What's the recommended fuel to run in a mostly stock (at least internal) motor? Any reason I can't run 93?
Recommend Running High Octane?
- Thread starter dz01
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You can run it but there's no real advantage on a stocker. It'll just me more expensive to fill up is all.
I've always ran at least 89, but no real reasoning why
I ran 89 in my original motor too. That was after doing fuel mileage calculations for 87, 89, 91, and 93.
They weren't very scientific calculations though. I was DDing the car at the time and totaled up mileage when the fuel gauge reached "E".
When I initially had it tuned, I was in an area where 91 was readily available and 93 was few and far between. Never bothered retuning.
This of fuel as an oil. What type to you NEED to run, vs what do you want to run?
On a stock 5.0 engine, they should be able to run 87 octane fine. Now, with age and carbon build up on the valves and heads and reduction of combustion chamber size, you may find you get detonation with 87 and might need to run 89 to head that off a bit. Or, you bump the timing a tad and need the higher octane as a result.
Either way, think of the fuel as what the motor needs to run well and make it's power. You want to run the lowest octane you can, but things like high compression, boost, timing, age, etc can adjust that upwards
On a stock 5.0 engine, they should be able to run 87 octane fine. Now, with age and carbon build up on the valves and heads and reduction of combustion chamber size, you may find you get detonation with 87 and might need to run 89 to head that off a bit. Or, you bump the timing a tad and need the higher octane as a result.
Either way, think of the fuel as what the motor needs to run well and make it's power. You want to run the lowest octane you can, but things like high compression, boost, timing, age, etc can adjust that upwards
mikestang63
SN Certified Technician
Another factor to consider is most fuels today mix ethanol, which IMO leads to reduced power and mpg. Also, if you raise your timing above stock you shoud also run higher octane. A higher octane gas will provide a better combustion and a cleaner burn, but that is just me. I run the highest octane around 93, however my car is no longer a DD.
I agree with Mike. Before my engine took a dump I ran 87. I ran 87 because I had base timing and no detonation. Running 93 would have been a waste of money. I never understand why people think that running higher octane is better or will gibe a performance increase if there car is not setup for it.
modulistic
Active Member
- Nov 26, 2002
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we can only get 90 up here. thankfully Im not knocking with my stock tune and v3si... at least not that I can hear.
You may never hear it if you have a louder than stock exhaust or ears that have spent too much time listening to music with the volume turned up to earthquake level...
My ears ring constantly, the result of having spent 8 years fixing Air Force aircraft. A ramp full of jets idling and taxing takes its toll on your hearing. There is some measure of sound and frequencies that I don't hear. I have advanced the timing to the 14 degree mark to get a little more low speed kick, but I may not hear the ping and detonation if it happened. Since the extra pennies for 93 octane are cheaper than the damage caused by ping and detonation I can't hear, I use 93 octane most of the time.
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