Tripledigitride

I am a new ls1 owner and have a question about gas...I have read a lot and now it's best to use 91 or higher octane.....my question is there is a gas station here with 100% gas 89 octane.....would it be better to use it or go with the higher octane with the 10% ethanol? Thanks in advance for any and all responses....

jrwilliams95z28

dont buy either,91+ octane should have no ethanol. if the station sells it with it go somewhere else

alexus6798

iTrader: (24)

Not true. Damn near all stations have up to 10% ethanol in the gas.

Tripledigitride

That's what I was thinking they all have about 10% ethanol.....that why I was wondering if the 100% gas 89 octane would be better....

alexus6798

iTrader: (24)

I think it may need to be tuned to run on 89 but I may be wrong. The stock computer may compensate but it will lose power and probably burn more in the end.

Tripledigitride

Thanks......I'll just keep using the "high test"

2000PewterT/A

Stick with the highest octane fuel you can find at the pump, and nothing over 10% ethanol, almost all gas stations are 10% ethanol.

z-maro

iTrader: (18)

From the owners manual it says running low or mid grade is just fine.
http://shbox.com/pdf/2001firebird.pdf



Not saying you should run regular, but it shouldn't cause any damage and you don't need a tune. There is a low octane timing table in the stock tune.

99 ss

iTrader: (12)

Just run shell v power or Bp gold and u will be fine

Ls1onLsd

iTrader: (1)

Almost all cars in the past 15 or so years are designed to run on 89' Octane, unless they have a a bigger or more advanced motor (GT500 Cobra/ZR1 Vette, etc). I had a 13' Model 5.0 and it ran just fine on 87 but I chose to put 93 in it. This is mostly due to gas prices

RPM WS6

iTrader: (3)

This is kind of a misleading statement. Knock sensors combined with low octane spark advance tables in modern PCMs do in fact allow for the safe use of lower octane fuel in performance engines, but for peak (designed) performance, engines such as the LS1 were in fact designed for the use of 91+ octane.

So if the question is, "Can you [safely] use 87-89 octane in your LS1?", then the answer is certainly yes. But the engine will not deliver the same level of peak performance that it was designed to deliver with higher octane fuel.

I don't think the OP was asking about what was "safe", but rather which was "better".

mirror12

So a fuel with Ethanol added at 91 octane would deliver better performance than a gasoline at 89 octane with no Ethanol added?

RPM WS6

iTrader: (3)

Octane rating itself doesn't deliver performace, it just represents a different amount of resistance to detonation. If you have a lower compression engine that doesn't require higher octane to resist detonation at optimal timing advance levels, then increasing octane further can only hurt performance. If the engine *does* require greater octane to resist detonation at optimal timing, then a reduction in octane (ethanol or not) is going to deminish potential peak performance. In modern engines, use of lower octane is "safe" because knock sensors will detect the detonation and the PCM will command the low octane spark table.

And lastly, I don't really see how there could be "ethanol-free" 89 octane at a station that doesn't also sell ethanol-free 91/93 octane. To the best of my knowledge, there is no "89" octane at any station, just a mix of 87 and 91/93 that occurs at the pump to deliver effective "89" octane.

mirror12

There is a gas station in my area that claims an Ethanol free 90 octane gasoline. It runs at about $3.79 a gallon. They have decals on the pump with this claim. Do you think this might be BS. They do offer 92 octane fuel with 10% Ethanol, at a about a .10 cent savings. Which fuel would you use. I just want to use the best I possibly can for my car.

RPM WS6

iTrader: (3)

I seem to remember that there was a time when stations had dedicated tanks for 89 (mid-grade) octane. To the best of my knowledge, the vast majority of modern pumps now just mix the low and high octane offerings to achieve the advertised mid-grade level.

If a station claims to have a mid grade product that does not contain ethanol, but low and high octane products that do, then they must have a dedicated tank for this special product. There are still some stations that sell ethanol-free fuel, but these are rare (especially here in the midwest, where E10 has been the typical standard for a very long time).

Ethanol-free fuel will deliver better MPG, but if the octane rating is too low to support optimal timing advance for a given engine, then peak engine performance will suffer. So the answer is, your engine will deliver best possible performance when the proper octane for optimal timing advance is used, but you will realize best possibile MPG when the lowest amount of ethanol is used. For the best of both worlds, you'd want 91-93 octane with no ethanol. Since that is not an option, you'll have to choose between best possible performance or best possible MPG.

S8ER95Z

iTrader: (3)

Fwiw I drive a lot (a tank a week / roughly 300miles) and with 91+ fuel I tend to see 24-26mpg averages... If I run 89 it falls to 21-23.. I've tested this numerous times and the results were the same regardless of how I drive. The small amount I saved buying cheap gas was always offset by poor fuel economy.

pewter2002

iTrader: (4)

There is a website that lists stations by region that have ethanol free fuels and what grade at the pump is ethanol free if some grades have ethanol in them. Around me, Shell 91 (v power premium ) is 100% gas, ethanol free. The other grades contain upto 10% ethanol.

I run Sunoco 94 in my SS (10% ethanol) , but tried the Shell 91 for a full tank. I felt no SOTP difference between the two, but I didn't do a mpg comparison which is where I would benefit most from ethanol free fuel.

However, my Subaru 3.0 (premium recommended ) feels more peppy with the Shell 91 than the Sunoco 94, which I run most of the time actually! The difference when filling from empty is noticeable , more power, better throttle response. Once again, I haven't done a mpg comparison between the fuels in the Subaru.

I guess it is possible that some engines prefer certain brands, depending on the weighting of the fuel formula; how much RON vs MON.