In a message dated 01/19/02 11:18:05 AM Central Standard Time, dardal@xxxxxxxxxxxxxxx writes:
Internal combustion engines (especially throttled spark ignited
engines) are more inefficient at light loads. That's why most high powered
cars are gas guzzlers even when not driven fast. As mentioned in other
responses, the modern engine has better fuel management, but that will only
make a huge difference if your fuel mixture is WAY off.
Absolutely,
Dual Carb's on low rise intake manifolds at low loads are VERY inefficient. Part of the reason is the short runner length of the manifold, where a single carb setup on a similar rise manifold will most always give better MPG, because the manifold runner length is longer.
I had a 60 Dodge Phoenix with the 361 dual AFB quad log ram that got about 14 MPG highway (65mph). I played around with different manifolds and switched to a dual plane low rise/dual quad manifold, even using the same AFB's the MPG dropped to 7-8mpg, a single Quad/low rise AFB to 11ish MPG. I put the Log ram setup back on, better MPG WAY more tire smoking power, and besides the Log ram setup looked so cool I stayed with it.
My 1977 Dodge motorhome with a 360 2 barrel (9,850 LB) gets 10.4 MPG @ 60MPH/flat road/no headwind
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