how dumb is this ?? or is it???
Burning Brakes
Joined: Aug 2008
Posts: 802
Likes: 6
From: Oro Valley AZ
You're missing the point. The LS1-up engine is designed to run on premium fuel. If you use low octane, the computer can adjust, but in doing so, has to rely on retarding the ignition to avoid engine damaging knock. There's limits to how much knock is eliminated, and I wouldn't want to find out where those limits are. Even small amounts of knock can damage your motor, and the forums are famous for stories of people having to replace/rebuild motors for running lean/detonation problems, etc. Is it really worth it for a couple of bucks?
Race Director
Joined: Jun 2005
Posts: 10,909
Likes: 2,701
From: Phila Suburbs 2023 C8 & 2013 650ix
It would seem your friend is a lot smarter than most of the people here.
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
Pay particular attention to paragraphs 6.3, 6.13, 6.14, 6.16, and 7.1-12. You'll note in section 7, lower intake air temps (ambient temps), lower engine operating temps, higher elevation, higher humidity and lower barometric pressures will lower an engine's octane requirement. In the Rocky Mountain states, regular gas is 85 octane due to the higher elevation. Mid grade and premium are 87 and 90. The law says if a county is above 4000 ft elevation, they can sell the lower octane fuels. You could put a C6 Z06 on a chassis dyno this Saturday in Jackson, WY with 85 octane regular in the tank and get full rated power (SAE corrected) with zero knock retard. The 6500 ft elevation coupled with the temps in the 30°F range reduce the octane requirement of that 505 HP fire breathing beast from 93 octane to 85 octane easily.
At 1200+ft elevation of Oklahoma city with your winter temps, 87 octane is a walk in the park for a C6. Your friend should be ok for most of the fall and spring too. The summer is where he's going to experience knock retard and the loss of MPG may offset the lower cost of the 87 octane gas, but he won't cause any damage to his engine as some have stated. It is the law that all cars sold in the US must be capable of running 87 octane fuel and GM wouldn't warranty this engine for 100K miles if they thought for an instant damage might occur even over the long term. My daughter is a "poor" college student and she runs 87 octane in her '99 Corvette during the winter even in Florida with zero knock retard and no loss of performance or MPG. The LS1 is more tolerant of lower octane fuel than the LS2/3 due to its smaller bore and she can even go into the spring and fall with no problems.
As stated in paragraph 6.16: "If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise." Or as my Mom used to say, a fool and his money are soon separated.
Having said the above, I use nothing but 93 octane gas in my '93 ZR-1 even though I know I could easily use 87 because the pent-roof combustion chamber is even more tolerant of lower octane fuel. But I use the car in autocrosses where it spends a good part of the time at full throttle (increases octane requirement) and the engine operating temps can get up to 230°F+ when hot lapping it with my daughter so I want the extra cushion. But I would never ridicule somebody for using 87 octane or say the things some people have said here some of which is pure BS. Seriously, 87 octane clogs the catalytic converter and fouls plugs...I'd love to hear the reasoning for that, haven't had a good laugh in a while.
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
Pay particular attention to paragraphs 6.3, 6.13, 6.14, 6.16, and 7.1-12. You'll note in section 7, lower intake air temps (ambient temps), lower engine operating temps, higher elevation, higher humidity and lower barometric pressures will lower an engine's octane requirement. In the Rocky Mountain states, regular gas is 85 octane due to the higher elevation. Mid grade and premium are 87 and 90. The law says if a county is above 4000 ft elevation, they can sell the lower octane fuels. You could put a C6 Z06 on a chassis dyno this Saturday in Jackson, WY with 85 octane regular in the tank and get full rated power (SAE corrected) with zero knock retard. The 6500 ft elevation coupled with the temps in the 30°F range reduce the octane requirement of that 505 HP fire breathing beast from 93 octane to 85 octane easily.
