Kudos to you for not falling prey to confirmation bias and re-evaluating when presented with new information. That's a quality not many internet posters possess.

 

I had a 2020 Supra prior to buying my C8. The Supra is probably the most tuned vehicle on the road so the science behind making power is pretty well understood. My engine was tuned for e50 which made for a MASSIVE increase in power over CA 91 octane. For a reasonable daily driver e50 was good for 500 whp which netted a 128 mph trap speed. As mentioned above, anything above e50 was a case of diminishing returns for a street car and was approaching the limit of the stock fuel system with minimal gain to show for it.

 

LOL, I'm sorry I read F1 and not Fi, Oh boy I need to rest my eyes....good night....where's my good reading glasses now????

 

LOL. You can SMELL the difference.

 

Or. maybe they will use a scan tool and look at the following parameters which are listed. I was not looking for this, but I ran across it in the list of Scan Tool Parameters for the ECM while I researching another topic. When I saw it, it reminded me of this thread, where the question came up about how GM would know if one put fuel in with too much alcohol content. I have no idea how these are measured, nor if these particular parameters are even active, but they are found in the ECM Scan Tool Parameter List in the 2020 version of the Service Manual that I have.

1. Recommended Alcohol Content Exceeded.
2.Recommended Maximum Fuel Alcohol Content When Recommended Maximum Fuel Alcohol Content Exceeded.
3. Refueling Events Since Recommended Maximum Fuel Alcohol Content Exceeded.

Edit: I found a few more. Two of them, Fuel Alcohol Content Learn in Progress and Fuel Alcohol Content Too High appear under the list of reasons that will show up in the Scan Tool for "Cylinder Deactivation Disable History". These are just a list of Scan Tool Parameters related alcohol in the fuel, that someone could look at if they had a reason to do so. I did not look for the DTC and related diagnostic procedures that would prompt someone to look at these parameters.

 

Interesting. The trigger for that protocol is Reduced Engine Power (REP). Since the engine runs well on e30 there would be no reason to test ethanol content in the absence of customer complaint. Since there is no performance benefit to be gained by exceeding 30% it would be (silly, foolish, stupid; pick one) to do so.

 

I added a few more alcohol in the fuel related Scan Tool Parameters that I found to post 45. Two of them, Fuel Alcohol Content Learn in Progress and Fuel Alcohol Content Too High appear under the list of reasons that will show up in the Scan Tool for "Cylinder Deactivation Disable History". These are just a list of Scan Tool Parameters related alcohol in the fuel, that someone could look at if they had a reason to do so. I did not look for the DTC and related diagnostic procedures that would prompt someone to look at these parameters.

 

I have also been doing research. I'm familiar with the EE video, however I have seen the following that has led me to believe a stock C8 can run e85 and get around+10 HP, though a flex tune would obviously be better and can give + 30ish.

First point: Paragon straight up says you can run e85 without a tune, in their video advertising their flex fuel tune. Along the lines of "yes, you can do this, it's a closed loop, but yo make the most of e85 buy our package."

​​​​​​Second: I've seen 2 other tuning shops on YouTube simply run e85. Tuner #1 posted before the ECU crack, said 0-60 improved by just switching to e85, stated it's fine it's a closed loop - but it's probably only good for+10-11hp... until can be tuned.

Tuner #2 was using real e85 (Sunoco drum) and were selling up a car for a e85 tune - post HP Tuners crack. The first few dyno runs were with no ECU change at all and the car ran 461 rwhp (had bolt-ons) with the stock tune. Proceeded to do 20 more pulls trying different parameters and was having trouble getting much more out of it, said "GM did a great job from the factory with this!". Was finally able to get 475 sometime later.

3rd example was a dyno operator who had a pre-crack e85 build come in... but this also had port injection rigged up off the same pump, so we won't count it (but still no tune).

Continuing: the people that are currently selling flex fuel tuning packages include a flex fuel sensor to access the different mapping... but there are no modifications done to the injectors, pump, lines, etc. You are getting no more additional fuel delivery capacity - just a tune. Infact take flex-fuel out of the equation (it's just what I've been thinking about) anyone that sells you an e85 tune is not doing anything to increase fuel delivery - they are relying on the stock system.

So after 2 nights of "research" I had an ignorant hypothesis that was basically: the base C8 fuel system can deliver enough e85 to prevent running lean, the closed loop system would do a pretty good job of adjusting parameters to get more performance out of fuel, but up to 50% ethanol you're leaving a lot on the table by not loading a tune (stock car can't make use of 51%+) And a flex-fuel setup would be awesome because it would get you great results regardless of the %.

I obviously haven't put anything but 93 in my car, but I'm strongly considering getting a flex-fuel system ... and all the research I quoted is what is making me think one could run e85 in a base C8 and be fine (apparently the z06 cannot provide enough fuel).

Could you help me understand what I'm missing, and why this would be a problem? The only thing I can come up with is e85 requires 30% more volume, so the car would run lean.

Thanks to everyone who reads this; I'm certainly not trying to argue with anyone; if I'm an idiot for overlooking some very basis fact... well it is what it is - that's why I'm asking

 

You could probably get away with one tank of E85 because it will mix with the gas in the tank.
The 02 sensors would try to compensate and the fuel injectors could keep up at low rpm.
High rpm would run extremely lean and that would certainly be a problem.

 

There is a whole thread on this and you can 100% run some E85 (assuming you can even find TRUE E85) with no harm and no tune. I would not run a whole tank of it.....blend it to E30

Link to a good thread on this... https://www.corvetteforum.com/forums...tock-tune.html

 

It is my understanding that the injectors would keep up at high-rpm as well. As evidenced by the fact no fuel delivery modifications are made by Paragon Performance, and other respected shops, when setting up an e85 tune.

Wouldn't these shops need to install larger pumps/injectors if running lean at 85% ethanol was a concern?

Again - just a noob trying to make sense of stuff I don't know about. That is for everyone's insight!!

 

Forensic chemists.
Mercedes-Benz uses them to determine warranty coverage in the event of a claim on a catastrophic failure, due to use of fluids that aren't "MB recommended" in the OM.

 

As others stated above, without FI, I wouldn't bother. It is really hard to take full advantage of e85's benefits without having the ability to adjust boost to match it.

I am a die-hard fan of e85. I would not recommend running it in any N/A engine unless it was specificially purpose built (drag racing, etc)--and not just a streetable or daily use car. The problem with all flex-fuel vehicles (I have been saying for nearly 2 decades) is that the necessity of running off 87 octane means that you are not able to truly benefit from all that e85 has to offer. Even 93 octane engines are not suited to the 110 octane of e85. For an N/A, you'd need ~14:1 compression ratio; utterly incompatible with 93 octane.

FI just makes it easier to adapt to effective octane rating for whatever is in the tank; since you can run 8 psi or something with a 93 octane and 21 psi or something with e85 (compression ratio dependant, of course).

p.s.
If we ever do get a factory e85-specific engine, it will be smaller, lighter and likely on par with fuel efficiency vs a regular 93 octane engine. This is due to burn efficiency of e85 being higher than conventional gasoline--despite the lower BTU's per gallon.