What brand and grade of gas are you using? 87 or higher?
#21
09-23-2014, 01:54 AM
Top Tier Gasoline
I use whatever one I run into, but attempt to avoid Exxon because of their politics.
I use whatever one I run into, but attempt to avoid Exxon because of their politics.
Google Image Result for http://www.viewlogos.com/wp-content/uploads/2013/04/11.jpg
Last edited by Vanguard; 09-23-2014 at 01:57 AM.
#22
09-23-2014, 02:00 AM
"It may seem like buying higher octane “premium” gas is like giving your car a treat, or boosting its performance. But take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage, or run cleaner. Your best bet: listen to your owner's manual."
Paying a Premium for High Octane Gasoline? | Consumer Information
.
#23
09-23-2014, 06:01 AM
You guys need to investigate what "Top Tier" really is. It is a marketing thing. To advertise that you are "Top Tier" you must only agree that the fuel you sell is AT LEAST 8% ethanol. After that you stipulate that your fuel will exceed the EPA minimum standard for cleanliness (clean burning) which ethanol does.
The primary additive in "Top Tier" gasoline is ethanol. Since ethanol is already required in EPA-non attainment areas, there nothing else you need to do to qualify except sell ethanol diluted fuel in all marketing areas.
You also need to investigate what Octane rating is. There are three measurement types Reaserch (R), Motor (M) and R + M divided by 2 which we use in th US for automotive fuel. In simple terms octane is measurement of a given fuel's resistance auto-ignition (uncontrolled burning or explosion (pre-ignition). Octane does not have anything to do with the amount of energy contained in the fuel.
You want your fuel to start burning before Top Dead Center with the maximum burn at just past TDC and completed as quickly as possible from that point on.
Higher octane fuel, beside being able to resist self ignition at higher temperatures, also burns slower when control ignited by something like a spark plug. So some percentage of the energy produced under controlled burning is beyond TDC. The higher the octane the slower the burning and the lower the efficiency of conversion of that burn to mechanical energy. We are only talking couple of percent so it is not much.
Octane has noting to do with increased fuel mileage or performance. In fact Ethanol has a higher octane rating than the normal gasoline but lower energy when compared to straight gasoline. Besides burning cleaner it also is used as an octane booster, but it produces considerably less energy.
I did my best to explain this in non-technical terms. I hope I accomplished this. I had a big long explanation typed out but got rid of most of it and all of the technical terms.
The primary additive in "Top Tier" gasoline is ethanol. Since ethanol is already required in EPA-non attainment areas, there nothing else you need to do to qualify except sell ethanol diluted fuel in all marketing areas.
You also need to investigate what Octane rating is. There are three measurement types Reaserch (R), Motor (M) and R + M divided by 2 which we use in th US for automotive fuel. In simple terms octane is measurement of a given fuel's resistance auto-ignition (uncontrolled burning or explosion (pre-ignition). Octane does not have anything to do with the amount of energy contained in the fuel.
You want your fuel to start burning before Top Dead Center with the maximum burn at just past TDC and completed as quickly as possible from that point on.
Higher octane fuel, beside being able to resist self ignition at higher temperatures, also burns slower when control ignited by something like a spark plug. So some percentage of the energy produced under controlled burning is beyond TDC. The higher the octane the slower the burning and the lower the efficiency of conversion of that burn to mechanical energy. We are only talking couple of percent so it is not much.
Octane has noting to do with increased fuel mileage or performance. In fact Ethanol has a higher octane rating than the normal gasoline but lower energy when compared to straight gasoline. Besides burning cleaner it also is used as an octane booster, but it produces considerably less energy.
I did my best to explain this in non-technical terms. I hope I accomplished this. I had a big long explanation typed out but got rid of most of it and all of the technical terms.
#25
09-23-2014, 09:53 AM
You guys need to investigate what "Top Tier" really is. It is a marketing thing. To advertise that you are "Top Tier" you must only agree that the fuel you sell is AT LEAST 8% ethanol. After that you stipulate that your fuel will exceed the EPA minimum standard for cleanliness (clean burning) which ethanol does.
The primary additive in "Top Tier" gasoline is ethanol. Since ethanol is already required in EPA-non attainment areas, there nothing else you need to do to qualify except sell ethanol diluted fuel in all marketing areas.
The primary additive in "Top Tier" gasoline is ethanol. Since ethanol is already required in EPA-non attainment areas, there nothing else you need to do to qualify except sell ethanol diluted fuel in all marketing areas.
