Hi Octane Autogas

On Thu, 15 Apr 2004 09:15:31 -0500, Dino Shore
wrote:

On Wed, 14 Apr 2004 03:51:16 GMT, wrote:

I have had several vehicles over the years that produced enough extra
power (and therefore economy) on hightest to MORE than pay the
difference in cost.


This story has been told many times before by would be experts.
It is the stuff of which Urban Legends are made.

No story. Hauling my 17 foot trailer across the prairies behind the
3.0 Aerostar, on regular unleaded, about 17L/100km, with hightest
about 14l/100km

Thats a difference of from 423 to 514 km on a tank.
That is almost 21%
Around here, with hills and all, the mileage drops off significantly -
a bad day can give 21-24 liters/100km on regular, and 17-20 on
hightest. Thats 340-423 at best, to 300-360 at worst, more or less.
That's 20--24%. Might not make quite that difference, depending on
terrain and how hard I push up the hills.



Running without the trailer, averaged 12.4 l/100km on regular, and
11.25 on hightest.

Thats a difference of 580 to 640 km on a tank of gas.
That is roughly 10%

If regular gas costs $0.60, and hightest $0.70 per liter, the
difference in cost is 16%

Pulling the trailer I made money by using hightest.
Running easy, I lost.

On the 88 Chrysler 3.0, I can average 7,8 l/100km on regular
(according to the trip computer) and about 6.8-7.1 on hightest.
Take the conservative 7.1, and we are looking at 9%. Take the better
mileage, and we are looking at close to 15%.
The heavier loaded the vehicle, the larger gain in economy gained by
using hightest.

This ONLY works with computerized engine controls with knock sensing.

There are many variables, but if one accepts that there is
a realistic 10% increase in horsepower from the use of
high compression pistons, the MAX SAVINGS is 10%....
IF regular and hi-test cost the same - and they don't.

That is 10% improvement over the optimized setting for the standard
compression ratio. Then add the extra power available from being able
to fully optimize ignition timing. Or to look at it another way, look
at the power LOSS incurred by retarding ignition timing from otimum
under load, to prevent ping.
I believe this is where the economy savings come in on my vehicles.
The engines are loafing at normal highway speeds, and are either on
the edge of, or well into the "lugging" range under load.
We are NOT talking running at max HP output here. We are talking
pretty close to max torque, where internal cyl pressures are at their
highest. In the hills, the Aerostar with the trailer is running much
closer to max HP, and the savings drop off

I have sold the Aerostar - traded for a 3.8 Pontiac TransSport.
It runs at even lower engine speeds at cruise - under 2000RPM at legal
highway speeds. I have not done any mileage tests with the trailer yet
- had MAF troubles last summer and it ran poorly under load, and drank
gasoline like it was going out of style. It was also usually in 3rd
even on the level due to loss of power. I think the problem is fixed,
but won't know untill the trailer comes out this summer.
I do know the knock count on the OBD scanner drops significantly
between regular and mid premium under normal driving conditions, so
the engine IS octane sensitive. Under normal driving, going from mid
to premium does not affect the knock count. I suspect it will under
load.
I wish I had the scanner for the Ford, it would have been interesting
to watch the knock counts.

Highly refined"HI-TEST" will never replace LOW GRADE
diesel when it comes to real power and economy.

There are more BTU's in a gallon of "regular" than HI-TEST.
There are even more BTU's per gallon available in DIESEL.

BTU's per gallon is the key to miles per gallon.


YMMV - pun intended