Nothing unusual, just 9.8:1 compression achieved with 180B pistons, Z
intakes which were unshrouded along with some port work and 5 angle valve
job, dowelled intake manifold with matched ports, flat-top 160J-SSS SU's had
halved spindles and cap screws holding the butterflies, intake rams, K & N
filter using the oval orange SSS air-cleaner holder with some extra holes
drilled around the edge, headers with 2" exhaust to resonator and Dynomax
muffler, off-road rally cam with modest duration but good lift designed for
low to mid-range torque, fully balanced, baffled sump, max 60 psi oil, high
temp thermostat.
Considering how hard I drove it the economy was outstanding. Just about
every tank was more than 300 miles between refills, that is 10 gallons
Imperial. The standard engine which was much less powerful averaged 32-34
mpg by comparison, although at a much slower pace.
Other things that would improve the result further would be electric fan and
pump, electronic ignition, looking at optimising the squish design of the
head, back-cutting the valveheads, tuning the header length etc. Strangely
enough most people chase horsepower alone, not economy AND performance.
Actually I was impressed by the book "Tuning new generation engines for
performance and economy" by A Grahame Bell published about 1987, it's a must
read if you are interested in engine and vehicle efficiency.
When I hear of people getting 20-24 mpg with a single carb or twin SU's in a
light car such as the 1600 they must have a badly tuned and/or inefficient
engine. If they have twin twin-choke Webers I can understand that, as they
are not designed for economy.
----------
>From: "Paul W. J. Stanley" <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>
>Subject: Re: L20B mods. + mpg
>Date: Fri, 30 Mar 2001 1:07 AM
>
> How did you tune it like this Denzil? This sounds very desirable for what I
> want...ecconomy since I am a pizza deliverer. Except you need the occasional
> flurry of revvs to get you out of the way of that Mack truck that is
> whistling towards you...
>
>
> ----- Original Message -----
> From: Denzil Palmer <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, March 29, 2001 8:24 PM
> Subject: Re: L20B mods. + mpg
>
>
>> That's it, much greater efficiency. The same or greater amount of work is
>> done using less fuel.
>>
>> I should have clarified that my motor was carefully built on a "torque for
>> the road" basis, resulting in very good low and mid-range efficiency,
>> excellent cylinder filling and carbs tuned fairly lean. The concept was a
>> car that had a useful 4th gear from 25 -100 mph(1,500-5,800 rpm) for
> example
>> 30 -50 in 4th in 5.5sec or so, 60 - 80 in 4th in 7.5 or so. The "torque
>> back-up or torque reserve", that is, the potentially available torque over
>> the required torque at a given engine speed in the low to medium speed
> range
>> was greater than a motor tuned for big horsepower at high revs. This made
>> hills virtually unnoticeable, even in 5th on sustained climbs with
>> acceleration still available if required.
>>
>> I wouldn't expect the same economy with the same sort of driving with a
>> standard motor with the SU's. Instead of 31 maybe you would get 27mpg, and
>> significantly slower as well.
>>
>> ----------
>> >From: "James Cox" <[EMAIL PROTECTED]>
>> >To: [EMAIL PROTECTED]
>> >Subject: Re: L20B mods. + mpg
>> >Date: Wed, 28 Mar 2001 4:39 AM
>> >
>>
>> > Are you taking into consideration that a motor with head work,
> extractors
>> > and free flowing exhaust is going to operate more efficiently than a
> stock
>> > motor? My engine is stock and running SUs and I even noticed an
> increase in
>> > power, torque AND economy by fitting extractors and sports system. Sure
> the
>> > motor will use more fuel if you floor it but your going faster too,
> speed
>> > comes at the expense of fuel. Correct me if I am wrong, but I believe
> that
>> > if a stock motor goes say.. 0-100 in 12sec then a worked motor will be
> able
>> > to do the same time using less fuel due to greater efficiency.
>> >
>> > James
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