I call this the "accordian music cures disease" dilemma.
On the one hand, it is extremely unlikely that accordian music will cure anything---most reasonable people know this.
But on the other hand, the accordian player charges only $10, and you are sick and you have very little money and your uncle Charlie's friend's brother-in-law SWEARS he was cured, so you say "what the hell, what's $10) and you do it.
Then it's a matter of percentages...maybe there's a .1 of 1% chance it will work (placebo effect?), a good chance you'll die, and a good chance a certified doctor can fix you for a hefty fee.
So this is why I think most people still buy snake oils, and this is also what snake oil manufacturers count on---that you'll be willing to toss away $10 on the slim chance it will work.
Very often, someone will claim a "cure" from "fueleron" (I LOVE that name--LOL!) but what has actually happened is what is known as a "collateral effect", not a cause and effect. In other words, you put the snake oil in AND the car started shifting better....not....the car started shifting better BECAUSE of the snake oil.
Those are two different things entirely and people will confuse them. One is cause and effect, the other mere co-incidence.
Ask a mathematician, and he will tell you that co-incidence occurs far more frequently in the world than most people would guess. e.g., the odds of you thinking of someone and them phoning you later in the day are actually a lot better than you'd think.
Last of all, very few people (if any) take the time to check back and see if Charlie's friend's brother in law is still alive two weeks later.
I have a two part question. I usually like to use higher octane for my 06 nissan titan V8 to gain a little extra hp in the summer.
First off, does higher octane = lower volatility/ lower octane = higher volatility?
Secondly, should one use a lower octane in the winter months and higher octane in the summer months (assuming that the engine is spec'ed for higher compression ratio)?
Mine is spec'ed at 9.8:1 compression ratio, dunno if it's really high or not just assuming it is and from other peoples' views that i can definitely gain performance from use of higher octane fuel.
For starters, what grade of gasoline does Toyota recommend for your engine? Regardless of what time of year and what your local OAT is, the recommended fuel is still the recommended fuel; as such that fuel (and only that fuel) will give you the best performance AND the best fuel economy.
Now, on to your specific questions...
1) From a very simplistic sense yes, octane and volatility have an inverse relationship.
2) No you should not change fuel depending upon the time of the year. Why? Because cold dry air has a much higher density than warm moist air, and as such peak cylinder temperatures and pressures don't vary all that much from winter to summer.
3) 9.8:1 isn't all that high of a compression ratio these days, especially when compared to Audi's 2.0T which has a 10.0:1 compression ratio AND a turbocharger on top of it. Said another way, there are engines with higher compression than yours that are optimized for regular and other engines with lower compression that will self destruct with anything less than premium. This of course brings us full circle back to what Toyota recommends for your engine. Not that I'm a betting man mind you, but my guess is that you should probably be using Regular. Anything higher (or lower) than the recommendation will result in lower fuel economy and lower power at WOT.
Shipo, you are indeed correct. I've been doing more research since im a newb to this subject in hand. This is basically my first new vehicle; ive been driving an old used car before this, so just wanted to get some myths out of the way...
Well, i agree with you on a couple of things... 9.8:1 isnt all that high, so regular 87 can compensate for that compression ratio.
Been using premium 93 Shell & Chevron for 2 months in the summer, after switching back to regular 87, the engine seems to be more rev-happy. On top of that, lower fuel economy when using 93 vs 87 (approx. 10 mpg vs 13mpg city driving).
Nissan (not Toyota ) recommends 87 in my manual.
But with that having said, i've seen a Nissan Titan owner such as myself that did a dyno test with different octane readings to see if there could be hp gains during upper rpm WOT.
Owner ran 5 tanks of 87 and dynoed to obtain about 245hp. Then, ran 5 tanks of 93 and got about 254hp.
Here's a newbie question (still learning here)... if i wanted to possibly clean the fuel injectors, could using a couple of tanks of 93 shell V-power in the summer after using mostly 87 winter fuel, for example, help "clean" it out?
Owner ran 5 tanks of 87 and dynoed to obtain about 245hp. Then, ran 5 tanks of 93 and got about 254hp.
Unless the dyno runs were run back to back and within a few minutes of each other, the nine horsepower difference is statistically irrelevant. Why? Density Altitude. Different air temperatures, different altitude (or said another way, different barometric pressure), and different humidity levels all affect how much power an engine can deliver. True, most dynamometer operators attempt to normalize the results, however, I've never seen any definitive evidence that suggests that said normalization is terribly accurate.
Regarding the cleaning of the fuel injectors, I've yet to see any credible evidence that suggests that using a good name brand fuel of the grade recommended by your manufacturer will cause deposits to build up on the injectors. One of our current cars has 124,000 miles on the clock and has only been fed a diet of name brand Regular gasoline (errr, with the exception of one tank of Premium a few years ago where the station ran out of Regular). If I was to believe the "Sky is falling" crowd, I'd be forced to admit that this particular vehicle is currently running like crap. Well, the truth of the matter is that it ain't. The engine is as smooth as it was when new, it's easily as fast as it was when new and it's returning the best fuel mileage ever. Said another way, I don't believe there is any compelling reason for doing anything other than exactly what the manufacturer recommends (i.e. using the specific grade of fuel recommended and NOT using any additives).
