SamDoe1

Sarcasm?

To be fair, the engineers are correct in that there will not be any real damage from running on regular but there will be a performance loss and a fuel economy loss. These particular stories have been spun by journalists who have no idea what's going on or even how an engine works.

A few of those are DI engines and they cool the A/F charge by using the gas as a cooling agent. This enables them to run higher compression with lower octane rating. There are also a considerable number of variables as far as what dictates the use of higher octane rated fuels, it's not only compression ratio.

^ This.

The octane rating of the fuel does not affect the emission rating of the car.

Acura-OC

I am interested to find out where do we lose energy, that is all.

If it is same gas with same energy count than burning same amount will produce same energy. Many users said that there is energy loss.

Assuming that it is not a placebo effect here some of the ideas generated by this discussion:

Burning same amount of fuel at different time could result a few different outcomes one is not effective burning resulting in grater pollution I am assuming that this should be detectable during smog test. But I am also guessing that in this scenario ECU would adjust gas-to-air ration to make sure cleaner burning.

Another assumption is less energy directed toward piston more energy converted to heat, I am assuming I should be able to see some changes on my gauge this should result in loss of energy, higher temperature, relatively same exhaust and of course lover MPG.

And Last one I'd like to test is that under normal driving conditions (not racing) difference in fuel will be undetectable by ECU therefore no timing adjustment will be made resulting in same energy, same exhaust, same MPG.

I am not trying to prove anyone right or wrong. Just curious.

I hate cars

You're right, the energy has to go somewhere. When timing is regarded to protect the engine, the lost energy goes out the exhaust. I used to monitor exhaust gas temps and they would spike from 1400F to over 1800F when the timing was regarded. Coolant temp is not affected.

It's all about getting the in cylinder pressure spike to occur at 14 degrees after top dead center. Before 14 degrees that energy is trying to push the piston back the wrong way. After 14 degrees you lose a lot if it when the exhaust valve opens. Same energy content but it's not being put to use the same.

You can run the tests but your theory has already been disproven. I've run the car on the scanner 5 years ago with 87, 91, and 100 octane. It pulls timing on 87 no matter how easy you drive it. The only place it wasn't pulling timing was at idle. If your foot is on the gas it's pulling timing. On 91 octane it would occasionally pull timing but not all the time. It wasn't until I got to about a 96 octane mix or 91 and 100 octane that it stopped pulling timing under all conditions. I repeat, this is not my theory, the tests have already been performed and the results were in many years ago.

I hate cars

No sarcasm. I always agree with 90% of what you say.

NorCoTL

All I said was that a dirty air filter can cause the ECU to adjust the Air Fuel mix. Nothing else. Didn't mention an effect on mpg or power either way.

I never said that high octane burns more efficiently. I said an engine using a lower rated gas than it is designed for burns the lower rated gas less efficiently than the higher rated fuel due to the retarded ignition and that the hydrocarbons would increase if the engine is retarding the ignition due to the lower rated fuel. As you say later on, the energy loss due to a less efficient burn goes out the exhaust, not just in heat (exhaust temp spikes) but also in increased HC's as unburnt fuel due to the inefficient burn. Since we are talking about actual effect while driving, it would be under load. Maybe I'm assuming too much. I also never said that running a higher octane than required would generate more or less power.

We are not all arguing against you. I agree with everything you have said except the above where you essentially put words in my mouth. If you were clarifying/adding to my oversimplification then I apologize in advance.

SamDoe1

Judging by the fact that I've only posted in 2-3 threads on here and just bought my car two months ago, I'll take that as a compliment.

Acura-OC

This test was done in 2001

Premium fuel does not necessarily pack more energy content than does regular. Rather, it allows more aggressive engine designs and calibrations that can extract more power from each gallon of gasoline.


An engine's tendency to knock is influenced most by its compression ratio, although combustion-chamber design also has a large effect. A higher ratio extracts more power during the expansion stroke, but it also creates higher cylinder pressures and temperatures, which tend to induce knock. In supercharged engines boost pressure behaves the same way. That's why the highest-performance engines require higher-octane fuel.


