87,89 or 93 octane? (6.0 engine)
08-27-2010, 07:56 PM
#81
Drifting
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Location: Cambridge Illinois
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Since many lake reading comprehension and did not consider the qualifying remarks, I will offer an example of typical street driving.
This is how I use my Vettes and Viper: It is a nice sunny day with blue skies. I and my wife get into the Vette and drive down our street with a 30 mph limit. I turn north onto a county road with a 55 mph limit.
I come to U.S. route 6 and head west to U.S. route 84 northbound along the Mississippi River. At some point we select a dinner for lunch in any one of the interesting river towns along the river. After lunch we take another leisurely ride through county roads back to out home.
In the C6's which both have 6 speed manuals the typical shifting is 1 - 3 - 6 and the rpm is never over 2,500 rpm and at 55 mph is about 1,400 rpm.
At no time is there much load on the engine at all. Never any opportunity for knocking. That is exactly the driving situation that the Corvette engineer stated that it was a waste to high octane gas.
The driving is 100% of the use of my cars. They never go to a track, they never go to the strip and they most certainly are not driven hard on the street.
I tried to look in the Funfest yearbooks but they don't list the seminars that were held. The engineer is the one known as the C4 guru for all the books that he has written and the tuning seminars that he holds across the country.
So, a car driven in the manner that I have identified will never suffer any consequences from 89 octane use. Except better starting and better mpg. The LS3 routinely yields over 32 mpg.
For those that want to check the DIY to prove that, I will be in the forum parking at Funfest. It's the black 08 Coupe. You know the one that runs great.
This is how I use my Vettes and Viper: It is a nice sunny day with blue skies. I and my wife get into the Vette and drive down our street with a 30 mph limit. I turn north onto a county road with a 55 mph limit.
I come to U.S. route 6 and head west to U.S. route 84 northbound along the Mississippi River. At some point we select a dinner for lunch in any one of the interesting river towns along the river. After lunch we take another leisurely ride through county roads back to out home.
In the C6's which both have 6 speed manuals the typical shifting is 1 - 3 - 6 and the rpm is never over 2,500 rpm and at 55 mph is about 1,400 rpm.
At no time is there much load on the engine at all. Never any opportunity for knocking. That is exactly the driving situation that the Corvette engineer stated that it was a waste to high octane gas.
The driving is 100% of the use of my cars. They never go to a track, they never go to the strip and they most certainly are not driven hard on the street.
I tried to look in the Funfest yearbooks but they don't list the seminars that were held. The engineer is the one known as the C4 guru for all the books that he has written and the tuning seminars that he holds across the country.
So, a car driven in the manner that I have identified will never suffer any consequences from 89 octane use. Except better starting and better mpg. The LS3 routinely yields over 32 mpg.
For those that want to check the DIY to prove that, I will be in the forum parking at Funfest. It's the black 08 Coupe. You know the one that runs great.
08-27-2010, 08:14 PM
#82
Team Owner
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St. Jude Donor '13
You won't get any argument from me about that technique and using 89 octane.
You can also run a DC-7 (R3350's wtih PRT's), designed for 115/145 octane, on 100LL. But you need to cut way back on the maniforld pressure to avoid detonation.
You can also run a DC-7 (R3350's wtih PRT's), designed for 115/145 octane, on 100LL. But you need to cut way back on the maniforld pressure to avoid detonation.
08-27-2010, 11:41 PM
#83
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.. Rodney King, and he said "Can't we all just get along?"..lmao!!! 
08-28-2010, 12:34 AM
#85
Drifting
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You can also use regular unleaded
gasoline rated at 87 octane or higher, but the vehicle’s
acceleration could be slightly reduced, and you might
notice a slight audible knocking noise, commonly
referred to as spark knock. If the octane is less than 87,
you might notice a heavy knocking noise when you drive.
If this occurs, use a gasoline rated at 87 octane or higher
as soon as possible. Otherwise, you could damage the
engine. If you are using gasoline rated at 87 octane or
higher and you hear heavy knocking, the engine needs
service.
Here is your schooling. Most fail to read the parts that they choose to not believe.
Using 89 as I do with modest throttle application, there never has been knocking. And the part I copied from a previous post of GM provided info in the owners manual proves what I have been saying all along. That you can use lower than 91 Octane, but just pay attention. The driver is in control of the knocking as much as the ECM is. If you apply too much throttle and knocking start just back off the throttle. It takes what about two tenths of a second.
