I seen your post on the phone and I had 10 different ways I was going to answer. Now after rereading I agree totally that E85 or higher blends will produce 100 HP per liter but Honda doesn't have one available. The only way to get that HP on gasoline with the 1.5 is to have a dual cam cylinder head with the engine capable of 8000 rpms or turbo/supercharger.

Honda is slow bringing the tech here because they're trying to get there moneys worth and the US cars were behind and this gives them a change to catch up but Honda fell asleep and now trying to catch up.

 

Because the heat of combustion for E85 is much lower than pump gasoline it will be very difficult to get 100 hp/liter from E85. E85 has only the hope of tolerating more compression than gasoline to get to 100hp/liter.
Try the Corvette 600 + hp on 6.2 liters or the Honda S2000 (200+ hp on 2 liters) to see just how gasoline gets 100 hp/liter and you'll find neither are recommended for E85 fuels for track use.
For any given fuel intake the one with the most Btu per pound will always win. E85 doesn't cut it.

 

Your own comment alludes to something you're not taking into consideration.

Yes, E85 has fewer BTU's per pound than E10. A pound is a unit of weight. However, the energy density of a fuel has very little to do with how much power one can extract from it. This is because engine characteristics also determine how much energy can be extracted from the fuel put inside.

Would you dare to put 87 octane fuel into a high-boost turbo engine? Why not?

Different engines have different characteristics. Some fuels are better suited to some engines than to others.

As you mention, E85 has a higher knock tolerance. This means it is well-suited to higher-compression engines. Higher compression ratios mean more energy extracted from the combustion process, which means more power and higher efficiency. Of course, the same could be said of 93 octane E10, but it has a higher energy density. 85 or 87 octane fuel is not well-suited to such engines, however, so the efficiency of a high-CR engine may well be better with E85 than with 87 octane E10. This brings me to the real point.

E85 has only one meaningful inferiority compared to any other E10: lower energy density. In virtually every other respect, it is superior, from the lower emissions, to the possibility of better sustainability (corn foolishness notwithstanding), to keeping engines clean.

Now, if the only cars available had low-CR engines, OR if the only fuels available were 93 octane E10 or E85, and assuming they were the same price, I would probably go with the E10, since I could go further on that than with the E85.

Reality is quite different, though. The BTU per pound is not always proportional to the miles per BTU in every car. Further, with oil and E85 subsidies, the price per gallon--at the pump--is not always proportional to the price per BTU, which is not always proportional to the price per mile.

In short, that's why this debate even exists.

By the way, I got about 42 MPG on my last tank of E70 (3.2 gallons 87 octane E10 @ $3.78/gallon plus 8.1 gallons E85 @ $3.50/gallon) That came at a cost savings of about $2.24 over 87 octane fuel, but saving about $4.00 over 93 octane fuel. 87 fuel gives me about the same mileage as E70, but worse than 93 octane.

Recently, I also got a 93 octane E10 tank, and with some extraordinary hypermiling, I got 49 MPG, followed by another of about 45 MPG. My current tank of 93 octane E10 is shaping up somewhere between the two previous ones.

By my envelope calculations, with MY driving style, and with MY car, E70 is about break-even with 93 octane on a per-mile basis, to within a dollar per tank. 87 is cheaper where I live, and I think on a per-mile basis it's slightly cheaper for me as well (again, probably within a dollar per tank), but the slightly worse mileage and the dramatic power drop give me reason to spend a little more for the fuel that's better suited to me and to my car.

Your mileage may vary.

 

Not true. BTU is just a measure of how much heat they contain which is their energy density not how efficient they are in an Internal Combustion Engine. Don't forget that alcohols contain large amounts of oxygen which while it adds weight without increasing energy density also decreases intake and combustion temperatures and helps resist knock or predetonation.

Diesel is the biggest factor for Food prices and not because of the amount of diesel used in farming which is insignificant compared to how much diesel is used in trucks to deliver groceries. Plus manufacturing costs are far more expensive than agriculture. The price for corn can double and the store cost for a box of cereal will only change 10 cents max. Corn meal is obviously different but after milling, packaging, and delivery it's still far less of the total cost than you would think.

I believe we need to work harder, pay more per BTU if necessary, and make sacrifices to stop all Energy imports. It's not just about security and local economics, cheap foreign Oil could be used in countries where development is low and cheap Oil would get them going. We're in a far better position to work around expensive fuel, after some major changes, than a third world country. The boom we got from cheap Oil might be over but that doesn't mean we should stop growing our economy.

The Lea in the CR-Z is a piece of work, it is not a hi-tech marvel as much as an example of simple elegance and efficient engineering. The CR-Z is making headway and people are getting 40's-50MPG in that heavy tub of a sub-compact.

Yes actually I have heard of the FR-S/FT-86 . I need to add my avatar for this forum.

