Various Topics on Subaru

..

Impreza 1993, EJ18 engine, manual.

Exclusively city driving, average trip about 5-7 miles. Was trying to
drive keeping RPMs close to 2,000 or to 3,000. For the most part
in practice it meant choice between 4th and 3rd gear.

Same pump, fuel contains "up to" 10% ethanol, same weather, two
full tanks for each "condition". The milage was consistent between
two tanks in each case within 0.3 MPG. Results:

~ 1,800-2,300 RPM = 26.7 MPG
~ 2,500-3,200 RPM = 28.1 MPG
(No, EJ18 is not a marvel of fuel economy :-))

Based on what I read before, I expected the opposite result. In any
case, the difference is no more than 5%, so it's not really worth
it to keep attention to. Lower RPM is less noise and less power.
What's better for the engine in the long run?

DK

..amTHISb.. ..hoo.c..

On Aug 25, 1:16 pm, d...@no.email.thankstospam.net (DK) wrote:
> Impreza 1993, EJ18 engine, manual.
>
> Exclusively city driving, average trip about 5-7 miles. Was trying to
> drive keeping RPMs close to 2,000 or to 3,000. For the most part
> in practice it meant choice between 4th and 3rd gear.
>
> Same pump, fuel contains "up to" 10% ethanol, same weather, two
> full tanks for each "condition". The milage was consistent between
> two tanks in each case within 0.3 MPG. Results:
>
> ~ 1,800-2,300 RPM = 26.7 MPG
> ~ 2,500-3,200 RPM = 28.1 MPG
> (No, EJ18 is not a marvel of fuel economy :-))
>
> Based on what I read before, I expected the opposite result. In any
> case, the difference is no more than 5%, so it's not really worth
> it to keep attention to. Lower RPM is less noise and less power.
> What's better for the engine in the long run?
>
> DK


Not surprising as a result, smaller engines are set up to make better
power in the higher revs, the cylinder filling is just so much better
at those revs it offsets the pumping/friction losses.

I'd have to guess an engine wears out after part X rubs past part y
for the umpteen-billionth time and it just wears out.

As long as you're not lugging the engine, having the car travel in the
highest gear possible will minimize the number of 'rubs' per mile
driven.

Dave

..ncyclexcs.. ..ail.c..

On Aug 25, 10:16 am, d...@no.email.thankstospam.net (DK) wrote:
> Impreza 1993, EJ18 engine, manual.
>
> Exclusively city driving, average trip about 5-7 miles. Was trying to
> drive keeping RPMs close to 2,000 or to 3,000. For the most part
> in practice it meant choice between 4th and 3rd gear.
>
> Same pump, fuel contains "up to" 10% ethanol, same weather, two
> full tanks for each "condition". The milage was consistent between
> two tanks in each case within 0.3 MPG. Results:
>
> ~ 1,800-2,300 RPM = 26.7 MPG
> ~ 2,500-3,200 RPM = 28.1 MPG
> (No, EJ18 is not a marvel of fuel economy :-))
>
> Based on what I read before, I expected the opposite result. In any
> case, the difference is no more than 5%, so it's not really worth
> it to keep attention to. Lower RPM is less noise and less power.
> What's better for the engine in the long run?
>
> DK

I would believe this if you could average over many more, not just the
2 tanks.

..p..

dk@[EMAIL PROTECTED] (DK) Aug 25, 2008 at 05:16 PM wrote:

>Impreza 1993, EJ18 engine, manual.

>Exclusively city driving, average trip about 5-7 miles. Was trying to
>drive keeping RPMs close to 2,000 or to 3,000. For the most part
>in practice it meant choice between 4th and 3rd gear.

>Same pump, fuel contains "up to" 10% ethanol, same weather, two
>full tanks for each "condition". The milage was consistent between
>two tanks in each case within 0.3 MPG. Results:

>~ 1,800-2,300 RPM = 26.7 MPG
>~ 2,500-3,200 RPM = 28.1 MPG
>(No, EJ18 is not a marvel of fuel economy :-))

>Based on what I read before, I expected the opposite result. In any
>case, the difference is no more than 5%, so it's not really worth
>it to keep attention to. Lower RPM is less noise and less power.
>What's better for the engine in the long run?

>DK

Longer trips will do the most to increase your engine life and minimise
wear! Most engine damage occurs in the first few miles/Kms when the engine
is not properly warmed up. If you run a longer distance for your test, you
may notice more variety in your figures. Cheers

--
Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru/
More information at http://www.talkaboutautos.com/faq.html

.... ..re..

On Mon, 25 Aug 2008 13:44:14 -0400, spamTHISbrp@yahoo.com wrote
(in article
<15ff3e92-abd7-4335-a5a7-f1b662416551@79g2000hsk.googlegroups.com>):

> Not surprising as a result, smaller engines are set up to make better
> power in the higher revs, the cylinder filling is just so much better
> at those revs it offsets the pumping/friction losses.

I recall some years ago BMW did some tests with one of their cars and
found that the best gas mileage was achieved by accelerating at wide
open throttle (WOT) to cruise speed, then holding constant speed. That
would apply only to that model of car, whose engine was designed to run
most efficiently at WOT, and similar cars by BMW and others.

> I'd have to guess an engine wears out after part X rubs past part y
> for the umpteen-billionth time and it just wears out.
>
> As long as you're not lugging the engine, having the car travel in the
> highest gear possible will minimize the number of 'rubs' per mile
> driven.