At 1200+ft elevation of Oklahoma city with your winter temps, 87 octane is a walk in the park for a C6. Your friend should be ok for most of the fall and spring too. The summer is where he's going to experience knock retard and the loss of MPG may offset the lower cost of the 87 octane gas, but he won't cause any damage to his engine as some have stated. It is the law that all cars sold in the US must be capable of running 87 octane fuel and GM wouldn't warranty this engine for 100K miles if they thought for an instant damage might occur even over the long term. My daughter is a "poor" college student and she runs 87 octane in her '99 Corvette during the winter even in Florida with zero knock retard and no loss of performance or MPG. The LS1 is more tolerant of lower octane fuel than the LS2/3 due to its smaller bore and she can even go into the spring and fall with no problems.
As stated in paragraph 6.16: "If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise." Or as my Mom used to say, a fool and his money are soon separated.
Having said the above, I use nothing but 93 octane gas in my '93 ZR-1 even though I know I could easily use 87 because the pent-roof combustion chamber is even more tolerant of lower octane fuel. But I use the car in autocrosses where it spends a good part of the time at full throttle (increases octane requirement) and the engine operating temps can get up to 230°F+ when hot lapping it with my daughter so I want the extra cushion. But I would never ridicule somebody for using 87 octane or say the things some people have said here some of which is pure BS. Seriously, 87 octane clogs the catalytic converter and fouls plugs...I'd love to hear the reasoning for that, haven't had a good laugh in a while.
Thanks for adding some actual "facts" to all these "doom and gloom" opinions.
Pro
Joined: Dec 2009
Posts: 719
Likes: 2
From: Columbia South Carolina
It would seem your friend is a lot smarter than most of the people here.
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
Pay particular attention to paragraphs 6.3, 6.13, 6.14, 6.16, and 7.1-12. You'll note in section 7, lower intake air temps (ambient temps), lower engine operating temps, higher elevation, higher humidity and lower barometric pressures will lower an engine's octane requirement. In the Rocky Mountain states, regular gas is 85 octane due to the higher elevation. Mid grade and premium are 87 and 90. The law says if a county is above 4000 ft elevation, they can sell the lower octane fuels. You could put a C6 Z06 on a chassis dyno this Saturday in Jackson, WY with 85 octane regular in the tank and get full rated power (SAE corrected) with zero knock retard. The 6500 ft elevation coupled with the temps in the 30°F range reduce the octane requirement of that 505 HP fire breathing beast from 93 octane to 85 octane easily.
At 1200+ft elevation of Oklahoma city with your winter temps, 87 octane is a walk in the park for a C6. Your friend should be ok for most of the fall and spring too. The summer is where he's going to experience knock retard and the loss of MPG may offset the lower cost of the 87 octane gas, but he won't cause any damage to his engine as some have stated. It is the law that all cars sold in the US must be capable of running 87 octane fuel and GM wouldn't warranty this engine for 100K miles if they thought for an instant damage might occur even over the long term. My daughter is a "poor" college student and she runs 87 octane in her '99 Corvette during the winter even in Florida with zero knock retard and no loss of performance or MPG. The LS1 is more tolerant of lower octane fuel than the LS2/3 due to its smaller bore and she can even go into the spring and fall with no problems.
As stated in paragraph 6.16: "If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise." Or as my Mom used to say, a fool and his money are soon separated.
Having said the above, I use nothing but 93 octane gas in my '93 ZR-1 even though I know I could easily use 87 because the pent-roof combustion chamber is even more tolerant of lower octane fuel. But I use the car in autocrosses where it spends a good part of the time at full throttle (increases octane requirement) and the engine operating temps can get up to 230°F+ when hot lapping it with my daughter so I want the extra cushion. But I would never ridicule somebody for using 87 octane or say the things some people have said here some of which is pure BS. Seriously, 87 octane clogs the catalytic converter and fouls plugs...I'd love to hear the reasoning for that, haven't had a good laugh in a while.
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
Pay particular attention to paragraphs 6.3, 6.13, 6.14, 6.16, and 7.1-12. You'll note in section 7, lower intake air temps (ambient temps), lower engine operating temps, higher elevation, higher humidity and lower barometric pressures will lower an engine's octane requirement. In the Rocky Mountain states, regular gas is 85 octane due to the higher elevation. Mid grade and premium are 87 and 90. The law says if a county is above 4000 ft elevation, they can sell the lower octane fuels. You could put a C6 Z06 on a chassis dyno this Saturday in Jackson, WY with 85 octane regular in the tank and get full rated power (SAE corrected) with zero knock retard. The 6500 ft elevation coupled with the temps in the 30°F range reduce the octane requirement of that 505 HP fire breathing beast from 93 octane to 85 octane easily.
