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Non-Ethynol Racing Gas Available!

L78fanatic

L78fanatic

Well-Known Member
Senior Member
I took my MINI JCW to my Independent BMW mechanic last Friday and we got to talking about using ethanol free gas in my vintage BMW’s that have steel tanks (like what is in my Chevelle) and he recommended an old Sunoco station not far from me that still sells pure 110 octane gas!!!!!! Bingo! It’s not cheap but for those of us with high octane loving Chevelles (like my rare ‘67 L78 engine.....yet to be assembled) there is still hope!!! 🙂. I’ll be putting that stuff in all my old Bimmers and not worry about that crappy metal eating ethanol sitting in the tank! Lower octane non ethanol gas is somewhat easier to find but that’s not what a 11:1 compression stock L78 engine wants! So, those of you worrying about not using high compression due to fuel, look around for 100 or 110 octane gas! In Ohio you can find 100 octane at some gas stations! You of course can buy high octane Sunoco by the barrel as a back up. Long live Sunoco 260!!!! Those were truly the best of times when my ‘67 was brand new!!!
 
I’m lucky around here I can get 91,93, 100? Sunoco at the pump and at the same place get VP1 110 and higher Oct racing fuels but with 93 at $5.50ish a gal I usually get 91 for a little less, my engine was dynoed with 93 and 91 and made no difference, 10.8:1 comp but alum heads
 
kmakar said:
I've only found 91 non ethanol where I live (so far), but would like to find at least 93 non ethanol if I can.
Click to expand...
Have you seen that website that lists stations with non-ethanol gas? If not I’ll post it up.
 
With the big cam in the L78, you should be able to run 93 octane ethanol gas. If you seldom drive it, throw in some stabil.
Ethanol isn't a problem unless you let the car sit.
You can also enlarge the closed chambers (which drops compression) and not lose any power. Laying the chamber edge away from the intake valve adds cc's and improves flow.
I've read that GM was surprised in 1971 when they added 10 cc's and made the "open chamber heads" that power didn't go down.
 
kmakar said:
I've only found 91 non ethanol where I live (so far), but would like to find at least 93 non ethanol if I can.
Click to expand...
I can get 93 non-ethanol here but it's close to $5. I just run 10-1 comp and use 93 ethanol.

Here's that website for non-ethanol stations

Pure-gas.org - ethanol-free gasoline in the U.S. and Canada

Pure-gas.org is the definitive web site listing stations that sell pure gasoline in the U.S. and Canada.
www.pure-gas.org www.pure-gas.org
 
Not necessarily, the pistions are open chamber design, but kept the compression the same in '69 vs. 70. There's a rule of thumb on static cylinder pressure just don't know it off hand, but if you shorten the compression cycle, you need to compensate with compression ratio, or if you increase valve overlap, or a long duration cam, you need to bump up compression a bit.
On fuel, too high of octane and you'll actually lose performance....the higher the octane, the slower the burn rate. It's smart to start with 87, assess your plugs and timing. My jeep is running 38 degrees timing with 9.7 comp., so I run 92, but in my 9.0 comp 427, I run 89 octane. The jeep has 220 duration in a 327, the 427 is running 238 comp. The 427 sits for long periods, so I try to run non-ehynol, but we only have 3 stations around here that sell it, and they're all at least 6 miles away.
 
I was referring to the big drop in compression in 71 ? or 72 ? It went from 11 or 12 to 1 down to 9.
The LS6 only dropped from 450 to 425 hp.
I think opening up a set of closed chamber heads 5 cc or so would not cost any hp.

The Story of the LS6 Engine​

GM’s LS6 engine was among the most powerful engines available in 1970 and competed closely with Chrysler’s Hemi offerings. GM’s beast, the LS6, was developed by legendary designer Zora Arkus-Duntov (considered the father of the Corvette). Made out of cast iron, the engine used aluminum cylinder heads with a four-barrel 800 cfm Holley carburetor fitted on top of the aluminum manifold.

