knock counts and water injection
10-29-2007, 09:12 PM
#31
The Impaler
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10-29-2007, 09:52 PM
#33
So is there something more to it than just the latent heat of vaporisation?
On the issue of water/alcohol injection and engine internals... this is what A. Graham Bell says in Forced Induction Performance Tuning @ page 171:
... alcohol can leave behind white powdery deposits on anything aluminium, but worse it precipitates corrosion of the piston ring lands, the piston rings and the bore wall by washing away lubricant.
This, together with Porsche not approving of even 5% ethanol for any of their engines makes me very cautious.
Any comments?
On the issue of water/alcohol injection and engine internals... this is what A. Graham Bell says in Forced Induction Performance Tuning @ page 171:
... alcohol can leave behind white powdery deposits on anything aluminium, but worse it precipitates corrosion of the piston ring lands, the piston rings and the bore wall by washing away lubricant.
This, together with Porsche not approving of even 5% ethanol for any of their engines makes me very cautious.
Any comments?
10-29-2007, 09:55 PM
#34
Formula One Spin Doctor
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I would use straight methanol , instead of water and re-map , you will be able to run without knock at the 17-19 psi level , as long as you maintain your A/F values..
Beware both are corrosive , Meth more so than water....... you will start to lose power with straight water .....with no appreciable drop in knock ...
By the way , those plugs are too old to tell you anything , replace with new, run the car and then photograph the new plugs , go as close as possible.....
Beware both are corrosive , Meth more so than water....... you will start to lose power with straight water .....with no appreciable drop in knock ...
By the way , those plugs are too old to tell you anything , replace with new, run the car and then photograph the new plugs , go as close as possible.....
10-29-2007, 10:38 PM
#35
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To clarify the cooling capabilities of water vs methanol; it's a bit of a paradox:
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Using methanol/water as supplementary injection will not cause a corrosion problem; it all gets used in the engine cycles; there's none of it that ever gets left behind.
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Using methanol/water as supplementary injection will not cause a corrosion problem; it all gets used in the engine cycles; there's none of it that ever gets left behind.
10-29-2007, 10:39 PM
#36
The Impaler
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The cooling properties remain yes, but the water is used by many for a reason. One being cost, and the effect on pumps and seals etc, but the other is that water still has better in-cylinder cooling capabilities. Not saying that in some cases running 100% methanol isn't better, but for most people 50/50 is the perfect mix.
latent heat of vaporization for methanol is about 1000kj/kg @ it's boiling point, water is about 2200 at it's boiling point.
latent heat of vaporization for methanol is about 1000kj/kg @ it's boiling point, water is about 2200 at it's boiling point.
10-29-2007, 10:40 PM
#37
The Impaler
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To clarify the cooling capabilities of water vs methanol; it's a bit of a paradox:
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
10-29-2007, 11:45 PM
#38
To clarify the cooling capabilities of water vs methanol; it's a bit of a paradox:
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Using methanol/water as supplementary injection will not cause a corrosion problem; it all gets used in the engine cycles; there's none of it that ever gets left behind.
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Using methanol/water as supplementary injection will not cause a corrosion problem; it all gets used in the engine cycles; there's none of it that ever gets left behind.
As to the last part of your post, the point A. Graham Bell seems to be making:
"... alcohol can leave behind white powdery deposits on anything aluminium, but worse it precipitates corrosion of the piston ring lands, the piston rings and the bore wall by washing away lubricant."
Is not primarily an issue with residual alcohol but, rather, one caused by the alcohol washing away lubricant.
Any further comments?
10-30-2007, 12:37 AM
#39
Race Director
Some of my opinion and some from memory in others research.
Water injection works in three ways. Water injected into the intake system (before combustion), absorbs heat from the intake air. Water has a very high specific heat rating (meaning it absorbs a lot of energy with a small amount of temperature increase). So point one in the system is the intake air is cooled. Water also has a high latent heat of evapouration (when changing state it absorbs heat). So the intake air is cooled further on evapouration, point two, and finally the water reaching the combustion chamber, steam is produced, this reduces detonation and keeps the chamber clean of carbon deposits that cause hot areas.
Some research has founf pure water is best at surpressing detonation, while a 50/50 mix of water and methanol realises greater power before detonation occurs.
Once explantion for this may be because alcohol burns slower than petrol so peak cylinder pressures occur later in the crank rotation, increasing torque.