#27
09-23-2014, 11:06 AM
The compression ratio of the FIT is 11.5:1, so slightly higher than your normal small gas engine you would find on a lawnmower for example, which I typically see 8.5:1 or so. The FIT's engine is designed for 87 octane and max 10% ethanol blend. Running 89 octane in the FIT has always worked well for me. Read my reasoning below.
Cutting out the marketing BS, the point of higher octane fuels is to prevent pre-ignition in the combustion chamber, period. 89, 91 (even 93 octane if available) will not run any "cleaner" than 87 octane.
If the fuel ignites before the cylinder reaches TDC of the compression stroke it causes the knocking/pinging sound. This can cause damage over time to the engine so the ECM through the knock sensors and other sensors retard/advance the ignition timing to prevent this. Knock sensors are mandatory for EPA standards in new cars.
Its the quality control of the gasoline is where the issues come in. I can buy cheap 87 gasoline somewhere and for all I know it can be close to 30 days old, stale etc. Also the ethanol in the fuel is hydrophilic, meaning it attracts moisture. That's why gasoline has such a short shelf life before the fuel breaks down and becomes less than ideal to the engine. Water in the fuel system, even small quantities can have adverse performance effects. That's why dry gas was invented, to hydrolyze the H2o in the fuel so the engine can burn through it.
I run 89 octane as the higher grades seem to have more quality control, and often does not have ethanol blended in which means there are more btu's per gallon of gas. Ethanol while cleaner burning has less BTU's than gasoline. This accounts for less efficiency and lower MPG. No one ever tells you this though. An internal combustion engine is a heat pump, and if you have less heat (in BTU's) to transfer into power per gallon of fuel, you are not very efficient (in MPG)
End Rant.
Cutting out the marketing BS, the point of higher octane fuels is to prevent pre-ignition in the combustion chamber, period. 89, 91 (even 93 octane if available) will not run any "cleaner" than 87 octane.
If the fuel ignites before the cylinder reaches TDC of the compression stroke it causes the knocking/pinging sound. This can cause damage over time to the engine so the ECM through the knock sensors and other sensors retard/advance the ignition timing to prevent this. Knock sensors are mandatory for EPA standards in new cars.
Its the quality control of the gasoline is where the issues come in. I can buy cheap 87 gasoline somewhere and for all I know it can be close to 30 days old, stale etc. Also the ethanol in the fuel is hydrophilic, meaning it attracts moisture. That's why gasoline has such a short shelf life before the fuel breaks down and becomes less than ideal to the engine. Water in the fuel system, even small quantities can have adverse performance effects. That's why dry gas was invented, to hydrolyze the H2o in the fuel so the engine can burn through it.
I run 89 octane as the higher grades seem to have more quality control, and often does not have ethanol blended in which means there are more btu's per gallon of gas. Ethanol while cleaner burning has less BTU's than gasoline. This accounts for less efficiency and lower MPG. No one ever tells you this though. An internal combustion engine is a heat pump, and if you have less heat (in BTU's) to transfer into power per gallon of fuel, you are not very efficient (in MPG)
End Rant.
#29
09-23-2014, 11:39 AM
I live in an area where there is a lot of hills. Going up a hill obviously the engine works harder, and I noticed knocking with 87 octane gas (there are Citgo & Mobile gas stations near me) with BJ's and Stop and Shop 87 fuel. I started using 89 a few years ago and have no knocking/pinging since then.
#30
09-23-2014, 11:51 AM
DI features
One of the neat things about direct injection and be engines is the ability to compensate for fuel quality. High octane fuel us more stable which is why you need it in a high compression or bosted application. However with more stable fuel you can also increase timing advance which will increase efficiency of the motor. If you go look at Ford and Hyundai you'll see that they can run87 but their max hp is on93. If the engine is programmed right it will inject fuel and spark at the optimal time based on real time conditions. In the old days you had to tune your motor to benefit from premium but these new engines tune themselves. The way to test this is to use an ultra gauge and fill up with regular, disconnect the battery and then make the computer relearn it's optimal tune and watch the timing advance on the ultra gauge. Do the same thing with premium gas and if you see more timing advance then you'll know that the engine is capable of optimizing itself to run on high octane fuel. You would also want to dyno it and look for tq and hp increases and lastly any fuel economy gains. From people I've talked to, the gains in fuel economy wash out the price of premium but they still do it for the bump in hp. All that to say, theoretically these cars should see a benefit from running high octane fuel due to modern technology.
