Re: [DML] 30+ mpg in a DeLorean

["Donald L. Ekhoff" <ekhoff@xxxxxxxxxxxxxxxxxxxx>]

James,

I have been somewhat following the tread you have created with your 
millage claim. Personal experience combined with what I think I know 
about your Stage II changes would lead me to believe you have obtained 
30+ mpg results.

An engine is first and foremost is an air pump. What makes it an engine 
is that fuel derived energy is interjected in one of the four cycles to 
result in net power being provided to drive the load. Pumping losses are 
parasitic and subtract from usable derived power. If you have improved 
the overall breathing over the stock engine than you should benefit from 
these reduced  pumping losses. Your free flow exhaust alone is 
sufficient to obtain the improvement noted. The stock Delorean exhaust 
is an ideal candidate for improvement as it is very restrictive. The  
Island Twin Turbo manifolds are even more restrictive than the stock 
setup.  Energy used to push gases through the plumbing is energy not 
available to drive the car and directly effects the amount of fuel used 
to drive the system. Back pressure on the top of the piston during an 
exhaust stroke is working against having decent fuel economy and is a 
much bigger issue than aerodynamics, tire pressure or vehicle weight. 
Given our vehicles slick shape and low weight we should be getting 50 
mpg with a truely modern engine.

If you ever have the chance to dyno a stock engine vs your flow improved 
engine I think you will be able to scientifically qualify the results 
you have observed. Just check fuel consumption for a given power output, 
especially at part throttle (cruising) conditions.

Thanks for improving the breed.
Don Ekhoff



James Espey wrote:

>A few years ago, I drove our former company car five-speed from Houston to
>Scottsdale, Arizona. This car had the Stage II engine and I was surprised on
>at least two tankfuls to get over 30mpg. A woman client of ours just drove
>in from Oregon for a week while we installed the Stage II engine in her car,
>and she reported similar results on her way BACK to Oregon. I don't think
>30+ mpg on the highway is anything to complain about...the Rover I drive
>regularly and the XJS I hope to be driving soon are both sub-15mpg.
>
>30mpg and a 13.2 gallon tank make for a nearly 400 mile range...
>
>James
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