At 1200+ft elevation of Oklahoma city with your winter temps, 87 octane is a walk in the park for a C6. Your friend should be ok for most of the fall and spring too. The summer is where he's going to experience knock retard and the loss of MPG may offset the lower cost of the 87 octane gas, but he won't cause any damage to his engine as some have stated. It is the law that all cars sold in the US must be capable of running 87 octane fuel and GM wouldn't warranty this engine for 100K miles if they thought for an instant damage might occur even over the long term. My daughter is a "poor" college student and she runs 87 octane in her '99 Corvette during the winter even in Florida with zero knock retard and no loss of performance or MPG. The LS1 is more tolerant of lower octane fuel than the LS2/3 due to its smaller bore and she can even go into the spring and fall with no problems.
As stated in paragraph 6.16: "If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise." Or as my Mom used to say, a fool and his money are soon separated.
Having said the above, I use nothing but 93 octane gas in my '93 ZR-1 even though I know I could easily use 87 because the pent-roof combustion chamber is even more tolerant of lower octane fuel. But I use the car in autocrosses where it spends a good part of the time at full throttle (increases octane requirement) and the engine operating temps can get up to 230°F+ when hot lapping it with my daughter so I want the extra cushion. But I would never ridicule somebody for using 87 octane or say the things some people have said here some of which is pure BS. Seriously, 87 octane clogs the catalytic converter and fouls plugs...I'd love to hear the reasoning for that, haven't had a good laugh in a while.
I can put and probably get away with regular 5W-30 oil instead of paying for synthetic too. But somewhere down the road you will have pay the piper.......
I do see that in your ZR1 you state that you always use 93..........and that is what the car was designed for and from your post, you would not even think of putting 87 in it although it will TOLERATE it.......
That's like buying a high def TV and getting high def cable service but hooking the cable box to the TV via the RF cable. You can see the picture, but are you getting your money's worth?
My Two cents
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
I guess that the key here is More Tolerant of 87. Why put gas in your car that the car will tolerate, not what it was actually designed for?
I can put and probably get away with regular 5W-30 oil instead of paying for synthetic too. But somewhere down the road you will have pay the piper.......
I do see that in your ZR1 you state that you always use 93..........and that is what the car was designed for and from your post, you would not even think of putting 87 in it although it will TOLERATE it.......
That's like buying a high def TV and getting high def cable service but hooking the cable box to the TV via the RF cable. You can see the picture, but are you getting your money's worth?
My Two cents
I can put and probably get away with regular 5W-30 oil instead of paying for synthetic too. But somewhere down the road you will have pay the piper.......
I do see that in your ZR1 you state that you always use 93..........and that is what the car was designed for and from your post, you would not even think of putting 87 in it although it will TOLERATE it.......
That's like buying a high def TV and getting high def cable service but hooking the cable box to the TV via the RF cable. You can see the picture, but are you getting your money's worth?
My Two cents
Interesting you brought up the 5W30 synthetic vs non-synthetic. If you were driving on the street only with limited "spirited" runs, you would see no difference in wear after 100K miles. Synthetic oil stands up to higher oil temps like what I see on the track.
These octane discussions always get blown out of proportion. If you (or anybody) wants to run 93 octane year 'round, rock on. If somebody wants to use 87 octane, what does it matter to anybody, the car is designed for it.
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
I guess this is why some people like to buy new cars. That way, they get to drive 'em and feed 'em any way they want. And they don't get anyone else's method of operation. 
Melting Slicks
Joined: Sep 2006
Posts: 2,034
Likes: 0
From: Beaverton OR
Safety Car
Joined: Nov 2006
Posts: 3,860
Likes: 5
From: Tampa FL
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Michael S. Palmer
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
This entire POST shows that people DO NOT understand how their car works. 
Sure. Your C5/C6 will RUN on CRAP FUEL. GM made it that way just in case thats all the fuel that was available in one area to get you to a location that has adequate fuel.
