Re: Mileage vs. Performance (RPM Related)

From: Patrick Delgado (dadoctah@worldnet.att.net)
Date: Wed Jan 13 1999 - 16:13:03 EST


No, no, no.

If your truck NEEDS 100 HP to travel at 70 mph the engine WILL produce 100 HP
NO MATTER WHAT the engine is CAPABLE of producing. If you don't change
anything else on the truck, F/A ratio stays the same and engine friction stays
the same(crank-driven accessories, valve spring pressure, piston weight and
size etc.,etc.) your fuel consumption would stay the same. Many power
producing mods increase both mileage and Hp by decreasing fluid (intake air
and exhaust) headloss and engine friction(roller lifters,rockers etc.) . Some
mods
INCREASE engine friction (and thus fuel consumption). For example, higher lift

cams, higher rate valve springs, tighter piston rings,inreased
bore/stroke,super
and turbo chargers.

Dr. Pat
----------
>From: Jetmugg@aol.com
>To: dakota-truck@buffnet.net
>Subject: Re: DML: Mileage vs. Performance (RPM Related)
>Date: Wed, Jan 13, 1999, 11:26 PM
>

>While it's true that a more powerful engine can be more efficient, what
>determines the speed that your Dak is travelling is the rpm of the engine, not
>the HP. For example, if your truck is going 70 mph, we'll assume that the
>engine rpm's are 2000, and assume that the engine HP is 100. If the engine in
>the truck makes 150 hp at 2000 rpm, you will still only be travelling at 70
>mph at 2000 rpm, assuming no change in gears, etc. However, now you are
>supplying gasoline and air to an engine which is making 150 HP instead of 100
>HP. I think we can all agree that the 150 HP engine will use more gas.
>
>The numbers above are completely fictitious, so please don't jump on me for
>false numbers, but the concept is valid.
>
>Steve M.



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