91 Non Ethanol Fuel - Poor Performance

[BIOHAZARDCURE]

Hey everyone! I'm running into a strange issue with the 91 Octane fuel available at places like Kwik Trip / BP etc.

If it's 91 with no ethanol in it, multiple tuners I've worked with have had to actually pull timing out (like set the base timing to - 4.00) when dealing with like 17 psi from an s280 turbo to avoid the aggressive knock going on.

If I then add some corn juice all the knock goes away and the car is happy as a clam.

Have you guys seen anything like this or is there something actually wrong with my car is particular, thanks!

 

[cidsamuth]

No one will be able to say for sure if there is something mechanically wrong, given what you describe.

That said, when you go from normal Pump 91 to non-ethanol, you are going from 10% to 0% ethanol (Thank you, Captain Obvious). Since ethanol burns cooler, you can throw more timing at it …. which is why higher E tunes generate so much more power.

When you went to 0% E, it doesn’t surprise me that he had to pull timing because it was burning hotter and began to knock. Conversely, if you had gone from 10% to 20%, he could have added timing.

Keep in mind, the benefits of the cooler burning fuel have diminishing returns as you add more and more. Also, it burns leaner, which is why the tuner has to throw more fuel at it, you get less MPG, and eventually get beyond the abilities of the stock fuel pump/injectors.

Then, there are the long term problems that *might* be caused by ethanol, like sludge or corrosion. In my opinion, those concerns are negligible in modern cars.

 

[gtx3076]

Non-ethanol fuel is stupid for these cars. Don't run it.

 

[Capri to ST]

Non-ethanol fuel is stupid for these cars. Don't run it.

I don't have any intention of using non-ethanol fuel, but I'm just curious why it's bad for our cars.
I had not heard of that before.

 

[gtx3076]

I don't have any intention of using non-ethanol fuel, but I'm just curious why it's bad for our cars.
I had not heard of that before.

It’s not bad, it’s just stupid. Ethanol free pump gas is usually more expensive, harder to find, and since it’ll be more knock prone, give reduced performance. There’s no upside.

 

[cidsamuth]

There’s an argument to be made that ethanol damages cars long term. But, as I noted above, I think that’s a red herring for modern cars.

Paying extra for ethanol free absolutely makes sense for classic cars. If stock, their tunes are not set up for the correct AF and for the ignition settings, and the fuel tanks and other fuel components are not designed to resist the corrosion potential of E.

 

[Capri to ST]

This has been a helpful discussion, I've learned more about ethanol. Non-ethanol gas is quite scarce around here, I think there's one station way out in the country that has it, and it's out of the way for anywhere that I usually go. I would occasionally get it for an old lawn mower, and I think it was beneficial for that.
It's good to know that some ethanol is actually helpful for our cars in that it makes the car knock less, because the vast majority of gas around here is 10% ethanol.

 

[Jabbit]

Non ethanol is good for small engines, not really ideal for cars.

 

[BIOHAZARDCURE]

That's the thing though - The only 91 I have access to is non ethanol - I can go out of my way to find 91 with ethanol or even 93 (I just found a bp in the middle of nowhere that has it).

I guess my original thought was 91 is 91 - Doesn't matter if the fuel has ethanol as it shouldn't be knocking on a 91 rated tune. Obviously that's incorrect in my case but, I guess I'm curious as to why? Is it just the increase of egt / temps that causes per-detonation?

 

[BIOHAZARDCURE]

It’s not bad, it’s just stupid. Ethanol free pump gas is usually more expensive, harder to find, and since it’ll be more knock prone, give reduced performance. There’s no upside.

You wouldn't happen to know the exact reason why it's more prone to knock would you?

 

[dhminer]

You wouldn't happen to know the exact reason why it's more prone to knock would you?

As @cidsamuth said, it burns hotter. Hot = more prone to detonation.

 

[BIOHAZARDCURE]

As @cidsamuth said, it burns hotter. Hot = more prone to detonation.

Is it really just that though? Seems like that would be far to simple of an answer. It also doesn't alleviate the claim that the fuel is 91 octane - It's not performing a job that 91 octane is suppose to handle just fine.