#31
09-23-2014, 11:58 AM
Can you suggest any good sources for this information? I have actually read a lot on this, and just went looking for validation of your post, and I've never seen anything that indicates that a fuel can qualify as Top Tier from ethanol content alone. The assertions seem to be that higher detergent levels are necessary. It could be that ethanol qualifies as a detergent, but I didn't find any sources that suggest this. This leaves me for the moment having to see your post as seeming to be at odds with the other information I'm seeing. As I'm no expert, this could be a misunderstanding on my part.
I would love to spend the time looking up on line references for you but right now I'm headed out the door to a Motorhome rally in Wisconsin (near Minneapolis). If this thread is still going and your question has not been answered, I'll be back after October 4th.
Send me a PM to remind me.
It is the detergent properties of ethanol that cause problems with ethanol blended fuel. This is the reason Ethanol is prohibited in all US registered aircraft. These properties are also why ethanol can not be transported in pipelines designed for petroleum products. When ethanol first hit the US auto market 20 years ago as "gasohol". The prime problem that occurred what the ethanol loosen up petroleum deposits is in consumer gas tanks and lines. The result was clogged filters, carburetors, and fuel injectors. It also softened rubber hoses and softened sealants and gaskets used on tanks and fuel handling devices. The automotive industry responded by changing fuel lines to plastic (similar to nylon) and changed gaskets and sealant to ones with ethanol resistant properties.
Yes, Ethanol is a very strong detergent in automotive gasoline applications.
One other problem with ethanol is it will readily combine with water or moisture from the air. When the happens the ethanol settles out of solution to the bottom of the storage tank. I know pf people that remove ethanol from E-10 using this cheap and easy water mixing process. They use the remaining 100% gas in lawn mowers, boats, string trimmers, and aviation engines.
The Ethanol / water mix if left in the tank will cause all kinds of corrosion and rusting problems. This is not normally an issue in modern cars because most of them are driven frequently and their tanks are made of ethanol resistant plastics.
I'm sorry but I have to run and finish loading up the motorhome.
#32
09-23-2014, 12:00 PM
The toptiergas.com site goes into detail about what "top tier" means but it seems like mostly it has to do with additives like detergents that prevent deposits forming on places like your valves, and keeping your fuel injectors and such clean.
Higher octane has to do with resistance to "knock". You get more power with a higher compression ratio but higher compression is more prone to knock so requires higher octane gasoline. There is no advantage to higher octane gas if the compression ratio of your engine does not require it to prevent knock. (I believe that the higher octane gas actually contains slightly less total energy (BTU's) per gallon).
You get more efficiency with a higher compression ratio. More of the energy (a higher percentage of the energy) from burning the fuel gets converted to mechanical energy to push the car forward, when the compression ratio is higher. Diesels has a compression ratio of like 15 or 20 to 1, while my Fit has a compression ratio of something like 10.4 to 1. So when the piston is at the bottom, the volume inside the cylinder is about 10 times bigger than when the piston is at the top. At the top of the cylinder, the face of the piston is a much bigger percentage of the surface containing the combustion than when the piston is lower in the cylinder. Pop a fire cracker 5 feet away and you will hear it but not really feel it. Put your face right on top of it and you will feel it much more. Even if the gas burning produces a huge volume of combustion products, once the piston gets to the bottom you stop getting any more mechanical energy out of it. So if the piston travels a "short" distance you get little mechanical energy out of it compared with when the piston travels a (relatively) long distance.
The down side of high compression is that as you compress the fuel/air mixture it gets hotter. The more you compress it the hotter (all of it) gets. With a Diesel engine it gets so hot that you don't even need a spark plug. The problem in the gasoline engine is that it make the mix more prone to detonation. Detonation is when a shock wave travels through the mixture and all of it ignites at once. With an engine you hear this as a ping. That is why they put blasting caps in dynamite, to make it detonate. This is the problem the "underwear bomber" has, he has explosive but it did not detonate. It just burned really fast, right in his pants. A metal engine can handle the fuel burning really fast, and can convert it to mechanical energy. But frequent hard Knocking will eventually break the engine. Other things also effect tendency to knock like air fuel ratio and spark timing. I could get a little more power out of the 351 in my Bronco if I adjusted the distributor to advance the timing, IF I used premium fuel. But if I used 87 octane then it would knock with the advanced timing, and then the knock sensor would then retard the timing again and I would be right back where I started. If I left the timing where it was supposed to be then there would be no advantage at all to using higher octane fuel. It would just waste money.
