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InläggPostat: tis 07-05-29 12:39 
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hej alc-drivers,

in the German forums some people are discussing about the risks for the egine, esp. the outlet valves, caused by driving on E85.

some say, E85 burns cooler than gasoline, others say it vice versa.

what is the truth? does anyone have facts about the burning temp and its influence on the valves?

thx

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best wishes from here :)
Volvo V70 II on 30% E85 (just for starts) and LPG
Berti
http://www.ethanol-tanken.com
http://www.spritmonitor.de/de/detailansicht[url]/349366.html[/url]


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InläggPostat: tis 07-05-29 17:10 
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Hi Volvo-Berti

E85 burns cooler as petrol, LPG burns hotter as petrol.

With an old Volvo B18 engine that is not "unleaded ready" which I have in my camper I can drive on petrol, LPG and E85 (with diffrent jets).

On LPG I need to re-adjust valve clearances every 2000 km's with petrol every 4000 km's and with E85 I do not see any wear at all!

I'm going to make a high compression head with hardened valve seats like in any modern car of today, then there will be no wear on LPG either.

But as you can see there is now heat problem with E85 .

/Aryan


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InläggPostat: tis 07-05-29 18:18 
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aryan skrev:
Hi Volvo-Berti

E85 burns cooler as petrol, LPG burns hotter as petrol.

thats what i have read. did you have any sources? i didn't find any.

aryan skrev:
But as you can see there is now heat problem with E85 .

/Aryan

i hope you are right :)

_________________
best wishes from here :)
Volvo V70 II on 30% E85 (just for starts) and LPG
Berti
http://www.ethanol-tanken.com
http://www.spritmonitor.de/de/detailansicht[url]/349366.html[/url]


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InläggPostat: tis 07-05-29 19:56 
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A simple method of judging the combustion temperature of different fuels is to relate the heat value of the air-fuel mixture to the heat capacitivity and evaporation heat of the air-fuel mixture as well as of the exhaust gases.

Some basic (College-level) physics/chemistry knowledge and heat value tables (which can be found in engineering table books or at Wikipedia) are needed to do the calculations.

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InläggPostat: tis 07-05-29 22:20 
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Sceptics should read this..:
http://www.epa.gov/otaq/presentations/s ... 1-2743.pdf

"In addition, alcohols
generally give lower fuel heat release rates, resulting in
lower NOx emissions and reduced combustion noise [2]."


A logical problem for them thinking that the temperatures are higher, how can we then see less need for intercoolers for turbo-engines...?

Anyway;
The report shows (among other nice things) on reduced cooling losses, due to a higher efficient (not total burn duration!) burn speed and lower temperatures, giving outstanding fuel-efficiency.

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InläggPostat: ons 07-05-30 06:44 
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thanks for the interesting link to the pdf.

i find it hard to read and understand, because
1. my english is not good enough and
2. the text is filled with technical abbreveations, which i do not know.

okay, the essence is that ethanol burns cooler.

but on the other hand there is more fuel injected (and burned), so then the thermal load increases. is that right?

isn't it not possible that this load will be higher than the regular thermal load (driving benzine)?

_________________
best wishes from here :)
Volvo V70 II on 30% E85 (just for starts) and LPG
Berti
http://www.ethanol-tanken.com
http://www.spritmonitor.de/de/detailansicht[url]/349366.html[/url]


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InläggPostat: ons 07-05-30 08:50 
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Volvo-Berti skrev:
thanks for the interesting link to the pdf.

i find it hard to read and understand, because
1. my english is not good enough and
2. the text is filled with technical abbreveations, which i do not know.

okay, the essence is that ethanol burns cooler.

but on the other hand there is more fuel injected (and burned), so then the thermal load increases. is that right?

isn't it not possible that this load will be higher than the regular thermal load (driving benzine)?


