Ethanol Limits. Let's Talk Turkey

[Gollum]

Ok, so I've been reading, reading, and still reading about ethanol fuel blends and I like what I read. It's extremely hard to find good information out there through all the BS, but when you find some good info it makes ethanol look good for reasons most people aren't talking about.

 

What do we here care about? Horsepower. Yup, that's right. That's all I care to talk about. I don't want to discuss price or politics. Lets check those bags at the door.

 

1st myth to address. Ethanol doesn't make as much power.

 

Though ethanol has nearly 30% less energy per any given volume than petrolium based gasoline, it's extremely high octane naturally. If you're comparing ethanol to regular 91 octane gas then ethanol easily has just as much power potential, it just needs much higher compression to take advantage of it.

 

 

Ok, now if people ask I can link the article, but the information is all over the net. Ford is working on dual fuel turbocharged engine. Test bed is a 4 cylinder turbocharged to "2.0-2.5 times atmospheric" levels. It uses regular port injections with petrolium based gasoline (regular gas for us americans) and direct injection ethanol when under high load conditions. Here's the shock.... They're expecting to run 12:1+ compression, more likely around the 13:1 range. That's HIGH!!! They say ethanol usage will be minimal for the power gains, and the ethanol on their test bed is doing an extremely good job of cooling the charge temps, and that only small quanteties are needed to cool the charge enough to prevent knock.

 

Now, most of the information I've seen indicated that safe compressions for ethanol are in the 12:1-14:1 range, and that's assuming we're talking naturally aspirated. Ford is running those levels on a turbocharged vehicle still running gas on light load conditions.

 

So who here has tested the compression limits of ethanol? Given this information I'd imagine that a well designed high quench head could bring ethanol well beyond 14:1, maybe even into diesel realm. I'm not experienced in this regard, so maybe some race vets like tony D can chime in.

 

Now, onto why I'm bringing all this up.

 

I was going to pull my L28ET I have sitting in my project 280ZX, sell off the chassis and put the engine into my daily driver after getting MSll running on it.

 

But I realized that ethanol bleands are getting more severe here in california, and I can only expect it to get worse until they start offering various levels of blends (maybe instead of various octanes? or maybe say octane but really mean blend?). My best bet would be to raise the compression of the motor while it's out. So I can get a flat top piston engine and mate the two. Those engines are everywhere around here and cheap.

 

But that doesn't bring up my compression a ton. 8.82:1... That's not very high at all. Realistically I could run 9:1 on most of todays gasoline and not even worry about knock as long as my tune is good on that rating. Realize I'm not looking for insane HP levels. I doubt I'll ever push 300hp to the wheels, 250 at most. This is a daily driver that I want to have some guts, and my goal is to see 35mpg consistantly on tanks I'm not racing on.

 

So what compression should people like us shoot for at various blends? Say we're running a 10% blend, that should in theory be 10% of the difference between maximum compressions we could expect to run.

 

91 octane - 9:1

Ethanol - 12:1

(guesses for a L28ET)

 

So 10% of the difference would be .3

 

If we're considering the E85 mix that might be making it's way to stations in the near future (especially here in CA) that's a difference of 2.55

 

So I think I'm right in saying that on current gas I'd want to be around 9.3:1 and for E85 I'd want to be around 11.5:1

 

 

If anyone sees flaws in my logic, correct me. That's why I'm posting this.

 

And according to what I've seen, I should be able to make the same power with extremely similar mileage effiency. But who wants to make a 9.3:1 compression engine only to have to build a new one once E85 comes out... What I'm considering is building a 11+:1 compression engine and going one of two roads.

 

1. Run a second injection setup like a methanol injection setup, only using ethanol. This way I can just run as much ethanol as I need to keep out of engine knock.

 

2. Mix ethanol into each tank. I'm sure I can find ethanol retailers until E85 makes it to most pumps.

 

 

Am I alone in thinking about this switch to ethanol? Though I like many doubt it could supply our entire nation, I still see it as a worthwhile fuel as it's not too expensive and might... MIGHT not be as subject to price flux. I think for people like me trying to get a turbocharged motor that can still get good effiency off boost it might be a very good option to look into.

 

So what else does everyone know about performance with ethanol?

[Flexicoker]

My Formula SAE team ran a turbocharged CBR250RR (250cc 4cyl, 20k redline) on E85. I believe we were pushing 15psi boost, on the factory 11.5:1 compression, and relying only on the latent heat of vaporization of the ethanol to cool the air. It worked most of the time, but we had many "spontaneous crankcase ventilations" There were some engine management issues involved as well, but I think it probably needed an intercooler at those power levels. 72hp out of 250cc is quite alot.

 

Online you can find some 0-60 tests of flex-fuel tahoes, and the times are better on E85, so you don't 'need' more compression to make more power, but it will certainly help.

 

I've been blending my gas with E85 in my (non flex-fuel) daily driver camry, and I'm up to 40% ethanol without any issues, I've yet to finish a tank and check the mileage though.