If you feed such an engine a fuel with insufficient octane, it will knock. Since it is impossible, for now, to change an engine's compression ratio, the only solution is to retard the ignition timing (or reduce boost pressure). Conversely, in some engines designed for regular fuel, you can advance the timing if you burn premium, but whether this will yield additional power varies from engine to engine, only a few vehicles calibrated for regular fuel can advance timing beyond their nominal ideal setting when burning premium.


We should note that even cars designed to run on regular fuel might require higher octane as they age. Carbon buildup inside the cylinder can create hot spots that can initiate knock. So can malfunctioning exhaust-gas-recirculation systems that raise cylinder temperatures. Hot temperatures and exceptionally low humidity can increase an engine's octane requirements as well. High altitude reduces the demand for octane.



Got all that? Good. Let's meet the test cars and ponder the results. At the lower-tech end of the scale was a regular-gas-burning 5.9-liter Dodge Ram V-8. This all-iron pushrod engine has a mechanical distributor and no knock sensors, so the computer has no idea what grade of fuel it's burning. A Honda Accord V-6 with VTEC variable valve timing represented the mainstream-family-sedan class, and a 4.6-liter V-8 Mustang stood in as an up-to-date big-torquer. Both of those were designed to run on regular unleaded. Our premium-grade cars included the hard-charging 333-hp, 3.2-liter BMW M3 straight-six boasting individual throttle by wire for each cylinder and enough computing power to run Apollos 11 through 13. A Saab 9-5 gave us a highly pressurized 2.3-liter turbo. For the sake of repeatable track testing, all but the M3 were equipped with automatic transmissions.
We ran all vehicles on both grades of fuel, at a drag strip near our offices and on a Mustang eddy-current dynamometer that was offered to us by the engine-tuning pros at Automotive Performance Engineering in nearby Clinton Township, Michigan. On arrival, all fuel tanks were drained and filled with 87-octane Mobil regular fuel and driven for two days before track and dyno testing. The tanks were drained again and filled with 91-octane Mobil premium and again driven for two days to allow time for the engine controllers to acclimate to the fuel type and tested again. All dyno and track results were weather-corrected.
Our low-tech Ram managed to eke out a few extra dyno ponies on premium fuel, but at the track its performance was virtually identical. The Mustang's knock sensors and EEC-V computer found 2 hp more on the dyno and shaved a more impressive 0.3 second off its quarter-mile time at the track. The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability. This, of course, may also be the case for the gains of similar magnitude realized by the Ram and Mustang.
The results were more dramatic with the test cars that require premium fuel. The turbocharged Saab's sophisticated Trionic engine-control system dialed the power back 9.8 percent on regular gas, and performance dropped 10.1 percent at the track. Burning regular in our BMW M3 diminished track performance by 6.6 percent, but neither the BMW nor the Saab suffered any drivability problems while burning regular unleaded fuel. Unfortunately, the M3's sophisticated electronics made it impossible to test the car on the dyno.


Our tests confirm that for most cars there is no compelling reason to buy more expensive fuel than the factory recommends, as any performance gain realized will surely be far less than the percentage hike in price. Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump. If the car is sufficiently new and sophisticated, it may not suffer any ill effects, but all such skinflints should be ready to switch back to premium at the first sign of knock or other drivability woes.

Acura-OC

Here is a link to 2010 article testing 2010 VW Jetta

http://www.europeancarweb.com/tech/p...n/viewall.html

Conclusion

In the end, you get what you pay for. If you want standard performance use standard gasoline. But if you want premium performance, pay for premium gas.

Acura-OC

My conclusion:

With the modern engine management systems, most (or all) cars designed to run on higher octane gas can run on a lower octane with diminished performance but no damage.

Some cars designed to run on the lower octane gas have the capacity to benefit from a higher octane but question remains how do they differ from the ones designed to run on a higher octane gas but able to use the lower octane gas?

I hate cars

Finally, an intelligent article.

Turbonut

iTrader: (1)

So, with the I guess you agree that running regular in a car that requires premium would yield no problems, something that's been stated early on.

I hate cars

You might want to read the articles again. If by no problems you mean less power, mpg, and more stress on the engine then yes, I agree.

nfnsquared

I have a real tough time believing that 93 octane is responsible for a 2-3 MPG increase over 91...

I hate cars

In city driving and especially if it was tested in the summer it's definitely possible. Remember, my car showed timing being pulled on 91 pretty often and it took about 96 octane to stop it completely. Knowing this, the ECU is going to add more timing on 93.

