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Jerseydave
01-27-2012, 12:34 PM
'93 prostar, LT-1 with 1:1 trans (non-powerslot)

-Manual calls for 89 octane gas, will this be ok or should I use premium?
-What prop are you guys running for the best top speed? Boat will be used for barefoot and slalom (50/50)

Is it spring yet? Man buying a boat in December stinks!

JimN
01-27-2012, 12:45 PM
'93 prostar, LT-1 with 1:1 trans (non-powerslot)

-Manual calls for 89 octane gas, will this be ok or should I use premium?
-What prop are you guys running for the best top speed? Boat will be used for barefoot and slalom (50/50)

Is it spring yet? Man buying a boat in December stinks!

If the manual calls for 89, use 89. If it will sit for any length of time after the fill-up, buy premium- the octane drops over time. If you'll be running it hard in hot, dry air, use premium. If your octane drops or is insufficient, the Knock sensor will send the signal to the ECM and the timing will be reduced in 5 degree steps until the knock is gone, or base timing has been reached. If you're at anything approaching WOT and the timing is retarded a lot, you'll know it- it will run like a stove.

At what altitude are you running it?

Jerseydave
01-27-2012, 12:52 PM
If the manual calls for 89, use 89. If it will sit for any length of time after the fill-up, buy premium- the octane drops over time. If you'll be running it hard in hot, dry air, use premium. If your octane drops or is insufficient, the Knock sensor will send the signal to the ECM and the timing will be reduced in 5 degree steps until the knock is gone, or base timing has been reached. If you're at anything approaching WOT and the timing is retarded a lot, you'll know it- it will run like a stove.

At what altitude are you running it?

Sea level most of the time, but never over 1000' altitude.
I agree with the 89 octane, same as I use in my MCX. No reason to spend extra $$ on super if not needed.

gotta_ski
01-29-2012, 06:54 AM
I know I'll get flamed for this, but I run regular in my LT-1 and its flawless. Granted I do drive across town to get Ethanol-free gas, but its 87 octane all day long. Maybe I'm an idiot for doing this. I know the majority of guys on here run 89 or 91, but who is running 87? Any documented issues?

Jerseydave
01-29-2012, 09:11 AM
I know I'll get flamed for this, but I run regular in my LT-1 and its flawless. Granted I do drive across town to get Ethanol-free gas, but its 87 octane all day long. Maybe I'm an idiot for doing this. I know the majority of guys on here run 89 or 91, but who is running 87? Any documented issues?

The LT-1 has 10.5-1 compression ratio so I think you're running a risk of shorter engine life by using 87 octane. The knock sensor is probably adjusting your timing back to compensate for the low octane gas.
At the very least I would think you're not getting the full horsepower out of the engine with that gas. Try a couple tanks of 89 and see if performance is better.

1redTA
01-29-2012, 10:39 AM
the LT1 has reverse cooling and is very forgiving as far as octane and keeping performance are concerned. are you safe? Most likely but you are running at a lower spark map

JimN
01-29-2012, 10:57 AM
I know I'll get flamed for this, but I run regular in my LT-1 and its flawless. Granted I do drive across town to get Ethanol-free gas, but its 87 octane all day long. Maybe I'm an idiot for doing this. I know the majority of guys on here run 89 or 91, but who is running 87? Any documented issues?

Lower octane fuel burns faster than higher octane, which means your ignition event occurs at a time that's not optimal. The event also doesn't last as long as it should and these combine to increase the chance of having detonation (knock) and decreased performance. The performance isn't as much of an issue as the ignition timing- you can't advance or retard the spark timing, so you run the risk of burning valves and valve seats. If the gas is old, the octane drops further and this increases the risk of burning piston heads or scoring the cylinders, especially if your engine runs hot anyway.

If you don't run at WOT, it shouldn't be a problem unless you're in a hot, dry place. This doesn't guarantee that you won't have a problem.

For a few cents per gallon, I'd rather be safe.

JimN
01-29-2012, 11:00 AM
the LT1 has reverse cooling and is very forgiving as far as octane and keeping performance are concerned. are you safe? Most likely but you are running at a lower spark map

Yeah, if it has a good impeller, the oil cooler is clear, the gas is fresh, the air is cool and not too dry, the bleeders are clear and working properly,.....