Whats the max octane i can use?

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Dec 12, 2007 | 11:19 PM

#21

mike#9

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From: Apopka, Fl

You will not pick anything up from using it....unless your application needs it. Are you a buily high compression motor that is experiencing detonation or knock.....

Then there is no need....get the 93 or whatever is available, and you will make the same power...if not more.

Dec 12, 2007 | 11:59 PM

#22

Beast96Z

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Same goes for 93, if you can run 89 with no pinging or detonation, go for it. You'll get a better burn. However, once you start tuning, tune with the fuel you plan to use constantly.

Dec 15, 2007 | 11:25 PM

#23

speedshifterNC

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If I planned on tuning my ls1 to run on a 93/110 mix would it be faster than just 93 or just 100. How high octane can you tune for on a stock engine and make the most power?

Dec 16, 2007 | 12:23 AM

#24

12secSS

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Quote:

Originally Posted by speedshifterNC

If I planned on tuning my ls1 to run on a 93/110 mix would it be faster than just 93 or just 100. How high octane can you tune for on a stock engine and make the most power?

Octane doesn't make the power, it is how fast (violent, yet controlled) the mixture can ignite. Timing controls when that mixture ignites before top dead center (peak cylinder pressure). Higher octane slows the process down. Stick with 93 octane and have it tuned for that, there is no need to go higher the 94 octane on most LS1 N/A engine setups. Unless you run extremely high compression ratios like 12.5:1 and higher, or ridiculous boost levels, or large nitrous jets. Running high octane was usefull to less efficient combustion chamber of the 60's era (SBCs), the LS1 chamber design is very efficient and doesn't require high octane to ignite the mixture more completely.

The highest unleaded octane easily available is about 100 octane, higher then this and most fuels use lead to boost octane, you do not want to run lead all the time in an EFI equipped engine.

Dec 16, 2007 | 12:55 AM

#25

1320 killer

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anything over 105 octane is leaded. once in a while is ok for performance reasons but running it all the time it will destroy the o2 sensors.

Dec 16, 2007 | 05:08 PM

#26

stroker_SS

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Quote:

Originally Posted by kwiksilverz28

Av gas is not designed for high altitude. It is 100 octance with lots of lead. It is called low lead, however, it has 8 times the lead of the old 87 octane...

there are actuall 6 types of avgas, but the new avgas is rated at 80(red) 100(green) and 100Low Lead(blue). At something like $4-5 a gallon i sure wouldn't be wasting money on it. And if your getting it for 20 bucks a tank, your probably getting the old stuff the airport won't put in the planes. So it's likely stale nasty gas. This is coming from an a+p tech in training.

Dec 9, 2012 | 10:03 AM

#27

juSStin4171

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Resurrecting this OLD dead thread... Octane - how much is too much or how little is not enough...

I completely agree with this statement:

Quote:

Originally Posted by Beast96Z

A motor makes peak hp/tq on the brink of detonation. The further past that you go, the less you make. Basically, run the lowest octane you can run without detonation.

BUT - I know the LS1's have a "low octane table" to help avoid knock. Is there anyone that can get technical about this with proven evidence for what the MINIMUM octane is before the car pulls timing or what the Maximum is before you start loosing power?

FWIW I run Shell's 93 octane in a bolt on, stock internal/bottom end. Is there any reason to change? I used

but couldn't find anything other than speculation (and this thread)

Dec 10, 2012 | 05:24 AM

#28

Sail Hatan

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Guy I bought my car from put regular in it and it ran poorly. I ran 93 only in it, and then had it tuned. when we had the hurricane and there was no gas, I put in a few gallons of 108 or something like that, and now I get a P0131 code for one of my O2s.

so ill stick with 93

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Dec 10, 2012 | 08:59 AM

#29

Sales@Tick

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Not worth it at all. Run 91 or 93 in it, have fun.

Dec 10, 2012 | 09:21 AM

#30

JakeFusion

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Even better if you can run 93 without Ethanol in it

Dec 10, 2012 | 09:57 AM

#31

redtan

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Quote:

Originally Posted by JakeFusion™

Even better if you can run 93 without Ethanol in it

Why's that?

Seems plenty of people like to use gasoline with ethanol in it (E85) and make more power both N/A and boosted over straight gasoline.

Dec 10, 2012 | 10:02 AM

#32

metalmilitia606

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Quote:

Originally Posted by redtan

Why's that?

Seems plenty of people like to use gasoline with ethanol in it (E85) and make more power both N/A and boosted over straight gasoline.

E85 is completely different from regular gas. Normal gas is only like 10 percent ethanol. E85 is 85 percent.

Dec 10, 2012 | 10:17 AM

#33

redtan

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Quote:

E85 is completely different from regular gas. Normal gas is only like 10 percent ethanol. E85 is 85 percent.

Still, if E85 (85% ethanol/15% gasoline) is better than straight gasoline (0% ethanol/100% gasoline) then wouldn't you think that E10 (10% ethanol/90% gasoline) is also better than straight gasoline?

Dec 10, 2012 | 10:21 AM

#34

metalmilitia606

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Quote:

Originally Posted by redtan

Still, if E85 (85% ethanol/15% gasoline) is better than straight gasoline (0% ethanol/100% gasoline) then wouldn't you think that E10 (10% ethanol/90% gasoline) is also better than straight gasoline?

Your first post implied that E85 and regular gas were the same. That's what I was commenting on. As far as what blend is best, old schoolers will say no ethanol is best. FI guys will say E85. On a stock car I think just premium gas is fine.

Dec 10, 2012 | 10:45 PM

#35

joecar

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From: So.Cal.

Quote:

Originally Posted by juSStin4171

...
I completely agree with this statement:

BUT - I know the LS1's have a "low octane table" to help avoid knock. Is there anyone that can get technical about this with proven evidence for what the MINIMUM octane is before the car pulls timing or what the Maximum is before you start loosing power?
...

To use the LO table, knock has to be detected...

so be careful to not rely on the LO table and/or the knock sensors

( tune to avoid knock )