Acura-OC

Why would you need his endorsement? Hi didn't contribute anything to this topic except some childish well known information posed 4-5 times. Not even that but he also said some plain stupid things because this subject is way over his head.

I hate cars

Are you talking about me? I was very nice to you in the beginning when you clearly understood nothing. It was hard being patient because you just didn't get it and you based your stance on myths and assumptions yet you were too arrogant to think for a second that you might be wrong. I posted the same info 5 times because you weren't getting it. I tried to make it simpler every time for you. That's the last time I will be nice. For the future I'm going to make it a point to show you just how little you know. You would be smart to humble yourself because I'm going to pick apart all of the garbage you posted starting from the beginning.

Show me one time where I was "in over my head". Hell , show me one time I was wrong. Show me anything "stupid" I said. I'll be glad to point out all of your inaccuracies. That do called childish information that everyone knows went over your head 5 times. You still don't get it.

I hate cars

Let's start here. You actually think the ECU lean out the mixture while the timing is retarded due to knock!!! What do you think leaning it out will do? It will cause more knock. How would leaning it out ensure complete combustion anyway?

You admit you have zero experience with the TL which requires premium. You start out by wondering if there will be a difference in regular to premium yet you later state it as fact that it will make no difference without running any tests. You ignored when I said I have run the car with the scanner hooked up for a couple weeks on 87, 91, and 100 octane. I told you the TL pulls a ton of timing on 87 octane and it pulls some timing on 91. I also told you I got better mileage on the higher octane on a very well controlled long distance cycle. Another member posted similar results. So you have not done any sort of testing yet you doubt those of is that have.

I'll tear the rest apart tomorrow. You could use some humble pie.

Acura-OC

One of the major problems/limitations of Internal Combustion Engines is chemistry. Engineers do whatever they can with design but one thing they are not able to change is chemistry. Therefore they must adapt to it. With me so far?

87, 89,91,93 fuel that burns exactly the same but one thing I didn't mention before which is very important it burns with the same SPEED. Engineers can delay burning process by reducing air 13:1 is the optimal air-fuel ratio that burns fastest and that is the problem my friend that you do not understand. Once again fuel burns as fast as it can at 13:1 ratio and it cannot burn any faster.

Keeping spark to occur at exactly 14 degrees is not a problem exactly opposite is true. You need spark to occur at different degrees NOT at 14 degrees.

For example: piston at 4K RPM will travel 4 times faster to the dead point than at 1K RPM but remember our chemistry lesson fuel burns with the same speed and nothing you can do about it.

Because of that the fire has to be ignited just at the right time to get the peak pressure at the optimal point. Not at 14 degrees. By the way usually it between 15 - 22 degrees. As the engine speed increases, you need to ignite the mixture in the combustion chamber earlier because there is less time between spark and optimum peak pressure angle. If the mixture density is changed due to for example boost or higher compression ratio, the spark has to be ignited later to hit the same optimal point. Doesn't meter what type of fuel you are using computer electronics do it all the time it doesn't "work overtime" does what it is was designed to do regardless of whether it is 87, 89, 91,93. Remember you've said that it does it occasional with 91? Well it must do it with different RPMs regardless of type of fuel. So either you have not done the test or you have not done it right or your scanner was broken or some other reason.

The advances in power of modern engines, despite the lower quality of gasoline today, comes partially from improvements in combustion chamber and spark plug location. Modern engines are optimized so that the flame front has the least distance to travel and consumes the mixture as fast as possible. An already burned mixture can no longer explode and therefore higher compression ratios are possible with lower octane fuel. Some race or high performance engines actually have 2 or three spark plugs to ignite the mixture from multiple points. This is done so that the actual burn time is faster with multiple flame fronts. Again, this is to consume the mixture faster without giving it a chance to self-ignite.

By the why I've noticed that anytime you are not capable to provide any real evidence but you have this urge to have your ego stroked you resort to using same argument "I've done it and results were ....... and later we laughed about it with my buddy".

The reason why engineers designed this engines with ability to retard or advance ignition in order to adapt to chemistry not just in case some one will fill up with a lower grade gas.

Acura-OC

I am sorry it took me too long to write an initial reply and you had time to dig yourself even deeper.
You do not understand true reason for timing . Just stop it.

