Datalogging For Optimum Octane Level
09-03-2005, 09:47 AM
#1
Melting Slicks
Thread Starter
Datalogging For Optimum Octane Level
Has anyone here done any datalogging specifically to determine the minimum octane level you can run in a stock LT-1 ('95 / '96)? I mean the minimum octane level before detonation and the PCM pulls timing.
I'm thinking GM recommends high octane fuels more for safety reasons. If you run your engine hot (like stock LT-1 fan settings) higher octane will help control detonation. So since I changed my fans temps and my car runs cooler than stock I'm thinking I can drop my octane level to save $$$ and improve performance slightly.
What are your thoughts? Any experience out there?
I'm thinking GM recommends high octane fuels more for safety reasons. If you run your engine hot (like stock LT-1 fan settings) higher octane will help control detonation. So since I changed my fans temps and my car runs cooler than stock I'm thinking I can drop my octane level to save $$$ and improve performance slightly.
What are your thoughts? Any experience out there?
09-03-2005, 10:01 AM
#2
Drifting
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St. Jude Donor '05
To be honest with you the best time in my LT1 when I was NA and stock short block was a 12.54 with 87 octane.
the LT1's are pretty forgiving especially compared to alot of other things. If you do decide to try it just remeber to watch your knock counts and understand that you may need less timing.
the LT1's are pretty forgiving especially compared to alot of other things. If you do decide to try it just remeber to watch your knock counts and understand that you may need less timing.
09-03-2005, 01:39 PM
#3
Melting Slicks
Thread Starter
Thanks Alvin. Time to do a few tests I think. I went through all my datalogs running 91 octane and haven't see a single knock count so I think there's room there.
09-03-2005, 04:09 PM
#4
6th Gear
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remember, the lower the octane, the better the combustion.
87 burns hotter, faster, and cleaner, which is why it has more potential for detonation.
93 burns cooler, slower, and dirtier.
87 will actually help prevent deposits on the valves and pistons as well.
but of course, your chance of detonation increases exponentially the lower you go.
If you have problems passing emmisions, running 87 should be your first step to passing.
If you are WOT a lot, i wouldn't even think of running 87.
For all the data logging i've done on 87 through 93, i've never seen knock under normal daily driving / cruising conditions. I think you'd need to decide how you plan to drive your car the majority of the time.
87 burns hotter, faster, and cleaner, which is why it has more potential for detonation.
93 burns cooler, slower, and dirtier.
87 will actually help prevent deposits on the valves and pistons as well.
but of course, your chance of detonation increases exponentially the lower you go.
If you have problems passing emmisions, running 87 should be your first step to passing.
If you are WOT a lot, i wouldn't even think of running 87.
For all the data logging i've done on 87 through 93, i've never seen knock under normal daily driving / cruising conditions. I think you'd need to decide how you plan to drive your car the majority of the time.
09-03-2005, 08:59 PM
#5
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When my 87 was stock, it ran ok on 87. With a Hypertech chip it had to have at least 91. The fact is it got better fuel milage with the Hypertech so $$wise it was a wash. If you could bump up the timing and still get good mileage on cheap gas without pinging you could come out ahead.
