knock counts and water injection
10-28-2007, 04:05 AM
#17
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So what do we do once we stray from the stock into the darkside? What are all the other aftermarket tuners doing for other makes of cars? Do we just tune up as best as possible and hope for the best?
Is it a compromise between max efficiency and safety.
Is it a compromise between max efficiency and safety.
10-28-2007, 05:12 AM
#18
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Hi, just to be clear, the numbers are from a full throttle run from 2k rpm to redline in each case using third gear.
333pg333, I understand when you ask how much is acceptable knock, I dont know,but I would like to see zero if at all possible.However my engine is a stock 2.5 so I wont have the problems you mention, but as you said I can see it being a problem if you bore/stroke the motor.
zsboost90, I also find that you will get counts from very low load knock even when driving around with low throttle use and low revs, but from my understanding these are not to be worried about. But using the full throttle run method does produce repeatable results.
Geneqco, as far as using a water methanol mix, from checking out as much info as i can, most has come from aquamist. I know t is quite a well practiced method to use a 50/50 mix, but I am not using any at the moment because:
Methanol helps cool the charge air better as it has a lower evaporation point than water so it takes the heat out easier, it also has a higher octane the petrol/gas but it is a fuel and has no anti knock properties, it is the water that helps prevent knock in the combustion chamber.
Also adding methanol would richen the combustion mixture, which is another variable i dont want to deal with yet.
Thats not to say I may not try using it,especially when summer comes back around.
Anyway I a now off to go take a photo of the plugs.
333pg333, I understand when you ask how much is acceptable knock, I dont know,but I would like to see zero if at all possible.However my engine is a stock 2.5 so I wont have the problems you mention, but as you said I can see it being a problem if you bore/stroke the motor.
zsboost90, I also find that you will get counts from very low load knock even when driving around with low throttle use and low revs, but from my understanding these are not to be worried about. But using the full throttle run method does produce repeatable results.
Geneqco, as far as using a water methanol mix, from checking out as much info as i can, most has come from aquamist. I know t is quite a well practiced method to use a 50/50 mix, but I am not using any at the moment because:
Methanol helps cool the charge air better as it has a lower evaporation point than water so it takes the heat out easier, it also has a higher octane the petrol/gas but it is a fuel and has no anti knock properties, it is the water that helps prevent knock in the combustion chamber.
Also adding methanol would richen the combustion mixture, which is another variable i dont want to deal with yet.
Thats not to say I may not try using it,especially when summer comes back around.
Anyway I a now off to go take a photo of the plugs.
10-28-2007, 08:29 AM
#19
Hi, just to be clear, the numbers are from a full throttle run from 2k rpm to redline in each case using third gear.
333pg333, I understand when you ask how much is acceptable knock, I dont know,but I would like to see zero if at all possible.However my engine is a stock 2.5 so I wont have the problems you mention, but as you said I can see it being a problem if you bore/stroke the motor.
zsboost90, I also find that you will get counts from very low load knock even when driving around with low throttle use and low revs, but from my understanding these are not to be worried about. But using the full throttle run method does produce repeatable results.
Geneqco, as far as using a water methanol mix, from checking out as much info as i can, most has come from aquamist. I know t is quite a well practiced method to use a 50/50 mix, but I am not using any at the moment because:
Methanol helps cool the charge air better as it has a lower evaporation point than water so it takes the heat out easier, it also has a higher octane the petrol/gas but it is a fuel and has no anti knock properties, it is the water that helps prevent knock in the combustion chamber.
Also adding methanol would richen the combustion mixture, which is another variable i dont want to deal with yet.
Thats not to say I may not try using it,especially when summer comes back around.
Anyway I a now off to go take a photo of the plugs.
333pg333, I understand when you ask how much is acceptable knock, I dont know,but I would like to see zero if at all possible.However my engine is a stock 2.5 so I wont have the problems you mention, but as you said I can see it being a problem if you bore/stroke the motor.
zsboost90, I also find that you will get counts from very low load knock even when driving around with low throttle use and low revs, but from my understanding these are not to be worried about. But using the full throttle run method does produce repeatable results.
Geneqco, as far as using a water methanol mix, from checking out as much info as i can, most has come from aquamist. I know t is quite a well practiced method to use a 50/50 mix, but I am not using any at the moment because:
Methanol helps cool the charge air better as it has a lower evaporation point than water so it takes the heat out easier, it also has a higher octane the petrol/gas but it is a fuel and has no anti knock properties, it is the water that helps prevent knock in the combustion chamber.