In 1955 I spent six months as a co-op student working at the Ford Motor
Co. proving grounds, then located in Dearborn, Michigan. One of the
things I helped do was to run fuel efficiency tests on Ford and
competitors' cars, all at constant speeds (that is, not from a standing
start like the BMW test above). The highest efficiency was invariably
obtained at the lowest possible speed in the highest possible gear.

Things may have changed in 50 years, but I expect that relationship
still holds.

--
John Varela
Trade NEW lamps for OLD for email.

.... ..a..

DK wrote:
> Impreza 1993, EJ18 engine, manual.
>
> Exclusively city driving, average trip about 5-7 miles. Was trying to
> drive keeping RPMs close to 2,000 or to 3,000. For the most part
> in practice it meant choice between 4th and 3rd gear.
>
> Same pump, fuel contains "up to" 10% ethanol, same weather, two
> full tanks for each "condition". The milage was consistent between
> two tanks in each case within 0.3 MPG. Results:
>
> ~ 1,800-2,300 RPM = 26.7 MPG
> ~ 2,500-3,200 RPM = 28.1 MPG
> (No, EJ18 is not a marvel of fuel economy :-))
>
> Based on what I read before, I expected the opposite result. In any
> case, the difference is no more than 5%, so it's not really worth
> it to keep attention to. Lower RPM is less noise and less power.
> What's better for the engine in the long run?
>
> DK
>
>
Hmm,
2 tankful? Have you looked at power band curve of your eingine? And
frequency of brake use. My '98 Honda CRV alwasy produce 10L/100Km gas
mileage regardless of season or where I drive in the city. If you drive
your car most of time like that in the city better go out onto turnpike
and burn off all the carbon build up inside the engine.

Two things, every engine has optimum cruising rpm and speed by desing
which will give best efficiency. Of course this is based on sea level
driving. I live near Rockies at altitude of ~2700 feet.

.... ..a..

hippo wrote:
> dk@[EMAIL PROTECTED] (DK) Aug 25, 2008 at 05:16 PM wrote:
>
>> Impreza 1993, EJ18 engine, manual.
>
>> Exclusively city driving, average trip about 5-7 miles. Was trying to
>> drive keeping RPMs close to 2,000 or to 3,000. For the most part
>> in practice it meant choice between 4th and 3rd gear.
>
>> Same pump, fuel contains "up to" 10% ethanol, same weather, two
>> full tanks for each "condition". The milage was consistent between
>> two tanks in each case within 0.3 MPG. Results:
>
>> ~ 1,800-2,300 RPM = 26.7 MPG
>> ~ 2,500-3,200 RPM = 28.1 MPG
>> (No, EJ18 is not a marvel of fuel economy :-))
>
>> Based on what I read before, I expected the opposite result. In any
>> case, the difference is no more than 5%, so it's not really worth
>> it to keep attention to. Lower RPM is less noise and less power.
>> What's better for the engine in the long run?
>
>> DK
>
> Longer trips will do the most to increase your engine life and minimise
> wear! Most engine damage occurs in the first few miles/Kms when the engine
> is not properly warmed up. If you run a longer distance for your test, you
> may notice more variety in your figures. Cheers
>
> --
> Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru/
> More information at http://www.talkaboutautos.com/faq.html
>
Hi,
If that is his usual driving pattern, at least the car needs more
frequent oil change for sure.

.... ..

>
> In 1955 I spent six months as a co-op student working at the Ford Motor
> Co. proving grounds, then located in Dearborn, Michigan. One of the
> things I helped do was to run fuel efficiency tests on Ford and
> competitors' cars, all at constant speeds (that is, not from a standing
> start like the BMW test above). The highest efficiency was invariably
> obtained at the lowest possible speed in the highest possible gear.
>
> Things may have changed in 50 years, but I expect that relationship
> still holds.

Nah, the laws of thermodynamics are still the same in Dearborn, last I
checked. They have a bit more eclectic food these days, but that track is
still there. I'll be breaking bread with one of many current Ford engineers
this weekend and I'll ask if they still use that track for such stuff.

-John O

..

In article <9u3tk.43424$hx.26520@pd7urf3no>, Tony Hwang <dragon40@shaw.ca> wrote:
>hippo wrote:
>> dk@[EMAIL PROTECTED] (DK) Aug 25, 2008 at 05:16 PM wrote:
>>
>> Longer trips will do the most to increase your engine life and minimise
>> wear! Most engine damage occurs in the first few miles/Kms when the engine
>> is not properly warmed up. If you run a longer distance for your test, you
>> may notice more variety in your figures. Cheers

I drove the way I use the car for, that's all.

>If that is his usual driving pattern, at least the car needs more
>frequent oil change for sure.

The oil change has been done regularly at 5,000 miles for the entire
life of the car, which is 15 years and 110,000 miles on it. Frankly,
if it dies on me soon, I wouldn't care that much - I am starting
to get tired of it. On the other hand, its maintanence so far averaged
perhaps $50/month, so for as long as it runs and gets me from point
A to point B, I can't justify buying another one.

DK

..Fi..

DK wrote:

> to get tired of it. On the other hand, its maintanence so far averaged
> perhaps $50/month, so for as long as it runs and gets me from point

15y*12m*$50=$9000 - wow