I agree with shipo on this. There is no more "power" in higher octane fuel and the dyno results are too small in difference to be definitive about anything.
Boy, i am sure getting some myths out of my head... just when you thought that everything seems to fit into your head/theory... it all gets fuzzied up again. Im such a newbie :mad: .
Oh, and the answer is No, the dyno test runs were not done on the same day as with using 87 vs 93. I believe they were tested on different days. So yes, this can be ruled out.
I'd agree totatlly with what you guys are saying. Looking back now, i just wasted 100's of dollars this summer Even cold startups start easier now using 87 than when using 93....
Thanks for the informative infos. Mr_Shiftright and you, esp. Shipo.
The myth shattering gets worse. In fact, an operator can program a dyno to give any result he wants, and he can also conduct the tests in such a way as to fudge results. Just opening the shop door can change results.
While I agree the dyno results aren't definitive. There is sometimes "more power" in higher octane fuel. If the engine is designed for higher ocatane fuel such as my Nissan Pathfinder because of a higher compression ratio, then using lower octane with a knock sensor can retard the ignition timing & produce less power.
I know it seems that way but that's due to engine design. There is no extra power in high test fuel, no more energy in the fuel itself. It's all in how it burns (slowly and evenly).
That's what I meant. I realize that octane is just a rating of the fuel's resistance to premature ignition from compression (knocking or pinging)but my point is if his Nissan Titan calls for premium then there would in fact be a power increase over the regular as the ignition timing would not be retarded with the premium.
Actually im gettin confused again... i've only heard from several others (who worked at the production plant in Canton, Mississippi) that the first nissan titan (in the 04 manual), supposedly stated to use premium then switched their recommended octane to 87 regular because they believe that many consumers wouldnt buy the trucks since it's rated as 14 mpg city and 19 mpg hwy.
The Infiniti QX56 (315hp and 390 torque) actually shares the same 5.6L V-8 of the nissan titan and the nissan Armada (305hp and 379torque). The Infiniti QX56 calls for premium unleaded fuel 91 and shares the same engine design: (VK56DE, 9.8 compression ratio, 5,552 cc, DOHC 32-valves, 28 gal fuel tank, multi-fuel injection system, all exactly the same as the Titan's and Armada's)...
So....should i be using premium now??? :confuse: The main reason i want to use the correct octane is to prevent detonation, knock, or even prevent overheating? (the coolant temp. would rise to the High mark if i'd use the wrong octane, at least that's what i was told) My source: www.automotive.com Use the compare feature to compare the 06 nissan titan and the 06 infinit QX56.
If your engine was designed to use Premium, then yes, you will most likely get better mileage and power when using that fuel. That said, just because the Infiniti engine is optimized for Premium doesn't mean that yours is. Even if the two engines are mechanically identical all it would take would be some different OBC code to "de-tune" your engine so that Regular is the optimal fuel. I'm thinking that some experimentation is in order here.
Regarding detonation, don't worry about that, detonation can only occur when the fuel you are using is below what the manufacturer recommends (and in this day of computer controlled engines, the fuel would most likely have to be WELL BELOW the recommended octane rating).
As for the coolant temp rising because of the incorrect octane rating, that is total horse hockey. The only way the incorrect fuel will cause the coolant temperature to rise to unacceptable levels is if you are running such a low grade fuel that the engine does start into moderate to heavy detonation (light detonation is actually considered good by many engineers, something that I do not subscribe to), and if your engine is detonating, your coolant temperature is the least of your worries.
Agreed. No relation between octane rating and engine temperature. The only fuel/coolant relationship I can think of is if you were running an extremely lean mixture.
I am of the opinion that factory engineers with pocket protectors have gone to good schools and are really smart, and so, given no evidence to the contrary, I would tend to believe them rather than what some stranger says on the Internet regarding the octane rating for your particular engine. You don't HAVE to take the factory recommendation, but I bet it is in fact an optimum for your engine.
"Agreed. No relation between octane rating and engine temperature. The only fuel/coolant relationship I can think of is if you were running an extremely lean mixture."
Yeah, a real lean mixture equates to coolant that is the same temperature as the ambient OAT. ;-)
All kidding aside, there is a pervasive myth that a "Lean Mixture" will cause all sorts of havoc with engine internals. As it turns out, that little factoid couldn't be further from the truth.
"Blasphemy!" You say. "Every engineer, race car tuner, and back yard mechanic I've ever worked with can PROVE that too lean of a mixture will lead to detonation that if left unchecked will destroy an engine within minutes."
