Quote:
Originally Posted by 19bonestock88
I don’t know if it works out to better cents per mile, but...
To go from 9.5 to 11 to 1 compression would theoretically give me 6% more power, or about 8bhp... more power leads to shorter pulse cycles(compared to glide length), which leads to better overall FE...
Slightly better mileage and more power to play with when I’m not hypermiling, may be worth the higher fuel cost...
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Honestly, if you don't have at least a cheap source of e85 if you're considering any fuel except 87 you will be disappointed. The real world price of regular and premium in my location right now is $2.47 and $2.90. That for me is a 17% increase in price. If your car was power limited the power thing would come into play more, but its a v8 car so just throw that out and focus on efficiency numbers using the thermal efficiency equation. Check you're valve clearances and quench... have the head decked and buy a thinner head gasket which still allows the engine to function and have a reliable seal.
Make the changes you can while running 87 octane (timing, leaner afr's, decked head, thinner head gasket), and find a good double overdrive transmission and work on aerodynamics. Your car is realistically making too much horsepower for the rpm it's spinning to go x speed so follow Chevrolet's mark and skip shift (1-4) under 2000 rpm with high load and have your car geared to spin about 1500 rpm at 70 mph.
Also, the head cooling is true. Real world numbers I do not know but aluminum engine blocks cool better than iron blocks, and I recently saw a company talking about their better integrated cooling circuit into their heads on the car which allowed them to decrease knock because of cooler cylinder head temperatures.
If you wanna play with numbers this a good video too:
On point three he uses the equation normalize thermodynamic efficiency numbers from compression ratios. It's a logarithmic curve though so don't expect a ton.
Also, another point to consider is the bar is probably already so low you'll never even reach the efficiency numbers of an LS drivetrain. Thats why a ton of people don't even mess with rebuilding 350s that came in their car anymore unless they want to be concours original.
That and the reason why LS's are so cheap is because you can buy an aluminum block ls based 5.3 from the junkyard for cheeeeep.