E15 or E85 Fuel in Vortec Engines

[Boots97]

Hi Everyone,

I have a 1997 Chevrolet K1500 ECSB Z71 with the Vortec 5700. I live in MN and we have a few gas station chains in my area sell E15 gas. The sticker looks like this on the pump:

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I've searched this Forum, but have never got a clear answer on how safe it is to run E15 or E85 in Vortec engines. In my experience, I've had 1/2 tank of E15 and 1/2 tank of unleaded gas (10% ethanol) and it ran just fine. My truck has a 25 gallon tank. Yes, I KNOW it says that it's meant for 2001+ vehicles, but I also know that non LS Vortec engines were used up until 2003. Is there any difference with post 2001 non LS Vortec engines that make them E15 compatible? Has anyone ran a full tank of this fuel in a pre 2001 truck/suv? Is there a way to make non LS Vortecs E15 or E85 friendly? I'm asking bc E15 gas is $0.10 cheaper/gal in my area and I do a lot of city driving so I'm not getting great mileage either way. I also would like to have a wider variety of fuel that my truck could take.

 

[Schurkey]

Bad idea.

E15 is bad enough. E85 is a really terrible idea.

Vehicles that can use E85--which, by the way is not actually 85% Ethanol, it varies intentionally by season and also unintentionally by mistake/carelessness/dontgiveashit--have fuel sensors that tell the computer how much fuel to squirt based on the TRUE ratio of alcohol to gasoline.

There's hot-rodders that use E85, but they're known to jack-up the compression ratio, AND they need to dick with the carb jetting with every tankful to keep on top of the varying alcohol content in pump E85; or they're buying "race" E85 by the 55-gallon drum.

E15 will run in a "regular" vehicle, with poor fuel economy and even greater potential for water absorption and corrosion. It will void various engine manufacturer warranties, although that's not a concern for a 5.7L Vortec vehicle any more--unless you've got a "crate engine".

If you're unlucky enough to have taxpayer-subsidized "Blender Pumps", keep in mind that it's probably illegal, and absolutely crazy to fill a portable container, or any other small fuel tank (motorcycle, snowmobile, most boats, etc.) from a blender pump because the pump's guts and fuel hose may be filled with E85 from the previous user until enough fuel flows through the pump to get the ratio down to whatever you think you're supposed to be getting.

The EPA should never have allowed E15, or E85, or for that matter, enforced the use of Ethanol in gasoline to begin with. It's a scam, and we're the victims. It's terrible ecological, food, farm, and transportation POLICY, although E10 is pretty fair fuel in my experience. I've used E10 since it was called "Gasohol", and before that, about six months worth of M05. In 40+ years of using "gasohol" I've never had a problem that I could genuinely blame on the fuel. HOWEVER, turning topsoil into fuel is both irresponsible and crazy.

 

[Yeetsmyfeets]

I'm just waiting for E100 to drop, then I'm gonna fill a 55 gal drum for personal use.

 

[df2x4]

E15 might work, but I wouldn't for the reasons that Schurkey mentioned.

E85, definitely not. The Stoichiometric ratio of E85 is 9.8:1 vs 14.7:1 for pump gas. Even if the stock fuel system was capable of delivering enough E85 for the engine to run properly (I doubt this) the PCM tune would be all wrong, and any savings you'd see at the pump would be canceled out by the fact that you'd be burning much more fuel all the time.

 

[Erik the Awful]

Gasoline Btu​	Ethanol Btu​	Price/Gal​	​
125000​	77000​	$3.50​	​
​	​	​	​
Percentage Ethanol​	Total Btu​	Btu Loss​	Price Point​
0.00%​	125000​	0.00%​	$3.50​
5.00%​	122600​	1.92%​	$3.43​
10.00%​	120200​	3.84%​	$3.37​
15.00%​	117800​	5.76%​	$3.30​
20.00%​	115400​	7.68%​	$3.23​
25.00%​	113000​	9.60%​	$3.16​
30.00%​	110600​	11.52%​	$3.10​
35.00%​	108200​	13.44%​	$3.03​
40.00%​	105800​	15.36%​	$2.96​
45.00%​	103400​	17.28%​	$2.90​
50.00%​	101000​	19.20%​	$2.83​
55.00%​	98600​	21.12%​	$2.76​
60.00%​	96200​	23.04%​	$2.69​
65.00%​	93800​	24.96%​	$2.63​
70.00%​	91400​	26.88%​	$2.56​
75.00%​	89000​	28.80%​	$2.49​
80.00%​	86600​	30.72%​	$2.42​
85.00%​	84200​	32.64%​	$2.36​
90.00%​	81800​	34.56%​	$2.29​
95.00%​	79400​	36.48%​	$2.22​
100.00%​	77000​	38.40%​	$2.16​

I'm no fan of ethanol, it's an environmental and economic disaster, but I also think a lot of people purposefully overblow the detriments of running ethanol fuel. I wouldn't worry about dropping E15 into my truck, but E85 would require retuning. I threw in the table above so you could see the column on the right. If pure gas is $3.50 a gallon, E85 is only a bargain if it's less than $2.36 a gallon because you'll lose a third of your gas mileage.

 

[Tommy1234]

The ethanol would wreck havoc on the rubber lines along with other parts

 

[Boots97]

@df2x4 @Erik the Awful @Tommy1234

Yeah I figured running E85 would be a stretch for a late 90s Vortec. I don't know how long E85 has been available in the US but I know that I personally didn't see it much until the early 2010s.

