E85 and Gasoline Mix Burnt Exhaust Valves

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50-50% premium gas and E85 and WOT on the highway by 120 MPH.
Engine had 256k miles, now fully refurbished the cylinder head and changed all piston rings and rod bearings as well.
I am a fan of alternative fuels, but no more bioetanol into my car.
 
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Wow, sorry to see that result.

I have to wonder if your car is properly set up for the fuel you are using.

A lean air/fuel mixture burns more slowly. When high power is required, an excessively lean mixture will tend to overheat exhaust valves. Is this a possibility? Or is your engine running the proper air/fuel ratio?
 
What size injectors did you install to support the increase in fuel flow? What form of tuning software did you use to compensate for both the extra fuel need, and to adjust to the different stoichiometric rate needed to run 50/50?
 
Let me start off by saying first that I am by no means any expert, however....I have seen first hand how E85 and Standard E10 or 100% pure gasoline do not mix and one will sit on top of the other in the tank. I believe the E85 sits at the bottom if Im not mistaken. This is the exact reason in GM's manuals for their vehicles that are E85 compatible it says "try and wait till tank is at least 1/4 full before choosing to fill back up with one or the other" If the car is being tuned for a higher octane and you run this gas and it hits a standard gas level in the tank, then BOOM!!!!
 
Originally Posted By: zoli
Thx for all input, guys!
Factory set, no any tune in my engine.


Is your car/engine designed for E85 ? If not, there is your problem. As E85 requires a substantially enriched mixture.
 
I know, that it was my fault. But I am a fan of E85 and I had fuelled E85 and E95 mix (up to 50% E85) in the past 4 years several times - without any issue.
I did not shot a photo about the top of the pistons: they were so clean I was able to read the SAAB marks on they. Even the turbo exhaust side had no any soot deposit.
Yes, the culprit was the non-tuned fuel injection system caused too lean mixture overheated the exhaust valves.
 
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Originally Posted By: zoli
I know, that it was my fault. But I am a fan of E85 and I had fuelled E85 and E95 mix (up to 50% E85) in the past 4 years several times - without any issue.
I did not shot a photo about the top of the pistons: they were so clean I was able to read the SAAB marks on they. Even the turbo exhaust side had no any soot deposit.
Yes, the culprit was the non-tuned fuel injection system caused too lean mixture overheated the exhaust valves.


So you start the thread blaming a fuel for damaging your vehicle, then you finally fess up and state that you knew the fuel wasn't a fuel that should be used in the vehicle at all?

At least you got one thing right-it was your own fault.
 
There are some daily drivers fueling E85 into their non-tuned cars due to different reason (price, environment protection, cleaning effect, etc.) - like me.
I only intended to describe a situation and its consequency as worst case scenario.
 
Of course, you must remember that many engines can operate at substantially lean mixtures and LOW LOADS, with no problems. Low loads = low heat.

Also, the oxygen sensor controls mixture at part throttle operations. It may have enough authority to allow a partial mixture of E85 to be used and still run OK.

EXCEPT for full throttle operations, where the O2 sensor is not used and the mixture then becomes unusually lean AND loads are high.

If you continue to use E85, don't operate the engine at high loads.
 
Thx a lot, Cujet!
Your summary is great: this is my caution for bioethanol fans without tuned injection system.

EDIT: I found a mistype above; normal gasoline is not E95, but EN95; 95 means the octane number, but E85 is the abbreviation of bioethanol has 85% ethanol and 15% gasoline
 
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Was the CEL lit when it happened? Is your MAF-sensor ok? If there were no issues the adaptation should've taken care of the mixture. Fuel pressure ok?
 
Very good questions, zpa!
No, no CEL or any other warnings popped up.
MAF and all related units working perfectly.
Only issue was: open loop for too much time. 120 MPH was not a good idea at WOT...
 
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If you had burnt exhaust valves its not the fuels fault its the tune in your computer. What AFR at WOT did you see?
I run solid 100% e85 in my race motor in my 4 cylinder turbo talon and never had a problem.
If you have no way to tune the AFR im sure it went real lean and blew the head gasket as well.
 
Originally Posted By: 05Blazer
Let me start off by saying first that I am by no means any expert, however....I have seen first hand how E85 and Standard E10 or 100% pure gasoline do not mix and one will sit on top of the other in the tank. I believe the E85 sits at the bottom if Im not mistaken. This is the exact reason in GM's manuals for their vehicles that are E85 compatible it says "try and wait till tank is at least 1/4 full before choosing to fill back up with one or the other" If the car is being tuned for a higher octane and you run this gas and it hits a standard gas level in the tank, then BOOM!!!!


They should mix just fine, both are soluble in each other otherwise E85 would separate in the underground tank, so would E10 and unless theres enough water present they don't do that. I think the bigger problem is the engine tuning is built to handle one or the other, a mix that falls between the two had the engine trying to compromise between two AFR tables and management strategies that are not ideal in either scenario. The E10 tables can probably handle E0-E20 and the E85 tables can probably handle E60-E95. I do know that the actual ethanol content of gasoline isn't very well controlled and have tested fuel that is listed as E10 and had it come in as high as 30% ethanol.
 
Originally Posted By: zpa
Was the CEL lit when it happened? Is your MAF-sensor ok? If there were no issues the adaptation should've taken care of the mixture. Fuel pressure ok?


Not in my experience.

Normally, unless the engine is flex fuel design and can judge the ethanol in the fuel and adjust the injector pulse width accordingly, too much alky at high output is a recipe for exactly what the OP experienced. Adaptives are only good for smaller variations...
 
I'm sorry to doubt your veracity, but those picts look like the valves hit the pistons and broke. Sharp edges and all don't look like a melt. Ya know?
 
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