Yup, I've heard the same for decades, however, it simply ain't true. Why? First off, it's a matter of language. What really should be said is, "If the mixture isn't rich enough OR lean enough, it will lead to detonation that if left unchecked will destroy an engine within minutes."
Think about it this way, if your mixture is set at exactly stoichiometric (often called "Stoich" [pronounced STYO] which is 14.7:1 air:fuel ratio), your peak cylinder pressures and temperatures will be WAY too high to contain for long and your engine will self destruct. As you enrich OR lean the mixture the peaks drop as the mixture tends to burn slower. That having been said, as you enrich the mixture the fall off of the power curve is fairly flat (there is only so much air so only a certain amount of fuel can burn), and the unburned fuel is simply ejected out of the exhaust pipe. As you lean from Stoich the fall off on the power curve is rather precipitous and as such it is MUCH more difficult to keep an engine running on that razor's edge between losing too much power (or quitting altogether) and running into too much detonation.
FWIW, there are now ignition systems available for some types of IC engines that can run Lean of Peak (LOP), however, to the best of my knowledge, those systems are currently only for engines that spend most of their operational life running at a steady state (i.e. airplane engines).
First off guys, thanks for all the replies and comments so far...
Well here's some more food for thought, this has mostly to do with my experimentation on which octane is optimum for mpg and power: I've been experimenting all summer with 93 premium octane in use to determine what this engine is optimized for... I get slightly 1-2 mpg less with 93 vs with regular 87. With the mpg loss, can i assume that 87 is indeed optimized for power and mpg?
Another question: I was experimenting this summer and while using premium, my rpm's would be lower when at WOT, with 87 at Wot, the rpm would elevate higher (to make it sound more simplistic, when i go 2/3 full throttle, it would be at 3rpm with premium and 4rpm with regular).. does this indicate more power or less power or it doesnt indicate anything? I guess my question is how can one determine if there's more power when switching to different octanes?
I now know that using good filters are important in prolonging the life of your engine. Question: I 've changed to K&N filters because they say (retail store) that it does a better job of filtering dirt in the air. Any comments/ experiences/ studies?
The users of K&N products almost universally claim noticable improvements, however, virtually all of the tests that I've read suggest otherwise.
Question: Why not just trust the highly qualified engineers who designed your car and its engine (and what filters it works best with), and use OEM or equivilant filters?
I used a K&N in the last Dodge Ram P/U (1997) I owned. I did notice a slight increase in the throttle response. I saw no gains in fuel economy.
If the engine is computer controlled to maintain a certain fuel/air mixture, and the K&N allows more air into the combustion chamber, then it would only make sense that using a K&N filter would lead to increased fuel consumption. Does this make sense, or am I way off base.
Every credible dyno test I've seen shoots down the K&N drop-in filters for any HP increase. If you are talking about an entire cold air ram intake, that's different.
OCTANE: You can't really measure throttle by feel and even small variations in your "feel" would change RPM considerably.
K&N air filters and most other performance-wise air filters allow more fresh air to go in your car's engine by more penetration, means will not block away dusty particles so well as OEM filters. By doing that, your car will increase some 1-3%HP at high end torque but lower your low end torque. I have it on my 97 Civic Vtec for one year. I noticed when I accelated from a complete stop, its worser than the OEM filter, but rpm will be more easily rose to 6,000 rpm and extreme speed can go to around 10 mph more. But you can felt the car breath more freely and hear the breathing sounds louder.
The OEM air filter will protect your engine better than these high performance filters.
Air filters are compared by using efficiency. In other words, the relationship between the volume of air and the amount and size of the contaminants. Filters mentioned so far are good for the race track. The Ea Filter has no competitors.
If it's a solvent(dilutes oil) use it just before an oil change and if it's a detergent use it anytime. Redline is a detergent, but a lot of them are solvents.
IMO BG and Redline are the best. Before knock sensors were common using these products was more obvious, but now they still work but the sensors alter timing as carbon accumilates.
"K&N air filters and most other performance-wise air filters allow more fresh air to go in your car's engine by more penetration, means will not block away dusty particles so well as OEM filters. By doing that, your car will increase some 1-3%HP at high end torque but lower your low end torque."
Un-huh. Sorry, not buying. I've been hearing such rhetoric for years and I've yet to see even a single scientific report that supports those kind of claims.
I have it on my 97 Civic Vtec for one year. I noticed when I accelated from a complete stop, its worser than the OEM filter, but rpm will be more easily rose to 6,000 rpm and extreme speed can go to around 10 mph more.
Anecdotal evidence, yours or anyone else's is irrelevant. Like it or not there are just too many factors in play here for your sampling of one unit to prove that a K&N filter does anything more than introduce oil into the intake system.
