Gains from Ethanol..

[Flannelman]

It is my understanding that Ethanol increases power by reducing intake temperatures. While a fair power comparison is between 98 and E10, by all rights E10 can take 1-2 degrees more advancement because of this cooling effect.

As a point of interest, E85 has been found to have an octane rating of 96. However, the octane test is very unfair as it requires the intake temperature to be set. I dont remember the exact temp but its close to 40C. Everyone who uses E85 knows that the true octane is much higher. Boost pressures, compression ratios and timing all support this.

So, how much horsepower can be made on any ethanol fuel? It will depend apon the application its put in. Obviously the more ethanol, the more power potentual there is. Turbos work the best from the cooling effect on the intake charge. This also rolls through to the exhaust turbine as the exhaust gasses have greater force to spool the turbo earlier and harder delivering more boost. They are also the cheapest as N/A requires an increase in compression which means new pistons.

Add compression to boosted engines and the results are magical.

[Lith]

As a point of interest, E85 has been found to have an octane rating of 96. However, the octane test is very unfair as it requires the intake temperature to be set. I dont remember the exact temp but its close to 40C. Everyone who uses E85 knows that the true octane is much higher. Boost pressures, compression ratios and timing all support this.

That is interesting - what is your source on the octane test of E85? What E85 did they use, and what base petrol did they use for the test? I'd always understood "typical" E85 mixtures to float between 104-106RON.

Now that I am thinking about this again, I figure I might share an observation I've made tuning with ethanol that I might share for discussion or interest (if there is any). I've seen gains of up around 30% tuning a car from E85 over petrol at boost levels of around 18-20psi, while the gains are more like 5% over petrol on a naturally aspirated setup.

The interesting point about that is that I usually find that when tuning on petrol I find that when adding boost the gains are fairly relative to their pressure ratio versus what they'd make naturally aspirated.

As a disclaimer this is a hypothetical example based off things I've experienced tuning with ethanol blends... more for discussion and I've not ACTUALLY tested this specific combination so much as created a situation from things I *have* seen and tried.

Say we have a naturally aspirated Honda making around 130kw @ wheels gets a turbo added and then tuned to run 12psi (pressure ratio ~1. with a suitable turbo attached then makes around 240kw @ wheels - ie, 80% more power... pretty much around the same as the pressure ratio.

Now same car is built up example the same, but it's running E85 - makes 139kw @ wheels while naturally aspirated but then when the turbo gets added and it gets tuned on E85 it makes 290kw, or 2.1x as much as it had without a turbo.

Quite an interesting phenomenon if you ask me... imho not one you can link to cooling effect as arguable all that'd be doing with increased boost would be negating some of the temperature increase of the charge air versus ambient from squeezing it and ambient already had ethanol squirted into it as well.

[Flannelman]

Food for thought. The Octane test info was from another website.

As for the E85 Honda example, I would guess that the fuel increased by the same amount as power gained. If so, then I would be looking at the oxygen in the ethanol adding more power in the same manner as NOS. Thinking about it, both have similar effect on an engine by cooling intake charge and delivering oxygen in a chemical fasion. The difference is that NOS only assists combustion rather than be combustible.

Just adding to the discussion.

[Lith]

As for the E85 Honda example, I would guess that the fuel increased by the same amount as power gained

Are you saying that say a 30pc increase in fuel requirement would be matched with a 30pc increase in power? If so then no, the power increase is less than the increase in fuel needed. Substantially less. The power gains versus increase in fuel requirements seems to drop as the ethanol percentage increases too

[sergei]

Food for thought. The Octane test info was from another website.

As for the E85 Honda example, I would guess that the fuel increased by the same amount as power gained. If so, then I would be looking at the oxygen in the ethanol adding more power in the same manner as NOS. Thinking about it, both have similar effect on an engine by cooling intake charge and delivering oxygen in a chemical fasion. The difference is that NOS only assists combustion rather than be combustible.

