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High octane fuel.

Old 02-26-2019, 11:58 AM
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jhopper408
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Default High octane fuel.

What do you guys think about running 116 octane no ethanol. $ 9.00 per gallon. Would it burn the top of the piston? Or a valve? This place that I can get it builds monster trucks.
Thanks
John
Old 02-26-2019, 12:20 PM
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ajrothm
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Originally Posted by jhopper408
What do you guys think about running 116 octane no ethanol. $ 9.00 per gallon. Would it burn the top of the piston? Or a valve? This place that I can get it builds monster trucks.
Thanks
John
High octane fuels do not burn pistons, to the opposite actually, they save pistons. However if you are putting race fuel in a stock motor or mild compression motor, you are wasting money, and probably losing some power when running it. Depending on the fuel, it drastically effects burn rates, combustion temps and efficiency etc etc...

Basically, if you don't NEED it, don't run it, its a waste. BUT it won't hurt anything..

Now if its an oxygenated race fuel, which has lots of alcohol/ethanol, it will gum up everything if it sits even a short time. Really stay away from this stuff unless you know what you are doing with it.
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Old 02-26-2019, 12:27 PM
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Jebbysan
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Total waste of money. An engine make its best power on the onslaught of detonation.....the lowest octane fuel that the engine will safely run on is order of the day.
Now you might want to go get 5 gal to mix in your pump gas if you like the "smell".....or if you have an 11 to 1 engine that is on the edge of running safely on pump fuel......race fuel is an excellent octane booster.
If you own motorcycles or lawn equipment or store your car for long periods of time.....race fuel will keep for over a year in a fuel tank......as long as it is not exposed to sun, race fuel lasts a long time.
If you want to start your bike or weed whip first pull in the spring....store it with race fuel in the tank.

Jebby
Old 02-26-2019, 12:48 PM
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sstonebreaker
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Higher octane fuels typically have LESS power per gallon than lower octane fuels. As AJ mentioned above, if you don't NEED higher octane, it doesn't do squat for you. In fact, the lower the octane, the more power you can make. Take Steve Morris for example. He was a member of the Impala SS club for a long time, even though his car was a caprice wagon:


And what do you think he fills this beast up with?



So if he can make 1740 hp and run 8 seconds in a 4,500 lb station wagon on pump gas, you don't need 116 octane.
Old 02-26-2019, 12:48 PM
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jhopper408
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I have a 77 383. It's had plenty of power!
Old 02-26-2019, 12:59 PM
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Telling us you have a 383 doesn't give enough information. Unless you have 10.0:1 compression or more running 93 octane is more than enough.
Old 02-26-2019, 01:15 PM
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BTW, if anyone ever does need race fuel, you can usually find it at local fuel distributors for way cheaper than getting it at race shops or the track. VP race fuels sells Methanol M1 race fuel in 54 gallon drums for $345 retail. I can get it at my local fuel distributor for $180. Of course, I only needed to buy it once and now I have methanol for life for my meth injection system.
Old 02-26-2019, 01:25 PM
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resdoggie
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A gallon of gas contains a specific amount of energy commonly measured in calories or the calorific value of gas. It's the same calorific value regardless of octain level. But higher octane allows an engine to run at higher compression which results in more power but the energy in the gas hasn't changed.
Old 02-26-2019, 01:31 PM
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It's 11.1 compretion. The guy at the speed shop, said just running non ethanol fuel would make a huge difference. But it sounds like you guys know more? Thanks
John
Old 02-26-2019, 02:32 PM
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So let me get this straight. Running non alcohol fuil. Is not any better than, running alcohol 93 octane fuel? It's a waist of money?
Old 02-26-2019, 02:41 PM
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Originally Posted by jhopper408
It's 11.1 compretion. The guy at the speed shop, said just running non ethanol fuel would make a huge difference. But it sounds like you guys know more? Thanks
John
I don’t know who started this but that is just fiction....it will make ZERO difference....See photo above of Steve Morris’ 1700hp Caprice....
The ONLY things Non Alcohol fuel is good for is storage....it keeps a LOT longer and you may see a slightly higher boiling point with non-alcohol fuel.
The same guys that started the non ethanol fuel also believe that higher octane is better even if you do not need it.
I run a 10 to 1 1979 CBX 6 cylinder bike on 93 pump gas with alcohol and it runs wonderful....

Jebby

Last edited by Jebbysan; 02-26-2019 at 03:04 PM.
Old 02-26-2019, 03:52 PM
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sstonebreaker
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Originally Posted by jhopper408
It's 11.1 compretion. The guy at the speed shop, said just running non ethanol fuel would make a huge difference. But it sounds like you guys know more? Thanks
John
"Non ethanol" is a whole different subject from octane. If you don't drive your car very often, non-ethanol gas will help keep corrosion to a minimum, particularly on a carburated engine. But that has nothing to do with octane. If you're trying to avoid ethanol, there are some websites online that list stations that sell ethanol-free gas. If you can't find premium non-ethanol, THEN you might look at mixing a little race gas with the pump gas. That would certainly be a hell of a lot cheaper than running straight race gas.
Old 02-26-2019, 03:57 PM
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Originally Posted by jhopper408
It's 11.1 compretion. The guy at the speed shop, said just running non ethanol fuel would make a huge difference. But it sounds like you guys know more? Thanks
John
At 11.0:1, assuming you have a distributor set up to give you 36 degrees of mechanical at about 3K rpm, adding about 4 to 5 gallons of 116 to 93 will improve the engine performance.
Old 02-26-2019, 04:14 PM
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Ethanol blends can cause premature failure of some soft parts in the fuel system (hose, fuel pump/carb rubbers, etc.) and I've heard plenty of stories though personally I've never had a problem.