Ummm, are you aware that you just replied to a post that was more than five years old and more than just a little bit out of context with the current threads? :confuse:
Ea is made from Amsoil... google Amsoil Ea filters and you'll get their oil and air filter products. They're supposedly really good in their oil products.. (marketing too )
i aways thought the higher-test fuel will retard premature detonation, and thus on vehicles designed for it (read higer compression) they will actually benefit by letting the vehicle get the piston closer to the top and maximal compression before sparking the cylinder, thus more horsepower per unit fuel delivered.
For high compression engines, Premium gasoline actually allows the spark event to occur earlier (i.e. a greater number of rotational degrees before TDC). What that effectively does is to cause the burn process to augment the mechanical compression of the engine (without causing detonation of large amounts of end gas). This in turn results in a higher combustion chamber temperature and pressure (occurring exactly at the point of the greatest mechanical advantage of about 17 degrees after TDC, plus or minus 3 degrees depending upon the engine), which will then in turn yield greater power to the crankshaft.
So, while the caloric content of Premium fuel is virtually identical to that of Regular, the ignition map with which a high performance/compression engine extracts that power isn't, and as such, more of the available power is realized.
Some folks reason that since the intake charge is colder it is okay/desirable to use a more volitale fuel when winter hits. What they don't realize is that since the cold/dry air is considerably more dense than the warm/moist air of summer time, that peak cylinder temperatures/pressures won't really drop much (if at all), and as such, the recommended fuel is still the recommended fuel.
" Premium gasoline actually allows the spark event to occur earlier " Does it mean if the engine is 10.5 compression and asks for min. 91 Octane, if I put 93 or 94, will the spark occur too early to the reach the maximum power? Means lower power for the same amount of gas burnt.
Does it mean if the engine is 10.5 compression and asks for min. 91 Octane, if I put 93 or 94, will the spark occur too early to the reach the maximum power? Means lower power for the same amount of gas burnt.
Well, sort of, maybe.
Given: Engine with 10.5:1 compression recommending 91 Octane fuel and is fed 94 Octane fuel.
- If the engine is capable of adjusting the timing of the spark event (and possibly the valve timing as well), then the engine should very well be capable of increasing the power yield from any given amount of fuel, however, not to the same extent as that same engine with say a 12.0:1 compression ratio (or some type of forced induction).
- If the engine is NOT capable of adjusting the timing of the spark event, then the plugs will fire too late for the engine to extract as much power out of the fuel as would otherwise be possible.
The problem with "pre-ignition" or detonation is that you have the force of the piston coming up and the force of the pre-ignition going down (at the wrong time)....result? A nice hole right through the top of your piston, or a chunk of it floating in your oil pan.
NOT PRETTY-- never take heavy and constant pinging lightly! Detonation is massively harmful business.
Just to be on the safe side I'd like to restate the actual definitions of the two above terms:
Detonation: The sudden explosion of one or more small pockets (or even not so small) of "End-Gas" (unburned gas usually located in the furthest points of the combustion chamber from the spark plug(s)). Detonation always occurs AFTER the spark event and usually within say ten degrees either way of TDC. Light detonation is considered desirable by some engineers and harmless by most of the rest. Moderate detonation should be remediated immediately as it can cause engine damage in and of itself and will usually lead to heavy detonation in relatively short order. Heavy detonation WILL destroy an engine in a matter of minutes.
Pre-Ignition: The unscheduled ignition of the intake charge BEFORE the spark event (hence the name "Pre-Ignition"). Pre-Ignition WILL destroy an engine in a matter of moments, literally within just a few revolutions from onset.
The users of K&N products almost universally claim noticable improvements, however, virtually all of the tests that I've read suggest otherwise.
Here I disagree... From what I know, and the independent tests that Road & Track did , the K&N filters may help increase air flow...depending on the engine and maker. For some makers , the limiting agent in engine efficiency is the rather restrictive air flow, and thus there is noticeable improvement. Example: the 5.7 l V8 in the GM suburban. In others, like my Jetta TDI, the limiting agent is not the air flow, but the dynamics of the diesel engine, thus using the K&N filter will not do a thing .
The folks at the mags did a comparo..using dyno...and measured before and after...and saw differences in some engines..and no diff in other engines.
Question: Why not just trust the highly qualified engineers who designed your car and its engine (and what filters it works best with), and use OEM or equivilant filters?
I would normally agree with that statement, but after we bought a Mercury Lynx ( FORD product), the ""highly trained engineer"" that you alluded to designed and placed the headlight controls at knee level on the lower left side of the dash...so it was nearly impossible to find, non intuitive, and frequently when one exits the vehicle, one's knee would accidentally hit the switch, and turn on the lights all day, so one would return to a dead battery....UGH !!! I appalls me that an engineer would even think of putting a light switch there....why not put it in the second row ,where it may be more accessible ??? ( sarcasm injected here )
ANd the almighty engineers at Acura designed the first generation Acura TLs ( nice car ) , but if you tried to change the wipers , you would not be able to lift the blades..not until you you release the hood, and opened the hood up.... :mad:
Someone messed up there in design again !!
excuse my cynical attitude
Engines are tuned to a certain degree and all variables are held to certain values.....for the most part, the engineers could be right....but even they tinker around the engine...and squeeze more hp or better fuel economy, by doing all sorts of adjustments.
