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Old 08-22-2007, 09:15 PM   #16
rudypoochris
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Quote:
Originally Posted by vwhobo
Really? Are you sure? Horsepower and economy oppose each other? If I have two engines of the same design and displacement, engine A with a VE of 90% that produces 100 hp and engine B with a VE of 50% that produces 90 hp, which one uses less fuel at maximum power? If you answered engine A you're correct, but it makes less power, so... Care to explain the discrepancy?

Think, type, submit.

Yes. It takes fuel to make power. The more power you make, the more fuel will be consumed. I wasn't talking about different engines. I was refering to the same engine. Hence VE would be the same. Thus if you are making less HP on the same engine for whatever reason, you are using less fuel. Unless it is leaving unburned.

For this reason if you drive an economy car or a car that makes shit power down low, you have no problem getting good economy. If you drive a V8 that isn't geared super low or with out devices (such as cylinder deactivation or alot of EGR) you are going to consume. Thats all. When I drive the explorer shifting before 1000 rpm I get phenomenal gas mileage, ya the power isn't good, but it is a trade off. If I were to actually have the ECU set up properly to not throw it rich down low then it would be even better.

If his ECU leans out the mixture based off of the O2 readings or something similar, than ya, he will be getting better mpg. Until he pays the extra $XX at the pump for the premium.
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Old 08-22-2007, 10:02 PM   #17
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Quote:
Originally Posted by rudypoochris
Yes. It takes fuel to make power. The more power you make, the more fuel will be consumed. I wasn't talking about different engines. I was refering to the same engine. Hence VE would be the same. Thus if you are making less HP on the same engine for whatever reason, you are using less fuel. Unless it is leaving unburned.

For this reason if you drive an economy car or a car that makes shit power down low, you have no problem getting good economy. If you drive a V8 that isn't geared super low or with out devices (such as cylinder deactivation or alot of EGR) you are going to consume. Thats all. When I drive the explorer shifting before 1000 rpm I get phenomenal gas mileage, ya the power isn't good, but it is a trade off. If I were to actually have the ECU set up properly to not throw it rich down low then it would be even better.

If his ECU leans out the mixture based off of the O2 readings or something similar, than ya, he will be getting better mpg. Until he pays the extra $XX at the pump for the premium.
Wow! No matter how many times you repeat something you read in "Sixth Grade Basic Engine Theory" magazine, it still doesn't make it right. Let me supply you with some facts, in no particular order, that I'm sure you won't let get in the way of your opinion.


1. The ECU in your Exploder DOES NOT "throw it rich down low", no matter what you may think. Once in closed loop, the ECU, based mostly on input provided by the oxygen sensor(s), will keep the engine running as close to stoichiometry (14.7:1 for a gas engine) as possible. The only time it richens the mixture is at large throttle opening, usually WOT. This is in no way relevant to your described scenario.

2. Lack of "power down low" in no way increases fuel economy. In fact, a vehicle propelled by an engine with a weak low RPM power curve will normally get worse fuel economy than an engine with a strong lower power curve. An engine is most efficient when running at or near it’s torque peak. Torque rules.

3. If you take a car with any engine and gear it "super low", you will always increase fuel consumption in the real world, not decrease it. I don't know where you get your information, but I suggest you throw the magazine in the trash.

4. If you take a car with an engine that is optimized for 87 octane, such as an '05 Elantra, and run 93 octane gasoline, you will see a concurrent reduction in power, performance and fuel economy. Because it is optimized for 87 octane, it needs the additional BTU’s carried within the lower octane fuel to run as designed. Increasing the octane will cause it to require more fuel to create the same amount of power per combustion cycle. That mean’s you’ll make less power at any given RPM or need more RPM to attain a given level of power.


These are all proven and documented facts. I know they do nothing to further your ill informed and closed minded position, but they are the facts. Until you are able to repeal the laws of physics, they will remain the facts.
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Old 08-22-2007, 11:41 PM   #18
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Also, when cold, I have a bit of valve noise...my buddy who is in school for mechanics said its running lean when its cold, and said replacing the spark plugs might solve the problem...this happens when the engine is still cold and tapers away after 3krpm usually...