Higher octane has to do with resistance to "knock". You get more power with a higher compression ratio but higher compression is more prone to knock so requires higher octane gasoline. There is no advantage to higher octane gas if the compression ratio of your engine does not require it to prevent knock. (I believe that the higher octane gas actually contains slightly less total energy (BTU's) per gallon).
You get more efficiency with a higher compression ratio. More of the energy (a higher percentage of the energy) from burning the fuel gets converted to mechanical energy to push the car forward, when the compression ratio is higher. Diesels has a compression ratio of like 15 or 20 to 1, while my Fit has a compression ratio of something like 10.4 to 1. So when the piston is at the bottom, the volume inside the cylinder is about 10 times bigger than when the piston is at the top. At the top of the cylinder, the face of the piston is a much bigger percentage of the surface containing the combustion than when the piston is lower in the cylinder. Pop a fire cracker 5 feet away and you will hear it but not really feel it. Put your face right on top of it and you will feel it much more. Even if the gas burning produces a huge volume of combustion products, once the piston gets to the bottom you stop getting any more mechanical energy out of it. So if the piston travels a "short" distance you get little mechanical energy out of it compared with when the piston travels a (relatively) long distance.
The down side of high compression is that as you compress the fuel/air mixture it gets hotter. The more you compress it the hotter (all of it) gets. With a Diesel engine it gets so hot that you don't even need a spark plug. The problem in the gasoline engine is that it make the mix more prone to detonation. Detonation is when a shock wave travels through the mixture and all of it ignites at once. With an engine you hear this as a ping. That is why they put blasting caps in dynamite, to make it detonate. This is the problem the "underwear bomber" has, he has explosive but it did not detonate. It just burned really fast, right in his pants. A metal engine can handle the fuel burning really fast, and can convert it to mechanical energy. But frequent hard Knocking will eventually break the engine. Other things also effect tendency to knock like air fuel ratio and spark timing. I could get a little more power out of the 351 in my Bronco if I adjusted the distributor to advance the timing, IF I used premium fuel. But if I used 87 octane then it would knock with the advanced timing, and then the knock sensor would then retard the timing again and I would be right back where I started. If I left the timing where it was supposed to be then there would be no advantage at all to using higher octane fuel. It would just waste money.
#33
09-23-2014, 12:34 PM
Top Tier is a marketing gimmick. It just means that the gasoline has detergents in it and all gasolines sold since 1995 have them due to federal requirements. Gas companies like to use fancy terms like "Platformate," "Nitrogen-enriched," "Techron," "EC-1," etc. to describe pretty much the same product. All fuels come from the same suppliers and the various brands trade them freely among themselves. Your Shell gas might have been pumped from a Exxon well, refined at an Arco refinery and hauled in a United Oil tanker.
My current car has gone 160,000 miles on a steady diet of "whatever gas was cheapest" with zero problems. The only stations I avoid are the obvious dumps where I am concerned about the cleanliness of their tanks.
My current car has gone 160,000 miles on a steady diet of "whatever gas was cheapest" with zero problems. The only stations I avoid are the obvious dumps where I am concerned about the cleanliness of their tanks.
Last edited by GeorgeL; 09-23-2014 at 12:36 PM.
#34
09-23-2014, 12:44 PM
You guys need to investigate what "Top Tier" really is. It is a marketing thing. To advertise that you are "Top Tier" you must only agree that the fuel you sell is AT LEAST 8% ethanol. After that you stipulate that your fuel will exceed the EPA minimum standard for cleanliness (clean burning) which ethanol does.
The primary additive in "Top Tier" gasoline is ethanol. Since ethanol is already required in EPA-non attainment areas, there nothing else you need to do to qualify except sell ethanol diluted fuel in all marketing areas.
The primary additive in "Top Tier" gasoline is ethanol. Since ethanol is already required in EPA-non attainment areas, there nothing else you need to do to qualify except sell ethanol diluted fuel in all marketing areas.
Actually no, we don't need to investigate further... you have just given a good explanation below...