Also adding methanol would richen the combustion mixture, which is another variable i dont want to deal with yet.
Thats not to say I may not try using it,especially when summer comes back around.
Anyway I a now off to go take a photo of the plugs.
My main concern with water methanol mix is that Porsche doesn't even approve of the use of E5 (5% ethanol) for any of its engines... as yet, no one seems to have come up with a good reason as to why (or why not).
It is the fact that alcohol actually draws the heat out so well that makes it very good at preventing knock. As for Octane... it is actually a measure of the knock resistance of a fuel... methanol actually has a lower heat value than petrol.
10-28-2007, 09:16 AM
#20
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well after spending bloody ages with my webspace i have finally managed to get it to work, pics of the plugs are here
http://myweb.tiscali.co.uk/ross255/
from left to right, they are plugs 4,3,2,1.
I took more than one photo to try and get better lighting, but its as good as i can do.
http://myweb.tiscali.co.uk/ross255/
from left to right, they are plugs 4,3,2,1.
I took more than one photo to try and get better lighting, but its as good as i can do.
10-29-2007, 04:05 PM
#21
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10-29-2007, 04:51 PM
#23
Since the engine itself would have the ethanol (or alcohol) on its surfaces (valves faces, piston crowns, intake runners) for a short time, thats not usually the issue. The issue is with the fuel lines, injectors (maybe) and the rails and pumps. It has a different electrical characteristic, which makes the pump come into question, and the rubber is not compatible with very much ethanol at all. Up to 10% is in most gas in the USA, but when you go over that, it first becomes a cleaning agent, and then could be a real detriment to anything aluminum, brass, uncoated steel, rubbers, nylon.
http://classes.engr.oregonstate.edu/...materials.html
Oh, and as mentioned, Methanol would help reduce the intake air temp quite a bit, and would contribute some BTU to the stream instead of plain water. Lowering the air temp going into the chamber would improve your air density, which therefore would improve your spool up time, as more mass coming OUT of the exhaust ports would move your turbines more. While it would lower your combustion temps in total, there would be more mass.
10-29-2007, 07:06 PM
#24
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So 5% ethanol in a 100oct mix is OK?
10-29-2007, 07:49 PM
#25
The Impaler
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Correct me if i'm wrong, but it is actually the other way around... what you said doesn't make much sense.
Water is better at dispersing heat, because it is capable of absorbing more latent heat before it evaporates. The water is much more succesful than methanol at cooling the intake charge, therefore increasing the knock threshold. The methanol is used because it cools as well as raising the octane chemically. Mixing the two creates a good balance between colling the intake charge to reduce knock and lower egt's, and actually boosting the octane of the fuel itself.
Water is better at dispersing heat, because it is capable of absorbing more latent heat before it evaporates. The water is much more succesful than methanol at cooling the intake charge, therefore increasing the knock threshold. The methanol is used because it cools as well as raising the octane chemically. Mixing the two creates a good balance between colling the intake charge to reduce knock and lower egt's, and actually boosting the octane of the fuel itself.
Hi, just to be clear, the numbers are from a full throttle run from 2k rpm to redline in each case using third gear.
333pg333, I understand when you ask how much is acceptable knock, I dont know,but I would like to see zero if at all possible.However my engine is a stock 2.5 so I wont have the problems you mention, but as you said I can see it being a problem if you bore/stroke the motor.
zsboost90, I also find that you will get counts from very low load knock even when driving around with low throttle use and low revs, but from my understanding these are not to be worried about. But using the full throttle run method does produce repeatable results.
Geneqco, as far as using a water methanol mix, from checking out as much info as i can, most has come from aquamist. I know t is quite a well practiced method to use a 50/50 mix, but I am not using any at the moment because:
Methanol helps cool the charge air better as it has a lower evaporation point than water so it takes the heat out easier, it also has a higher octane the petrol/gas but it is a fuel and has no anti knock properties, it is the water that helps prevent knock in the combustion chamber.
Also adding methanol would richen the combustion mixture, which is another variable i dont want to deal with yet.
Thats not to say I may not try using it,especially when summer comes back around.
Anyway I a now off to go take a photo of the plugs.
