no 93 octane

[intheclouds1977]

Do these LS1 cars even have separate timing tables for 91 and 93 octane? I'd guess the performance would be exactly the same with both octanes. Same advance, no pre-detonation. More octane doesn't do you any good if the car can't adjust for it. If it's still running the same table, same timing, etc; you get the same performance.

The only way performance would be different is if there are tables for 91 and 93...or if the upper performance table got some detonation out of 91 and had to retard the timing.

[WS6ICK]

I live in Colorado which only sells 91 at he pumps with sucks. I use a fuel additive called Torco with the 91 octane and its better than 93 octane. Click on the link below.

http://torcoracefuels.com/component/...d,32/vmcchk,1/

[tonyjnjz]

somone posted that 112 octane is 6 bucks a gallon? starting to sound more and more reasonable getting your car tuned for race fuel and runnning that......it used to be TRIPLE the cost of regular gas when gas was just over a buck a gallon.....was 3 a gallon for 110 here.....if im paying 4 bucks a gallon for 93 and 6 bucks for 110 it makes me think about having my car tuned for 110....its not a daily driver........what kinda hp would i pick up doing this??? .......50 horses or so? is it safe?

[Firebirdjones]

Do these LS1 cars even have separate timing tables for 91 and 93 octane? I'd guess the performance would be exactly the same with both octanes. Same advance, no pre-detonation. More octane doesn't do you any good if the car can't adjust for it. If it's still running the same table, same timing, etc; you get the same performance.

The only way performance would be different is if there are tables for 91 and 93...or if the upper performance table got some detonation out of 91 and had to retard the timing.

Yes they do. They have a low and a high table. Or I should say at least my 02 does.
It uses the low table to revert back to when detonation is present. After a while I understand that it also has a learning curve and is only reset when the tank is refilled.
While tuning mine I have done what most tuners do and that is copy the high timing table over the low timing table,,,makes dialing in the timing curve easier and you get more consistent performance from the car.
With that said, I run nothing but 94 in it,,,,,and have the timing table tuned accordingly. If I drop the octane I start to see a couple degrees here and there being pulled out via knock retard,,,so if I really want to run lower octane I would have to revamp my timing curve to make it happy.

I would lose some performance and some gas mileage as a result.

[intheclouds1977]

I live in Colorado which only sells 91 at he pumps with sucks. I use a fuel additive called Torco with the 91 octane and its better than 93 octane. Click on the link below.

http://torcoracefuels.com/component/...d,32/vmcchk,1/

Less octane is needed the higher in altitude you go. More altitude = less dense air = less compression. 91 octane in Colorado has the same resistance to detonation as 93 octane at sea level in the same vehicle.

[intheclouds1977]

Yes they do. They have a low and a high table. Or I should say at least my 02 does.
It uses the low table to revert back to when detonation is present. After a while I understand that it also has a learning curve and is only reset when the tank is refilled.
While tuning mine I have done what most tuners do and that is copy the high timing table over the low timing table,,,makes dialing in the timing curve easier and you get more consistent performance from the car.
With that said, I run nothing but 94 in it,,,,,and have the timing table tuned accordingly. If I drop the octane I start to see a couple degrees here and there being pulled out via knock retard,,,so if I really want to run lower octane I would have to revamp my timing curve to make it happy.

I would lose some performance and some gas mileage as a result.

I'm aware the car has 2 timing tables stock. What I don't know is where the tables draw the line. Typical autos run 87 and 89 in the lower timing table, and anything 91 and above in the upper timing table. Are you indicating that 91 and lower octane force the computer to run the low timing table in an LS1 car (at sea level)?

[Firebirdjones]

I'm aware the car has 2 timing tables stock. What I don't know is where the tables draw the line. Typical autos run 87 and 89 in the lower timing table, and anything 91 and above in the upper timing table. Are you indicating that 91 and lower octane force the computer to run the low timing table in an LS1 car (at sea level)?

It's not as cut and dry as saying "this octane level runs this table and that octane level runs that table etc...." I wish it were that easy.

It's simply what ever that particular engine can tolerate as far as octane verses detonation. So many variables come into play here. Not all the LS1 cars are the same. The earlier years ran a larger camshaft and had EGR to deal with,,,,,the 01 and 02 cars had a much smaller (truck) camshaft and EGR was eliminated.

All of this has an effect on octane tollerance. The 01-02 cars generally don't like much more than about 24 degrees of total timing,,,,where the earlier LS1 cars can have as much as 28 degrees.

Which timing table the car runs on is solely dependant on the gas in the tank, how much knock the sensors pick up, the altitude at which you are driving (as you mentioned) etc...just so many variables. But for best performance I believe GM recommends high test for these cars,,,although they CAN run on something lower.

Does that help any??? There are just so many variables I don't think I can give a solid answer here. But to answer your last question,,,,I would say yes to an extent. If you run lower than 91 octane,,,,89 for instance,,,,it's very possible that any aggressive driving would trigger a knock sensor,,,in which case the computer would revert back to the lower timing table to correct the problem. Probably wouldn't get any knock if you put around and keep your foot out of it. Make sense???