You can try to get it translated by Google for instance, othervise I can try to help you out.
Ofcourse there is a limit where the injected amount of fuel is so high that the power increase is tremendous.
This is a nice extra feature with alcohol, the engine can't get enough of the stuff...;-) so you can inject much more than with gasoline.
But there are several examples both from DIY:s and OEMs that this problem will need a lot of extra power before it occurs.
Have a look att the 300 hp 2.0 l SAAB:
http://www.saabnet.com/tsn/press/070328.html
or the 814Hp BMW M3 engine...:
http://www.limmet.se/

If there was a temperature problem, I'm sure that these engines where melted immediately..

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Senast redigerad av karlmb ons 07-05-30 14:41, redigerad totalt 1 gång.

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InläggPostat: ons 07-05-30 09:04 
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Volvo-Berti skrev:
okay, the essence is that ethanol burns cooler.

but on the other hand there is more fuel injected (and burned), so then the thermal load increases. is that right?

isn't it not possible that this load will be higher than the regular thermal load (driving benzine)?


The short answer is no, the long answer is a bit of math:

A given volume of E85 represents 73% of the BTU*) (energy) value of the same volume of gasoline (= Benzin / petrol).

In a gasoline car you need a weight of air that is 14,7 times the weight of the fuel to reach lambda 1 (the ideal combustion mixture), with E85 you need only 9,765 times the mass of air compared to the mass of E85. So in other words, you need 1,5 times (14,7/9,765) the mass of ethanol in a given amount of air. But watch out, these are mass values, not volumes!

Ethanol is heavier than gasoline. The mass of a liter of gasoline is ca 737g at 15°C, the density of E85 is 780gr/l at 15°C. This means that we need (737/780) * (14,7/9,765) = ca 1,4 times as much volume of E85 per amount of air.

Now that we know that the amount of energy from burning E85 is only 73% this would mean 1,4 * 0,73 = 1,02

Aha, so the engine gets 2% hotter with E85?

Nope, because there are two more things to take into account:

A) How much fuel is needed per km:
From the energy content you would expect (1/0,73 = 1,37) that a car needs 37% more fuel to drive the same amount of distance and thus produce the same amount of heat.

In reality, a car running on E85 uses ca 30% more fuel, so you would put in 1,3 x 73 = 95,4% of energy(heat) to do the same thing! In other words, the engine gets more efficient with E85.

Now why is that? There are several reasons, one reason is that the combustion is more complete another is the ignition timing can be optimized wthout risks for detonation etc. but a very important is

B) The latent heat of vaporization of ethanol vs gasoline

The latent heat of vaporization is the amount of heat absorbed/needed to evaporate a liquid to a gas. We all know how alcohol feels cooler on the skin than water, right?

In a combustion engine liquid fuels cool the intake charge and the combustion chamber when they get evaporated. This makes the intake charge more dense and packs more energy per volume into the engine. The cooling effect also helps to stop detonation and reduces the temperatures of engine and oiling system components. This is also the reason many (turbo) engine designers make the mixture extra rich at wide open throttle (WOT), to cool the engine with fuel and to prevent overheating of the engine at full load.

The lack of the effect of latent heat of vaporization is also the major reason why gaseous fueled CNG and LPG car engines run so much hotter and produce more NOx.

The latent heat of vaporization of gasoline is ca 150 Btu/gal for E85 it is 359 BTU/gal; a given amount of ethanol cools the engine 2,4 times as much! Now if you add the fact that there is more fuel too (1,4 times as much at full throttle) you'll see a cooling effect of 2,4 x 1,4 = 3,36 as much compaired to gasoline!

No wonder why ethanol enhances the engines energy efficiency, it works as an intercooler!

/Aryan

*) BTU is a unit for the amount of energy, one btu represents the amount of heat required to raise one pound of water one degree Fahrenheit at sea level. More commonly, one btu is the energy produced by a match.


Senast redigerad av aryan ons 07-05-30 16:08, redigerad totalt 2 gånger.