That being said,,,,,,,,,,,,,,, running your engine on CRAP Fuel and pretending that its not hurting anything is just plain DUMB!
The C5 & C6 was designed to run on premium fuel. If you do not have the cash to run PREMIUM, at least run MID PREMIUM for Christ sake.
If you have to use 87 octane,,,,,PLEASE STOP saying that your car runs normally because it does not. Your running in a fail safe mode.
Your C5/C6 will run on regular 87 fuel BUT,,,,,,,,,,,,,,It WILL NOT preform to its FULL POTENTIAL!
You WILL be in the LOW OCTANE timing tables and down on power.
Will it hurt anything, Most Likely not! Well, in a way YES! Your PERFORMANCE will surly suffer!
BC
Sure. Your C5/C6 will RUN on CRAP FUEL. GM made it that way just in case thats all the fuel that was available in one area to get you to a location that has adequate fuel.
That being said,,,,,,,,,,,,,,, running your engine on CRAP Fuel and pretending that its not hurting anything is just plain DUMB!
The C5 & C6 was designed to run on premium fuel. If you do not have the cash to run PREMIUM, at least run MID PREMIUM for Christ sake.
If you have to use 87 octane,,,,,PLEASE STOP saying that your car runs normally because it does not. Your running in a fail safe mode.Your C5/C6 will run on regular 87 fuel BUT,,,,,,,,,,,,,,It WILL NOT preform to its FULL POTENTIAL!
You WILL be in the LOW OCTANE timing tables and down on power.
Will it hurt anything, Most Likely not! Well, in a way YES! Your PERFORMANCE will surly suffer!
BC
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
It saddens me to see you and others posting incorrect info due to a lack of understanding. Read up on flame speed vs RPM, dynamic compression ratio, quench/squish, and pressure ratio (as opposed to compression ratio) and how it relates to LSx engines. Then come back and let's have a discussion about octane vs ambient conditions/elevation and how it relates to knock in the LSx engines. An engine's octane requirement is a constantly moving target dependent on many variables.The C5 & C6 was designed to run on premium fuel. If you do not have the cash to run PREMIUM, at least run MID PREMIUM for Christ sake. If you have to use 87 octane,,,,,PLEASE STOP saying that your car runs normally because it does not. Your running in a fail safe mode.
If you have to use 87 octane,,,,,PLEASE STOP saying that your car runs normally because it does not. Your running in a fail safe mode.At least you admit in your last paragraph it won't hurt anything. Making progress...
Last edited by glass slipper; Mar 5, 2010 at 09:52 PM.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
Like I noted before, if I had a LS6 or LS3 or LS7 then I'd be more careful but I can't tell any difference except for the price with the LS1. My LS1 has 225,000km on it so it's too late to baby it now.
Surly?
Peter
Race Director
Joined: Jun 2005
Posts: 10,909
Likes: 2,701
From: Phila Suburbs 2023 C8 & 2013 650ix
Now I never do it, BUT in winter you need less octane because of the colder air temps and you can't use the power anyway because the tires won't grip cold roads, so 87 would probably work just fine since all the engine is designed for is 91.
Racer
Joined: Jan 2009
Posts: 405
Likes: 1
From: SPRING CREEK NEVADA
do you guys really think that the same octane is required at 5000 ft. as at sea level, GM makes the octane requirements to cover the most extreme contitions, that does not mean it is the ideal fuel for all conditions, the higher you go in elevatoin the lower the octane requirements, and you lose performance due to losing atmospheric pressure which means less air and less compression which requires less octane. so if you run more octane than is needed you are losing performance from the lower atmospheric pressure and then you are losing more performance by running too much octane, contrary to what some have said here your hurting performance by running too much octane. higher octane is a slower colder burning fuel which requires more compression and timing to burn properly, put 110 octane in your car and see how much performance you gain, you won,t be impressed.
Burning Brakes
Joined: Aug 2007
Posts: 962
Likes: 0
From: SPRING HILL FL
Why does it matter what other people do and then explain how is right or wrong with information. I run the manual says. Others can do what they want. It's like if I mod my car will I still have a warrenty?
Racer
Joined: Jan 2009
Posts: 405
Likes: 1
From: SPRING CREEK NEVADA