One cause of knocking in a car with some miles on it is carbon build up.
As some have posted, they have had knocking with 91 and 93 octane.
I bet they have never had the motor serviced for carbon removal.
I don't need to run the car to redline through the gears to enjoy it. I will leave that to the immature azzhat street racers.
Here is what is in my garage at this point in time. Tomorrow is a different day.
gasoline rated at 87 octane or higher, but the vehicle’s
acceleration could be slightly reduced, and you might
notice a slight audible knocking noise, commonly
referred to as spark knock. If the octane is less than 87,
you might notice a heavy knocking noise when you drive.
If this occurs, use a gasoline rated at 87 octane or higher
as soon as possible. Otherwise, you could damage the
engine. If you are using gasoline rated at 87 octane or
higher and you hear heavy knocking, the engine needs
service.
Here is your schooling. Most fail to read the parts that they choose to not believe.
Using 89 as I do with modest throttle application, there never has been knocking. And the part I copied from a previous post of GM provided info in the owners manual proves what I have been saying all along. That you can use lower than 91 Octane, but just pay attention. The driver is in control of the knocking as much as the ECM is. If you apply too much throttle and knocking start just back off the throttle. It takes what about two tenths of a second.
One cause of knocking in a car with some miles on it is carbon build up.
As some have posted, they have had knocking with 91 and 93 octane.
I bet they have never had the motor serviced for carbon removal.
I don't need to run the car to redline through the gears to enjoy it. I will leave that to the immature azzhat street racers.
Here is what is in my garage at this point in time. Tomorrow is a different day.
08-28-2010, 12:36 AM
#86
Safety Car
A couple of things that don't seem to be too clear in this thread. When running 87 octane, in order for the computer to use the bad fuel spark table it must sense knock first. This means your car has had an opportunity to detonate enough that the computer has pulled timing already and is now running on a lower timing table.
The PCM will eventually increase timing back to the good spark table values unless it detects knock again, then it will pull timing again.
All of this means that your engine has to knock in order to use the bad fuel table. The engine also gets an opportunity to knock more as the timing is increased back to the good spark table.
The other issue, for those who think they can hear knock, you might want to hook up a scanner to make sure because I don't believe you can hear all engine knock.
Use the octane that your manual recommends. If you have F/I, you better use 91+, pretty simple.
The PCM will eventually increase timing back to the good spark table values unless it detects knock again, then it will pull timing again.
All of this means that your engine has to knock in order to use the bad fuel table. The engine also gets an opportunity to knock more as the timing is increased back to the good spark table.
The other issue, for those who think they can hear knock, you might want to hook up a scanner to make sure because I don't believe you can hear all engine knock.
Use the octane that your manual recommends. If you have F/I, you better use 91+, pretty simple.
08-28-2010, 03:24 AM
#87
Safety Car
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Location: Northeast MA & Mad Beach FL
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When it comes to what Octane to run, understanding why there are different Octane ratings, should be why you choose to run a certain Octane in the engine in the vehicle you drive.
In simple terms for the sake of conversation, there are 2 kinds of engines.
Low compression and High Compression.
And again, in simple terms for the sake of conversation, there are 2 kinds of Octane.
Low Octane and High Octane.
Contrary to popular belief, High Octane is not more powerful and has a higher ignition temperature which means it doesn't ignite as easy as Low Octane fuel.
Low Octane has a lower Ignition temperature making it easier to ignite.
Each Octane is meant to be run in a certain engine depending on the Compression Ratio.
Low Compression engines run Low Octane fuel because the fuel ignites easier and higher compression is not needed to help ignite the fuel.
Lets just call it an economy or plain engine or whatever you like for the sake of conversation.
High Compression engines ( and everything else, cam etc., that goes along with a high performance engine ) run High Octane because the fuel, which ignites at a higher temperature, has help from the higher Compression to ignite it.
An engine timing/tuning is usually set to fire at top dead center whether high compression or low compression.
Here's where Octane rating applies to what happens running Low Octane in a High Compression/High Octane/High Performance engine:
with Low Octane fuel in a Performance/High Compression engine, the Low Octane fuel ignites "before" top dead center because it has a lower flash point than High Octane!
This in turn is trying to push the piston back down "before" it is at top dead center of the crankshaft revolution.