How is the 928 doing ? I hope all is well. I think with the double intake of the 928 and cayenne, there is no need for a K&N, though like you said, it may be an improvement.
I agree with your opinion. It is my experience also, that with only one intake filter, the Suburban with a 5.7 liter V8 with supercharger was just dying of asphyxiation , until a K&N was installed.
OTOH. my VW TDI , with the small 1.9 liter , 4 cylinder diesel, the K&N is a non issue..and may even be worse for the engine..,,
So overall, to be fair, I would have to say that for larger engines, with greater need for high volume of air, then the K&N may be useful, provided that the limiting agent ( WRT design of engine) in the volumetric efficiency equation is the air intake filter.
Some automakers will limit the air box slightly so that you don't get the intake noise that a K&N filter allows. Many new car buyers would not like this amount of intake noise.
I have a 1999 chevorlet silverado 5.3L V8 Vortec it has two hundred fifteen thousand miles on it. every morning it hesitates when i start it up and drive it but if i let it idle for 5 min it will not hesitate will fuel additives help and which additives do you recomend.
Remember the emergency fuel you could safely carry in your vehicle in case you ran out of gas? Pennzoil made one called Rescue & there were others. It seems everyone has stopped making this. Anyone know if this is still being made by anyone?
I too have been looking for this product but have been unable to find it anywhere. It seems as though is was originally made in 1999 but I'm not sure when they stopped. I was able to find some at an online store in 2005 but since then I can't find it anywhere. I would love to get some more of this stuff because it worked great. I read somewhere that all it really was is kerosene. Has anybody tried that? Kerosene can be stored in the trunk for years without breaking down and can be used in a warm engine just like Rescue. But I'm not sure if it would damage any of the engine components.
i really think carrying any form of fuel on a regular basis that isn't in your tank is a really bad idea whos benefit is well outweighed by its dangers.
carrying a container that could be used to put fuel (or water) in if you run out isn't such a bad idea, but why would you want to jeopardize your safety by carrying fuel in something other than the gas tank?
maybe they stopped manufacturing and selling it because of accidents, injuries and lawsuits.
Kerosene can be used in a warm gasoline engine? I have not heard this before and am curious to know if it's true. Kerosene is 6- $7 a gallon for the clean stuff so obviously is not a gasoline substitute, but if it stores better than gasoline, might be a good emergency backup.
Comments
On the one hand, it is extremely unlikely that accordian music will cure anything---most reasonable people know this.
But on the other hand, the accordian player charges only $10, and you are sick and you have very little money and your uncle Charlie's friend's brother-in-law SWEARS he was cured, so you say "what the hell, what's $10) and you do it.
Then it's a matter of percentages...maybe there's a .1 of 1% chance it will work (placebo effect?), a good chance you'll die, and a good chance a certified doctor can fix you for a hefty fee.
So this is why I think most people still buy snake oils, and this is also what snake oil manufacturers count on---that you'll be willing to toss away $10 on the slim chance it will work.
Very often, someone will claim a "cure" from "fueleron" (I LOVE that name--LOL!) but what has actually happened is what is known as a "collateral effect", not a cause and effect. In other words, you put the snake oil in AND the car started shifting better....not....the car started shifting better BECAUSE of the snake oil.
Those are two different things entirely and people will confuse them. One is cause and effect, the other mere co-incidence.
Ask a mathematician, and he will tell you that co-incidence occurs far more frequently in the world than most people would guess. e.g., the odds of you thinking of someone and them phoning you later in the day are actually a lot better than you'd think.
Last of all, very few people (if any) take the time to check back and see if Charlie's friend's brother in law is still alive two weeks later.
I have a two part question. I usually like to use higher octane for my 06 nissan titan V8 to gain a little extra hp in the summer.
First off, does higher octane = lower volatility/ lower octane = higher volatility?
Secondly, should one use a lower octane in the winter months and higher octane in the summer months (assuming that the engine is spec'ed for higher compression ratio)?
Mine is spec'ed at 9.8:1 compression ratio, dunno if it's really high or not just assuming it is and from other peoples' views that i can definitely gain performance from use of higher octane fuel.
-Eric
Now, on to your specific questions...
1) From a very simplistic sense yes, octane and volatility have an inverse relationship.
2) No you should not change fuel depending upon the time of the year. Why? Because cold dry air has a much higher density than warm moist air, and as such peak cylinder temperatures and pressures don't vary all that much from winter to summer.