With a compression ratio of 11.25:1, the LS6 (in peak form) redlined at 6500 RPMs to produce 450 hp and 500 lb-ft of torque. A forged steel crankshaft with forged aluminum connecting rods (this is incorrect ?) was used to maximize the output of this high revving engine. And to control emissions, engineers installed an air injection reactor pump to increase air into the exhaust system.

In the 1970 Chevelle, the LS6 was paired with either a four-speed Muncie M22 manual or an M40 Turbo three-speed automatic transmission. While the LS6 Corvette was available with both drivetrain options, the vast majority were built with the Muncie M22 four-speed. To accommodate the Corvette’s structure, Chevy had to detune the LS6.

The reworked LS6 now had a 9.0:1 compression ratio and produced 425 horsepower @5600 RPM and 475 lb-ft of torque @ 4000 RPM. Despite the reduced output, the LS6-equipped 1971 Corvette could still hit 0-60 mph in 5.3 seconds, only 0.3 seconds slower than the LS6 Chevelle from the previous year.

www.trustauto.com

Why The 1971 Chevy Corvette LS6 Is So Special | Trust Auto

The 1971 Chevrolet Corvette LS6 Is A Treasured One-Year Only Model Among Enthusiasts. Emission Regulations Would Make The Massive Big-Block Engine Extinct.
www.trustauto.com www.trustauto.com
 
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It's hard to comment on all that, since it's really two very different engines, different heads, alum. vs. iron, different comp. ratios, different timing, and different cars, the corvette being a 400lb lighter car. That article had the corvette slower in 0-60 by .3 seconds with a 400lb weight advantage. That's probably a full second in the quarter, which is 100hp, all things the same. But they're not, it's 400lbs lighter, so it probably is 140hp less. Stats, magazine articles and gm prophecy are so misleading. Test results tell the truth.
 
cheveslakr said:
It's hard to comment on all that, since it's really two very different engines, different heads, alum. vs. iron, different comp. ratios, different timing, and different cars, the corvette being a 400lb lighter car. That article had the corvette slower in 0-60 by .3 seconds with a 400lb weight advantage. That's probably a full second in the quarter, which is 100hp, all things the same. But they're not, it's 400lbs lighter, so it probably is 140hp less. Stats, magazine articles and gm prophecy are so misleading. Test results tell the truth.
Click to expand...
I'm just talking about how much power (if any) you lose when you drop compression by opening up a closed chamber.

Rick : I think the Rods being forged Aluminum in the article is wrong, forged steel rods & crank, forged alum pistons
Yeah, GM has never put aluminum rods in any engine that I know of. Just steel or titanium (y)
 
And so am I, the main difference between the two Ls6 engines was the 10 cc increased chamber and the smaller dome pistion.....which led to 140hp loss.
 
In 71 they dropped the compression so all the engines could run on the new unleaded gas that was available. I said could run on unleaded but they didn't say you had to run on unleaded gas ....... until you bought a 1975 catalytic converter equipped car. :mad:
Also you're right there never was a Chevy motor from the factory with aluminum rods. I think maybe that should have read "aluminum heads" and not rods.

I was referring to the big drop in compression in 71 ? or 72 ? It went from 11 or 12 to 1 down to 9.
 
I’m thinking when GM came out with the Semi open “063” “215” “290” heads starting in 1969 is when they figured a full open chamber would get the job done with what was coming with emissions and unleaded gas, didn’t they also change cam design for perf engines?
 
When spec'ing my '67 L78 engine, I used Dynamic Compression Ratio to analyze things, and I am certain it will run on 93 octane. I have a good friend in Washington State (on the old Chevelle forum) who owns a basically stock '69 L78 Chevelle SS (I have the same or very similar cam as he used that is close to the stock L78 GM solid lifter cam (by Howards). I have all the parts for the build, mostly all original GM vintage correct part numbers ($$$), but with my health issues I may never build it sadly. But, like Jim Carry said in "Dumb & Dumber" when he asked the pretty red head what his chances with her were based on 1 to 100 (or was it million?), & she replied "1". "So I have a chance!" he said! There's always hope!
 
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