detailed TECHNICAL info on engine (ETHANOL) modifications

[bioethanol100]

Hi,

I'm Mike from Belgium and i would like to convert my car (AUDI 80 1800S) to run on ETANOL (100% ethanol is my goal otherwise, 85% would be enough.

I tried to find informations on what the main differences between the engine of a FFV and that of a normal benzin vehicle are. It's not difficult to find information on ethanol fuel, but detailed TECHNICAL informations on engine modifications/ differences are what I can't find. Could someone give me some ideas/where to look/hints ...?

Many thanks,

Mike

 

[bioethanol100]

if it's possible, i would be very interested about the modifications on the carburetor.

and if someone has an car which run on ethanol, please share your experience with me.

tanks

Mike

 

[LateApexEE]

There really aren't any engine modifications you need to do as far as the internal hardware goes. Most of the work needs to be done on the fuel system and the engine management computer. Long story short, your entire fuel system needs to be able to cope with ethanol. While not as corrosive as methanol, ethanol still requires that the tank, pump, lines, pressure regulator, etc be alcohol compatible. Standard rubber fuel lines will be eaten through in short order.

The largest task is going to be recalibrating the ECU on a dyno. E85, while containing less energy per mass unit does have some upsides. 105 octane is nice because it allows more timing or boost or both while staying below the knock threshold (compared to standard 93 octane pump gasoline).

I have tuned a few turbo Hondas on E85 with great results. Cooler exhaust temps, more power, but at the cost of worse fuel consumption.

If you have any specific questions about the conversion, let me know.

 

[patprimmer]

Carburetor engines don't have an ECU.

You will need to ensure all materials in your fuel system, from the tank to the inlet port gaskets are ethanol compatible. Anything methanol compatible will be good for ethanol.

You will also need to ensure the fuel pump and all fuel lines and passages are big enough to flow the extra fuel required. This includes all internal passages in the carby from needle and seat to discharge nozzle and especially transfer ports and emulsion tubes.

Fitting twice as many carbies helps as it doubles the fuel flow potential, however it dies reduce signal to flow, unless you also substantially reduce the venturi dia in each carb.

You can normally get an advantage in fuel efficiency and power from a considerable increase in compression ratio when changing to alcohol.

The spark timing curve might also benefit from recalibrating.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[bioethanol100]

Hi,

I need to know exactly what should i do to convert my Audi 80 1800 s to run on ethanol.

I want you (if possible) to tell me exactly what should i do from the beginning to the end.
or if you know a internet site (or a book) that could be helpful, let me know.

thanks a lot

Mike

 

[reidh]

Patprimmer,

I agree with everything you said except that carburetted engines don't have ECUs. There are some carburreted engines that have a spark controller, which I would consider an ECU, albeit not like an ECU that is seen on modern cars today.

 

[NickE]

Mike- you might want to google more about your car, and ethanol. See if you can find an internet user group for audi/vw there is likely someone who has converted that motor already. Is it a turbo or N/A motor? I think the best gains are to be had w/ forced induction.

Pat has described the various things necessary (in general) to change a car to alcohol fuel.

In essence the Stoich AFR for alcohol is much richer... I think around 1:10 (fuel:air), and since the enthalpy of vaporization is much higher (guess) along with the flash point you can run more ignition advance and compression than with gasoline.

Thus you need to do three things: (to effectively run your car on E85, E100, etc...)

1) Provide much higher fueling to the intake charge.
2) Compress the mixture more.
3) Spark it at the right time.

you may notice lower overall fuel economy... but at least we can make more alcohol... making fossil fuels takes a long time.

Nick
I love materials science!

 

[AlkyUser]

You will need another means of starting the engine.

Gas injection, or start on gas and switch to ethanol, or preheating of the fuel or the intake charge.

I almost failed geography but if I remeber Belgium is not exactly warm. Brazil even requires altenative starting means for 100% Ethanol.

I cut my lawn with a converted push mower this summer on self made ethanol. It would not start with out a drink of gas unless it was a very hot summer day.

Below 70 degrees F ethanol will not vapourize.

It is like starting a desel in extremly cold weather. Even on a average day it will not start until there is heat in the combustion chamber.

There is lots of sites on carbruator jetting for ethanol Basicaly increase the jets cross sectional area by 29%

9 to 1 is Stoch. for ethanol.

 

[patprimmer]

If it has 14:1 compression it should start unless very cold. Compressing a gas makes it hot.

If you tip some ethanol on an impervious surface on a 70 deg F day, you will notice it drys quite quickly by evaporation, but it will get cold as it does. This drop in temperature due to evaporation is what makes it harder to start.

We do not write free DIY manuals here. If you can't figure it out from what has been supplied, by site rules, you really should not be here.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[globi5]

If you added enough water to ethanol you could probably run 20:1 compression ratio, run a diesel engine on ethanol and substituting the injection nozzles with spark plugs.
(A gasoline engine might not be strong enough to cope with that pressure.)
The advantage would be that one could increase rpm of the diesel engine - assuming the heavier rods, pistons and ultimately the crankshaft can bear that rpm.

 

[Azmio]

if your car has lambda sensor, the ECU should be able to make the necessary fuel injector adjustment. There is a catch though, at wide open throttle, the ECU will switch to open loop meaning that it will run lean because the open loop table is calibrated using regular gasoline and not E85. If you manage to sort out the material compatibility issue caused by corrosive nature of ethanol, it is possible to run your car with E85 provided that you keep your throttle below 80%.

 

[NickE]

Azimo- and then when you need that extra 20% throttle becasue you have to make an emergency move, you get to melt your pistons.

 

[Azmio]

Nicke,

at least it's possible to run it. The risk is that at WOT the AF will definitely go lean. The mitigation plan is not to go WOT.

If he wants to go WOT, buy the Flexifuel vehicle or remap the ECU.

 

[GregLocock]

And how do you avoid full torque at low speeds, which might be achieved at around 50% throttle opening?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Azmio]

Max torque can never be achieved at low speed.

I seldom go beyond 80% throttle unless I want to overtake hard or climb very steep hill. I still have an option to lower my gear rather than having open up the throttle bigger it at higher gear. With CVT and big displacement engine, going WOT is often unnecessary, even if I have to, I can shift to L.

Low speed pinging is not very destructive. You can hear it and you can go easy on throttle.

So, back to my point, it is still possible. If you want to go WOT, go buy FFV or remap your ecu.

 

[GregLocock]

You do not understand my point.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Azmio]

what do you mean by full torque? is it max torque?

Max torque can never be achieved at 50% throttle. Max torque cannot be achieved at low rpm as well.

 

[GregLocock]

By max torque I mean the full torque at that particular engine speed.

"Max torque can never be achieved at 50% throttle"

Really. Assuming by throttle you mean throttle opening, then you are wrong. If not, what do you mean by throttle? And how would you limit it to 80%?



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Azmio]

yup, i meant throttle opening. Everytime the throttle is less than 100%, it gives restriction to the airflow going into the cylinder. We could not reached the maximum volumetric efficiency of over 100%. When we could not reached 100% VE, we couldnot reached the max torque.

Anyhow, all the engines that i have worked on could not reached max torque with over 13 bar of BMEP. I'm interested to learn more about your engine.

 

[GregLocock]

Suppose you plot torque vs throttle opening at the red line.

Now plot torque vs throttle opening at half that speed.

Do you understand why there is a difference?



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.