mark kibort

now its 10%?

I didnt say that timing doesnt effect mileage, what i said was the knock sensors bring back the timing, only if they sense a knock. the engine management system doesnt adapt to fuel, it reacts to pinging.

There is no logical reason why you got better gas mileage with premium, unless you were pinging, had knocksensors that pulled the timing way back.
which the 87s could have had in the 325s or 525s, but the system didnt adapt to octane levels in fuel.

mk

i have a

dprantl

My '91 SAAB 9000 Turbo adapts to fuel octane nicely I wish my 928 did that.

Now I have to put in 928 content. The SAAB is just like my new GT's half-brother:

928
-----
Model year 1991
Black exterior
5-speed
5.0 liter DOHC supercharged V8
LH 2.3
~500hp
~206k miles

SAAB
-------
Model year 1991
Black exterior
5-speed
2.3 liter DOHC turbocharger inline-4
LH 2.4.2
~230hp
~192k miles

The SAAB has piston squirters and 8.5:1 compression though. If I could just figure out a way to graft a double version of the SAAB's direct ignition to the 928...

Dan
'91 928GT S/C

Droplink

I agree with this statement, however the 85/86 cars do not have any type of knock sensing retardation. That only started in 87. So if you run a lower octane than recommended gasoline in your 85/86, you may save on gas, but your engine could suffer detonation and thus result in a much higher expense in the long run. This is why I sought an 87+ car.

Running a higher octane gas may help protect from knock, but is generally a wast of cash for normally aspirated cars as has been noted.

bronto

I was thinking 10%, I wrote 5% originally because it was so long ago and wanted to be conservative. 5% would be appropriate for the 525, really too close to be sure. But the 325 really did consistently get about 3 more mpg on the freeway with premium. Why? beats me. But it did. The SB to Fresno route involved going over the grapevine or alternatively on 46 between Atascadero and Shandon. Both routes have opportunities to use engine power, and I did often.

mark kibort

yeah, probably way too many variables to call conclusive. I owned both,and own a 328 now, and it doesnt matter what type of gas, and i dont ever floor the car, so im not too worried about pinging. A better test would be teh same one way travel on hyway 5 before the grapevine. maybe do a test every 100miles. anyway, If you could get 10mpg more for using premium, I certainly would do it! I might put out the 5 bucks next big trip and see.

remember there are also those that think they get this kind of better gas mileage with a clean air filter too!!


mk

QUOTE=bronto;5505663]I was thinking 10%, I wrote 5% originally because it was so long ago and wanted to be conservative. 5% would be appropriate for the 525, really too close to be sure. But the 325 really did consistently get about 3 more mpg on the freeway with premium. Why? beats me. But it did. The SB to Fresno route involved going over the grapevine or alternatively on 46 between Atascadero and Shandon. Both routes have opportunities to use engine power, and I did often.[/QUOTE]

bronto

Does your 328 say "Premium Fuel Only" on the gauge or in the manual?

mark kibort

I think it does. Ill have to check again. It is 10.2:1 compression.
it also says only use synthetics only for oil. hmmm, 100,000 miles of 5kmile oil changes and its running strong!
castrol 10-40!!

mk

Ron_H

In my '86 I have used 87 octane fuel since I bought it with 120,000 miles on it. It now has approximately 210,000 miles on it. I still use 87 octane fuel in it. It runs like a clock, humming along, like it did when I got it. I will continue to use 87 octane in it from the cheapest source I can find, including ARCO. When I travel across this country and can find it, I use 85 octane and spend the extra money on foolish indulgences, and love it. If the engine ever fails, I'll rebuild it and use 87 octane again for another 200,000 plus miles and spend the money I save on wild women and foolish indulgences. It still pins me back in the seat, (I'm light), and fishtails when shifting into second gear, and runs all day long in remote areas and high ambient temperatures at sustained speeds and rpm levels that some people tell me it is not supposed to reach. I only regret that I don't own a gas station selling ultra high octane fuel so I could have more money to spend on foolish indulgences and wild women.

heyjeffm

$4.10 gal. avg. price 87 octane
$4.30 gal. avg. price 91 octane

$0.20 per gal. savings with 87 octane
x 22.7 gal. fill-up
$4.54 - savings

conclusion:
wild women in Sunnyvale are a BARGIN!!!!!!

Ron_H

They're not a bargain.....they're just CHEAP !!

Hey, gas is really a bargain in Florida. Californians should be so lucky. We passed $4.10 a gal long ago.