3) 9.8:1 isn't all that high of a compression ratio these days, especially when compared to Audi's 2.0T which has a 10.0:1 compression ratio AND a turbocharger on top of it. Said another way, there are engines with higher compression than yours that are optimized for regular and other engines with lower compression that will self destruct with anything less than premium. This of course brings us full circle back to what Toyota recommends for your engine. Not that I'm a betting man mind you, but my guess is that you should probably be using Regular. Anything higher (or lower) than the recommendation will result in lower fuel economy and lower power at WOT.
Best Regards,
Shipo
Well, i agree with you on a couple of things...
9.8:1 isnt all that high, so regular 87 can compensate for that compression ratio.
Been using premium 93 Shell & Chevron for 2 months in the summer, after switching back to regular 87, the engine seems to be more rev-happy. On top of that, lower fuel economy when using 93 vs 87 (approx. 10 mpg vs 13mpg city driving).
Nissan (not Toyota
But with that having said, i've seen a Nissan Titan owner such as myself that did a dyno test with different octane readings to see if there could be hp gains during upper rpm WOT.
Owner ran 5 tanks of 87 and dynoed to obtain about 245hp. Then, ran 5 tanks of 93 and got about 254hp.
Here's a newbie question (still learning here)... if i wanted to possibly clean the fuel injectors, could using a couple of tanks of 93 shell V-power in the summer after using mostly 87 winter fuel, for example, help "clean" it out?
-Eric
Unless the dyno runs were run back to back and within a few minutes of each other, the nine horsepower difference is statistically irrelevant. Why? Density Altitude. Different air temperatures, different altitude (or said another way, different barometric pressure), and different humidity levels all affect how much power an engine can deliver. True, most dynamometer operators attempt to normalize the results, however, I've never seen any definitive evidence that suggests that said normalization is terribly accurate.
Regarding the cleaning of the fuel injectors, I've yet to see any credible evidence that suggests that using a good name brand fuel of the grade recommended by your manufacturer will cause deposits to build up on the injectors. One of our current cars has 124,000 miles on the clock and has only been fed a diet of name brand Regular gasoline (errr, with the exception of one tank of Premium a few years ago where the station ran out of Regular). If I was to believe the "Sky is falling" crowd, I'd be forced to admit that this particular vehicle is currently running like crap. Well, the truth of the matter is that it ain't. The engine is as smooth as it was when new, it's easily as fast as it was when new and it's returning the best fuel mileage ever. Said another way, I don't believe there is any compelling reason for doing anything other than exactly what the manufacturer recommends (i.e. using the specific grade of fuel recommended and NOT using any additives).
Best Regards,
Shipo
Oh, and the answer is No, the dyno test runs were not done on the same day as with using 87 vs 93. I believe they were tested on different days. So yes, this can be ruled out.
I'd agree totatlly with what you guys are saying. Looking back now, i just wasted 100's of dollars this summer
Even cold startups start easier now using 87 than when using 93....
Thanks for the informative infos. Mr_Shiftright and you, esp. Shipo.
The Infiniti QX56 (315hp and 390 torque) actually shares the same 5.6L V-8 of the nissan titan and the nissan Armada (305hp and 379torque). The Infiniti QX56 calls for premium unleaded fuel 91 and shares the same engine design: (VK56DE, 9.8 compression ratio, 5,552 cc, DOHC 32-valves, 28 gal fuel tank, multi-fuel injection system, all exactly the same as the Titan's and Armada's)...
So....should i be using premium now??? :confuse:
The main reason i want to use the correct octane is to prevent detonation, knock, or even prevent overheating? (the coolant temp. would rise to the High mark if i'd use the wrong octane, at least that's what i was told)
My source: www.automotive.com Use the compare feature to compare the 06 nissan titan and the 06 infinit QX56.
Regarding detonation, don't worry about that, detonation can only occur when the fuel you are using is below what the manufacturer recommends (and in this day of computer controlled engines, the fuel would most likely have to be WELL BELOW the recommended octane rating).
As for the coolant temp rising because of the incorrect octane rating, that is total horse hockey. The only way the incorrect fuel will cause the coolant temperature to rise to unacceptable levels is if you are running such a low grade fuel that the engine does start into moderate to heavy detonation (light detonation is actually considered good by many engineers, something that I do not subscribe to), and if your engine is detonating, your coolant temperature is the least of your worries.
Best Regards,
Shipo
I am of the opinion that factory engineers with pocket protectors have gone to good schools and are really smart, and so, given no evidence to the contrary, I would tend to believe them rather than what some stranger says on the Internet regarding the octane rating for your particular engine. You don't HAVE to take the factory recommendation, but I bet it is in fact an optimum for your engine.
Yeah, a real lean mixture equates to coolant that is the same temperature as the ambient OAT. ;-)
All kidding aside, there is a pervasive myth that a "Lean Mixture" will cause all sorts of havoc with engine internals. As it turns out, that little factoid couldn't be further from the truth.
