Octane

Tech discussions on the L77 6.0L V8.
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storm9c1
Posts: 418
Joined: Wed Mar 27, 2013 6:47 pm
Location: Pittsburgh, PA

Re: Octane

Post by storm9c1 »

I see MPG increases on both my B-Body cars and PPV with higher octane fuel. The timing tables shift, which is a good thing. But since my owners manual for my 2011 always said to use 87, I haven't bothered using anything higher. Perhaps I will now if it makes a difference.

One other thing I thought was funny about the user manual pic posted earlier -- read the section about "Use of Seasonal Fuels". Specifically this gem: "Drive the vehicle with the engine running until the fuel is a half tank or less."

Um, let me see someone DRIVE it down to a half tank or less WITHOUT the engine running. LMAO :lol:
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.
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ButtonPuncher
Posts: 14
Joined: Tue Mar 13, 2018 8:30 pm
Location: WI

Re: Octane

Post by ButtonPuncher »

Silversled wrote:The stock tune Lo Octane spark table have as much as 12 degrees of timing retard compared to the Hi Octane table in the mid throttle areas. On LS engines this area usually corresponds to the peak torque, so what you feel is not imaginary.
Is there also a separate spark map for E85? If so, does it vary the timing with the detected level of ethanol or does it just switch to the E85 table with the ethanol content get over, say, 50%? It's my understanding that these flex fuel vehicles have an ethanol sensor so that they can tell when you got a tank with a mix of regular gas and E85. (And I've also head that E85 isn't always 85%. It can vary all the down to something like 60%.)

Thanks,
Ben
Trolling your forum while saving up for a 9C3. Dreaming and bench racing for now.

2011 Mazda 6s GT - 3.7L - 6-speed ATX- Kona Blue
smwalker
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Joined: Mon Jul 29, 2013 1:44 am
Location: Azusa,CA

Re: Octane

Post by smwalker »

Happen to have a 15 SS tank and a 14 PPV tank to compare.
Found out the tank is actually the same part number (mold number) but the plumbing is different, I assume for the Flex capability.

The PPV tank on the bottom has this extra sensor on the side of the tank is in the path of the fuel output. My guess is that would be the sensor that tells the ECM what fuel is coming it's way from the back. Have to look in the service manual to see if it says what method it uses to determine what fuel is there. Maybe ethanol has a different resistance from gasoline?

Image

Description from the service manual:
Image
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White
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ButtonPuncher
Posts: 14
Joined: Tue Mar 13, 2018 8:30 pm
Location: WI

Re: Octane

Post by ButtonPuncher »

Very cool! Thanks for the side-by-side pic.

Now I'm just wondering if the ECU has a seperate timing map for ethanol and if it varies based on the ethanol content.

BP
Trolling your forum while saving up for a 9C3. Dreaming and bench racing for now.

2011 Mazda 6s GT - 3.7L - 6-speed ATX- Kona Blue
9C1fanatic
Posts: 430
Joined: Tue Dec 30, 2014 8:58 pm
Location: Texas Hill Country

Re: Octane

Post by 9C1fanatic »

I have run my car and the track with both 87 and 93 in the tank. There is a difference in both seat of the pants and times/trap speeds. My 1994 9C1 was also this way but not quite as dramatic. The wife's LS2 GTO even has preminum fuel sticker right on the inside of the fuel door and just like the caprice, it runs fine on 87 but really wakes up with 93.
Garner Ames



1975 Pontiac Grand Am L77 - 14.82 @ 92.89
1991 Chevrolet C1500 L31 Vortec/5 Speed
2002 Chevrolet Suburban 1500 LM7
2014 Chevrolet Caprice 9C1 L77 - 13.60 @ 105.87
2019 Chevrolet Express 3500 L96
9C1fanatic
Posts: 430
Joined: Tue Dec 30, 2014 8:58 pm
Location: Texas Hill Country

Re: Octane

Post by 9C1fanatic »

My best is 13.60 @ 105, Sometime in April I'm gonna run a few tanks of E85 and see what I get at the track (Not the pump which I know will be much much worse)
Garner Ames



1975 Pontiac Grand Am L77 - 14.82 @ 92.89
1991 Chevrolet C1500 L31 Vortec/5 Speed
2002 Chevrolet Suburban 1500 LM7
2014 Chevrolet Caprice 9C1 L77 - 13.60 @ 105.87
2019 Chevrolet Express 3500 L96
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ButtonPuncher
Posts: 14
Joined: Tue Mar 13, 2018 8:30 pm
Location: WI

Re: Octane

Post by ButtonPuncher »

9C1fanatic wrote:My best is 13.60 @ 105
Very nice!

Yeah, I'm really interested in E85. It's everywhere in WI.

There needs to be a Dyno/Drag/Tuning forum on this site. One place to see who got what numbers with what combination of parts/mods and what tuning they did to get there.

Regional Forums would be nice too.

BP
Trolling your forum while saving up for a 9C3. Dreaming and bench racing for now.

2011 Mazda 6s GT - 3.7L - 6-speed ATX- Kona Blue
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