186lbs of pressure per cylinder advanced timing +7 and use leaded 110 to keep from pre-ignition cause of the pressures. If you think increasing cylinder head pressures doesn't decrease reliability, longevity, even in the slightest, I'm all ears. I use forged cranks, forged pistons, forged billet heads, the best of everything and eventually the high pressures will take there toll. This is with really any engine that has higher combustion pressures. But like I said, if I reduce these pressures, this motor will last many many years of trouble free use. That's what really makes the best motors, is a motor built with high compression rated components, pistons, crank etc. and use it in a low compression situation. Motor will last forever, though with cost wise and even weight increase, it's not feasible in most cases. But hey, I don't know anything about motors, so feel free to prove your point.

 

that was funny i must admit,but whats not funny is in tread #9 on page 1....I, G2k already stated that i was going to use 91 in my car from now on.... so who's laughing now im not sure why you think its about money when its not if you take the time to read the whole tread, you might understand ,all most all of my cars are top floor and i take well care of all of them... so im not real sure on what your trying to get at with this money thing

 

lol, you think im being hostile? ummm... not!!! and no one is trying to get you to agree i was trying to get you to understand but i geuss since i dont write in full sentences you cant see what im trying to say so.... anyway i know you get my piont, you might agree but you understand that is why your getting all huffy and calling names

 

If you notice my post I say "almost nothing" Almost means if the engine would be severely pre-detonating it could be harmful but this kind of an engine would not move the car either.

I think you are wrong with comparing some racing engines to what we talk about and for the most part, your engines blow up from excessive heat, not excessive pressure in the cylinder.

 

You think pressures and temperatures don't have a relationship? You think if I compress a mixture of gas and air at a higher PSI, you think I can get more energy from it? If not, skip the rest of this post.

Detonation is like running high compression, though much much worse, the longer you run it the more it wears on the motor until boom, something gives.

I'm only comparing race engines because those motors do 200k miles of work in a couple weeks or one drag down the track. We are able to see the immediate affects of different situations and most of motor technology comes from these experiences. It doesn't matter how you slice it, high compression engines create more power, which in turn creates more heat, more stress on the moving parts of an engine. For those that don't understand motors, an analogy would be like a morbidly obese persons knee and hip joints. They wear out sooner cause of the extra down forces. Anyway follow the thread, my race engine response had nothing to do with your statement so don't get all confused in it.

 

Good Morning People...

I got up this morning and realized that the Premium vs. Regular poll I put up last night still has 100% people are using premium gas only on his car.

https://mbworld.org/forums/e-class-w...-gas-poll.html

Hmmmmm....

 

I really think you are missing the point of this thread. I would almost bet that 98%+ people here are using premium as the owners manual directs. I feel they should. This motor will then meet it's power, efficiency and EPA specifications that have been posted. It's not about being cheap or costs, at least not for me. It's whether or not using any octane gas less than 91 will either slowly affect your engines longevity to grenading your motor immediately or somewhere inbetween. Is Mercedes able to engineer a motor that will handle that bad tank of gas with less than premium octane ratings as these cars are all over the world and many places don't offer premium. Or is there many of these cars that don't meet their life span cause someone used regular unleaded, OR is a Mercedes engine just as capable as a Porche motor with the use of regular unleaded?

I think it's a great debate but with any discussion you have those few that take things way out of context, start name calling, take it personal as if someone that does use regular is committing murder (and that's ok).

My stance is this and I use premium. But if I switched, I say prove that this motor will not last when people are putting in regular unleaded in these cars absolutely every day of it's life and lasting just as long if not longer than using premium. These cars are designed to handle this with no ill affects whatsoever. Then we addressed timing cause that's what the car does to compensate, and does a reduction in timing anyway affect the longevity of the motor? I don't just say no but HELL no and quite the contrary. Thus my race motor analogy in comparison above. So that's what it boils down to. And until I see MB or any manufacturers motors they develope pinging, pre-igniting, dropping dead prematurely from the use of regular unleaded, I say these motors will work fine. Everyone should read this statement below, and I'll tell you this as well whether you believe it or not. Mercedes Benz can say the absolute same thing. Why? Cause Porsche and MB use the exact same technology to compensate for the differences in gas octane. Or maybe Porsche as well as Audi, Jag, Lexus, Acura are just better engine builders with better technology.

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches. Someone please pull out their Porsche owners manual and see what octane is required.

Most people here also disagree with this post and these are referenced from people in the industry.
Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.

But hey maybe in the end when some of you come across a circumstance where your almost out of gas and your at the only station around and their premium is out, some of you can feel confident in putting in the regular and some of you will always feel the need to call a tow.

 

I use 91 and in 20k miles with the car never put 87 in. I drive fairly hard though and like to give the throttle a good blast. Maybe Im getting ripped off...but I doubt it. I don't think MB has a lot of incentive to get me to spend more money on fuel just for the sake of it.

In our MDX which also requires premium - everytime my wife puts 87 in and then I drive it can easily tell. Knocks badly under heavy throttle.

 

I ABSOLUTELY think and KNOW you do not get more energy from the same amount of gas no matter how hard you compress the fuel mixture so I will not read your post any further than the first sentence. More heat in race engines mostly come from higher RMP, which is also where ALL of the higher HP also comes from.

Yes, engine gives more power from higher compression as the fuel detonates and expands in a smaller volume so causing higher pressure (=force) against piston to make it go down but with a given engine premature detonation is not what destroys the engine. The maximum pressure in the cylinder is just about the same when detonation is premature and when it is at its optimum point. Now, having timing wrong and premature detonation way early it could make you feed more fuel in the cylinder as you are not getting the power out from it what you feel you should get. This, of course, leads to situation where you have more fuel burning in the cylinder, that can burn hotter with higher pressure and by this mechanism cause piston failure. But now we then have two totally different scenarios.

