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Mr 5 0 · 08-21-2002, 07:51 PM

gizmo83:

As PKRWUD stated, simply adding 93 octane gas to your tank will not increase HP or performance over using 87 or 89 octane gas. Advancing your timing will give you some more power and the higher octane allows you to do that, as you stated. I think that's obvious.

I've run 15 degrees of initial advance on my near-stock 5.0 since I bought it, new, in 1990. I've also run Sunoco Ultra 94 octane in the tank for all 118,000 miles on the engine.

My injectors are clean, my valves are intact, my 5.0 runs strong and sweet and I've never regretted the extra cost of the gas.

As a side note: I run 12 degrees advance on my wife's '95 Mazda 626 2.0 (stock is 10) with 87 octane gas and never a problem in seven years.

If you want to run 93 octane gas (and advance the timing) do so and enjoy the benefits but don't run the 93 octane with stock timing and expect better performance...it won't happen. The seat-of-the-pants dyno is highy inaccurate.

08-21-2002, 07:51 PM	#15
Mr 5 0 Conservative Individualist Join Date: May 1997 Location: Wherever I need to be Posts: 7,487	Octane myths and facts gizmo83: As PKRWUD stated, simply adding 93 octane gas to your tank will not increase HP or performance over using 87 or 89 octane gas. Advancing your timing will give you some more power and the higher octane allows you to do that, as you stated. I think that's obvious. I've run 15 degrees of initial advance on my near-stock 5.0 since I bought it, new, in 1990. I've also run Sunoco Ultra 94 octane in the tank for all 118,000 miles on the engine. My injectors are clean, my valves are intact, my 5.0 runs strong and sweet and I've never regretted the extra cost of the gas. As a side note: I run 12 degrees advance on my wife's '95 Mazda 626 2.0 (stock is 10) with 87 octane gas and never a problem in seven years. If you want to run 93 octane gas (and advance the timing) do so and enjoy the benefits but don't run the 93 octane with stock timing and expect better performance...it won't happen. The seat-of-the-pants dyno is highy inaccurate.