Acura-OC

For anyone who is still interested in a subject here is the link to ignition map I just googled for the purpose of discussion.

http://www.romraider.com/forum/viewt...&view=previous

As you can see in this case timing will adjust between 10-36 degrees depending on the RPMs and throttle position.

For example at idle it is at 10 degrees and at 3K it will range between 24-29 depending on which gear you are.

I hate cars

I'll be home in a few minutes. I hope you have thick skin because not one thing you said was remotely correct. Again, you understand nothing yet you're so arrogant you do t realize you know less than most people. More to come and it's not going to be nice. You aren't smart enough to comprehend what I've said so far such as 14 degrees.

Steven Bell

iTrader: (2)

I'm warning you guys now.....if this gets out of hand with name calling and personal jabs, I'll be handing out vacations and not think twice about it.


I've always said this to everyone on AcuraZine. Postings are NOT to get personal....no name calling either.

If we can't have a good back and forth conversation, this thread will be closed.

tones160

*Speechless* o_o

I hate cars

Everything was fine again until the above post.

Acura-OC

As soon as I will ran out of 91 I will fill with 87 and take it to a smog check. I said earlier that I am doing it just to cure my own curiosity. Not trying to prove anything, at the same time would like to keep this thread as honest as possible. Hopefully it can be "Saved by the Bell".

I hate cars

No personal attacks, no verbal attacks, no name calling, no threats:

If anyone wants to see where most of Acura-OC's post was plagiarized from, visit: http://www.innovatemotorsports.com/resources/myths.php .

Really?

Credit for this (word for word) goes to: http://www.consumerenergycenter.org/...s_premium.html
I have results, after lots of long trips, the same exact trip I learned that the TL gets better mpg with 91. With the scanner hooked up I learned it pulls timing on 91. No theory involved in those tests that took place over 30,000 miles. But you still argue:
Even after having no experience with the TL:
Then you add this list of cars with higher compression ratios than the TL that require regular and do not acknowledge they're all direct injected. I don't know if you don't know the difference or if you were hoping no one else would notice.
All direct injected engines.

Taken from: http://www.innovatemotorsports.com/resources/myths.php

Yes, which is why peak power is made between 12.8-13.2:1. Stoich is the point at which the least amount of air is required for the fuel to burn completely. For gasoline it's 14.7:1. With ethanol added it's very slightly different.

AFR is constantly varied as well. It will usually go leaner under light load and richer under heavy load. The ECU has a target AFR in it's fuel tables and it tries to hit it by measuring (or calculating in our case) how much air is being ingested. This calculation is then checked post combustion via the 02 sensors and adjusted via fuel trims if need be.

Whoa there. I said nothing about SPARK occurring at 14 degrees ATDC. I said PEAK PRESSURE should occur at 14 degrees.

Here you go from myself earlier in this thread:

"The point of leading the piston and igniting the mixture while the piston is still coming up (this would be called ignition advance) in the bore is to attempt to get the majority of the cylinder pressure created by combustion at 14 degrees after top dead center."
"The dead point"? Can you explain what you mean, I honestly don't know?

You can most definitely do something about the speed at which fuel burns based on engine rpm. You fire the sparkplug sooner at higher rpm (also known as ignition timing) so peak pressure still occurs at 14 degrees ATDC. Timing is constantly varied while driving and even at idle. Our engines redline at 6,900rpm. Formula One and Indy spin upwards of 17,000rpm. Many drag cars spin over 10,000rpm and a lot of them are run on gasoline with the same burn rate as we use. How are they able to do this? Ignition advance. Whether at 6,900rpmm or 17,000rpm, the peak pressure needs to be around 14 degrees BTDC so maybe, just maybe an F1 engine uses more ignition advance to make up for the higher rpm. We could get into piston speeds too but I don't want to open that can of worms.
Who said anything about ignition occurring at 14 degrees? 14 degrees is where you want the pressure peak to occur to get maximum mpg and power from a given amount of fuel. You do not understand the difference in ignition timing and peak pressure timing.
You might want to credit Innovate Motorsports for that quote. Here's the full quote you stole from: As the engine speed increases, you need to ignite the mixture in the combustion chamber earlier because there is less time between spark and optimum peak pressure angle. If the mixture density is changed due to for example boost or higher compression ratio, the spark has to be ignited later to hit the same optimal point. As seen here:http://www.innovatemotorsports.com/resources/myths.php I knew you couldn't write something like that so I looked it up lol.