I still stand by the fact that as long as our W212 engines can handle lower octane fuel, i.e. 87, it does not harm the engine. Handling it well means when it simply runs smooth. If premature detonation would occur at rate it could harm the engine it would not run smooth any more, the engine would definitely give jerking that can be felt by anybody driving it.

Amd I only use 91-93 octane. I would use 95 if it was available. It does not make sense to run low octane as the power from the engine is down, so mpg with it. There is no money or other savings in running 87 vs, 91-93. What you save at the one filling you loose filling it more often.

 

Which is it? YES you do get more power out of the same amount of gas, because of how hard you compress it which you made note of in your second paragraph which directly contradicts your first. No wonder your confused. Study the quote below for me please then get back with us. It doesn't take a rocket surgeon to figure this stuff out.



"Compression is directly related to power and to thermodynamic efficiency (see engine tuning), so engines that require higher octane usually deliver more motive power and do more work for a given BTU or calorie of fuel."

 

I'm not confused. Power and energy are NOT the same thing. I think who is confused is someone else than me.

 

Why does your owners manual state in the event that regular fuel is the only fuel available in such a situation that you fill only half full and fill the tank with premium at the earliest chance.
Poor advice is poor advice and all your hell no's won't change that fact.

 

No one said anything about power and energy as being the same though they are related. Now don't try to steer this discussion off topic. Remember we are talking about getting more energy from our fuel by using an increase in compression with a higher octane fuel. This means actually getting more power & energy from our motors with the EXACT same amount of fuel. It's not that the fuel has more stored caloric energy, it's that the engine is able to capture more of the energy released thus operating more efficiently. Don't try to ignore the fact that an engine is central to our discussion!

 

Wow.... Now I understand why this started off with several "not this again" posts.

It simply amazes me that folks who are obviously inteligent and successful enough to afford a $50-$75k vehicle have a hard time actively debating a simple concept/theory without resorting to name calling.

Make your points, cite your facts or reference those who do, share your logic on why you think this way or that and most importantly accept the fact that everyone who doesn't agree with you isn't an idiot...they just have a different set of beliefs that are based on a different set of facts. The great debate over 87/89/91/93 octane isn't an IQ test, simply a discussion with two sides and two beliefs.

 

You advertise yourself as a big engine builder but you seem to have lack in basic knowledge of very simple physics. If you don't know the basics you can build as many engines you want and keep blowing them up blaming it on too early ignition timing. Get real man.

I'm done with this thread.

 

Just explain why you think the way you do? Explain why higher compression doesn't create more power? Explain why detonation or pre-ignition won't destroy a motor? Explain what happens when a motor has high compression with low octane gas? Why can it detonate under high pressure without spark? Explain the physics I'm missing. You know why you can't explain it? Cause there is no explanation PERIOD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!

You said this not me!!!
:Wrong!!smash: You said premature detonation is not what destroys motors not me!!

You really believe this stuff you post? Read below and then tell me again how pre-ignition, detonation, or any other abnormal engine combustion scenario is not harmful to an engine. Site your source. Mine is from Wikepedia and www.masterfixit.com/deton.htm though I really don't need it but for correctness sake. Please do the same if you can even find anything to support your statement or refute mine.

"Pre-ignition:
Instead of the fuel igniting at the right instant to give the crankshaft a smooth kick in the right direction, the fuel ignites prematurely (early) causing a momentarily backlash as the piston tries to turn the crank in the wrong direction. This can be very damaging because of the stresses it creates. It can also localize heat to such an extent that it can partially melt or burn a hole through the top of a piston!" What did I say about pre-ignition? Here's my quote from earlier: "Good points but pre-ignition will kill a motor, it will blow holes in the top of your pistons after a while." My quote was almost word for word the definition.

"Detonation:
(also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

Mild or occasional detonation can occur in almost any engine and usually causes no harm. But prolonged or heavy detonation can be very damaging. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem"

And you should be!!

 

Maybe you guys should read this again???

 

I had to put 4gal of the cheap stuff in my car yesterday.
I made sure I filled up with Premium as soon as I could but I made a 110m trip back and forth to work on the cheap stuff before I filled up.

 

was just wondering what happened to cause this?

 

Quote:

Originally Posted by hyperion667

was just wondering what happened to cause this?

I was late for work and I needed gas, I stopped at the gas station before I jumped on the highway and they didn't have midgrade or premium.
I didn't have the time to drive back to a gas station to drive back to the highway. 55mi Drive to work with no gas stations after the first 25 so I put 4gal to get me to work and back to the nearest gas station.
So in fact I only drove 60mi before I put premium in the car again.

 

Sounds like the drive to Mesquite...

or one of the many ranches out there.

 

Premium for me. No if(s), and(s), or but(s).

 

Unbelievable, that people keep making these thread about premium gas in MB's. It always happens when gas goes up, someone is always trying to rationalize about buying cheaper gas. Saving $2-$3 on a fill-up is a huge gamble in regards to MB's which are not cheap, and obviously there is a reason why premium gas is recommended.

The debate is stupid, and not worth a discussion. Use what gas is required for your car. Period.

 

Exactly. Saving a few measly dollars at the pump at the expense of your car, and making up lame rationalizations for it on top of that, are pointless! Just buy a different car!

We're talking a .20 per gallon difference from the "cheap stuff", which even on a 15 gallon fillup, is $3.00.

$3.00?!?!?! Get real peeps.