[Gollum]

Well, it seems to be pretty consistant that the lower compression engines can still make good power with more ethanol... but you're burning a lot more due to the richer stoich and best power ratios.

 

I'm thinking that if you want the maximum efficiency (mileage) AND best power, higher compression will be a must for the ethanol biased mixtures.

 

I'd like to know what kind of gas milage difference you're seeing in your camry, considering that many people see their mileage severely drop. My conclusion on this is that the ECU isn't advancing the timing enough to take advantage of the extra fuel.

 

 

Something I'd read online that seemed kinda sketchy to me, that was a quote from a book no less, said that between the main fuel options out there right now there was less than a 2% difference in power yield. I'm really curious as to what the author really ment or was trying to prove. Maybe that three engines of similar technology, opimized for their fuel, only so a 2% or less difference in power for a given volume of fuel.

 

Sounds kinda.... hogwash like a lot of the stuff out there.

 

Oh, by the way... those are some SERIOUSLY impressive numbers for 250cc.

[grumpyvette]

youll need about 12.5:1-14:1 cpr and run the fuel thru at about 35%-40% higher rates in the air/fuel; ratio to maximize the alcohols potential,(depends on the blend, but are you aware alcohol tends to screw up many rubber,plastic, steel and aluminum parts? are you aware ethanol absorbs moisture from the air?

 

In other words, for the same energy content as one liter or one gallon of gasoline, one needs 1.6 liters/gallons of ethanol , Although actual fuel consumption doesn't increase as much as energy content numbers indicate. because the compression tends to be lower and the fuel is a mixed blend of the two, which is nearly mandatory to prevent corroasion, on the plus side emissions tend to drop and the engine tends to run cooler.

run a high alcohol content and RUST and corroasion in your tanks, fuel lines and carbs/injectors can be and frequantly is a problem

[Gollum]

Thanks for the input grumpyvette. I knew about the corrosion aspects of alcohol, and was planning on staying around a E85 mix for that reason. And of course switching out what ever parts of the fuel system need to be (rubber obviously).

 

The moisture absorbtion shuoldn't be too big of a deal. I don't really ever have a tank that lasts more than a week.

 

Fine points to bring up that I'd skipped over.

[Flexicoker]

Until there was an E85 station within a reasonable drive we used to mix denatured alcohol and gas to make our fuel. We did it 5 gallons at a time though, so I don't know if it was the most cost effective method of doing it. In formula SAE if you run gasoline you have to run a 20mm air restrictor, and if you run E85 you run 19mm, so that sort of shows the power output difference. As far as gas mileage 1.6 was the factor that they used as well to normalize the fuel efficiency of the gas and the E85 cars.

 

I think that the vast majority of reasonably modern cars will not have a problem with corrosion due to the ethanol, Brazil has been running a significant amount of ethanol in all of their cars for a while, and all gas here has 10% ethanol in it. I plan to do flex-fuel on my 240Z with my megasquirt soon. I will probably only coat the gas tank, as it will have new rubber and stainless fuel lines already. I may or may not do something with the fuel rail, and I'm just running a normal walbro pump. I'm assuming that the injectors are all stainless, so that shouldn't be a problem.

 

http://www.megamanual.com/flexfuel.htm

 

Aluminum parts should be anodized, and steel should be stainless or coated. All new rubber fuel system parts should be compatible and I have heard that the walbro pumps, while not flex-fuel, will do just fine. JB Weld is NOT compatible... I know from experience.

[f430360e]

I've ran 40% blends in my 1992 celica gt before (2.2L 4 cylinder) and it ran fine. I lost 1-2 mpg in my mixed mileage. The last time I put fuel in it I put in 3 gallons of E85 and the car was on empty, so it's probably 3 gallons E85:1.5 gallons of gas.

 

It ran fine, started fine, idled fine. Didn't throw any O2 sensor codes. I advanced the base timing a few degrees to give it some more pep.

 

I also have a Toyota MR2, and most people who want to try running E85, just switch to 550cc injectors, and rely on the overly rich stock tune to get the necessary fuel.

[grumpyvette]

I used to run a mix of METHANOL and TOLUENE in my BBC race engine, trust me on one thing, alcohols VERY coarrosive, and absorbs water like a sponge.

it makes the engine run much cooler and if you get the fuel/air mix just right it produces very good power, easily 10% better than pure gas, and detonations almost a non-factor with that mix.

[Gollum]

I didn't even know what toluene was and had to look it up. Thanks for that rabbit trail.

 

What type of ratios were you using in this methane/toluene mix?

[woldson]

Hey...

[Gollum]

Hey...

 

What can I say? I think you're onto something.

 

For those that don't know, I was talking to woldson recently about running ethanol on a L28ET. His interest in it sparked an already growing interest of mine for ethanol.

 

I have to admit though, I'm still kinda doubting if I'll go ethanol on my engine because I simply might not be able to get the compression I want on a budget. 9:1 simply won't be high enough to really take advantage of the fuel I think.