[intheclouds1977]

Makes good sense. Your guess would be though for a standard car, there would be no gains from 91 to 93 octane? Both would probably yield the higher table without pre-detonation?

I wish there was a way to know if my car was reverting to the lower table on me. The only 100% gasoline around here I can find is 91 (500ft above S/L). I'm not a big fan of 93 octane with 10% ethanol blended in. The mid-west loves their corn! Gotta get me HP Tuners (or the like) someday.

[stevenm357]

we have 93 here in WV and most of OH that i go to.

I find that when using 87 octane ( in a 1997 grand am and 2005 G6 GT) that it ( and the ethanol blended gas) all provide less MPG than does premium gas so it's not really saving Much money. and if premium is 20Cents/gallon higher you will break even on MPG vs. price. and have cleaner burning fuel.

[LS1buckey]

I am from Ohio and currently living in North Carolina, I'm trying to think but I can not remember seeing gas without ethanol in it. I am guessing from what you are all saying that it's better without it but where can I find it and how much of a benefit would it be?

[intheclouds1977]

10% ethanol mix has 3% less power than pure gasoline (for the same octane rating). The average driver probably would never notice that. I like the idea of 3% more power and 3% better gas mileage though. Sometimes the pure gasoline is more than 3% more expensive though, so you gotta watch the price if you're interested in the mpg gains.

For a 330hp car, 3% is 10 hp.

The only stations around here with 100% gasoline 91 octane are BPs.

[Firebirdjones]

Makes good sense. Your guess would be though for a standard car, there would be no gains from 91 to 93 octane? Both would probably yield the higher table without pre-detonation?

I wish there was a way to know if my car was reverting to the lower table on me. The only 100% gasoline around here I can find is 91 (500ft above S/L). I'm not a big fan of 93 octane with 10% ethanol blended in. The mid-west loves their corn! Gotta get me HP Tuners (or the like) someday.

I understand. Going from 91 to 93 and seeing a difference would be hard to measure by seat of the pants. To really see what is going on you need software as you have already stated. I use HPtuner as alot of others here do. Logging while driving is a cool feature, and you get a real world idea of what the engine is asking for.

Around here we still have 93 octane that is easy to find, I have not seen 91 around here yet. It drops to 89 and then 87.

[Firebirdjones]

The only stations around here with 100% gasoline 91 octane are BPs.

I will have to pay more attention to this. I know most of the stations around advertise 10% ethanol. And I am with you,,,I don't care for it.

But I don't buy much at BP, I'll have to look more closely at BP and Shell both. Since I have been buying 94 Sunoco for the last 25+ years,,,but pretty soon that will be gone, so I will have to resort to other stations.....The Sunoco that I use does not advertise any ethanol mix,,,so I assume the don't do it

[LS1buckey]

I'm going to start looking for that pure gas from now on.

[LS1buckey]

I live in Colorado which only sells 91 at he pumps with sucks. I use a fuel additive called Torco with the 91 octane and its better than 93 octane. Click on the link below.

http://torcoracefuels.com/component/...d,32/vmcchk,1/

How many points does that raise your octane level?

[intheclouds1977]

http://volvospeed.com/Reviews/torco_accelerator.html

[Firebirdjones]

http://volvospeed.com/Reviews/torco_accelerator.html

Good info,,,but they need to update the prices. I know,,,it's ever changing......but they base their reasoning off of a starting price for 93 octane at $3.00 a gallon I can't remember the last time I paid that for a gallon of gas.

I am still curious about the 10% ethanol. I am wondering if there is any law that would make a gas station advertise as such if they are mixing with ethanol?????
Sunoco does not have anything on their pumps about ethanol,,,but I'm not so sure that means they don't mix it.

I should ask Scott up the street who owns the local gas station up the street, (a quicky mart) he doesn't advertise ethanol at his pumps either,,,maybe he could shed some light for me.

[intheclouds1977]

The BP I go to does not have the typical 10% ethanol sticker on their pump. I went inside and asked the attendant. They were well aware that their 87 and 91 octanes did not have ethanol in them. Their 89 octane did though. I'd say just go inside and ask. If the person behind the counter is clueless, I'm sure they can give you the phone number of the owner/manager if you ask.

[Fred H.]

Be careful with octane boosters. The owners manual states not to use fuel additives and octane boosters that contain methylcyclopentadienyl manganese tricarbonyl (MMT).

91 Octane is fine, and there is no benefit in using a higher octane than you need, which is stated to be 91 in the owners manual. Actually the reverse is true. Lower octane fuels have a higher specific energy output. So you should always use the lowest octane you can that doesn't cause pinging or detonation.

Chevron Techron fuel cleaner is about the only gas additive I will use in any vehicle I own, and it is endorsed by many of the major manufactures, including Honda and BMW.

Any pump that contains Ethanol is required by law to have a sticker on it that says so.

And for anyone living at higher altitudes, like in Colorado, you can safely reduce your octane if you are at a higher elevation, and you will find the octane levels at the pumps lower in Colorado as a result. There is a formula for calculating it, and if I remember right it is something like minus one octane point for every 3k or 4K ft in altitude.

[LS1buckey]

Lower octane fuels have a higher specific energy output.
.

Forgive my ignorance but I have never heard that before (nor the opposite) what do you mean?