"Blasphemy!" You say. "Every engineer, race car tuner, and back yard mechanic I've ever worked with can PROVE that too lean of a mixture will lead to detonation that if left unchecked will destroy an engine within minutes."
Yup, I've heard the same for decades, however, it simply ain't true. Why? First off, it's a matter of language. What really should be said is, "If the mixture isn't rich enough OR lean enough, it will lead to detonation that if left unchecked will destroy an engine within minutes."
Think about it this way, if your mixture is set at exactly stoichiometric (often called "Stoich" [pronounced STYO] which is 14.7:1 air:fuel ratio), your peak cylinder pressures and temperatures will be WAY too high to contain for long and your engine will self destruct. As you enrich OR lean the mixture the peaks drop as the mixture tends to burn slower. That having been said, as you enrich the mixture the fall off of the power curve is fairly flat (there is only so much air so only a certain amount of fuel can burn), and the unburned fuel is simply ejected out of the exhaust pipe. As you lean from Stoich the fall off on the power curve is rather precipitous and as such it is MUCH more difficult to keep an engine running on that razor's edge between losing too much power (or quitting altogether) and running into too much detonation.
FWIW, there are now ignition systems available for some types of IC engines that can run Lean of Peak (LOP), however, to the best of my knowledge, those systems are currently only for engines that spend most of their operational life running at a steady state (i.e. airplane engines).
Best Regards,
Shipo
Well here's some more food for thought, this has mostly to do with my experimentation on which octane is optimum for mpg and power: I've been experimenting all summer with 93 premium octane in use to determine what this engine is optimized for... I get slightly 1-2 mpg less with 93 vs with regular 87. With the mpg loss, can i assume that 87 is indeed optimized for power and mpg?
Another question: I was experimenting this summer and while using premium, my rpm's would be lower when at WOT, with 87 at Wot, the rpm would elevate higher (to make it sound more simplistic, when i go 2/3 full throttle, it would be at 3rpm with premium and 4rpm with regular).. does this indicate more power or less power or it doesnt indicate anything? I guess my question is how can one determine if there's more power when switching to different octanes?
Regards,
Eric
studies?
Question: Why not just trust the highly qualified engineers who designed your car and its engine (and what filters it works best with), and use OEM or equivilant filters?
Best Regards,
Shipo
I used a K&N in the last Dodge Ram P/U (1997) I owned. I did notice a slight increase in the throttle response. I saw no gains in fuel economy.
If the engine is computer controlled to maintain a certain fuel/air mixture, and the K&N allows more air into the combustion chamber, then it would only make sense that using a K&N filter would lead to increased fuel consumption. Does this make sense, or am I way off base.
I don't bother with K&N's anymore.
OCTANE: You can't really measure throttle by feel and even small variations in your "feel" would change RPM considerably.
I have it on my 97 Civic Vtec for one year. I noticed when I accelated from a complete stop, its worser than the OEM filter, but rpm will be more easily rose to 6,000 rpm and extreme speed can go to around 10 mph more. But you can felt the car breath more freely and hear the breathing sounds louder.
The OEM air filter will protect your engine better than these high performance filters.
IMO BG and Redline are the best. Before knock sensors were common using these products was more obvious, but now they still work but the sensors alter timing as carbon accumilates.
Un-huh. Sorry, not buying. I've been hearing such rhetoric for years and I've yet to see even a single scientific report that supports those kind of claims.
I have it on my 97 Civic Vtec for one year. I noticed when I accelated from a complete stop, its worser than the OEM filter, but rpm will be more easily rose to 6,000 rpm and extreme speed can go to around 10 mph more.
Anecdotal evidence, yours or anyone else's is irrelevant. Like it or not there are just too many factors in play here for your sampling of one unit to prove that a K&N filter does anything more than introduce oil into the intake system.
Best Regards,
Shipo
close?
For high compression engines, Premium gasoline actually allows the spark event to occur earlier (i.e. a greater number of rotational degrees before TDC). What that effectively does is to cause the burn process to augment the mechanical compression of the engine (without causing detonation of large amounts of end gas). This in turn results in a higher combustion chamber temperature and pressure (occurring exactly at the point of the greatest mechanical advantage of about 17 degrees after TDC, plus or minus 3 degrees depending upon the engine), which will then in turn yield greater power to the crankshaft.
So, while the caloric content of Premium fuel is virtually identical to that of Regular, the ignition map with which a high performance/compression engine extracts that power isn't, and as such, more of the available power is realized.
Best Regards,
Shipo
can you answer this: why would one go to a lower octane fuel during winter months?
Some folks reason that since the intake charge is colder it is okay/desirable to use a more volitale fuel when winter hits. What they don't realize is that since the cold/dry air is considerably more dense than the warm/moist air of summer time, that peak cylinder temperatures/pressures won't really drop much (if at all), and as such, the recommended fuel is still the recommended fuel.