[grumpyvette]

"What type of ratios were you using in this methane/toluene mix?"

 

13.7:1 and 13.9:1 on the two BBC engines I built to race with, in my 1968 vette,

 

btw

 

http://www.team.net/sol/tech/octane_b.html

 

http://www.gnttype.org/techarea/misc/octanebooster.html

 

http://www.elektro.com/~audi/audi/toluene.html

 

mixing the two and adding it as an octane booster to race gas vertually eliminates detonation but get a bit to much and throttle responce suffers when the compression ratio and cam are not high enough and your jetting the EFI or carb to match the air flow is mandatory and keeping the engine hot enough can be a problem untill you get some experiance ballancing the factors, and ignition curves will necessarily change, but get it right and youll have a very powerful combo, keep in mind methanol or ethanol alcohol run much cooler and richer a/f ratios, youll spend a good deal of time tunning and don,t forget to flush the fuel lines with gas after, letting ethanol or methanol sit and collect moisture screws up aluminum fast!

[TimZ]

I used to run a mix of METHANOL and TOLUENE in my BBC race engine, trust me on one thing, alcohols VERY coarrosive, and absorbs water like a sponge.

it makes the engine run much cooler and if you get the fuel/air mix just right it produces very good power, easily 10% better than pure gas, and detonations almost a non-factor with that mix.

 

Just for the record, methanol is far more corrosive than ethanol. Most modern fuel lines are not made from rubber any more, and it's not too hard to find hoses that are compatible.

 

For my E85 conversion, I ended up having the aluminum bits in my fuel system anodized, replaced the injector o-rings with viton rings and had the fuel tank cleaned and coated.

 

So far I the only issue I have noticed is that the hardware store teflon paste that I used on a couple of fittings got dissolved by the ethanol. The higher quality teflon pastes don't seem to have this problem.

 

As far as power goes, there is a noticeable difference (i.e., more ), and the flammability limits of E85 are wider, so I can cruise at considerably farther north of stoich than I ever could on gas. I'm able to run 11.5 to 12:1 AFRs on cruise, which is equivalent to 16.9 to 17.6 on gas.

 

Also, while not good for fuel economy, e85 continues to make power all the way down to around 6.97:1 (like 10.4 on gas)

[woldson]

Your a mighty man Gollum. Hopefully this thread you have started will give me more insight for future applications;) ROCK ON!!

[a6t8vw]

I'm in the process of converting my turbocharged sbc Z to e85. Should be up and running in 2 months.. e85 is a poor mans race fuel!

I wouldn't convert a n/a car to e85, The real benefit to be had is the forced induction cars.

Yes higher CPR is good but more boost can be better.

 

My problem is the closest E85 fill station is 1 hour drive away..

i plan on filling a 55 gal drum at a time until they build a fuel station near me.

anyone know the shelf life of e85?

 

andy

[Soundmasterg]

This thread is really interesting....I'll be following it.

 

 

Greg

[thehelix112]

http://www.drivingethanol.org/motorsports/racing_fuel_characteristics.aspx

 

Dave

[ktm]

Not to discount running E85, but why not simply run an ethanol or methanol injection system? You do not have to convert your fuel system, you only use it under boost, you get the economy of gasoline, you get more power than E85 when tuned, and for forced induction motors you get the added benefit of a cooler intake charge. Add some water into that methanol mix and you get some benefits of in-cylinder cooling.

 

I am truly curious and not saying that methanol injection is better, but asking why opt for E85 over it.

 

E85 is, simplistically, gasoline with 15% ethanol.

[TimZ]

Not to discount running E85, but why not simply run an ethanol or methanol injection system? You do not have to convert your fuel system, you only use it under boost, you get the economy of gasoline, you get more power than E85 when tuned, and for forced induction motors you get the added benefit of a cooler intake charge. Add some water into that methanol mix and you get some benefits of in-cylinder cooling.

 

I am truly curious and not saying that methanol injection is better, but asking why opt for E85 over it.

 

E85 is, simplistically, gasoline with 15% ethanol.

 

No you've got it backwards - E85 is Ethanol with 15% gasoline in it. I'm pretty sure there is no power advantage for Ethanol or Methanol injection over E85. I wouldn't have bothered if it had just been 15% Ethanol. Plus - it's "pump gas" (more accurately "pump fuel"), so there is no secondary tank that will cause my more to run lean if it runs dry.

[(goldfish)]

Hey...

 

What can I say? I think you're onto something.

 

For those that don't know, I was talking to woldson recently about running ethanol on a L28ET. His interest in it sparked an already growing interest of mine for ethanol.

 

I have to admit though, I'm still kinda doubting if I'll go ethanol on my engine because I simply might not be able to get the compression I want on a budget. 9:1 simply won't be high enough to really take advantage of the fuel I think.

 

Either use a large turbo and high boost, or use then Maxima head for higher compression. ( i forget what that gets you with dished pistons)