 

As a retired engine combustion engineer who has run thousands of power and mpg tests within emissions requirements I can assure you that the less Btu per pound or cubic centimeter the less power and mpg you will get. The difference is virtually exact proiportioned to the btu per pound on a given engine. There are things that can be done to make a vehicle use the Btu more efficiently but as long as the engine and drive is not changed between comparisions the more energy in the fuel the higher the power and economy.
The tolerance for antiknock properties of E85 fuels is greater but not by enough to make a radical difference in power or mpg WITH COMPRESSION.
Regardless of any idea of utilization of energy, any given engine and drive train/aero will get more with higher btu per pound fuel.
This past weekend I had to make a trip to VA where ethanol gas is required AND I too had the chance to evaluate my mpg and power. On the same trip going on gasoline I got 11.6 seconds 60 to 100 mph and returning on E85 I got 12.1 seconds. Both involved an average of 3 trials ON THE SAME LEVEL GROUND. As far as gasoline mpg vs E85 there was a 1.8 mpg in favor of gasoline, but thats stricly guesswork because tho going and coming on the same route there isn't enough precision data to compare. It takes a computer controlled test schedule.
No one can match the precision required with a driver vs a computer. So until you test with precision test procedures your 'testing' is biased.

 

mahout is right. It all boils down to energy content per unit volume.

Also to support an identical amount of mass airflow, especially under "high boost," you need up to 50% more E85 than gas depending on what the motor likes and I consider "high boost" to be over 30psi on a 9.0:1CR or greater motor.

Stoich is ~9.8:1AFR for E85, and ~14.6:1 for pure Gas. An NA motor switching to Gasohol of any concentration (E10-E85) will lose power and fuel economy will suffer even with a more aggressive timing scheme and leaning out.

There is just less energy available in a comparable volume of ethanol vs. gas..

So not only are you down on power, but you are using more fuel to go the same distance with less power. Lose-Lose, IMHO.

Because your compression ratio doesn't change you cannot really take advantage of ethanol in an NA.

There are advantages in a boosted setup because the ethanol can absorb more heat from the incoming charge than gas, is less prone to knock and can run leaner in terms of lambda which can put you closer to it's "Max Power Rich" range.

Using a gas scale UEGO, under "high boost" with gas you would typically have to run in the high 10's - low 11.x:1AFR range and pull timing.

On that same gas scale UEGO you can dial in more timing and run as lean as 12.0:1AFR on E85. This is where you pick up a ton of power at the same boost. Even then you can usually run yet more boost as long as your fuel system can support the sheer amount of fuel you will need.

 

Like I said before there is variables on top of variables. Ethanol is the reason the compression ratios are coming up and ethanol takes up volume so there is more pressure in the combustion chamber. MEP in a Honda is around 175 and with a 10.5 compression ratio with 100 percent efficiency would be 195. The extra volume raises the volumetric efficiency so it leans out. Thats why S&D is able to run so much ethanol because at 11 fuel air at loads over 70 percent it leans out and you can run as lean as 16.8 before power drops. Higher octane allows more timing at full throttle and leaner mixtures for a more efficient running car at loads over 70 percent. Running lean causes more heat but if theres no knock then it should not hurt the motor.

In my GD3 it would run in close loop even on the dyno.

Every brand and fuel has a air fuel ratio that it burns complete. C16 for example is used a lot in racing because it has a fuel air of 14.8 so tuning a car is easy. Here is some reading http://www.tomorrowstechnician.com/a...and_hooch.aspx

 

@DSM: what would happen if you put 87 octane fuel into an engine like you described, that is, running 30 PSI boost in a 9:1 CR? Specifically, what would be the effect on power and efficiency versus 93 octane fuel?

Keep in mind that 87 octane E10 and 93 octane E10 have nearly identical energy density.

 

I give it about 33 seconds to spectacular detonation or maybe 3 minutes if run 10 seconds at a time. Either fuel. I could sell lots of tickets to watch that. Drag racing audiences do that regularly.

As far as comparing 87 octane with 93 octane though the difference is 17k Btu/lb vs 112k btu/lb, the density is only 1 to 2% different due mostly to toluene and additives content. The density of ethanol is .789gm/cc and the density of both 87 and 93 octane gasoline is .725 to .765 gm/cc.
Even if the ethanol content is 15% (E85) the density is about .745 gm/cc yet the heat of combustion is reduced by 15-20%. Besides the corrosion potential of E85 the reduced energy available and the large increase in cost any alcohol diluted fuel, the result is the illegitimate pregnancy of the 'green' movement.
There's nothing to keep in mind.