What is "mixture density"? You have AFR and you have compression ratio, which one are you talking about? Under the compression ratio heading you have static and dynamic compression ratio. If boost is turned up you end up with a higher dynamic compression ratio. Whether or not spark has to be retarded depends on whether or not it pings in that area. There may be enough headroom built in that timing does not have to change. The optimum timing (as it calls for in the timing map) is not altered until knock occurs.
I said it does "it" with 91? What is "it". You don't understand how timing works; You have a base timing map that the ECU follows based mostly on rpm, temperature, and load. It follows this table until it receives input from the knock sensor. Once the knock sensor is tickled the ECU pulls back timing which is called timing retard. It's where the timing deviates from the base timing map. So if by "it" you mean timing retard, a variance on the base timing map, it does pull timing on 91 in some instances.

I have never one time said I monitor absolute timing. I monitor timing retard. Look up the difference in the two. Case in point a few of my own quotes from this thread:

The reduction in gas mileage is due to the timing being retarded from knock and from the knock itself.

The timing retard that's a result of the ECU trying to protect the engine from detonation will really hurt mpg and power.

the ECU also steps in and retards timing to protect the engine from damage. This means the plugs are firing later and your in cylinder pressure peak is occurring too late.

I've done the research with the scanner hooked up to verify the TL most definitely retards timing on 87. It even retards the timing on 91 a little.

In the above examples, "retard" is a verb and it describes how much the timing is retarded in relation to the base map. It is not absolute timing. It is how much the timing deviates from the base map, also measured in degrees though much lower in value. In my turbo car, .5 degrees is acceptable. The TL might be able to get away with 10 degrees of retard. No engine runs on .5 degrees or 10 degrees of total timing.
Of course the timing varies with rpm. Timing is increased with rpm but it is increased less when the knock sensor detects knock.

Yes, my scanner must have been broken because it doesn't fit your theory. Even at idle the timing jumps all over the place to keep a steady idle. The ECU can respond almost instantly with timing to keep rpm steady while there's a slight delay with the throttle. Remember this for idle speed: Timing changes = small idle corrections. DBW = large idle corrections such as high cold idle.
You may want to credit Innovate motorsports with that one too.

Lower quality of gasoline today? That's a new one. Detergent packages and QC is better than ever. The only thing worse is the ethanol content.

From Google lol:
"Gasolines are immensely better than in the past. Unfortunately, today's cars are very picky with respect to purity, heat content, and the additives needed for very precise combustion."

And this one also stolen from Innovate.

Combustion chambers have been continually improved since the internal combustion chamber was invented. There have been no breakthroughs, just optimization. The increase in power over the years is mostly attributed to the head design, mostly intake and exhaust ports and valve placement and angle along with leaving less "power on the table" in the form of induction tract and exhaust restrictions.
This was also stolen from Innovate.
You forgot swirl and quench area.
Also from innovate.

Here's the paragraph you plagiarized in it's entirity:

"The advances in power of modern engines, despite the lower quality of gasoline today, comes partially from improvements in combustion chamber and spark plug location. Modern engines are optimized so that the flame front has the least distance to travel and consumes the mixture as fast as possible. An already burned mixture can no longer explode and therefore higher compression ratios are possible with lower octane fuel. Some race or high performance engines actually have 2 or three spark plugs to ignite the mixture from multiple points. This is done so that the actual burn time is faster with multiple flame fronts. Again, this is to consume the mixture faster without giving it a chance to self-ignite."

2 or 3 plugs in a production engine are mostly for emissions. They can help older combustion chamber designs a little but are of little value to a modern combustion chamber. Buy the SAE paper on Ford's laser ignition system still in development that uses 100 ignition sources scattered throughout the combustion chamber. They specifically state they saw a slight reduction in emissions and zero hp increase.
Wait, I can't provide any real evidence....... Should I plagiarize then lol. And yes, I have provided evidence in this thread.
Hmmm. So what are these changes in chemistry? Common sense would tell me that two gasolines with the same octane will have very similar behavior in regards to knock. In fact, some people just might consider high octane vs low octanes different chemistry. Now if two different fuels with the same octane must knock at about the same time, how is the knock sensor going to help the ECU adapt to "different chemistries"?