Also, does seafoam really help clean the valves and such? We put it through his mustang, and my friends accord, but not my car cause I was a bit skeptical
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Old 08-23-2007, 12:30 AM   #19
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Calm down dude... Im not trying to argue with you at all. I hardly think I have a closed mind about things. I appreciate your opinion and perspective on things. Seriously though, cool your jets. Don't try and start an argument for the sake of arguing...

Quote:
Originally Posted by vwhobo
Wow! No matter how many times you repeat something you read in "Sixth Grade Basic Engine Theory" magazine, it still doesn't make it right. Let me supply you with some facts, in no particular order, that I'm sure you won't let get in the way of your opinion.

You don't need to speak down to me, seriously. Thats rude. I didn't talk down to you, don't talk down to me. You don't know anything about what I know, read, or do. You may THINK you are all knowledgable and that the facts (regardless of if they are or aren't) you are supplying are invaluable. I simply put out what I believe to be true... A little respect on your end would be MUCH appreciated. Thanks.

Quote:
Originally Posted by vwhobo
1. The ECU in your Exploder DOES NOT "throw it rich down low", no matter what you may think. Once in closed loop, the ECU, based mostly on input provided by the oxygen sensor(s), will keep the engine running as close to stoichiometry (14.7:1 for a gas engine) as possible. The only time it richens the mixture is at large throttle opening, usually WOT. This is in no way relevant to your described scenario.

You make the big assumption, just like you assumed last post that I was talking about different engines, that I am not at WOT down low. In fact I am going WOT. I use it for good economy. I go wot below 1000rpm where the ECU fuel tables are vague at best. I BELIEVE it enriches the fuel beyond normal because A, it burns my eyes behind it at that RPM and B, I can blow black smoke (think it is carbon...) out the tail pipe after driving low rpms for a while and C, because my brother who happens to have an AFR meter and a Ford EEC-IV equipped vehicle DID tune his EFI below 1000rpm and found that it was throwing out a rich mixture (possibly to keep from dying, I dunno???). That is what I based my comments upon. Take it for what you will, but that si what I believe from my experiences. Weather or not it does enrich down low like that is not that important or relevant to the topic anyway...

Quote:
Originally Posted by vwhobo
2. Lack of "power down low" in no way increases fuel economy. In fact, a vehicle propelled by an engine with a weak low RPM power curve will normally get worse fuel economy than an engine with a strong lower power curve. An engine is most efficient when running at or near it’s torque peak. Torque rules..

Maybe an engine is most efficent near its torque peak, FOR A GIVEN POWER, maybe it isn't. I don't know or care. I don't need anywhere near as much power as I get at torque peak when going around town. I just know that going to my torque peak when driving around usually has me at 1/4 throttle or something light. There is no reason for me to have the TB restricting air into the engine and causing it to work harder. SO I shift and gear it down to make the motor work a little harder at a lower RPM. There is a reason the Camaros got 28mpg when they added skip shift (amongst other things). They didn't force you to shift 2nd to 4th because it hurt your economy.

Quote:
Originally Posted by vwhobo
3. If you take a car with any engine and gear it "super low", you will always increase fuel consumption in the real world, not decrease it. I don't know where you get your information, but I suggest you throw the magazine in the trash.

By super low I mean putting in a lower numerical ratio. Or simply shifting to the next gear up, say taking 5th instead of 4th. Sorry if that was confuzing or if I didn't use your certified terminology. Im not reading any magazine. I really am kind of baffled that you are straight up attacking my experiences for no apparent reason. Its extremely rude. I don't think you would talk to me like that in public so I don't see why you should over the internet.

Quote:
Originally Posted by vwhobo
4. If you take a car with an engine that is optimized for 87 octane, such as an '05 Elantra, and run 93 octane gasoline, you will see a concurrent reduction in power, performance and fuel economy. Because it is optimized for 87 octane, it needs the additional BTU’s carried within the lower octane fuel to run as designed. Increasing the octane will cause it to require more fuel to create the same amount of power per combustion cycle. That mean’s you’ll make less power at any given RPM or need more RPM to attain a given level of power.