Regular 87 octane gas (10% ethanol) is between $3.34-$3.45 as of now in my area. Not bad considering I was paying $3.79 about 6 months ago. E15 is running $3.24-$3.35 respectively and I haven't checked E85 prices bc I figured it wouldn't work in such an old application like mine.

IIRC 93 or 95 octane should be ethanol free? I don't see 95 octane in my area but 93 octane is $0.15 more than 87 octane and I've never had an issue with 87 octane so I've never tried 93 octane.

Some gas stations further up north and rural areas of Wisconsin have ethanol free gas pumps with higher octane (>93 octane). I know that people run that in boat engines bc boats are more finicky with ethanol content.

@Tommy1234 I agree that the ethanol would ruin rubber lines. That's what I've heard in other threads regarding higher ethanol fuel.

@Erik the Awful I agree that people over exaggerate how much ethanol is damaging to cars. I've tried 1/2 tank of E15 with 1/2 tank of regular gas (10% ethanol) and I didn't notice anything strange and I didn't lose any fuel economy either. Pure gas is hard to come by in my area and almost no one runs it bc of price. Regular (10% ethanol) runs $3.34-$3.45 in my area so running E15 would be a savings for me since I do mostly city driving anyways.

 

[454cid]

When E85 was first sold in this area, it was long enough ago that my truck was still new-ish. I tried it in my truck thinking it might have the programming for it. It was fine on the way home from the gas station, but the next time I tried driving the truck it ran horribly. I had enough room in the tank to be able to dilute it with regular gas, and then it was fine.

On the flip side, yesterday I was at a gas station and noticed they had 90 octane non-ethanol fuel, but it was unfortunately more expensive than 93 octane premium. I'd probably buy it for my mowers if it was local.

 

[Boots97]

@Schurkey

1. Yes, I know that E85 ranges from 51%-85% ethanol blend depending on the mix and that flex fuel vehicles can read the true mix of ethanol-gas and adjusts accordingly. Figured it would be a stretch to put E85 in such an old application which is why I never have.

2. I never asked about racing with E85. I run a bone stock Vortec 5700 and I would never put a turbocharger or supercharger on it even if I had the space, time, money, and resources to rebuild the engine bc I'm a firm believer in naturally aspirated power for reliability. All I asked if it was good for daily driver use and what I could do to make it run E85. From what people have stated, it's not worth it for such an old car.

3. I do 90% city driving with plenty of stop and go traffic. I have a 4WD truck with the Z71 off road package. Meaning that my stock height 4WD is higher than a stock 2WD truck and I run 265/75/R16 tires which are factory oversize from the standard 245/75/R16 tires. GM may have used smaller tires, but those are the sizes I know these trucks used. I run TrailFinder all terrain tires that I bought used at my local salvage yard for $250/set last year. They're Discount Tire's store brand tires made by Kuhmo and while they're great for the price, they aren't the most durable tire and definitely not designed to get better gas mileage in mind. In other words, I know that I'm getting poor gas mileage and I've run 1/2 tank of E15 with 1/2 tank of Regular (10% ethanol) in my truck with no decrease in fuel economy.

I have no warranty on anything engine related except the radiator bc it was replaced alongside my transmission when I got the transmission replaced. I know that higher ethanol=more water absorption/corrosion and that can be concerning. However, this is my daily driver that rarely sits for more than 24 hours so with as much use as I have, I'm not concerned about that.

4. We have blender pumps all across my town and neighboring towns around me. I used to work for my friend who ran his own landscaping business and we would fill everything (riding lawnmowers, push mowers, weed eaters, our cars etc...) and have never had a problem. I worked there on and off for 4 years until he sold off the business to someone else. Honestly, you're worrying too much about that IMO. My parents and I still use the blender pumps in my area for my own lawnmower and car and have never had an issue.

5. People have created alternative fuels well before the EPA was founded in the 70s. Alternative fuels go back almost as far as cars do and it would be inevitable that it would be used today. My friend and I had a conversation about ethanol and he said that it's usually made from rejected corn unsuitable for food (His extended family grows corn). Ethanol can also be made from other crops such as sugarcane which is common in countries like Brazil, which use ethanol much more than we do here in the U.S. I just like ethanol bc it's another option for people to use in their cars. I like variety and I don't want to have to use one type of fuel if I don't have to. Unfortunately, E15 would probably be the furthest I could go without serious modification of the fuel system. Oh well...

 

[Boots97]

When E85 was first sold in this area, it was long enough ago that my truck was still new-ish. I tried it in my truck thinking it might have the programming for it. It was fine on the way home from the gas station, but the next time I tried driving the truck it ran horribly. I had enough room in the tank to be able to dilute it with regular gas, and then it was fine.

On the flip side, yesterday I was at a gas station and noticed they had 90 octane non-ethanol fuel, but it was unfortunately more expensive than 93 octane premium. I'd probably buy it for my mowers if it was local.

Wow. Hard to believe you got E85 that long ago. Here in SE MN I didn't see E85 pop up until around 2010. Thank god you were able to dilute the E85 and your truck ran fine afterwards. That would've scared the s*** out of me. Most people have told me that E85 won't work and your experience reinforces that. E15 should work though and my truck ran fine on 1/2 tank of E15 with no decrease in gas mileage.

Glad that you have non ethanol gas in your area. In my area we have 87,88,89,91,and 93 octane depending on the gas station. None of which are ethanol free IIRC. I know ethanol free gas is popular for boats, mowers, and special performance engines so yeah I would use it in my mower too if I could get it.