 

I assume you meant 117k BTU/lb for 87 octane and 112k BTU/lb for 93. I can't tell in your second paragraph if you're talking about ethanol 15% (E15) or ethanol 85% (E85). I won't even bother refuting your assertion of corrosion potential since you can find that on Youtube. (Incidentally, gasoline corrodes some materials; nobody's scared of gasoline corrosion.)

Back to the main point: you say that about 33 seconds of 87 octane use in a 9:1 engine with 30 PSI boost will likely destroy the engine. Think about the implications of that statement. You're effectively saying that despite the higher energy density of the fuel as compared to E85, the power extraction potential of 87 octane E10 effectively drops to zero after 33 seconds for that engine. So, then, more is involved than simply pouring something into a chamber and igniting it. How and when and how quickly and how easily the fuel burns also are factors in the ability to extract energy from the fuel. Furthermore, the design of the engine is a factor, as you just confirmed. If the engine is not capable of sustaining the forces in the cylinder and converting those forces into usable torque, then power output drops to zero regardless of the energy density of the fuel. Imagine using nitroglycerin as a motor fuel.

I will also mention that nitromethane has only about 1/4 of the energy density of gasoline, but is used for extremely high-power applications because of the way it burns in extremely high-boost engines.

 

After 33 seconds of 2 atmosphere intake the engine blows up. Whats that have to do with energy density?
Correct that I mistyped 17 instead of 117 but the higher heat of combustion is for 93 octane not 87. Generally pump high test yields slightly better mpg than pump 87 octane but not enough to justify the cost..
Anytime you load a 9:1 compression engine with 30 psi you have effectively tripled the combustion pressure and it better be a very heavy built diesel engine to handle that. Many dragsters do build engines to operate under such conditions but then only for 10 seconds with rebuilds every run or two.
The straight fact is the more the heat of combustion the greater the power and the more fuel you cram into the combustion chamber the bigger the explosion. Period. If the explosion is not properly controlled no amount of words will excuse the result. A lot of research has gone into the better mixtures of chemicals that make better gasolines, all based on heats of combustions spread over a single piston stroke. There is no energy density involved.
Sure you can dilute the charge such that the combustion takes a week to complete but that defeats the purpose of completing combustion in one piston stroke.
Nitomethane is a catalyst. Seen any nitromethane only fuels?
As far as corrosion is concerned a good deal of development has gone into seals that withstand ethanol diluted fuels and there are still problems. Consult SAE documents instead of internet proposals. Its the water absorbtion that goes with ethanol. Gasoline not antwhere near the problem with ethanol in engine fuel systems.

 

You lost me when you say explosion. Fuel burns not explodes like in a grass fire where the flame moves out from the center. Explosions are bad which is detonation. Pre-ignition is like compression knock like in a diesel but at the wrong time.


Not all the fuel burns when its richer than 14.7, yes best HP is 12.5 and 13.2 for max brake torque and 13.4 to 13.8 is lean brake torque. But the extra fuel is to cool the pistons and air charge at the same time building more pressure because of the added volume.


Ethanol carriers its own oxygen and fuel so more power is made. Leaner mixtures burn hotter so it could knock but not like gasoline.

Last year someone had their car tuned and took it out on the highway and ran full boost for a few miles and the engine blew and tried to blame the tuner. So your statement of 33 seconds is close. Most tunes are for the 10 seconds at a time.

 

Okay I think we are getting ahead of ourselves here...

Lets pick an example platform and go with it as that will keep things from getting further confused.

If we are going to start discussing Nitromethane cars, real high boost and drag racing we have to nail down the basics first and tuning Nitromethane is nothing like the other fuels.

Ok so first lets pick ONE platform, intended use and then compare fuels. Here's one we can all relate to:

Platform:
N/A 10.4:1CR
Daily Driver

Atmosphere:
70* IAT's, sea level and ~20% Humidity

Fuels to be compared:
E85 105octane, E0 93octane & E0 87octane

Now lets go from there S&D

You are interested in what will return the best performance AND economy?

In this scenario 93 E0 would be the "best," followed by 87, and then E85.

Now we are assuming a few things to make this a level playing field, the biggest being that the fuel system can handle the volume of E85 required.

If you left everything else the same, but boosted that motor it would have E85 with the most power potential but dismal fuel economy, with 93 being the option for peak economy while able to support some boost and at least high single digit peak spark advance. And then 87 a distant third place in terms of power (low boost w/ no timing & pig rich just to survive) and similar economy to 93.

This is an extremely watered down explanation of course.

 

Thanks for getting us back on track.

That's the point I've been trying to make: energy density is not everything when it comes to fuels under all circumstances, since the engines we use are such horribly convoluted devices. They're extremely sensitive to knock, and as such, you have to take the octane rating into consideration when evaluating any fuel. As you mention, 93 will do better than 87 in some engines, even though the energy density is almost identical.