Water injection works in three ways. Water injected into the intake system (before combustion), absorbs heat from the intake air. Water has a very high specific heat rating (meaning it absorbs a lot of energy with a small amount of temperature increase). So point one in the system is the intake air is cooled. Water also has a high latent heat of evapouration (when changing state it absorbs heat). So the intake air is cooled further on evapouration, point two, and finally the water reaching the combustion chamber, steam is produced, this reduces detonation and keeps the chamber clean of carbon deposits that cause hot areas.
Some research has founf pure water is best at surpressing detonation, while a 50/50 mix of water and methanol realises greater power before detonation occurs.
Once explantion for this may be because alcohol burns slower than petrol so peak cylinder pressures occur later in the crank rotation, increasing torque.
10-30-2007, 12:52 AM
#40
Some of my opinion and some from memory in others research.
Water injection works in three ways. Water injected into the intake system (before combustion), absorbs heat from the intake air. Water has a very high specific heat rating (meaning it absorbs a lot of energy with a small amount of temperature increase). So point one in the system is the intake air is cooled. Water also has a high latent heat of evapouration (when changing state it absorbs heat). So the intake air is cooled further on evapouration, point two, and finally the water reaching the combustion chamber, steam is produced, this reduces detonation and keeps the chamber clean of carbon deposits that cause hot areas.
Some research has founf pure water is best at surpressing detonation, while a 50/50 mix of water and methanol realises greater power before detonation occurs.
Once explantion for this may be because alcohol burns slower than petrol so peak cylinder pressures occur later in the crank rotation, increasing torque.
Water injection works in three ways. Water injected into the intake system (before combustion), absorbs heat from the intake air. Water has a very high specific heat rating (meaning it absorbs a lot of energy with a small amount of temperature increase). So point one in the system is the intake air is cooled. Water also has a high latent heat of evapouration (when changing state it absorbs heat). So the intake air is cooled further on evapouration, point two, and finally the water reaching the combustion chamber, steam is produced, this reduces detonation and keeps the chamber clean of carbon deposits that cause hot areas.
Some research has founf pure water is best at surpressing detonation, while a 50/50 mix of water and methanol realises greater power before detonation occurs.
Once explantion for this may be because alcohol burns slower than petrol so peak cylinder pressures occur later in the crank rotation, increasing torque.
So, I'm guessing that would mean water injection could be used effectively without altering the map, but to gain the added benefit of going to a 50:50 mix you'd have to do some tweaking?
10-30-2007, 02:48 AM
#42
Formula One Spin Doctor
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To clarify the cooling capabilities of water vs methanol; it's a bit of a paradox:
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Using methanol/water as supplementary injection will not cause a corrosion problem; it all gets used in the engine cycles; there's none of it that ever gets left behind.
Water will take more heat of the charge, however it doesn't evaporate as easily as methanol
(Which is the same as saying: water doesn't evaporate as easily as methanol, therefore if you get it to evaporate completely it cools much better than methanol)
Methanol evaporates easier but doesn't take out as much heat. That's why wetting your finger with methanol will feel cooler; it just evaporates quicker. But, if you evaporate the same amount of water and methanol, the evaporated water charge will be much cooler. The key is to get it all evaporated.
Using methanol/water as supplementary injection will not cause a corrosion problem; it all gets used in the engine cycles; there's none of it that ever gets left behind.
Huh! would have to disagree ...
10-30-2007, 05:14 PM
#44
Rennlist Member
Again, as far as the corrosion issue:
I don't know in exactly what context A. Graham Bell was talking about, but it seems to me that if alcohol (specifically methanol) was left in contact with aluminum, corrosion takes place.
Yes, methanol is corrosive.
But, that's not what is happening here. Water/methanol enters combustion chamber (preferably as a vapour), it gets consumed, and is gone. There is not enough contact time between the methanol and the particular surface for any corrosion to take place.
A. Wayne, what are you talking about, exactly?
I don't know in exactly what context A. Graham Bell was talking about, but it seems to me that if alcohol (specifically methanol) was left in contact with aluminum, corrosion takes place.
Yes, methanol is corrosive.
But, that's not what is happening here. Water/methanol enters combustion chamber (preferably as a vapour), it gets consumed, and is gone. There is not enough contact time between the methanol and the particular surface for any corrosion to take place.
A. Wayne, what are you talking about, exactly?
10-30-2007, 05:39 PM
#45
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