I know... I said that it would lose power AND economy. So I don't know why your trying to correct me. I did say it MAY be possible if the O2 sensors leaned out the mixture that you could realize better economy. I went on to say that that "I DOUBT THIS WOULD BE HAPPENING THOUGH".


Quote:
Originally Posted by vwhobo
These are all proven and documented facts. I know they do nothing to further your ill informed and closed minded position, but they are the facts. Until you are able to repeal the laws of physics, they will remain the facts.

Thanks... I guess you know it all.

Last edited by rudypoochris : 08-23-2007 at 12:35 AM.
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Old 08-23-2007, 03:11 AM   #20
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Originally Posted by tbaxleyjr
Can you show us some references, literature written by a licensed Professional Engineer, SAE Fellow or other automotive engineering authority proving VWHobo wrong?

No. I do not have access to SAE papers. I am studying for my Mechanical Engineering degree right now and am/was (its summer) on the FSAE team. Im not saying VWHobo is wrong... I never did... I don't understand why you guys keep putting words in my mouth. I don't get the extremely argumentative nature. Im not retarded I have been working on cars a while and I build Megasquirt EFI computers. I know a thing or two... Im sure I could find papers that state what I am and what Hobo is saying and they would both be right. I just don't have the time or the will honestly.

Quote:
Originally Posted by tbaxleyjr
By the way - O2 sensors "leans down" nothing - there is no MAY, WHAT, Possibly, etc about this - the O2 sensor provides a control input to the ECM which in conjunction with air flow, and a couple of other inputs optimizes the air-fuel ratio to approximately 14.7:1 for complete and efficient combustion - I think you were told this earlier in the post

Okay... symantics. I meant the injectors lean out the mixture from a signal from the ECU which in part is based off of the signal from the O2 sensors. So the O2 sensors are leaning out the mixture if they feel it is needed. Its saying the same thing. At WOT the computer tries for less than 14.7:1 since 14.7:1 is not ideal for every condition. Less than 14.7 is richer, more is leaner. These calculations are done impart by the O2 sensor. So I said the O2 sensor can lean and richen up the mixture, which is true. Sometimes the computer completely ignore the HEGO's it really depends. It bases these calculations off load and other things as well, depending on your EFI maybe it is different for EEC-IV it is that way. I still don't know what this has to do with what I said before...

Sorry if you don't believe me. Thats fine it really isnt a big deal. Doesn't change anything either way.
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Old 08-23-2007, 04:54 PM   #21
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Originally Posted by tbaxleyjr
A college level mechanical engineering text on thermodynamics and combustion (usually taught during the third year) and a good engineering text on internal combustion engines (sometimes taught as an elective in many universities in the Senior year) would be a starting place.

Another place would be the Ford Motorcraft website - it has summary level information concerning Ford's OBD2 compliant engine management systems work

Thanks... What is it exactly that you want me to find?

You want me to prove that the ECU will lean or richen the mixture based off of O2 sensors?

You want me to supply the fuel tables?

You want me to prove that having a lower numerical gear ratio gets better fuel economy?

You want me to prove that if you take the same engine and make more power on it that it will consume more fuel?

These are all pretty basic things. I don't understand exactly what you want? Hence why I don't understand VWHobo calling me out on things I didn't necessarily say. Im new to this forum, but I am hardly an idiot. I just don't see the reason to argue with me over things I did not say then request sources and citations over mostly common knowledge to disprove someone else who supplied... zilch.

I do what works for me and supplied what I feel to be true. As I said before I have and do build EFI computers, I might know something. If you have certain points you want me to supply some info for I can try. As I said though, limited access. Honestly Im not here to argue thermodynamics and never said I was. I simply stated what the ECU MIGHT do if premium fuel was introduced and it was tuned for regular.