So "physically", the piston can Not go back down until it finishes going all the way up first,.. and that is where Knock occurs,...
Ignition explosion "banging" on the piston before it is all the way up and ready to go down for the power stroke.
So what happens here with modern day Computerized engines?
The Computer Retards the timing to compensate and ignites the Low Octane fuel at a later point in the piston's up and down cycle to prevent engine/piston damage.
But, .... it doesn't do it at top dead center because Low Octane fuel is still too volatile to ignite in a Higher Compression chamber at top dead center.
So it fires when the piston is already on it's way down, however so slightly, which in turn is just burning up the fuel with less power, ... again, to simply save the engine from damage.
Personally, I run the Highest Octane, which around here is 93.
I don't race my car but, I noticed the lack of performance when trying low Octane fuel in my LS3.
Bottom line, take it for what it's worth and run whatever you want, just info for thought
In simple terms for the sake of conversation, there are 2 kinds of engines.
Low compression and High Compression.
And again, in simple terms for the sake of conversation, there are 2 kinds of Octane.
Low Octane and High Octane.
Contrary to popular belief, High Octane is not more powerful and has a higher ignition temperature which means it doesn't ignite as easy as Low Octane fuel.
Low Octane has a lower Ignition temperature making it easier to ignite.
Each Octane is meant to be run in a certain engine depending on the Compression Ratio.
Low Compression engines run Low Octane fuel because the fuel ignites easier and higher compression is not needed to help ignite the fuel.
Lets just call it an economy or plain engine or whatever you like for the sake of conversation.
High Compression engines ( and everything else, cam etc., that goes along with a high performance engine ) run High Octane because the fuel, which ignites at a higher temperature, has help from the higher Compression to ignite it.
An engine timing/tuning is usually set to fire at top dead center whether high compression or low compression.
Here's where Octane rating applies to what happens running Low Octane in a High Compression/High Octane/High Performance engine:
with Low Octane fuel in a Performance/High Compression engine, the Low Octane fuel ignites "before" top dead center because it has a lower flash point than High Octane!
This in turn is trying to push the piston back down "before" it is at top dead center of the crankshaft revolution.
So "physically", the piston can Not go back down until it finishes going all the way up first,.. and that is where Knock occurs,...
Ignition explosion "banging" on the piston before it is all the way up and ready to go down for the power stroke.
So what happens here with modern day Computerized engines?
The Computer Retards the timing to compensate and ignites the Low Octane fuel at a later point in the piston's up and down cycle to prevent engine/piston damage.
But, .... it doesn't do it at top dead center because Low Octane fuel is still too volatile to ignite in a Higher Compression chamber at top dead center.
So it fires when the piston is already on it's way down, however so slightly, which in turn is just burning up the fuel with less power, ... again, to simply save the engine from damage.
Personally, I run the Highest Octane, which around here is 93.
I don't race my car but, I noticed the lack of performance when trying low Octane fuel in my LS3.
Bottom line, take it for what it's worth and run whatever you want, just info for thought
08-28-2010, 09:54 AM
#88
Safety Car
Using 89 as I do with modest throttle application, there never has been knocking. And the part I copied from a previous post of GM provided info in the owners manual proves what I have been saying all along. That you can use lower than 91 Octane, but just pay attention. The driver is in control of the knocking as much as the ECM is. If you apply too much throttle and knocking start just back off the throttle. It takes what about two tenths of a second.
08-28-2010, 10:34 AM
#89
Team Owner
What is funny about this thread is that it is counter to what the Corvette is....a high performance car. Thread after thread, year after year, people are asking how to get more horsepower from their car. They will spend $500 on a CAI that might give them a 12 HP increase, another $500 for a dyno tune that might give them another 10 HP increase. They will then spend another $1200 for headers for hopefully another 15 horsepower increase. Never mind the one's that will spend thousands more for a cam and heaven forbid someone spend $8,000 for a supercharger.....all in the name of increasing performance of the already high performance Corvette.
And then we have someone who spends days trying to convince us that we should accept lower performance by using less the optimal gasoline(i.e. low octane) in our cars in order to save a couple of bucks on each tankful of gas.
My daily driver has, in huge letters, on the inside of the gas lid........USE PREMIUM FUEL ONLY.............and I do. A four door Mercedes isn't really considered a High Performance car in the same light as a Corvette, but the Mercedes engineers designed it to give maximum performance and that requires premium fuel.