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InläggPostat: ons 07-05-30 11:11 
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WOW!

that is a great and easy to understand answer for a Layman like me, too :D

and a translation of that pdf is not necessary, i think.

so my Volvo, which is a turbo intercooler, is one of that cars which are predestinated to be driven with ethanol mixtures :D

translating of Aryans text is not so difficult to me, so i can use it to argument in the german forums against the speculation of overheating by driving under E85 (or ethanol)

thank you all very much

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best wishes from here :)
Volvo V70 II on 30% E85 (just for starts) and LPG
Berti
http://www.ethanol-tanken.com
http://www.spritmonitor.de/de/detailansicht[url]/349366.html[/url]


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InläggPostat: ons 07-05-30 14:40 
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Very well written, Aryan!
Did you do it yourself or did you find out somewhere?

Berti, you could even take away the intercooler...and save some turbopressure..

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InläggPostat: ons 07-05-30 16:17 
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Thank you, yes I wrote it myself but of coarse I do not know all the figures from the top of my head so I had to look them up.

Indeed Berti, a turbo or compressorcharged engine is ideal for E85 and you could skip the intercooler, it will give you better driva ability on colder days when the latent heat of vaporization of E85 otherwise can get too much and you notice drivability issues after a cold start.

If you would be intrested in more power you could raise the turbo pressure or compression ratio too without risk of detonation.

/Aryan


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InläggPostat: ons 07-05-30 18:13 
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dismounting the intercooler?? :shock:

i even do not know how it looks like and where it is installed, i just know there has to be one because of the engine/car type
Volvo 945 tic = turbo intercooler

_________________
best wishes from here :)
Volvo V70 II on 30% E85 (just for starts) and LPG
Berti
http://www.ethanol-tanken.com
http://www.spritmonitor.de/de/detailansicht[url]/349366.html[/url]


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InläggPostat: tor 07-05-31 11:45 
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Hehe, it's in front of your radiator.
Big pipes + xpensive siliconhoses to it, guess who designed them?

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InläggPostat: fre 07-06-01 06:53 
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Blev medlem: mån 07-01-15 13:10
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okay, now i know how it works and where it is :) thanks

the turbo only really works above 3000 rpm. below that there is no effect.

so the turbo works rarely, because i don't reach 3000 rpm, only when i go faster than 120 km/h.

running too fast will cause running too lean. :roll:

it's a vicious circle, and my only way to leave is to drive on E50 or installing bigger injectors, which are rare and expensive :cry:

*shout: does anyone have injectors of a Porsche 924? :mrgreen:

_________________
best wishes from here :)
Volvo V70 II on 30% E85 (just for starts) and LPG
Berti
http://www.ethanol-tanken.com
http://www.spritmonitor.de/de/detailansicht[url]/349366.html[/url]


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InläggPostat: fre 07-06-01 08:14 
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Volvo-Berti skrev:
okay, now i know how it works and where it is :) thanks

the turbo only really works above 3000 rpm. below that there is no effect.

so the turbo works rarely, because i don't reach 3000 rpm, only when i go faster than 120 km/h.


Even more reasons to make a "bypass" so that the intercooler doesn't cool the air into the engine anymore. It will give make your car run smooth quicker after start, reduce emmissions and fuel consumption. The intercooler is only neccesary to get max power out of the engine on petrol, under partial loads and with ethanol the car will only run better with preheated air from the turbo.

Volvo-Berti skrev:
running too fast will cause running too lean. :roll:

it's a vicious circle, and my only way to leave is to drive on E50 or installing bigger injectors, which are rare and expensive :cry:

*shout: does anyone have injectors of a Porsche 924? :mrgreen:


Haven't you converted your car at all? Raise the fuel pressure with a malpassi fuel pressure regulator or install an electronic device that prolongs injector timing, than you can drive on E85 and still swich back to gasoline if no E85 is available.

I didn't tell you that in my long story above but if the engine runs too lean on E85 the flamefront gets slower and exhaust valves can get hotter too. Now I dont think that is the case but you should drive prolonged times with too lean mixtures (Lambda light on).

Here http://www.flexitune.se/pages/Installation.htm you can by a DIY elektronic kit for only 50 euro and it really isn't dificult to assemble if you can hold a soldering iron.

/Aryan


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