Seems there was quite a range of compression ratios for the Olds/Buick 215 V8.. In stock form they ranged from 8.75 - 11 to 1 ..
I was wondering what you are finding for octane requrements in the higher compression engines in real world driving?
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I get by on premium with my factory 11:1 Buick 215 which I assume has a bit less than advertised static compression.
I ran 91 premium with 10.25 to 1 pistons.
87 cheapy regular with 8.8 to 1 cast pistons.
91 premium with 8.5 to 1 forged pistons and boost.
Bill
I run regular in my Rover 3.5. Has 10.5 pistons but I'm using a Felpro composite gasket instead of the factory steel gasket so I think I would be in the 9.5 to 9.75 range. No problems with detonation or other issues.
Thanks..I'm getting cheaper as I age.
Anybody tried running E85? It is somewhere between 105 and 115 octane. They rate it at 105, but with the alcohol cooling effect, it is closer to 115. A buddy runs 11.5:1 compression with 15 pounds of boost on his street car with E85. It is a much newer engine, but the concept is the same.
I'm in the habit of putting Premium in my aluminum V8 even though it's probably a waste of money to do so.
I'm told that when corn and ethanol are in short supply, "E85" pumps sometimes dispense mid-level fuel that has a higher gasoline proportion. The pumps might be dispensing E30 or E50 or whatever, this week. In those cases, the pumps should be labeled accordingly but I wouldn't count on it. If you've got a late model Flex Fuel vehicle, it's no big deal because your engine can sense the difference in fuel performance and adapt automatically. More gasoline in the blend means you get higher MPG. For an engine with a carburetor or a less elaborate fuel injection system...
reference (http://www.ethanolretailer.com/customer-benefits/flex-fuel-vehicles/)
Good to know the 11 to 1 engines are getting by on Pump Premium.
Premium here in East TN is 93. I can get it with or without ethanol.
The local Shell station has two pumps with Turbo Blue race gas for $6.99. One pump is 100 octane unleaded that you can pump into your tank. The other is 110 leaded race gas that you are supposed to pump into gas cans. I used to run a mixture in my Camaro.