View Poll Results: Turning water into wine, and 87 into 91
Just drive and don't worry about it.
35
70.00%
Slowly add premium as tank space becomes available.
14
28.00%
Add octane booster from parts store.
1
2.00%
Add 100 octane race gas.
0
0%
Voters: 50. You may not vote on this poll
What should I do?
Thread Starter
Instructor
Joined: Feb 2018
Posts: 147
Likes: 5
From: Cochise County, AZ
What should I do?
Absentmindedly filled my 1992 with 87 octane today and did not realized until i had literally filled the entire tank.
I did some searching on old threads and determined I can either:
1. Just drive up this tank and fill with premium when I need gas next
2. Slowly add premium to the tank maybe 1/4 of a tank at a time as space becomes available
3. Add octane booster
4. Add race gas
I did some searching on old threads and determined I can either:
1. Just drive up this tank and fill with premium when I need gas next
2. Slowly add premium to the tank maybe 1/4 of a tank at a time as space becomes available
3. Add octane booster
4. Add race gas
Le Mans Master
Joined: Jul 2004
Posts: 6,228
Likes: 698
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Absentmindedly filled my 1992 with 87 octane today and did not realized until i had literally filled the entire tank.
I did some searching on old threads and determined I can either:
1. Just drive up this tank and fill with premium when I need gas next
2. Slowly add premium to the tank maybe 1/4 of a tank at a time as space becomes available
3. Add octane booster
4. Add race gas
I did some searching on old threads and determined I can either:
1. Just drive up this tank and fill with premium when I need gas next
2. Slowly add premium to the tank maybe 1/4 of a tank at a time as space becomes available
3. Add octane booster
4. Add race gas
Team Owner
Joined: May 2000
Posts: 53,797
Likes: 5,628
From: Plantation Florida USAF(Retired) 1966-1990
U.S. Air Force
St. Jude Donor '05 thru '26
NCM Sinkhole Donor
Just have fun, and drive the car like you stole it, nothing going to happen, the engine won't fall out, just have fun.
Race Director
Joined: Oct 2012
Posts: 17,383
Likes: 6,527
From: Melbourne, FL
Depends how long the tank lasts. Of you fill up once a month... I'd probably mix in premium after It got some room, just to get the octane up sooner and not have to worry if I beat on it. If it' a few days, is roll with it.
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From: Gurley (Keel Mtn, Sweet Home) Alabama
96 reads Premium Fuel Only.
Go figure..... I've used 87 octane in both over the years. Vehicles did not turn to dust or melt or develop catastrophic engine failure.
As otherwise mentioned, engine computer will compensate
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
Ah, but Sir. What you fail to mention is the price for that compensation. The ECM is not a magic box. There will be a price to pay as can be seen in the below post from another thread
My daughter questioned this "folly" on one of our monthly trips to LA. So we had a full tank of premium, zeroed out the MPG and trip meters. We avg'd 32 for a 350 mile run. For the return trip we burned regular and avg'd 29 for the same number of miles on the same roads. After the calculator was turned off she was convinced that either fuel will net approximately the same costs.
350 / 32 = 10.93 gallons @ $3.49 or $38.17
350 / 29 = 12.06 gallons @ $3.29 or $39.70
350 / 32 = 10.93 gallons @ $3.49 or $38.17
350 / 29 = 12.06 gallons @ $3.29 or $39.70
Common ground is the ECM will compensate. So far I have seen it retard the timing. What that translates to power an mpg is yet to be determined. I took another car out with 87 and later on 93. Only thing was the scanner gives more knock counts to the lower grade fuel.
Last edited by aklim; Apr 1, 2018 at 11:49 PM.
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Zackly correct!
In fact, in (circa) the late 80s the EPA mandated that all cars be able to run on 87 octane, AND thanks to knock sensors and computers, they can!
Just run the "87" out and refill with premium at next fill-up. Within a few miles the computer will refresh the memcal and will have bumped the timing back up to where it was. All will be well!
Aside from fueling, the primary tool for squeezing the last drop of power from an engine, is timing. If ever you have a chance to observe timing on a car while on a dyno, note what happens to spark advance once knock counts crop up. And, too, notice what happens to hp at the knock point.
Except for heaviest loads/rpm, 87 octane is "OK". But, to optimize performance, with the help of a dyno tune, tweak the timing (and fuel) with a tank of whatever the highest octane you will be racing with. You'll see a direct correlation between timing and performance at the rear wheels.
Last edited by Paul Workman; Apr 2, 2018 at 08:38 AM.