Is there an octane booster that really works? I have access to non-ethanol gas but it is only rated at 87 octane. My FI cars require more octane. Any suggestions other than racing or aviation fuel?
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Re: Octane boosters
You can mix the 87 non-ethanol with higher octane leaded (or unleaded) race fuel to achieve the desired octane...
Kramden -
Re: Octane boosters
I run either Octane Supreme, advertised in Driveline, and use it per the chart in Wild Bills site. In my case half bottle per tank of super unleaded. I also run 6 gal of Avgas added to 12 gal of super unleaded in my LS5.Comment
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Re: Octane boosters
I know you said other than AV gas or racing fuel but unless you drive your fuel cars a lot it is well worth the cost or inconvenience - in my opinion & the opinion of many F.I. guys. (Obviously when you are on the road you have no choice.) Good luck, Don H.Comment
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Re: Octane boosters
In my fuelies, I run a 90 octane ethanol free and that seems to work fine. However, I am at 7000 feet so the octane requirement is not as high for me as sea level would be. I also usually run a few gallons of 100 octane racing fuel in a tank too. I think you would be better served to use the 100 octane racing fuel rather than any AvGas. AvGas tends to have things in it that are not good for vintage fuel injection systems, like the anti-icing inhibitors.Big Tanks In the High Mountains of New MexicoComment
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Re: Octane boosters
Mathew------
I don't know why you would need any of this in an LS-5. If it's a 1970, it MIGHT need some sort of supplement but I doubt it. I think that 91 or 93 octane pump gas should work fine.
If it's a 1971-72, it's hard to imagine that 91 or 93 octane pump gas wouldn't be enough. In fact, mid grade or, even, regular grade might be enough.
Have you tried running it on pump gas and does it pre-ignite when using that? If not, you absolutely don't need and supplement or avgas.In Appreciation of John HinckleyComment
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Re: Octane boosters
I have run AV gas in one of my F.I. cars for over 35 years with NO ill effects. I rebuilt that unit earlier this year (not because it was running bad but because it had been 20 years since it had a new kit installed) and the fuel meter was clean as a whistle. Also the NCRS fuel injection adviser recommends it.Comment
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Re: Octane boosters
I agree with you. I run premium pump gas in my stock LS-5 & it runs fine. don't understand why people think you need 100 octane gas in stock engines. I even used it in my 70LT-1 without a problem as long as I would keep the RPM'S down. It would knock at higher RPM;S & did like the racing gas.65 350 TI CONV 67 J56 435 CONV,67,390/AIR CONV,70 454/air CONV,
What A MAN WON'T SPEND TO GIVE HIS ASS A RIDEComment
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Current Corvettes owned 1957 two top stealth 383 dual quads--1965 original low mileage 300 h.p. coupe.
Other Corvettes owned over the years:
1954. 1957 AIRBOX FI. Two 1958s one FI, One 2x4. 1961. 1964 convertible A/C auto trans. Two 1965s one coupe with 300 h.p. loaded A/C car, one 365 h.p. convertible Two 1966s one loaded A/C, BB coupe one loaded A/C, SB coupe. Two 1968s one BB convert, 1969 BB coupe. 1971. 1973. 1978 L-82. 1985, 1986 both 4+3s.Comment
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Re: Octane boosters
Not quite true. But I don't want to start an argument as part of this thread. There are a few available that are the real deal. But they are in the minority.
This topic has been discussed repeatedly in years gone by..........and is available in the archives.
LarryComment
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Re: Octane boosters
You might try toluene as an additive. Toluene is a pure hydrocarbon (C7H8) and contains only hydrogen and carbon atoms. It belongs to a particular category of hydrocarbons called aromatic hydrocarbons. Gasoline contains about 10-20% toluene. Check safety data sheets to verify that number.
Toluene has a RON octane rating of 121 and a MON rating of 107, leading to a (R+M)/2 rating of 114. (R+M)/2 are how ordinary fuels are rated in the US. To figure the expected octane of adding additional toluene to 91 octane gasoline, use this:
(% gasoline * 91) + (% toluene added * 114) = Octane
Mixtures with 91 Octane Premium
10%...93.3 Octane
20%...95.6 Octane
30%...97.9 Octane
That should cure your fuel problems. Of course, use it only on pre-emission engines.
You can purchase toluene at paint or chemical supply stores. It is going to be $10 to $20 per gallon, but a 10% mixture will raise the price of $4 per gallon gasoline to $5.60 per gallon. I had a client that painted finished aluminum window extrusions and had several 55 gallon drums of toluene in stock for blending with the paint. Maybe some of your friends can go in on a drum?
JoeComment
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Re: Octane boosters
Joe, The previous owner massaged my 70 LS5 a little (ported heads, exhaust manifold, and different cam). I had a little pinging in it with 12 deg base timing, in 4th gear in the summer. I could back the timing down, but it runs better with the additional advance. The Avgas or lead substitute is peace of mind as well.Comment
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Re: Octane boosters
You can't say that for sure unless you know the entire spark advance map. As an emission controlled engine the '70 LS-5 probably has a short and lazy centrifugal curve, so more than the OE recommended initial timing will improve total WOT advance by getting it into the optimum 36-40 degree range, but this can result in detonation due to too much low rev advance. The solution is to increase centrifugal and reduce initial to keep the engine out of low rev, high load detonation.
Excess vacuum advance can cause detonation upon light acceleration or a bit of transient detonation on upshifts, but the bottom line is that in order to solve any detonation issues the actual INSTALLED spark advance map has to be MEASURED and then competently analyzed to obtain a solution. In addition to the emission controlled OE spark advance map, Mathew states that this engine has been modified with a different cam, and that can have a significant effect on the optimum spark advance map.
The details of how to do this are in my tuning seminar, which his on the Web.
DukeComment
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