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Old 04-27-2009, 05:34 PM   #6 (permalink)
EXPIOWA
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Join Date: Nov 2008
Location: Central Iowa / Memphis TN
Posts: 28

Fiero SE - '87 Pontiac Fiero SE
90 day: 30.17 mpg (US)

EXP SC - '87 Ford Escort EXP SC
Last 3: 36.75 mpg (US)
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Quote:
Originally Posted by NeilBlanchard View Post
Hi,

I don't think that high octane will help you, and it might even hurt your FE (because it resists burning!) -- try using what it is rated for? In high compression engines, you need the higher octane to prevent predetonation, but this is not what we need for higher FE.
One of the things that higher octane allows me to do is shift earlier. There was an immediate difference in engine smoothness at low rpm after switching grades from 87.

When my headgasket blew a few years back I had the head rebuilt and it was planed in the process. It has a slightly higher compression than stock due to the milling and it likes 93 a lot better. If I am only filling up 10 times a year in this car I might as well go with the best stuff for the engine.

It runs cooler on high octane as well. Ford chose a tiny radiator for this horrible design. (Aluminum head on a steel block). Heat is my engine's worst enemy. In the case of this car, premium gas is warranted. I use 87 in all of my other cars.

My belly pan actually helped the heat situation. I believe that it blocked incoming air from rising up from under the car and filling the space behind the radiator and now allows for better flow. I may be getting a venturi effect as well behind the belly pan as a result of smoother under-car airflow.
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Last edited by EXPIOWA; 04-27-2009 at 05:41 PM..
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