Lol. Everything I've written is from my own brain and it's accurate.


Honest? Is plagiarism honest?

Finally, if anyone is curious about the truth, you can buy this SAE white paper for $25. I can't post the results here for obviouis reasons but this paper done by engineers, not journalists backs up everthing I've said The truth is literally right there in that link:

http://papers.sae.org/2006-01-3407/

Seriously, please buy this paper, it will back up everything I've said. Don't take my word for it.

Acura-OC

What you are saying is that because I have an interest in this subject I've done some reading and research on it. It is not like you discredited the information I've provided you just pointed out where I got pieces of it. Sorry that you had to waste your Saturday just to replay to nobody who never claimed to be anybody.

I hate cars

So that's how you're going to play it. When you post someone else's work as your own it's called plagiarism. There were no quotes around it, no references cited, no link given to give credit to the author. You tried to pass it off as your own thoughts, even changes a few words around and then you went on to talk about honesty. You will never find anything I write on a website.

I did discredit the parts that were untrue. Read it again and you will see. There are some mistakes on that website but it's mostly correct. I could go on and pick out the parts that are wrong but I'm sure everyone is sick of hearing it by now.

Again, if you want the truth instead of a pissing match, buy that $25 paper written by engineers that are impartial that followed a scientific approach. If you read it you will see everything I've said is true. It's that easy to end this.

nfnsquared

Total bullshit. He never represented anything he posted as his own work, not even close.

Plagiarism is the "wrongful appropriation" and "purloining and publication" of another author's "language, thoughts, ideas, or expressions," and the representation of them as one's own original work

I hate cars

Watch the verbal attacks and language. You need to get control of that temper.

Your definition fits what he did perfectly. Question: Before I exposed it, did you have any idea those were not his words? Did you know it was copied from the Innovate Motorsports website? Remember your answer and read your definition again.

nfnsquared

I'll say it again. He never in any post represented his post as his own work. Not even close. But nice try.

I suppose next you'll be accusing Turbonut of plagarism?

I hate cars

Did you know those were not his own words when you first read it? Did you know most of his post was copied from Innovate Motorsports?

Did I accuse turbonut, nope, so I don't know why you would ask.

Is it that hard to answer two simple questions?

I hate cars

Speaking of the internal combustion engine I was thinking about how closely rocket propulsion is related. I was thinking the configuration of a chemical rocket engine consists of the combustion chamber, where the chemical reaction takes place, and the nozzle, where the gases expand to create the exhaust. An important characteristic of the rocket nozzle is the existence of a throat. The velocity of the gases at the throat is equal to the local velocity of sound and beyond the throat the gas velocity is supersonic. Thus the combustion of the gases within the rocket is independent of the surrounding environment and a change in external atmospheric pressure cannot propagate upstream.

The thrust of the rocket is given by the theoretical equation :

F = lm(dot) ve + ( pe - pa ) Ae

This equation consists of two terms. The first term, called the momentum thrust, is equal to the product of the propellant mass flow rate m(dot) and the exhaust velocity ve with a correction factor l for nonaxial flow due to nozzle divergence angle. The second term is called the pressure thrust. It is equal to the difference in pressures pe and pa of the exhaust velocity and the ambient atmosphere, respectively, acting over the area Ae of the exit plane of the rocket nozzle. The combined effect of both terms is incorporated into the effective exhaust velocity c. Thus the thrust is also written

F = m(dot) c

where an average value of c is used, since it is not strictly constant.

The exhaust exit pressure is determined by the expansion ratio given by

e= Ae / At

which is the ratio of the area of the nozzle exit plane Ae and the area of the throat At . As the expansion ratio e increases, the exhaust exit pressure pe decreases.

The thrust is maximum when the exit pressure of the exhaust is equal to the ambient pressure of the surrounding environment, that is, when pe = pa. This condition is known as optimum expansion and is achieved by proper selection of the expansion ratio. Although optimum expansion makes the contribution of the pressure thrust zero, it results in a higher value of exhaust velocity ve such that the increase in momentum thrust exceeds the reduction in pressure thrust. So my conclusion is it's a balancing act just as too much timing and too little ignition timing is in the internal combustion engine.