There are three measurement types Reaserch (R), Motor (M) and R + M divided by 2 which we use in th US for automotive fuel. In simple terms octane is measurement of a given fuel's resistance auto-ignition (uncontrolled burning or explosion (pre-ignition). Octane does not have anything to do with the amount of energy contained in the fuel.
You want your fuel to start burning before Top Dead Center with the maximum burn at just past TDC and completed as quickly as possible from that point on.
Higher octane fuel, beside being able to resist self ignition at higher temperatures, also burns slower when control ignited by something like a spark plug. So some percentage of the energy produced under controlled burning is beyond TDC. The higher the octane the slower the burning and the lower the efficiency of conversion of that burn to mechanical energy. We are only talking couple of percent so it is not much.
Octane has noting to do with increased fuel mileage or performance. In fact Ethanol has a higher octane rating than the normal gasoline but lower energy when compared to straight gasoline. Besides burning cleaner it also is used as an octane booster, but it produces considerably less energy.
You want your fuel to start burning before Top Dead Center with the maximum burn at just past TDC and completed as quickly as possible from that point on.
Higher octane fuel, beside being able to resist self ignition at higher temperatures, also burns slower when control ignited by something like a spark plug. So some percentage of the energy produced under controlled burning is beyond TDC. The higher the octane the slower the burning and the lower the efficiency of conversion of that burn to mechanical energy. We are only talking couple of percent so it is not much.
Octane has noting to do with increased fuel mileage or performance. In fact Ethanol has a higher octane rating than the normal gasoline but lower energy when compared to straight gasoline. Besides burning cleaner it also is used as an octane booster, but it produces considerably less energy.
#35
09-23-2014, 01:09 PM
It is common in modern cars to have a knock sensor. As it relates to octane, knock occurs when the octane is too low for the compression ratio of a given engine.
True fact see page 347 in the manual.
However, just because you can use the more expensive gasoline does not mean you will derive any benefit. With the Fit you will only be wasting your money. High octane gas is for engines that require it. The Fit does not need it and does not run better with it.
"It may seem like buying higher octane “premium” gas is like giving your car a treat, or boosting its performance. But take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage, or run cleaner. Your best bet: listen to your owner's manual."
Source: Paying a Premium for High Octane Gasoline? | Consumer Information
.
True fact see page 347 in the manual.
However, just because you can use the more expensive gasoline does not mean you will derive any benefit. With the Fit you will only be wasting your money. High octane gas is for engines that require it. The Fit does not need it and does not run better with it.
"It may seem like buying higher octane “premium” gas is like giving your car a treat, or boosting its performance. But take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage, or run cleaner. Your best bet: listen to your owner's manual."
Source: Paying a Premium for High Octane Gasoline? | Consumer Information
.
#36
09-23-2014, 01:17 PM
<start text quoted from source referenced below>
Top Tier fuels feature more of these additives than regular gas. In 1995 the Environmental Protection Agency (EPA) set a minimum standard for gasoline additives. Since then, refiners and fuel blenders have actually reduced the amount of detergent they put in fuel by about 50 percent. In the long run this cutback has impacted the ability of vehicles to meet emission standards.
According to Bill Studzinski, Fuels Technical Specialist at General Motors, a number of OEMs saw this problem and got together to push for higher levels of detergency. He said Top Tier gasoline is a better fuel for engines, and that it takes the mystery out of what a good fuel is and what an average fuel is.
Chris Martin, a spokesman for Honda said “we’ve supported it [Top Tier gasoline] because we’ve seen a benefit from it for our consumers in the long run.” He also said the average driver doesn’t know about detergent additives, they just look for the cheapest gas available but “Top Tier fuel goes a step beyond that.”
“We don’t require that our vehicle owners use Top Tier gas” Martin said, but it helps “make sure the engines are going to last as long as they could.” This is obviously beneficial, especially since Honda drivers historically keep their cars for a long time.
Responding to questions via e-mail, Marie Valentine, the Senior Principle Engineer, Vehicle Regulation and Certification Engineering, Toyota Technical Center, said the amount of detergents in Top Tier gas is about twice what’s required by the EPA. However, it can vary depending “on the base gasoline and the chemistry of the detergent additive.”
<end quoted text>
Source: Which Gas Stations Sell the Best Quality Gasoline? » AutoGuide.com News
I'll stick with the Honda's recommendation for fuel whenever I can. Why wouldn't I???
But, thanks for your input none the less...
.
