E85 and Gasoline Mix Burnt Exhaust Valves

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what sort of air filter are you using? Any possibility of dirt(grit) getting into the engine? (that brings up the K&N gauze air filters that I've used but abandoned after elevated silicon reading in UOA). Also: was the automobile bought used? If so, what sort of condition was it into? what mileage? how was the previous owners operate/maintain this vehicle? Additional accumulation of carbon on the intake valve back, if dislodged for whatever reason, jammed on the valve to seat contact surface, will lead to such burn. (*I've dealt with 2 of these engine rebuilts in 2 decades time: both were due to severe owner's neglect*) Q.
 
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Could be burnt then fractured, they didn't get hit by a piston though. This happened at high RPM so the damage was quick. You see this sort of damage on high RPM, nitrous and boosted engines. Burn valves from too little clearance tend to burn around the edges.
 

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Originally Posted By: TiredTrucker
Wow! Considerably different that this engine, a non-flexfuel variety running E85, in a Camaro. http://www.camaros.net/forums/showthread.php?t=143372&highlight=e85+wear+eric
From that link:
Quote:
BibBlock69RS -- I use an AED 850cfm Holley based E85 carb. Mine was one of the early designs and I have since seen later models that were much closer out of the box (mine needed tweaking -- make sure whatever carb you buy has the idle/transition fuel coming from the main well, NOT the float bowl). Can you get E85 in California now?
So the Camaro was setup for E85. The OP's car was not.
 

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Originally Posted By: Trav
Could be burnt then fractured, they didn't get hit by a piston though. This happened at high RPM so the damage was quick. You see this sort of damage on high RPM, nitrous and boosted engines. Burn valves from too little clearance tend to burn around the edges.
Exactly. A buddy of mine had a mouse chew his injector harness on his Mustang. Engine was a stock '90 5.0L with a 150 shot on it. One cylinder went lean and the valve looked identical to the OP's.
 

zoli

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Thx for all the great comments in this topic. Well, after the refurbishment (new cylinder head, piston rings, rod nearings) it was pulling like a train with 0 oil burning per 6000 miles. Meantime, this car was gifted to my niece as her first car getting practice in the traffic at Budapest.
 
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When you had the cylinder head re-done, how MANY of the valve guides needed "work"? THAT is important in this situation! Certainly, exhaust valves can "burn" due to combustion heat that is higher than the design standard of the valves themselves. BUT what really happens, as my machine shop operative noted once, is that as the valve guide wears, it will allow the valve head/valve itself to wobble/bounce as it seats, before the valve finally resides in its valve seat. With time, that little wobble CAN deform the valve head enough to allow for a little less "seal" as it seats, then the exhaust gasses can start seeping through, not letting all of the heat in the valve head be transferred to the seat area for cooling, and it's that combination that can lead to exhaust valve "burning". The side loads placed on the valve stem ends were greater with the non-roller tip rocker arms we had on older engines. Getting one of those engines past 80K miles without ONE burnt valve was the exception, back then, when most engines didn't turn past 3000rpm most of their lives (in the USA). You have an engine that is computer controlled and each cylinder is optimized for fuel/air/spark efficiencies. If all is working well at part-throttle, then WOT should be equally-well done Yet you have two adjacent cylinders with problems. To me, that kind of makes it hard to claim just "fuel" as the main issue, especially for an engine with the higher distance-use yours has. At least in the USA, E85 from all vendors is not true E85 (unless you purchase verified racing fuel in drums). Some brands can have more than the other brands, just because the fuel spec is written that way. Key thing is that it's NOT an absolute spec, as E10 is closer to being, at least at the fuel station level. E85, E10, etc. start as regular-style gasoline and the ethanol component is "splash blended" at the fuel distribution terminal. With blender pumps, it can become more accurate, possibly, at the consumer level. E85, due to its moisture absorption properties probably CAN end up at the bottom of the fuel tank. That "phase separation" thing it is noted for (which CAN also happen withE10!). So how much of it "phase reacts" (and how soon it happens) can depend upon ambient humidity at the time of fueling and how much humidity can creep into the fuel system vent mechanisms and such. Alternative fuels can be good and such, BUT I suspect you'll discover that the best fuel economy is achieved with E0 fuels and optimized tuning for the lowest cost per distance unit. IF the E__ fuels do have a lower unit cost, the fact it can take more fuel/distance can make such fuels more expensive in the long run . . . unless you optimize your engine to run those fuels ALL of the time. For those concerned about crude oil use, then we should IMMEDIATELY return to "pure gas", even leaded pure gas. It takes approximately 5% MORE crude to make unleaded fuel than it took to make the older leaded fuel we had in the earlier 1970s. THEN, we lost about 6% fuel economy with E10 fuels, with greater fuel economy losses as the ethanol content increases for engines optimized more for E10 than for E85 (i.e., design content of the engine and such). It's a better situation to design for low-ethanol use and then adapt to higher ethanol blends than to go the other way (down-convert from E100 to E10, which is much more problematic unless we might get racing gas of 100+ Research Octane readily-available again. I fully understand the reason we went to unleaded fuel in the first place, other than purely environmental reasons. But then we had to decrease compression ratios for even greater inefficiencies, at that time, which meant greater fuel economy losses. Greater-evolved combustion dynamics engineering and electronics now allow compression ratios which were only used for pure racing engines in the later 1960s on leaded racing gas. In those same earlier times, there were a few gasoline brands, regional ones, who sold 100 Research Octane unleaded fuels with no real issues of valve seat recession or fuel system damage from "alcohol blending components". How could they do it then and we can't do it now? CBODY67
 
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Actually FFV here are warranted for any amount of mix of each fuel. You can go anything between E27 (min ethanol content in pump) to E100. Most gas cars in the streets are tuned to E22, but run on E27 by refinery law as gov. Mandate. No phase separation and acetone is great to keep homogeneous fuel. So ,if you add 5% acetone, you can run any mix of E0 with E85 even at low tempetatures without the phase separation ocuring. Most gasolines already have acetone on its formulations, for that measure.
 
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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!!!!
All my GM manuals stated for my last 2 Silverado's with flex fuel was when filling and changing grades, it is best to run more than 7 miles to allow the sensor to adjust everything to the new level of ethanol.
 
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