And then we have someone who spends days trying to convince us that we should accept lower performance by using less the optimal gasoline(i.e. low octane) in our cars in order to save a couple of bucks on each tankful of gas.
My daily driver has, in huge letters, on the inside of the gas lid........USE PREMIUM FUEL ONLY.............and I do. A four door Mercedes isn't really considered a High Performance car in the same light as a Corvette, but the Mercedes engineers designed it to give maximum performance and that requires premium fuel.
Last edited by JoesC5; 08-28-2010 at 10:41 AM.
08-28-2010, 10:42 AM
#90
Melting Slicks
What is funny about this thread is that it is counter to what the Corvette is....a high performance car. Thread after thread, year after year, people are asking how to get more horsepower from their car. They will spend $500 on a CAI that might give them a 12 HP increase, another $500 for a dyno tune that might give them another 10 HP increase. They will then spend another $1200 for headers for hopefully another 15 horsepower increase. Never mind the one's that will spend thousands more for a cam and heaven forbid someone spend $8,000 for a supercharger.....all in the name of increasing performance of the already high performance Corvette.
And then we have someone who spends days trying to convince us that we should accept lower performance by using less the optimal gasoline(i.e. low octane) in our cars in order to save a couple of bucks on each tankful of gas.
My daily driver has, in huge letters, on the inside of the gas lid........USE PREMIUM FUEL ONLY.............and I do. A four door Mercedes isn't really considered a High Performance car in the same light as a Corvette, but the Mercedes engineers designed it to give maximum performance and that requires premium fuel.
And then we have someone who spends days trying to convince us that we should accept lower performance by using less the optimal gasoline(i.e. low octane) in our cars in order to save a couple of bucks on each tankful of gas.
My daily driver has, in huge letters, on the inside of the gas lid........USE PREMIUM FUEL ONLY.............and I do. A four door Mercedes isn't really considered a High Performance car in the same light as a Corvette, but the Mercedes engineers designed it to give maximum performance and that requires premium fuel.
08-28-2010, 10:44 AM
#91
Safety Car
Here is your schooling. Most fail to read the parts that they choose to not believe.
Using 89 as I do with modest throttle application, there never has been knocking. And the part I copied from a previous post of GM provided info in the owners manual proves what I have been saying all along. That you can use lower than 91 Octane, but just pay attention. The driver is in control of the knocking as much as the ECM is. If you apply too much throttle and knocking start just back off the throttle. It takes what about two tenths of a second.
Here is what is in my garage at this point in time. Tomorrow is a different day.
Using 89 as I do with modest throttle application, there never has been knocking. And the part I copied from a previous post of GM provided info in the owners manual proves what I have been saying all along. That you can use lower than 91 Octane, but just pay attention. The driver is in control of the knocking as much as the ECM is. If you apply too much throttle and knocking start just back off the throttle. It takes what about two tenths of a second.
Here is what is in my garage at this point in time. Tomorrow is a different day.
Here's a good write up:
http://www.streetrodstuff.com/Articl...tion/index.php
In particular, note the types of damage that can occur on page two, like striking your engine with a hammer.
Last edited by goatts; 08-28-2010 at 10:49 AM.
08-28-2010, 11:19 AM
#92
Le Mans Master
OK, while I have read all the arguments here, the fact remains that in some areas like mine, 91 is the very best you can do. Often, 89 is the highest you can find and that is 10 Ethanol. What is your best option for an additive in cases like these?
08-28-2010, 11:28 AM
#93
Team Owner
I'll leave it up to you to work out the minor details such as finding a place of employment, etc.
08-28-2010, 11:48 AM
#94
Drifting
I always enjoy these threads. For what it's worth: yesterday I filled up with 92. I paid $1.64. Not per gallon. For the entire TANK. ......
((a marketing promo here with one Marathon station and two grocery stores yielded this result ))
(( the promo has been going on for two years, I hope it never stops ))
((a marketing promo here with one Marathon station and two grocery stores yielded this result ))
(( the promo has been going on for two years, I hope it never stops ))
08-28-2010, 01:00 PM
#95
Race Director
Since many lake reading comprehension and did not consider the qualifying remarks, I will offer an example of typical street driving.
