OCTANE BOOST NEEDED -- What works?
Thread Starter
Instructor
Joined: Jul 2007
Posts: 108
Likes: 0
OCTANE BOOST NEEDED -- What works?
Recommendations appreciated --
After pouring much $ into the rebuild of my L36 big block, it is now "pinging". Adding 2-3 gallons of 110 octane race gas to a tank cures the ping & makes it happy. BUT... too expensive and hard to find.
Do any of the octane boosters work? I've tried a couple of brands with poor results. Any recommendations much appreciated.
Background -- Original 427/390 was completely rebuilt by reputable builder. Milds mods, Edelbrock Performer RPM heads, Comp Cams "Thumpr" cam, 454 crank, stock intake, carb, & exh manifolds. I'm not sure of compression, but I believe it's around 10:1.
After pouring much $ into the rebuild of my L36 big block, it is now "pinging". Adding 2-3 gallons of 110 octane race gas to a tank cures the ping & makes it happy. BUT... too expensive and hard to find.
Do any of the octane boosters work? I've tried a couple of brands with poor results. Any recommendations much appreciated.
Background -- Original 427/390 was completely rebuilt by reputable builder. Milds mods, Edelbrock Performer RPM heads, Comp Cams "Thumpr" cam, 454 crank, stock intake, carb, & exh manifolds. I'm not sure of compression, but I believe it's around 10:1.
Drifting
Joined: Nov 2007
Posts: 1,683
Likes: 265
From: New York
I had a 350/350 that had the heads taken down twice and used to ping on high test. When I rebuilt the motor, even though they were forged pistons, you could see the chips from detonation.
I never found an octane booster that worked and used to rely on racing gas. Now that I have a new motor, I did the same thing. Get the compression ratio down to be able to run pump gas.
I never found an octane booster that worked and used to rely on racing gas. Now that I have a new motor, I did the same thing. Get the compression ratio down to be able to run pump gas.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Have you tried pulling timing? With aluminum heads and a decent cam, 10:1 shouldn't be that bad at all.
Check to see what your max timing is at, it could be that you're going beyond what you need.
FYI, I looked at the cam cards - even for the weakest "thumpr" I could find, you shouldn't be pinging on that combo. (at 10:1)
Check to see what your max timing is at, it could be that you're going beyond what you need.
FYI, I looked at the cam cards - even for the weakest "thumpr" I could find, you shouldn't be pinging on that combo. (at 10:1)
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
At 10:1, it's likely not an octane issue if you're runing premium unleaded.
I'd go back and find out FOR SURE what compression - and what quench - was attained for the build. I'm still surprised at the number of engine builders that don't provide a detailed "build book" for their engines...something I always do.
Otherwise, I agree that I'd start by looking at the timing curve before looking for an octane booster. The Thumpr in particular should help the situation as it has a ton of overlap at idle to give a "rumpty" sound.
I'd go back and find out FOR SURE what compression - and what quench - was attained for the build. I'm still surprised at the number of engine builders that don't provide a detailed "build book" for their engines...something I always do.
Otherwise, I agree that I'd start by looking at the timing curve before looking for an octane booster. The Thumpr in particular should help the situation as it has a ton of overlap at idle to give a "rumpty" sound.
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
What you're doing adding racing fuel's, really the best way. Torco claims to be concentrated race fuel, but never acually tried it, and not cheap. Another biggie, is how longs the present gas been sitting in the tank, as loses octane rating over time, such as sitting for 4 months over winter.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
Not surprising as the Feds have regulated all the good stuff out of existence. I had good results using 104+ Octane Boost. But that was the old formula not found anymore. You could always try retarding your timing a smidgen.
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Melting Slicks
Joined: Jun 2004
Posts: 2,077
Likes: 0
From: westmoreland N.H.
i used 100LL avgas in my stock motor with 11.1 compression. worked great. just add 1 gal per tank. less expensive than racing gas. 104+ is junk. it's just marketing bull.
Melting Slicks
Joined: Mar 2005
Posts: 2,187
Likes: 7
From: Chetwynd B.C.
Recommendations appreciated --
After pouring much $ into the rebuild of my L36 big block, it is now "pinging". Adding 2-3 gallons of 110 octane race gas to a tank cures the ping & makes it happy. BUT... too expensive and hard to find.
Do any of the octane boosters work? I've tried a couple of brands with poor results. Any recommendations much appreciated.
Background -- Original 427/390 was completely rebuilt by reputable builder. Milds mods, Edelbrock Performer RPM heads, Comp Cams "Thumpr" cam, 454 crank, stock intake, carb, & exh manifolds. I'm not sure of compression, but I believe it's around 10:1.
After pouring much $ into the rebuild of my L36 big block, it is now "pinging". Adding 2-3 gallons of 110 octane race gas to a tank cures the ping & makes it happy. BUT... too expensive and hard to find.
Do any of the octane boosters work? I've tried a couple of brands with poor results. Any recommendations much appreciated.
Background -- Original 427/390 was completely rebuilt by reputable builder. Milds mods, Edelbrock Performer RPM heads, Comp Cams "Thumpr" cam, 454 crank, stock intake, carb, & exh manifolds. I'm not sure of compression, but I believe it's around 10:1.
I have been using NOS Octane booster -- street formula. Says "Increases octane effect as much as 3 points"
Use all 355 ml (12oz) for a 60 litre (16 gal) tank of fuel.
Here's a picture of the can.
What does anyone else use?
shmoky
Last edited by shmoky; Aug 19, 2011 at 09:02 PM. Reason: added picture
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
I agree with finding out why it pings and fixing it. Octane boosters in general are a scam. I know people in that business. The points of octane increase they claim is not a full point such as raising from 91to 94, but in .1 points. If it says on the can it will raise the octane 3 points, you will go from 91 to 91.3. Xylene and toluene will work as boosters, but it takes a lot of either one to produce results. Boosters with MMT will work better, but the level that is allowed by the EPA for street use in not high enough to do much. There are race formulas with much higher levels of MMT, but they will eventually foul your plugs with a reddish deposit from the manganese,
Last edited by v2racing; Aug 20, 2011 at 02:53 AM.
Le Mans Master
Joined: Oct 2010
Posts: 6,900
Likes: 833
From: melbourne florida
2023 C3 of the Year Finalist - Modified
its timing related more than likely the chamber design is better in your new heads and needs less timing. you will find better performance when you get your curve right
Racer
Joined: Jul 2006
Posts: 478
Likes: 56
From: Woodstock Georgia
As stated above, check the total timing ... at what RPM is ALL of the mechanical advance in? Are you having hot start issues? If the answer to those questions are unknown, you could just be putting a band aid on a tuning issue. Is the fuel mixture and APT adjustment right on that q-jet?
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