Best Regards,
Shipo
Does it mean if the engine is 10.5 compression and asks for min. 91 Octane, if I put 93 or 94, will the spark occur too early to the reach the maximum power? Means lower power for the same amount of gas burnt.
Well, sort of, maybe.
Given: Engine with 10.5:1 compression recommending 91 Octane fuel and is fed 94 Octane fuel.
- If the engine is capable of adjusting the timing of the spark event (and possibly the valve timing as well), then the engine should very well be capable of increasing the power yield from any given amount of fuel, however, not to the same extent as that same engine with say a 12.0:1 compression ratio (or some type of forced induction).
- If the engine is NOT capable of adjusting the timing of the spark event, then the plugs will fire too late for the engine to extract as much power out of the fuel as would otherwise be possible.
Best Regards,
Shipo
NOT PRETTY-- never take heavy and constant pinging lightly! Detonation is massively harmful business.
Detonation: The sudden explosion of one or more small pockets (or even not so small) of "End-Gas" (unburned gas usually located in the furthest points of the combustion chamber from the spark plug(s)). Detonation always occurs AFTER the spark event and usually within say ten degrees either way of TDC. Light detonation is considered desirable by some engineers and harmless by most of the rest. Moderate detonation should be remediated immediately as it can cause engine damage in and of itself and will usually lead to heavy detonation in relatively short order. Heavy detonation WILL destroy an engine in a matter of minutes.
Pre-Ignition: The unscheduled ignition of the intake charge BEFORE the spark event (hence the name "Pre-Ignition"). Pre-Ignition WILL destroy an engine in a matter of moments, literally within just a few revolutions from onset.
Best Regards,
Shipo
So "pre-ignition" could be caused by say glowing carbon in the cylinders taking the place of the spark, correct?
The users of K&N products almost universally claim noticable improvements, however, virtually all of the tests that I've read suggest otherwise.
Here I disagree... From what I know, and the independent tests that Road & Track did , the K&N filters may help increase air flow...depending on the engine and maker. For some makers , the limiting agent in engine efficiency is the rather restrictive air flow, and thus there is noticeable improvement. Example: the 5.7 l V8 in the GM suburban. In others, like my Jetta TDI, the limiting agent is not the air flow, but the dynamics of the diesel engine, thus using the K&N filter will not do a thing .
The folks at the mags did a comparo..using dyno...and measured before and after...and saw differences in some engines..and no diff in other engines.
Question: Why not just trust the highly qualified engineers who designed your car and its engine (and what filters it works best with), and use OEM or equivilant filters?
I would normally agree with that statement, but after we bought a Mercury Lynx ( FORD product), the ""highly trained engineer"" that you alluded to designed and placed the headlight controls at knee level on the lower left side of the dash...so it was nearly impossible to find, non intuitive, and frequently when one exits the vehicle, one's knee would accidentally hit the switch, and turn on the lights all day, so one would return to a dead battery....UGH !!! I appalls me that an engineer would even think of putting a light switch there....why not put it in the second row ,where it may be more accessible ??? ( sarcasm injected here )
ANd the almighty engineers at Acura designed the first generation Acura TLs ( nice car ) , but if you tried to change the wipers , you would not be able to lift the blades..not until you you release the hood, and opened the hood up.... :mad:
Someone messed up there in design again !!
excuse my cynical attitude
Engines are tuned to a certain degree and all variables are held to certain values.....for the most part, the engineers could be right....but even they tinker around the engine...and squeeze more hp or better fuel economy, by doing all sorts of adjustments.
yes, you can get a HP increase on certain engines at certain RPMS.
As a rule, the bigger the engine, the greater the chance of a small HP gain, and the higher the revs, the greater the chance.
So, a big honker V8 at 5,500 rpm will show some HP blip on the dyno....a 1.5 liter Scion xA at 3,500 rpm, you can just forget it.
How is the 928 doing ? I hope all is well.
I think with the double intake of the 928 and cayenne, there is no need for a K&N, though like you said, it may be an improvement.
I agree with your opinion. It is my experience also, that with only one intake filter, the Suburban with a 5.7 liter V8 with supercharger was just dying of asphyxiation , until a K&N was installed.
OTOH. my VW TDI , with the small 1.9 liter , 4 cylinder diesel, the K&N is a non issue..and may even be worse for the engine..,,
So overall, to be fair, I would have to say that for larger engines, with greater need for high volume of air, then the K&N may be useful, provided that the limiting agent ( WRT design of engine) in the volumetric efficiency equation is the air intake filter.
Some automakers will limit the air box slightly so that you don't get the intake noise that a K&N filter allows. Many new car buyers would not like this amount of intake noise.
carrying a container that could be used to put fuel (or water) in if you run out isn't such a bad idea, but why would you want to jeopardize your safety by carrying fuel in something other than the gas tank?
maybe they stopped manufacturing and selling it because of accidents, injuries and lawsuits.