Acura-OC

For some reason from beginning you took it as a personal debate where there was none. There was a discussion between other members.

I've provided an article where different cars were tested with mixed results but at least it was a test specific to discussion. Then I provided another article were VW Jetta was tested. In both cases it looked like it was an article by someone else and in one I provided a link because it was 100% relevant to the topic. I offered to use my own car for similar test because I am not looking for top performance results from track I am interested in results produced by regular day driving.

Conversation between you and me are absolutely irrelevant I do not see a need to quote multiple sources from which I took 2-3 sentences or a paragraph since rest of it is not relevant.

Thank you for link soon I will be posting very interesting information directly related to the topic.

nfnsquared

No worries dude, no one else on here remotely thinks you plagarized anything. The accusation is quite ridiculous.

Let's assume all your posts are plagarized. Don't you think it's strange that Azine promotes plagarism by allowing your posts to stand as is?

Acura-OC

Anfortuantely not able to post it in a table format.

For a typical carburetted engine, without engine management:-
Compression : Octane Number
5:1 72
6:1 81
7:1 87
8:1 92
9:1 96
10:1 100
11:1 104
12:1 108

For an engine with recommended 6 degrees BTDC ( Before Top Dead Centre ) timing and 93 octane fuel, retarding the spark 4 degrees lowers the octane requirement to 91, whereas advancing it 8 degrees requires 96 octane fuel.

It should be noted this requirement depends on engine design.

The actual Octane Number Requirement depends on the engine design, but for some vehicles using standard fuels, the following (R+M)/2 Octane Requirements were measured. "Standard" is the recommended ignition timing for the engine, probably a few degrees BTDC.

Basic Ignition Timing Vehicle

Retarded 5 degrees Standard Advanced 5 degrees
A 88 91 93
B 86 90 94
C 85 88 90
D 84 87 91
E 82 87 90

A modern engine management system can compensate for altitude, ambient air temperature, and fuel octane.

n increase in ambient air temperature of 5.6C increases the octane requirement of an engine by 0.44 - 0.54 MON. When the combined effects of air temperature and humidity are considered, it is often possible to use one octane grade in summer, and use a lower octane rating in winter.

The effect of increasing altitude may be nonlinear, with one study reporting a decrease of the octane requirement of 1.4 RON/300m from sea level to 1800m and 2.5 RON/300m from 1800m to 3600m. Other studies report the octane number requirement decreased by 1.0 - 1.9 RON/300m without specifying altitude. Modern engine management systems can accommodate this adjustment, and in some recent studies, the octane number requirement was reduced by 0.2 - 0.5 (R+M)/2 per 300m increase in altitude.

An increase of absolute humidity of 1.0 g water/kg of dry air lowers the octane requirement of an engine by 0.25 - 0.32 MON.

Acura-OC

Unfortunately not able to post it in a table format.

For a typical carburetted engine, without engine management:-
Since I am not able to post in tabular format there are two numbers in this table first is Compression second is Octane Number
5:1 72
6:1 81
7:1 87
8:1 92
9:1 96
10:1 100
11:1 104
12:1 108

For an engine with recommended 6 degrees BTDC ( Before Top Dead Centre ) timing and 93 octane fuel, retarding the spark 4 degrees lowers the octane requirement to 91, whereas advancing it 8 degrees requires 96 octane fuel.

It should be noted this requirement depends on engine design.

The actual Octane Number Requirement depends on the engine design, but for some vehicles using standard fuels, the following (R+M)/2 Octane Requirements were measured. "Standard" is the recommended ignition timing for the engine, probably a few degrees BTDC.

Basic Ignition Timing Vehicle

This is one of the most interested tables which has 4 values first is vehicle A,B,C,D,E
Second is octane requirement when ignition retarded 5 degrees
Third Required (Standard) octane
Forth with 5 degrees advanced ignition.

Retarded 5 degrees / Standard / Advanced 5 degrees
A 88 91 93
B 86 90 94
C 85 88 90
D 84 87 91
E 82 87 90

A modern engine management system can compensate for altitude, ambient air temperature, and fuel octane.

n increase in ambient air temperature of 5.6C increases the octane requirement of an engine by 0.44 - 0.54 MON. When the combined effects of air temperature and humidity are considered, it is often possible to use one octane grade in summer, and use a lower octane rating in winter.