333pg333, I understand when you ask how much is acceptable knock, I dont know,but I would like to see zero if at all possible.However my engine is a stock 2.5 so I wont have the problems you mention, but as you said I can see it being a problem if you bore/stroke the motor.
zsboost90, I also find that you will get counts from very low load knock even when driving around with low throttle use and low revs, but from my understanding these are not to be worried about. But using the full throttle run method does produce repeatable results.
Geneqco, as far as using a water methanol mix, from checking out as much info as i can, most has come from aquamist. I know t is quite a well practiced method to use a 50/50 mix, but I am not using any at the moment because:
Methanol helps cool the charge air better as it has a lower evaporation point than water so it takes the heat out easier, it also has a higher octane the petrol/gas but it is a fuel and has no anti knock properties, it is the water that helps prevent knock in the combustion chamber.
Also adding methanol would richen the combustion mixture, which is another variable i dont want to deal with yet.
Thats not to say I may not try using it,especially when summer comes back around.
Anyway I a now off to go take a photo of the plugs.
10-29-2007, 08:03 PM
#26
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I'm not sure you're using enough water volume. I believe it should be closer to 500. Try this calculator at the bottom of the page:
http://www.rbracing-rsr.com/waterinjection.html
http://www.rbracing-rsr.com/waterinjection.html
10-29-2007, 08:40 PM
#27
Since the engine itself would have the ethanol (or alcohol) on its surfaces (valves faces, piston crowns, intake runners) for a short time, thats not usually the issue. The issue is with the fuel lines, injectors (maybe) and the rails and pumps. It has a different electrical characteristic, which makes the pump come into question, and the rubber is not compatible with very much ethanol at all. Up to 10% is in most gas in the USA, but when you go over that, it first becomes a cleaning agent, and then could be a real detriment to anything aluminum, brass, uncoated steel, rubbers, nylon.
http://classes.engr.oregonstate.edu/...materials.html
Oh, and as mentioned, Methanol would help reduce the intake air temp quite a bit, and would contribute some BTU to the stream instead of plain water. Lowering the air temp going into the chamber would improve your air density, which therefore would improve your spool up time, as more mass coming OUT of the exhaust ports would move your turbines more. While it would lower your combustion temps in total, there would be more mass.
http://classes.engr.oregonstate.edu/...materials.html
Oh, and as mentioned, Methanol would help reduce the intake air temp quite a bit, and would contribute some BTU to the stream instead of plain water. Lowering the air temp going into the chamber would improve your air density, which therefore would improve your spool up time, as more mass coming OUT of the exhaust ports would move your turbines more. While it would lower your combustion temps in total, there would be more mass.
I understnad the issues with fuel lines and pump... I've changed all mine anyway... I was more interested on the effect on engine internals (like the Alusil bores) and lubrication given its solvent properties.
Any ideas?
10-29-2007, 08:49 PM
#28
Correct me if i'm wrong, but it is actually the other way around... what you said doesn't make much sense.
Water is better at dispersing heat, because it is capable of absorbing more latent heat before it evaporates. The water is much more succesful than methanol at cooling the intake charge, therefore increasing the knock threshold. The methanol is used because it cools as well as raising the octane chemically. Mixing the two creates a good balance between colling the intake charge to reduce knock and lower egt's, and actually boosting the octane of the fuel itself.
Water is better at dispersing heat, because it is capable of absorbing more latent heat before it evaporates. The water is much more succesful than methanol at cooling the intake charge, therefore increasing the knock threshold. The methanol is used because it cools as well as raising the octane chemically. Mixing the two creates a good balance between colling the intake charge to reduce knock and lower egt's, and actually boosting the octane of the fuel itself.
As for the comparison with water... dip one finger in some water and another in metho and hold them in the air and see which feels colder... quite a pronounced difference!
10-29-2007, 09:02 PM
#29
The Impaler
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I think water has about 2x the latent heat potential at vaporization than methanol.
Not so sure about that Ryan... remember octane is simply a measure of knock resistance so I'm not sure exactly what you mean by "raising the octane chemically". My understanding is that it has such high anti knock properties (and therefore high octane) because of its ability to draw heat out of the system which is primarily how it reduces knock.
As for the comparison with water... dip one finger in some water and another in metho and hold them in the air and see which feels colder... quite a pronounced difference!
As for the comparison with water... dip one finger in some water and another in metho and hold them in the air and see which feels colder... quite a pronounced difference!