 

[cidsamuth]

Heat = knock.

E burns cooler. Octane also plays into it ….

From a knock mitigation standpoint ….

E85>E50>E30>93>91>89>87

OP, you have established that adding E fixes your knock. Accept it. Embrace it. Love it

 

[gtx3076]

Is it really just that though? Seems like that would be far to simple of an answer. It also doesn't alleviate the claim that the fuel is 91 octane - It's not performing a job that 91 octane is suppose to handle just fine.

Most people run e10-e30. If running ethanol free netted better performance tuners would recommend it and drivers would be going out of their way to fill up with it. E10 is cheaper, produces more power, is readily available, and tuners are familiar with it. The only place where it doesn’t win is in efficiency, pure gas will get you slightly better mpgs. I’ve run my car on E30 about 95% of the time for the past 3 years, 54k miles with no issues.

 

[gtx3076]

That's the thing though - The only 91 I have access to is non ethanol - I can go out of my way to find 91 with ethanol or even 93 (I just found a bp in the middle of nowhere that has it).

I guess my original thought was 91 is 91 - Doesn't matter if the fuel has ethanol as it shouldn't be knocking on a 91 rated tune. Obviously that's incorrect in my case but, I guess I'm curious as to why? Is it just the increase of egt / temps that causes per-detonation?

I missed this, if all you have is e0, then tune on what is readily available. It would do you no harm to fill up with e10 if you had to, your tune would already be more conservative. You don’t want to tune for e10 then fill up with e0 unless your tuner says it’s safe.

 

[cidsamuth]

It would do you no harm to fill up with e10 if you had to, your tune would already be more conservative.

Ehhhh, maybe. It would run lean. Lean enough to matter, in consideration to the cooler burn if E10? Maybe, maybe not.

 

[dhminer]

Is it really just that though? Seems like that would be far to simple of an answer. It also doesn't alleviate the claim that the fuel is 91 octane - It's not performing a job that 91 octane is suppose to handle just fine.

Here you go. Nerd out lol

https://www.sciencedirect.com/science/article/abs/pii/S0010218015002485

 

[M-Sport fan]

We just recently got Sunoco 94 E10 available in my area.

If I did not have to drive 10-15 miles each way to fill up with it (and if Sunoco fuels were not so totally lambasted by so many on here), I would consider using that on a factory, or Adapt-X tune.

On average, it is only about 20 cents a gallon more than the (also hated by some/many{?} on here) 93 octane, Shell V-Power E10 I am currently using.

I figure it could not hurt, especially during the summer heat on a factory radiator.

 

[Dpro]

Ok lots of stuff misinformation flying in this thread. There is nothing wrong with Standard 91 pump . I run a tuned s280 on it that puts out 284whp and 284 wtq those are not shabby numbers and I seriously doubt my timing is pulled back. I am not sure if it’s your tuner or something is not right if you are getting knock.
If anything it sounds like your tuner advances the shit out of your timing to begin with. That or you are getting shit gas from a station that has water condensation in the tanks. Which means they are not getting a lot of business or pumping the gas out to customers all the time or both.

I will add most pump 91 actually has up to 10% ethanol in it as refiners know its way to stretch the refine quantity. In fact they will quite often put small stickers on the pumps saying that has 10% ethanol. You do not need to worry about being tuned for that either.

Your 91 tune will function just fine in fact a lot of the local guys here have thrown a gallon of e85 in on a full tank with their pump gas tunes so the engines will run cooler in the canyons on warm 90+ days again it’s not enough to warrant being tuned for it.

Plus it burns a little cleaner as well. So ya you can run a S280 with pump 91 and have be fast as hell. You should get a E30 specific tune to run E30 though .My S280 with E30 just gets stupid and pushes 300whp and 340wtq with a base tune for E30. It’s almost too crazy for street use unless you live in the land of nothing but long straightaways.

 

[rallytaff]

I've used nothing but 91 in my car since Day 1. I'm more than happy with the 200 or so whp and the 270ft/lbs of torque. I have never had a mechanical failure, so why would I mess with it and cause problems.