#38
09-23-2014, 01:38 PM
The toptiergas.com site goes into detail about what "top tier" means but it seems like mostly it has to do with additives like detergents that prevent deposits forming on places like your valves, and keeping your fuel injectors and such clean.
Higher octane has to do with resistance to "knock". You get more power with a higher compression ratio but higher compression is more prone to knock so requires higher octane gasoline. There is no advantage to higher octane gas if the compression ratio of your engine does not require it to prevent knock. (I believe that the higher octane gas actually contains slightly less total energy (BTU's) per gallon).
You get more efficiency with a higher compression ratio. More of the energy (a higher percentage of the energy) from burning the fuel gets converted to mechanical energy to push the car forward, when the compression ratio is higher. Diesels has a compression ratio of like 15 or 20 to 1, while my Fit has a compression ratio of something like 10.4 to 1. So when the piston is at the bottom, the volume inside the cylinder is about 10 times bigger than when the piston is at the top. At the top of the cylinder, the face of the piston is a much bigger percentage of the surface containing the combustion than when the piston is lower in the cylinder. Pop a fire cracker 5 feet away and you will hear it but not really feel it. Put your face right on top of it and you will feel it much more. Even if the gas burning produces a huge volume of combustion products, once the piston gets to the bottom you stop getting any more mechanical energy out of it. So if the piston travels a "short" distance you get little mechanical energy out of it compared with when the piston travels a (relatively) long distance.
The down side of high compression is that as you compress the fuel/air mixture it gets hotter. The more you compress it the hotter (all of it) gets. With a Diesel engine it gets so hot that you don't even need a spark plug. The problem in the gasoline engine is that it make the mix more prone to detonation. Detonation is when a shock wave travels through the mixture and all of it ignites at once. With an engine you hear this as a ping. That is why they put blasting caps in dynamite, to make it detonate. This is the problem the "underwear bomber" has, he has explosive but it did not detonate. It just burned really fast, right in his pants. A metal engine can handle the fuel burning really fast, and can convert it to mechanical energy. But frequent hard Knocking will eventually break the engine. Other things also effect tendency to knock like air fuel ratio and spark timing. I could get a little more power out of the 351 in my Bronco if I adjusted the distributor to advance the timing, IF I used premium fuel. But if I used 87 octane then it would knock with the advanced timing, and then the knock sensor would then retard the timing again and I would be right back where I started. If I left the timing where it was supposed to be then there would be no advantage at all to using higher octane fuel. It would just waste money.
Higher octane has to do with resistance to "knock". You get more power with a higher compression ratio but higher compression is more prone to knock so requires higher octane gasoline. There is no advantage to higher octane gas if the compression ratio of your engine does not require it to prevent knock. (I believe that the higher octane gas actually contains slightly less total energy (BTU's) per gallon).
You get more efficiency with a higher compression ratio. More of the energy (a higher percentage of the energy) from burning the fuel gets converted to mechanical energy to push the car forward, when the compression ratio is higher. Diesels has a compression ratio of like 15 or 20 to 1, while my Fit has a compression ratio of something like 10.4 to 1. So when the piston is at the bottom, the volume inside the cylinder is about 10 times bigger than when the piston is at the top. At the top of the cylinder, the face of the piston is a much bigger percentage of the surface containing the combustion than when the piston is lower in the cylinder. Pop a fire cracker 5 feet away and you will hear it but not really feel it. Put your face right on top of it and you will feel it much more. Even if the gas burning produces a huge volume of combustion products, once the piston gets to the bottom you stop getting any more mechanical energy out of it. So if the piston travels a "short" distance you get little mechanical energy out of it compared with when the piston travels a (relatively) long distance.
The down side of high compression is that as you compress the fuel/air mixture it gets hotter. The more you compress it the hotter (all of it) gets. With a Diesel engine it gets so hot that you don't even need a spark plug. The problem in the gasoline engine is that it make the mix more prone to detonation. Detonation is when a shock wave travels through the mixture and all of it ignites at once. With an engine you hear this as a ping. That is why they put blasting caps in dynamite, to make it detonate. This is the problem the "underwear bomber" has, he has explosive but it did not detonate. It just burned really fast, right in his pants. A metal engine can handle the fuel burning really fast, and can convert it to mechanical energy. But frequent hard Knocking will eventually break the engine. Other things also effect tendency to knock like air fuel ratio and spark timing. I could get a little more power out of the 351 in my Bronco if I adjusted the distributor to advance the timing, IF I used premium fuel. But if I used 87 octane then it would knock with the advanced timing, and then the knock sensor would then retard the timing again and I would be right back where I started. If I left the timing where it was supposed to be then there would be no advantage at all to using higher octane fuel. It would just waste money.
