CiCiC3

It's rebuild time for my BB which is currently at 10:1 compression. The rumor is they are taking gas to higher alcohol levels? If this is true I should probably consider dropping the engine compression to possibly 9.5:1 or lower to prevent possible valve trouble? Any thoughts on it?

bashcraft

What rumor?

73racevette

I am no expert, but thoughts are all over the board on this regardless of your political persuasion. Last I heard manufacturers are wanting to push the fed for higher octane ratings in order to meet (sure to come) higher and higher CAFE standards. Other's (corn belt) want higher and higher ethanol content. Not sure anyone is smart enough to know what is coming next, including the Fed or the many proponents one way or the other.

For me, I would not bet on what is coming next. And I certainly would not reduce compression on a BBC down to 9.5:1 at least with aluminum heads unless your really don't care as much for power and are content with what you get with 9.5:1. Probably still good, but not great unless you start with power adders, etc.

Just my $.02.

cv67

Ive been hearing lobbying for the opposite. Some new cars run as much as 12:1...stock!!
Alcohol is said to reduce mpg....mfrs have to increase theirs so it would make sense to perhaps see less at some point but what do I know.
For an occasional driver run as much as you can, get a head with a modern combustion chamber and the right cam.
Worst case you mix up some good stuff.....smal price to pay . (Wish Id gone 12.5:1 instead of 11.5)

It makes all the difference in the world, dont pay attention to a posted "its only %" youll feel and hear it (esp in the right pedal)

Fwiw 10:1 is not a lot of compression at all.

Kerz

CiCiC3
Not sure about your intended need to reduce compression ratio and valve issues. Let me take a stab at my guess.

Going to 20% ethanol. Recently there was some political noise in the corn belt about 15% ethanol. As previously stated, its anyone's guess at this point. It should be noted that ethanol octane (pump) value is around 110. The high octane value makes for a good blending component, thus the pump octane grades will stay the same thought blending formulations could differ. The BTU content of ethanol blended gasolines is lower than straight hydrocarbon gasoline.

"Valve rattle" has been commonly confused with spark knock. Actually spark knock is associated with preignition or detonation of the fuel air mixture within the combustion chamber. In one example, the mixture pre ignites before the spark plug fires. This would likely result in the mixture being ignited in different areas. Burning the candle at both ends, if you will. When the two fronts meet an audible ping can be heard. The ping is a result of uncontrolled combustion. In general, the higher the octane rating the less likely to have spark knock. Note there are other contributing factors. Excessive and continued "ping"/knock can result is engine damage. The uncontrolled combustion does not allow for uniform heat distribution in the combustion chamber to the cooling system.
Vic

stingr69

Where will all that new extra ethanol come from? We do not have a huge stockpile supply of unspoken for commodity just sitting around waiting for some new requirement to be initiated. this would cause havoc with the market if it goes into effect all at one time.

Gasoline is the best solution to run in an engine. There just is not a better mousetrap.

v2racing

There is already 15% ethanol available at some stations here in Minnesota, has been for a couple years.

The automakers are actually seeking higher octane fuels as high as 98 octane and even a higher minimum octane regular. The reason is they can tune the high compression engines to get better fuel mileage with a higher octane. It would make it easier for them to achieve the standards without spending a lot of money. The down side is the higher octane fuels will cost more so the cost goes to the consumer instead of the automakers.

I retuned my CTS coupe with a 3.6 for 93 octane using HP Tuners. The stock timing was pretty retarded so advancing it for 93 increased power, throttle response and I picked up fuel mileage. The increased fuel mileage compared to the increased cost of 93 pretty much evened out though.

Mike

Fredtoo

I did a similar test with Ethanol free fuel when driving with a modern fuel injected, computer controlled car down south.
The car got better MPG, but the same $PG

v2racing

I went from 87 E10 to 93 E10, so ethanol was not relevant in changes to my mileage. These newer engines with close to 12 to 1 are just begging for higher octane, but tuning is required to achieve any gains by increasing octane.

Mike

CiCiC3

I'll have to ask the mechanic again about these fuel changes he was talking about. He just volunteered the info when I mentioned doing a rebuild. Then another mechanic told me that 9.5 compression is about a high as you should go running on pump gas. I guess I'll just stay 10:1 and not worry about the crazy hear say. I used to hear some kind of knock or ping when going WOT with an 850 double pumper but might have been a timing thing. Thanks for all comments though.

resdoggie

Ethanol burns cleaner than real gas. So, it's more environmentally friendly thus helping to satisfy The Clean Air Act.

mrvette

Closed loop DPFI is what cleaned up the air......little to do with ethanol or much of .gov regs.....

TimAT

it's a great big scam.
Gasoline produces more BTU's per gallon than ethanol. So you mix ethanol with gas, it drives the BTU content down, so you use more. You use more, you spend more, the state and the fed gets more tax revenue.

ignatz

I generally agree. The internet "research" I did suggests there is maybe a 30% net gain in the energy released in burning ethanol compared to the energy required to plant the corn, grow, harvest, refine and distribute the ethanol. It's not a big win. That's if you can even believe the math as there is plenty of disagreement. It's about the Iowa primaries in my opinion. Sugar cane is actually a lot better.

Rescue Rogers

i believe you but i heard its actually a loss in the real math. but they will twist the numbers in their favor. I posted a link a month back in a EFI thread about Trump swapping sides. He was anti ethanol but to get his judge pushed through the approval process he swapped side to get the iowa and midwest senators on his side. I cant find that story since its blown up but heres alot of other stories, all bad, its going to happen. I guess this will get me closer to buying an EFI setup

heres other stories

https://www.treehugger.com/energy-po...ases-smog.html

https://finance.yahoo.com/news/trump...013558945.html

https://www.treehugger.com/energy-policy/us-government-loosens-restrictions-ethanol-increases-smog.html

https://www.treehugger.com/energy-policy/us-government-loosens-restrictions-ethanol-increases-smog.html

cv67

This. As usual its all about $

I can see mfrs pushing for whatever gas helps them meet the new stds. I bet we see better stuff at the pump in upcoming years.
Ill say one thing, never had a problem running old gas til a few yrs ago it goes bad quick. Completely glued up my carb thats never happened.
Present tank is 6 mos old, have to fire it on starting fluid then it stays running..otherwise need fresh stuff. Used to be able to let acar sit 5 yrs and still run.

resdoggie

ok....................

MX5000

Do you have any test results that prove this theory?

naramlee

The FACT...

It takes 1.8 gallons of ethanol to equal the same energy output as a gallon of gas

sure ethanol burns cleaner with less nox and co2, gallon per gallon its about 15% cleaner... but guess what, when you add that extra .80 gallon to get the same mileage, your co2 and nox emissions just went through the roof

racers like Ethanol because you can run more boost and more compression, they dont give a damn about milage or emissions

also you can easily run 36* total timing on a sbc at 12:1 compression with aluminum heads as long as you run a double quench chamber with .030-.035 quench zone between piston and head with zero knock.

In closing, it takes more energy to create ethanol than it gives back, so why are we bothering...
To make 1.5 gallons of ethanol it takes 1.0 of gasoline, leaving you in the negative 1/4 of a gallon of ethanol.
https://alternativeenergy.procon.org...s.php?question

Bernman

GM says using fuels with greater than 15% ethanol in non flex fuel engine can void warranty.