The effect of increasing altitude may be nonlinear, with one study reporting a decrease of the octane requirement of 1.4 RON/300m from sea level to 1800m and 2.5 RON/300m from 1800m to 3600m. Other studies report the octane number requirement decreased by 1.0 - 1.9 RON/300m without specifying altitude. Modern engine management systems can accommodate this adjustment, and in some recent studies, the octane number requirement was reduced by 0.2 - 0.5 (R+M)/2 per 300m increase in altitude.

An increase of absolute humidity of 1.0 g water/kg of dry air lowers the octane requirement of an engine by 0.25 - 0.32 MON.

Was not able to edit tables in original post due to time therefore made some comments in repeating post.
Please delete first post.

Acura-OC

If someone thought that any of it is/was my work then I am flattered. I am an accountant. I will not be able to repeat any of above mentioned ratios or degrees without copying it again.

According to my own research it appears that timing can easily compensate for 4 octane points without causing any damage, other variables to consider: altitude, air temperature and humidity. Which explain differences in individual results some experienced loss and MPG and some didn't notice any difference.

Majofo

IHC, brosef, let this go
Anyone with any common sense will see the bullshit and make the right judgement. And if a guy who doesn't know where his hood release is, checks your credibility, that guy is obviously trolling or severely mentally retarded.

I hate cars

Ok. Now remember back to the beginning of this thread when I specifically mentioned driving conditions such as driving conditions/climate, driving style, etc. influencing octane requirements. You're only now beginning to understand what I've been talking about all along.

The other part you're not aware of because you haven't read about it on the web is detonation requires more timing to be pulled once it starts than if the base map had less timing and no detonation to begin with. The goal should always be to avoid it. You will end up with more timing that way. You might be able to run 18 degrees of advance with no detonation. But get greedy with the timing, say 20'degrees for a little extra power and mpg and you may end up with an easy 5 degrees of retard for a total of 15 degrees of advance to try and stop the detonation.

The next step is understanding BSFC goes up when timing is retarded from detonation. Once you understand BSFC you will begin to understand why mpg MUST suffer along with power when timing is pulled.

I've honestly been avoiding BSFC because you're going to argue with me on that as well until you begin to understand it.

I write my own fuel and timing tables including the special requirements (less timing during spool up, less fuel during spool up, more fuel for a split second on the 2-3 and 3-4 gearshift due to the spike in load, I've even got my own anti lag logic that's gentler on the turbo than the traditional pop bang method) and I've been doing so since the late 90s. I even have a 100 octane economy tune and I've come close to hitting 29mpg on the freeway which is 7mpg better than stock while making over 700hp at the crank. In was not able to do this on lower octane fuel. I blew up 4 engines while learning the boost/timing/octane/AFR relationship. I've been running and building and tuning turbo cars for over 20 years. I've done consulting work. Hell, I'm in the process of building an old turbo Indy engine for my street car. I have more experience than most so called tuners with this stuff but I was trying to keep it TL related.

It's great you're interested in this stuff but you have to realize you're in the beginning stages here. Everything I write comes from first hand experience, not from a website. I don't need to quote other people because I've been fortunate enough to work with some of the legends and I've soaked up a lot of knowledge. That doesn't mean I'm never wrong but I'm not going to waste my time anymore debunking a bunch of nonsense. Keep in mind your "research" comes from google, not from hands on experience and you have no idea what the authors credentials are nor do you have the real life experience to know if it's accurate. You 3 guys can post as much misinformation off of the internet as you want, there's an endless supply of crap out there. When you're ready to speak in your own words from your own experience we'll talk. You have not acknowledged a single point I've made, you just move on to the next subject. You haven't acknowledged that half of the previous page was spent arguing because you did not know the difference in timing retard and total or absolute timing and you didn't know the difference in ignition timing vs peak pressure timing. If you had asked questions instead of trying to act like you knew all about timing already I would have explained it to you and we could have avoided all of this.

Did you buy the paper I linked? Everything you could want to know is there and it's all accurate, not some website written by some guy. If you're truly interested in learning and you're not going with the hands on approach there is nothing better than this SAE paper.