Last edited by rudypoochris : 08-23-2007 at 05:37 PM.
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Old 08-27-2007, 07:12 PM   #22
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My point is that the O2 sensor MIGHT pickup on the premium fuel due to differences in the emissions. I didn't claim to KNOW that it would or wouldn't. Also it most likely depends highly on what the ECU's capibilities are. There definately are mights, maybes, and I don't knows in engineering. Maybe you don't like to admit it?

I never came on here claiming anything out landish or unreasonable. You all jumped down my throat for no apparent reason. If you say I know nothing, then I must not know anything. Your the boss :/

As for all of your acredited technological knowhow and SAE certified master skills, you might want to work on your attitudes and social skills slightly. Members of YOUR forum are PM'ing me about how little you all know and how petty you argue using "google.com" as your technical resource. Just a heads up.
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Old 08-30-2007, 04:02 AM   #23
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Quote:
Originally Posted by tbaxleyjr
Yeah, yeah, yeah.......

Just a heads up - I would refer to this web site http://www.m-w.com/home.htm (Merriam-Webster Online) before making your next post in anger @ me or anyone else

Also suggest you ask about where some of us find our information - www.google.com actually does not supply with me with much. One has to look at the sources of infor carefully.
C'mon man ... no need for the holier than thou.

Seems a bit silly to point someone to a dictionary website when you mad a grammar mistake yourself in a 5 line post... and also shortened information to "infor", which doesn't seem to be a standard abbreviation as far as I'm aware. Silly mistakes to point out, right?? Well, so's trying to pick on his spelling.

[EDIT] : read my bit about google again, and removed it.... I retract all statements made
I don't think I quite hit the mark I was going for.
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Old 08-30-2007, 01:43 PM   #24
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Quote:
Originally Posted by rudypoochris
My point is that the O2 sensor MIGHT pickup on the premium fuel due to differences in the emissions. I didn't claim to KNOW that it would or wouldn't. Also it most likely depends highly on what the ECU's capibilities are. There definately are mights, maybes, and I don't knows in engineering. Maybe you don't like to admit it?

Maybe you should not be in the help section. Did you ever come to that conclusion? I know I did.

An O2 sensors primary functions is to relay a voltage to the ECM. It derives this voltage by measuring the amount of oxygen in the exhaust manifold.

You're thinking that because higher octane fuels burn slower(not burning all of the fuel) that the O2 sensor would pick up the rich mixture and send the voltage to the ECU which would, in return, supply less fuel. Hence better fuel economy.

Well you're wrong. VW already tells you why.

"4. If you take a car with an engine that is optimized for 87 octane, such as an '05 Elantra, and run 93 octane gasoline, you will see a concurrent reduction in power, performance and fuel economy. Because it is optimized for 87 octane, it needs the additional BTUís carried within the lower octane fuel to run as designed. Increasing the octane will cause it to require more fuel to create the same amount of power per combustion cycle. That meanís youíll make less power at any given RPM or need more RPM to attain a given level of power."


I even referred to my literature for the given subject because I didn't understand it at first. However, it is in there. I don't know what engineering program you are in but its not a very good one if they haven't thought you rudimentary physics. So your "point" was proven to be incorrect. Now what are you still trying to prove?
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Old 08-30-2007, 11:39 PM   #25
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Quote:
Originally Posted by tbaxleyjr
I stand corrected
hehe.. and now I notice that I misspelled "mad" as well

[EDIT]
Quote:
Originally Posted by DSMer
I even referred to my literature for the given subject because I didn't understand it at first.
can you let us know what literature this is?
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Old 08-31-2007, 04:39 AM   #26
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You're thinking that because higher octane fuels burn slower(not burning all of the fuel) that the O2 sensor would pick up the rich mixture and send the voltage to the ECU which would, in return, supply less fuel. Hence better fuel economy.

No, that was not what I was thinking.

I was thinking that possibly the O2 sensor would recognize the increased emissions resulting from a higher octane fuel and lean the mixture out in return. It was just a rudimentry hypothesis which depends entirely on how an O2 sensor actually meters. Hence MIGHT.