I should mention that, in my experience, E70 seemed to do better than 87 octane E10 as far as torque. I don't know if this was due to the knock resistance, the extra charge cooling, or the leaner mixture. Fuel economy was only about 6% lower than 93 octane E10.

By the way, I haven't found any stations nearby that sell E0 -- only E10.

@mahout: 100% Nitromethane has been used for many years in Top Fuel drag racing up until a few years ago. The mixture was changed to <=90% for safety concerns. It's actually a monopropellant, if I understand correctly, which means it can burn in the absence of oxygen.

 

Yeah, after reading all that you said you have no idea about E85 or alcohol fuels. Energy density is not the same as energy efficiency or potential power per lb when talking about alcohols vs petroleum. What you are saying is true for identical fuels with different BTUs but it has been proven that Premium is better than Regular for MPG but it's not always cost effective.

E85 isn't required in any states, that is Ethanol(typically 98% dry Ethanol with a denaturant) and the legal limit is 10% called E10 or gasohol! Don't spread misinformation!

If you knew more about Alcohols you would know that BTUs per gallon doesn't tell the whole story. And E85 is capable of supporting significantly higher dynamic compression than pump gasoline, like 13.5:1 N/A or 12:1(with only E50 boosted direct injection) and boost. Race gas is more comparable but we're talking 110-C16 levels but then the biggest difference is you pay up to $10 a gallon for it and it is not street legal.

I've already linked to a good academic study of the efficiency of Ethanol and Gasoline blends and their octane when mixed at the pump. It's absolutely silly to say that any pump Gasoline can beat Ethanol in any performance aspect besides BTU per gallon(which is not relevant) or $ per BTU(which varies) once you've read that article. I'll link it again for you: Energy efficiency and Power of Ethanol blended fuels http://delphi.com/pdf/techpapers/2010-01-0619.pdf

That's not true. There are several stock Gasoline engines capable of 9:1 Static Compression with 2 Barometric of boost. If you search for the "S2000 from hell" you can find a Honda S2000 with stock internals and the stock 11:1 SCR engine that was boosted to 2 bar and daily driven .

DiamondStarMonsters, you can't do that just no.

 

After looking at the Delphi PDF, it shows 9.2 compression is knock limited at 1500 rpm on regular but why did they not use 10.4 instead of 11.85. I would believe regular would be knock limited with 10.4 at more points and maybe E10 too. The higher ethanol blends with lower octane is the limit of most stock ecus and used for comparison I believe. I also wish the premium octane was higher but 93 octane is with ethanol and HO is with out at 91.6.

 

They used a custom set of pistons and adjusted the valve timing and spark ignition to the peak points including setting spark to Max brake torque. Most engines don't run Stoichometric to those kinds of loads so that's why some points didn't even run without predetonation. I'm also disappoint that they didn't use a 4th set of pistons for that 10:1 area but it's really the only one of it's kind at this point. It needs more study. Especially the bit about turbocharging with high compression

But note that both E50 and E85 were almost exactly 96 (R+M/2) octane and people that run E85, which in truth varies from 70%-85% Ethanol content, get results closer to C16.

And I should probably clarify that BTU does affect MPG heavily exactly as Mahout said but higher octane can help recover a few (3-6%) percentage points of the MPG lost between Regular Gasoline and E85. Anymore would require retuning the ECU. Generally though I've seen studies that mid grade like E40-E50 get better results than E85. Like the Ricardo experimental V6, the MPG loss was far less for E40 than E85.

 

I have a better understanding now, I just want to explain C16 is used a lot not because of high octane only but its fuel air mixture that it burns completely. 14.7 is Stoichiometric and C16 is 14.8 so less fuel is needed. Here is a link that will help May « 2009 « Total Performance Solutions . Look at the archive links for more info.

 

This I think is the confusion at least for me. In closed loop (14.7) and that changes to 14.2 for e10. Then e85 is 9.61 so the math works like this 9.61/14.7=.65 so 35 percent more fuel is need to reach stoichiometric then you take the 3-6 percent gain in better mpg because you are in MBT, so its only 29-32 percent more e85 needed. There are other variables but this gets you in the ball park.

 

Don't bother thinking in different ratios. Use Lambda and only speak about Gasoline AFRs as that is the standard. Stoich is always Lambda 1.0 which translates to 14.7 on Standard Gasoline. Peak power rich is around .85 while peak BSFC is around 1.15. New cars run Stoich for everything except for high load/RPM because of the emissions of running lean or rich.

And the amount of fuel to maintain stoich with E85 increases with RPM from what I've been told by a tuner. I've heard as low as +10% more fuel for low RPM to as high as +33% at peak power. Hondatech has a good population of guys running E85 and discussing the tuning aspect. It tends to be a troll den though . That's where I found a guy running 13.5:1 Static Compression ratio with 10lbs of Boost, sadly he sold it and didn't elaborate much about it.