baileysade

Can you use E15 gas (94 octane) in your 2014 C7 base mdel ??

c5arlen

Yes I can, but may I? is your question, I surmise, as a personal form of inquiry?

baileysade

yes

TJay74

Yes, the ECM can handle E15 with no issues. You can even run 93 octane and then add 3 gallons of E85 to a full tank of 93 octane for a nice octane boost.

Vetteman Jack

Your owner's manual, on page 9-51 gives the fuel requirements and it states you can use up to E15 in the car.

AnotherNorskie

My FI DI engines really like the higher ethanol blends, supposedly something to do with the additional fuel helping to cool down the combustion chamber. I wonder if that's the case with the LT1's too?

Vette Jockey

Well, since the octane rating for Premium Gas in California is 91, I would say yes! I do not like it, but, it is what it is.

baileysade

Thanks guys !! I can now rest easy as this was my first attempt at using the E15. I was seduced by the 94 octane registration on the pump .

squirrelchew

Ethanol not only burns slower, it contains less energy. You have to inject more of it to get the same bang, which effectively cools the cylinder for lower EGTs -- think water/meth injection, it's the same principle.

orca1946

Good to know when the G S comes out from Chicagoland winter.

9sec

its interesting it is read as 94 octane. I use e15 weekly from thorntons gas stations and it's marked 88 octane

baileysade

Interesting , the 94 octane on my E15 pump was quite pronounced.

aklim

The few E15 pumps I see here are 88 also. Might be 1 point above regular gas so why would I use that although it could? I'd use the highest octane I could whether it is E10 or E0.

baileysade

We should all contact "Mayor Pete " & as Sectary of Transportation he may be able to shed some light on this discrepancy.

squirrelchew

What discrepancy, exactly? Ethanol content is a separate concept from the fuel's AKI rating.

The AKI is the resistance to detonation. The ethanol content is simply the ethanol content. It's called out separately because older fuel systems (and certain engine blocks) cannot handle high concentrations of ethanol.

As a very high level explanation, ethanol has an AKI of about 99. When you blend ethanol into a fuel, it (usually) raises the AKI. That's why it's cheaper. If you start with an 85AKI fuel and blend it with 15% pure ethanol, you'll have a roughly 87AKI fuel.

LDB

It’s more complicated than just splashing some ethanol into gas. Ethanol has high vapor pressure, so the gas you splash it into must be very low vapor pressure or it will be illegal. Gas with ethanol does not go through pipelines or leave the refinery with ethanol in it. The ethanol is added at the local terminal. The refinery sends “RBOB” or “CBOB” down the pipeline. The R or C stands for either reformulated or conventional (depending on whether you are in a high pollution city requiring reformulated gasoline). The BOB stands for blendstock for oxygenate blending, and the BOB’s for E15 ,must be even lower vapor pressure than the BOB’s for E10 so that when the ethanol is blended in, you won’t end up illegal on vapor pressure.

As far as octane, most of the comments are correct. Just because you have 15% versus 10% ethanol doesn’t guarantee that the E15 is higher octane than the E10. It all depends on what octane the BOB was when it left the refinery. The BOB is blended so that after the ethanol is added, it will end up as whatever the customer gas station wants to sell. So believe the octane posting on the pump rather than assuming that E15 is higher octane than E10, or E10 is higher than ethanol free.

TJay74

This is why I dont buy E10/E15 from the pump, well that and most of the E10 stuff is 87 E10 or 88 E10. I usually get either 91 or 93 and then add enough E85 to the mix to get the ethanol content mix up to E15. This way I start at 91/93 octane and then am raising it up to around 95-96 octane.

aklim

Assuming that the get the thing to 95 or 96 octane, does the ECM use it?

Does it show reduced knock retard numbers when you scan the ECM?

LDB

Strictly speaking, when you blend gas that way in a non-flex-fuel vehicle, you are illegal on vapor pressure. Flex fuel vehicles have added capacity in their vapor recovery systems (ie, the charcoal canister) to control the extra evaporative emissions that arise from the higher vapor pressure of E85. The vehicle itself doesn’t care about the higher vapor pressure, but the environment suffers from the added evaporative emissions. Obviously, one individual car is a who cares to the environment. However, if a significant fraction of those who live in areas with 91 premium started fueling as you suggest to boost it up to 93, it would most definitely not be a trivial issue to the environment.

baileysade

Excellent analysis ! The issue of adding E15 to my LT1 Vette engine ( which is not a "flex fuel" engine) was my upmost concern . Thank you !