Quote:
I even referred to my literature for the given subject because I didn't understand it at first. However, it is in there. I don't know what engineering program you are in but its not a very good one if they haven't thought you rudimentary physics. So your "point" was proven to be incorrect. Now what are you still trying to prove?

I am in the UC Davis Mechanical Engineering program. I don't think I shall be switching. I am sure you are in MIT though. I am not trying to prove anything, it was just an idea as to how something might happen. I still don't believe my "point" (if you cna even call it that... it was just a rudimentary hypothesis) was disproven. That quote simply said premium in an 87 octane car will make less power and have worse economy. I know the performance will be reduced. I said the economy MIGHT not be. Yes lower octane fuel has more energy in it... The whole quote assumes that the car KNOWS how much power it is making and that the engine will want to compensate and make that same power. That is not necessarily true. The car does not necessarily know how much power it is making, nor does it care. Thus I don't see any reaosn for it to want to try and compensate by spilling more fuel.
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Old 08-31-2007, 05:15 AM   #27
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Originally Posted by windsonian
can you let "ME" know what literature this is?

"Internal Combustion Engine Fundamentals", "Combustion Physics" and "Theoretical and Numerical Combustion". A few of the MANY required readings in my program. If you want any more information than that you're going to have to buy these overly expensive books yourself. My 30k a year tuition doesn't cover YOUR learning. Sorry.

Quote:
Originally Posted by rudypochris
I am in the UC Davis Mechanical Engineering program. I don't think I shall be switching. I am sure you are in MIT though. I am not trying to prove anything, it was just an idea as to how something might happen. I still don't believe my "point" (if you cna even call it that... it was just a rudimentary hypothesis) was disproven. That quote simply said premium in an 87 octane car will make less power and have worse economy. I know the performance will be reduced. I said the economy MIGHT not be. Yes lower octane fuel has more energy in it... The whole quote assumes that the car KNOWS how much power it is making and that the engine will want to compensate and make that same power. That is not necessarily true. The car does not necessarily know how much power it is making, nor does it care. Thus I don't see any reaosn for it to want to try and compensate by spilling more fuel.

No, not MIT, Cal-Berkely, G-Tech or Stanford. I attend UIUC. So I guess 5th best in the nation will have to do. I'll break it down to you nice and simple, just like they used to do Freshman year.


If you require MORE fuel to produce a proper combustion on a higher octane gas, how will leaning out the mixture better your fuel economy if you're inevitably going to need MORE fuel than is normally necessary?
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Old 08-31-2007, 05:35 AM   #28
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Originally Posted by DSMer
"Internal Combustion Engine Fundamentals", "Combustion Physics" and "Theoretical and Numerical Combustion". A few of the MANY required readings in my program. If you want any more information than that you're going to have to buy these overly expensive books yourself. My 30k a year tuition doesn't cover YOUR learning. Sorry.
hahaha....

You're not the only one with book learning champ.
i was merely asking about your sources. Maybe other people's engineering degrees used different texts. Does that make yours the be all and end all? $30k a year is wasted if you don't learn to learn ... if you follow me.
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Old 08-31-2007, 05:56 AM   #29
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Originally Posted by windsonian
hahaha....

You're not the only one with book learning champ.
i was merely asking about your sources. Maybe other people's engineering degrees used different texts. Does that make yours the be all and end all? $30k a year is wasted if you don't learn to learn ... if you follow me.

No I don't follow you. I don't care to follow you and more importantly I don't want to follow you. I don't think I need to take lessons from you on "learning to learn" or whatever the f*ck that means.

Save your bullshit philosophy's for someone who actually feeds into that kind of crap.
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Old 08-31-2007, 06:05 AM   #30
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Originally Posted by DSMer
No I don't follow you. I don't care to follow you and more importantly I don't want to follow you. I don't think I need to take lessons from you on "learning to learn" or whatever the f*ck that means.

Save your bullshit philosophy's for someone who actually feeds into that kind of crap.
my point is that you're paying $30k per year to believe everything your teachers tell you. you're not learning to learn things for yourself.

you do not, and will never know it all ... and your school probably doesn't make you better than the rest of us with formal training.
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