Just adding to the discussion.

The Oxygen in ethanol is bonded to one carbon and to one hydrogen.
The Carbon bond is single.
So here are the numbers:

O-H bond is 464kj/mol
O-C bond is 360kj/mol
as contrast here are carbon hydrogen and various carbon-carbon bonds:
C-H bond is 414kj/mol
C-C bond is 347kj/mol
C=C bond is 418kj/mol
C:::C bond is 946kj/mol
O=O bond is 498kj/mol


To disassociate O from alcohol we need to break O-C bond which will require 360kj/mol. If that is being recombined with H (to make water) it will produce 464kj/mol, with net positive change of 464-360=104kJ/mol, now this H has to come from somewhere, and it comes from C-H bond (414). So to really disassociate O from alcohol we need to spend 414kJ from breaking up a C-H bond and 360kJ a C-O bond. which nets to 464-(360+414)= - 310kJ.
Basically having oxygen in alcohol does not give us any net gain from burning alcohol+petrol mix, but in fact costs us energy (this is why we require more alcohol to produce same amount of power relative to petrol).

TL;DR: Oxygen is already bonded in alcohol, thus does not add energy to the equation.

[steroidcontaskie]

Ok, how about a specific question.

I have a 2jzge turbo conversion, still 10:1 compression, with a water-methanol injection system and 550cc injectors that is about ready to be dyno tuned.

Am I better off to go with BP98 or put E10 from gull in the tank. I am guessing that the BP 98 will have more energy density, but will the E10 have better detonation suppression?

Cheers
Edward

[sergei]

Ok, how about a specific question.

I have a 2jzge turbo conversion, still 10:1 compression, with a water-methanol injection system and 550cc injectors that is about ready to be dyno tuned.

Am I better off to go with BP98 or put E10 from gull in the tank. I am guessing that the BP 98 will have more energy density, but will the E10 have better detonation suppression?

Cheers
Edward

What I have been told by Torque Performance, when I tuned my GT4 (550cc injectors, CT20b, 195kW at the 4 wheels) is that it would not make any noticeable difference running BP98 or Gull E10, the only thing is I would get less soot from Gull. Although saying that, my tune is for max torque and is on the safe side.

[Lith]

I have a 2jzge turbo conversion, still 10:1 compression, with a water-methanol injection system and 550cc injectors that is about ready to be dyno tuned.

Am I better off to go with BP98 or put E10 from gull in the tank. I am guessing that the BP 98 will have more energy density, but will the E10 have better detonation suppression?

I guess it depends on how much you are going to rely on WMI and how hard you are going to push the overall setup. If you have a decent WMI setup and will be using it whenever you are pushing it then I'd be tempted to just leave the underlying petrol tune to BP98 for a good decent octane base and then use WMI to combat knock etc. E10 uses 95octane as a base and you'll have a constant slight loss in economy - yes you can make a little more than BP98 thanks to the ethanol content but what is the point when you are going to be pouring methanol down it's gullet when on boost and only when on boost?

[steroidcontaskie]

Cool, sounds like BP98 is the way to go.

Cheers
Guys

[Flannelman]

No, apples for apples. The E85 Honda went from 135kW to 290kW with addition of the turbo. Did fuel use go up 2.1 times as well?

As point of comparison, the petrol Honda increased from 130kW to 240kW. Did fuel use go up 80%, the same as the power increase?

If the data is avalible, then this will show up the engines thermal efficiency through Brake Specific Fuel Consumption.

[Lith]

As point of comparison, the petrol Honda increased from 130kW to 240kW. Did fuel use go up 80%, the same as the power increase?

Nope, fuel usage went up around 100% - you use richer mixtures with boost if you want to keep things reliable.

No, apples for apples. The E85 Honda went from 135kW to 290kW with addition of the turbo. Did fuel use go up 2.1 times as well?

Close - but roughly the same relative increase as petrol which gained less power.