10% ethanol content also reduces fuel efficiency a little as ethanol has a lower heat capacity (basically available energy per pound) than gasoline. E85 is something like 25% less efficient than straight up gas.

On a side note there was a (maybe still is) a trend of guys building motors to run on E85 to take advantage of it's high octane rating at lower cost than race fuel. I've never had much interest in building a motor that I can't get gas anywhere/anytime so haven't paid much attention to that genre and don't honestly know how successful guys have been.

Anyway, more on topic. As already stated octane is a measure of burn rate with higher being slower. High compression engines need slower burn rates due to ignition by compression (the basic theory of diesel engines). If the fuel burns too quickly you'll get pre-ignition also called detonation or spark knock.

If you're getting detonation, short of actually going through the hassle of lowering CR, you can dial back timing a degree or three and/or switch to a higher octane fuel. That will solve most street driven motor detonation issues.

Also as stated, the comments from the speed shop guys on ethanol is utter nonsense. Probably talks about 3/4 race cams and high nickle blocks too.

In broad strokes: For a street driven, naturally aspirated motor run as much timing with as little octane as possible. Detonation is the limit on both.
Old 02-26-2019, 04:15 PM
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Is that 1700 hp Caprice sfi or does it has a non computer carb? Computer controlled fueling maps, timing and knock sensors probably allows pump fuel, on the street. Putting pump gas into a car like that makes no difference cruising the highways and byways, until it is time to go on track.

Octane makes a difference in a non computer controlled engine. I think with an street engine with a carb and distributor, 116 may be a bit of overkill, but that said, I run 112 leaded in my 69 427.
Old 02-26-2019, 06:37 PM
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It's GREAT for doing your laundry ...............

That sock that's on the end of your fuel pickup in your tank ...............

It'll clean that sock so dang good ... it'll disappear!!! ... mine did! ... only thing left was the grommet ... and my car's CLEAN fuel system.

AV Gas'll clean it out as well.

Mine ran a bit better but likely because it got cleaned. Unless yours truly needs 116 to prevent detonation etc, it really won't help.
Old 02-26-2019, 07:07 PM
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sstonebreaker
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Originally Posted by 3X2
Is that 1700 hp Caprice sfi or does it has a non computer carb? Computer controlled fueling maps, timing and knock sensors probably allows pump fuel, on the street. Putting pump gas into a car like that makes no difference cruising the highways and byways, until it is time to go on track.

Octane makes a difference in a non computer controlled engine. I think with an street engine with a carb and distributor, 116 may be a bit of overkill, but that said, I run 112 leaded in my 69 427.
Hotrod magazine did an article on Steve's car and at the time it was running 87 octane regular gas on a blow-through carb setup with a ginormous procharger. Not premium, regular. And running 8's. Since then, I think he built a new wagon and is running 6's with it. Don't know what the new setup is.

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Old 02-26-2019, 07:43 PM
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Originally Posted by trz1000
Ethanol blends can cause premature failure of some soft parts in the fuel system (hose, fuel pump/carb rubbers, etc.) and I've heard plenty of stories though personally I've never had a problem.

10% ethanol content also reduces fuel efficiency a little as ethanol has a lower heat capacity (basically available energy per pound) than gasoline. E85 is something like 25% less efficient than straight up gas.

On a side note there was a (maybe still is) a trend of guys building motors to run on E85 to take advantage of it's high octane rating at lower cost than race fuel. I've never had much interest in building a motor that I can't get gas anywhere/anytime so haven't paid much attention to that genre and don't honestly know how successful guys have been.

Anyway, more on topic. As already stated octane is a measure of burn rate with higher being slower. High compression engines need slower burn rates due to ignition by compression (the basic theory of diesel engines). If the fuel burns too quickly you'll get pre-ignition also called detonation or spark knock.

If you're getting detonation, short of actually going through the hassle of lowering CR, you can dial back timing a degree or three and/or switch to a higher octane fuel. That will solve most street driven motor detonation issues.

Also as stated, the comments from the speed shop guys on ethanol is utter nonsense. Probably talks about 3/4 race cams and high nickle blocks too.

In broad strokes: For a street driven, naturally aspirated motor run as much timing with as little octane as possible. Detonation is the limit on both.
Do you have any engineering data to support either of those statements?
Old 02-26-2019, 08:17 PM
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sstonebreaker
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Originally Posted by 69427
Do you have any engineering data to support either of those statements?
He's right. That's what octane measures.
Old 02-26-2019, 08:27 PM
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Originally Posted by sstonebreaker
Hotrod magazine did an article on Steve's car and at the time it was running 87 octane regular gas on a blow-through carb setup with a ginormous procharger. Not premium, regular. And running 8's. Since then, I think he built a new wagon and is running 6's with it. Don't know what the new setup is.
Thanks. Do you know what issue? I'd like to read it.

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