This is how I use my Vettes and Viper: It is a nice sunny day with blue skies. I and my wife get into the Vette and drive down our street with a 30 mph limit. I turn north onto a county road with a 55 mph limit.
I come to U.S. route 6 and head west to U.S. route 84 northbound along the Mississippi River. At some point we select a dinner for lunch in any one of the interesting river towns along the river. After lunch we take another leisurely ride through county roads back to out home.
In the C6's which both have 6 speed manuals the typical shifting is 1 - 3 - 6 and the rpm is never over 2,500 rpm and at 55 mph is about 1,400 rpm.
At no time is there much load on the engine at all. Never any opportunity for knocking. That is exactly the driving situation that the Corvette engineer stated that it was a waste to high octane gas.
The driving is 100% of the use of my cars. They never go to a track, they never go to the strip and they most certainly are not driven hard on the street.
I tried to look in the Funfest yearbooks but they don't list the seminars that were held. The engineer is the one known as the C4 guru for all the books that he has written and the tuning seminars that he holds across the country.
So, a car driven in the manner that I have identified will never suffer any consequences from 89 octane use. Except better starting and better mpg. The LS3 routinely yields over 32 mpg.
For those that want to check the DIY to prove that, I will be in the forum parking at Funfest. It's the black 08 Coupe. You know the one that runs great.
This is how I use my Vettes and Viper: It is a nice sunny day with blue skies. I and my wife get into the Vette and drive down our street with a 30 mph limit. I turn north onto a county road with a 55 mph limit.
I come to U.S. route 6 and head west to U.S. route 84 northbound along the Mississippi River. At some point we select a dinner for lunch in any one of the interesting river towns along the river. After lunch we take another leisurely ride through county roads back to out home.
In the C6's which both have 6 speed manuals the typical shifting is 1 - 3 - 6 and the rpm is never over 2,500 rpm and at 55 mph is about 1,400 rpm.
At no time is there much load on the engine at all. Never any opportunity for knocking. That is exactly the driving situation that the Corvette engineer stated that it was a waste to high octane gas.
The driving is 100% of the use of my cars. They never go to a track, they never go to the strip and they most certainly are not driven hard on the street.
I tried to look in the Funfest yearbooks but they don't list the seminars that were held. The engineer is the one known as the C4 guru for all the books that he has written and the tuning seminars that he holds across the country.
So, a car driven in the manner that I have identified will never suffer any consequences from 89 octane use. Except better starting and better mpg. The LS3 routinely yields over 32 mpg.
For those that want to check the DIY to prove that, I will be in the forum parking at Funfest. It's the black 08 Coupe. You know the one that runs great.
You may as well be driving a PRIUS...
oh and a lot of things have change since the c4, guru or not.
08-28-2010, 05:02 PM
#96
Safety Car
Don't add anything, 91 is fine. Use what you can get. The discussion here centers on guys using 87 octane by choice to save a few pennies. Hey, these guys can save even more by using recycled engine oil rather then bother with Mobil One.
Last edited by goatts; 08-28-2010 at 05:04 PM.
08-28-2010, 05:38 PM
#97
Melting Slicks
It amazes me that people buy this car (c6) and drive it like they are driving a Chevy Cavalier or some other DD. Putting around the roadways like some golf cart.
They then try and convince people that if they stay off the throttle, they might get away running 87 octane, if they hear detonation, then they need back-off.
WTF?
They then go on to claim that 91 octane is a ruse and not needed, yet they make posts telling people that it will detonate with 87 octane, you just have to keep the throttle light.
Get the jacket out and call the people with the white coats, it is time for someone here to go to the place with padded walls.
08-28-2010, 05:48 PM
#98
Safety Car
Thanks for the non-judgemental, clear explanation and informative explanation. Much appreciated. We don't need to bash op.
Props to DIF
Props to DIF
Last edited by speedlink; 08-28-2010 at 05:51 PM. Reason: Didn't give props to the right person
08-28-2010, 07:13 PM
#99
Drifting
Member Since: Jan 2008
Location: Cambridge Illinois
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Get over it. The Corvette is just a car. The current compression in my LS3 is the same as the low compression in the Olds that I had in the early 60's.
Any one of my five motorcycles have quicker 1/4 times than the Vettes.
Any one of my five motorcycles have quicker 1/4 times than the Vettes.
08-28-2010, 07:20 PM
#100
Safety Car