Very good explanation!
#39
09-23-2014, 02:11 PM
My research says otherwise. The EPA requirement is for the minimum amount of detergent additives that must be present. After that standard came out in 1995, fuel companies started dropping the detergent levels downward to that minimum.
<start text quoted from source referenced below>
Top Tier fuels feature more of these additives than regular gas. In 1995 the Environmental Protection Agency (EPA) set a minimum standard for gasoline additives. Since then, refiners and fuel blenders have actually reduced the amount of detergent they put in fuel by about 50 percent. In the long run this cutback has impacted the ability of vehicles to meet emission standards.
According to Bill Studzinski, Fuels Technical Specialist at General Motors, a number of OEMs saw this problem and got together to push for higher levels of detergency. He said Top Tier gasoline is a better fuel for engines, and that it takes the mystery out of what a good fuel is and what an average fuel is.
Chris Martin, a spokesman for Honda said “we’ve supported it [Top Tier gasoline] because we’ve seen a benefit from it for our consumers in the long run.” He also said the average driver doesn’t know about detergent additives, they just look for the cheapest gas available but “Top Tier fuel goes a step beyond that.”
“We don’t require that our vehicle owners use Top Tier gas” Martin said, but it helps “make sure the engines are going to last as long as they could.” This is obviously beneficial, especially since Honda drivers historically keep their cars for a long time.
Responding to questions via e-mail, Marie Valentine, the Senior Principle Engineer, Vehicle Regulation and Certification Engineering, Toyota Technical Center, said the amount of detergents in Top Tier gas is about twice what’s required by the EPA. However, it can vary depending “on the base gasoline and the chemistry of the detergent additive.”
<end quoted text>
Source: Which Gas Stations Sell the Best Quality Gasoline? » AutoGuide.com News
If I grant that you have had this experience, so what? You having this experience does not in any way show that always buying "whatever gas was cheapest" is a good way to operate your car. You know, George Burns lived to be 100 as a regular smoker... that doesn't mean it's a good idea to smoke. It means he was lucky and it says nothing about the quality of life he would have had if he did not smoke.
I'll stick with the Honda's recommendation for fuel whenever I can. Why wouldn't I???
But, thanks for your input none the less...
.
<start text quoted from source referenced below>
Top Tier fuels feature more of these additives than regular gas. In 1995 the Environmental Protection Agency (EPA) set a minimum standard for gasoline additives. Since then, refiners and fuel blenders have actually reduced the amount of detergent they put in fuel by about 50 percent. In the long run this cutback has impacted the ability of vehicles to meet emission standards.
According to Bill Studzinski, Fuels Technical Specialist at General Motors, a number of OEMs saw this problem and got together to push for higher levels of detergency. He said Top Tier gasoline is a better fuel for engines, and that it takes the mystery out of what a good fuel is and what an average fuel is.
Chris Martin, a spokesman for Honda said “we’ve supported it [Top Tier gasoline] because we’ve seen a benefit from it for our consumers in the long run.” He also said the average driver doesn’t know about detergent additives, they just look for the cheapest gas available but “Top Tier fuel goes a step beyond that.”
“We don’t require that our vehicle owners use Top Tier gas” Martin said, but it helps “make sure the engines are going to last as long as they could.” This is obviously beneficial, especially since Honda drivers historically keep their cars for a long time.
Responding to questions via e-mail, Marie Valentine, the Senior Principle Engineer, Vehicle Regulation and Certification Engineering, Toyota Technical Center, said the amount of detergents in Top Tier gas is about twice what’s required by the EPA. However, it can vary depending “on the base gasoline and the chemistry of the detergent additive.”
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Source: Which Gas Stations Sell the Best Quality Gasoline? » AutoGuide.com News
If I grant that you have had this experience, so what? You having this experience does not in any way show that always buying "whatever gas was cheapest" is a good way to operate your car. You know, George Burns lived to be 100 as a regular smoker... that doesn't mean it's a good idea to smoke. It means he was lucky and it says nothing about the quality of life he would have had if he did not smoke.
I'll stick with the Honda's recommendation for fuel whenever I can. Why wouldn't I???
But, thanks for your input none the less...
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