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Old May 30, 2010 | 04:47 AM
  #101  
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Originally Posted by ttg35fort
.... Nonetheless, if you cut back on the gasoline flow as the meth flow is increased and keep the AFR in an appropriate range, cylinder washing should not be an issue..
Are you sure about that? I'm not.
I don't get the feeling its about what the end A/F ratio is. I get the impression that its simply about having too much liquid phase in the cylinders.

For example, if you were to inject pure water, which has no effect on A/F ratio, it too can still wash out the cylinder walls if over used.

The 15% rule does sound reasonable though.
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Old May 30, 2010 | 06:33 AM
  #102  
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Originally Posted by Hydrazine
Are you sure about that? I'm not.
I don't get the feeling its about what the end A/F ratio is. I get the impression that its simply about having too much liquid phase in the cylinders.

For example, if you were to inject pure water, which has no effect on A/F ratio, it too can still wash out the cylinder walls if over used.

The 15% rule does sound reasonable though.
Methanol is a combustable fuel. It will start to combust when the gasoline starts to combust, albeit at a bit slower rate due to its higher octate level (118). If it were an issue with too much liquid phase in the cylinders, then it seems to me the guys running E85 would be having this issue as well, but they don't. E85 has a stoich value of 9.8:1 vs 14.6:1 for gasoline, and thus a lot more fuel is injected into the runners.

I ran some fuel flow calculations for a 4.0L motor with a target 750 rwhp. With a 85/15 gas/meth ratio, and 11:1 AFR. Here is the fuel flow:
4725 cc/min total flow rate - (4017 cc/min gasoline flow rate and 709 cc/min meth flow rate).

Now, with E85, the same 4.0L motor and target 750 rwhp (no meth injection), and 7.3 AFR, here is the fuel flow:
6657 cc/min total flow rate.

6657 cc/min for E85 is a 41% higher total liquid flow than 4725 cc/min for the 85/15 gas/meth ratio. Even if you double the amount of meth being injected, the total fuel flow with E85 still will be higher. I have never heard of washing of the cylinders being an issue when using E85, however. Also, remember that methanol and ethanol have a similar molecular structure, CH3-OH for methanol, and CH3-CH2-OH for ethanol.

Moreover, as with ethanol, straight methanol is sometimes used as a fuel by itself. http://en.wikipedia.org/wiki/Methanol_fuel. There are some corrosive issues associated with it, but it is my understanding that E85 has the same issues.

Last edited by ttg35fort; May 30, 2010 at 10:17 AM.
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Old May 31, 2010 | 12:32 PM
  #103  
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I think you are both right depending on what liquid is being injected. The quantity of unburnt liquid phase left in the cylinder being perhaps most relevant? AFRs are a good indicator for fuels, but meaningless for water. I would think that the propensity for cylinder wash would be greater with WI, but there again the water should be a gas at that point, not liquid, so unless the cylinder misfires I think the liquid content will always be very low.

In any case, I think marcelz is just running rich (appropriately) and the black smoke is from that. All our cars (without cats) put out black crap running WOT - have to clean my bumper daily to keep it from looking like it's covered in soot.

Last edited by rcdash; May 31, 2010 at 12:37 PM.
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Old May 31, 2010 | 01:19 PM
  #104  
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Originally Posted by rcdash
I think you are both right depending on what liquid is being injected. The quantity of unburnt liquid phase left in the cylinder being perhaps most relevant? AFRs are a good indicator for fuels, but meaningless for water. I would think that the propensity for cylinder wash would be greater with WI, but there again the water should be a gas at that point, not liquid, so unless the cylinder misfires I think the liquid content will always be very low.

In any case, I think marcelz is just running rich (appropriately) and the black smoke is from that. All our cars (without cats) put out black crap running WOT - have to clean my bumper daily to keep it from looking like it's covered in soot.
Raj, with all due respect, I'm not sure that you have fully read the respective posts. Both Tony and I concur that there is a certain limit which you do not want to exceed with injection of water.

The issue we are discussing is whether injecting additional fuels is a potential problem. My contention is that additional fuel may be injected without serious adverse consequences so long as the AFR is maintained within a reasonable value. Tony appears to believe that that the total amount of liquid injected is an issue. I do not believe that this is an issue based on the information I provided in my post.

Last edited by ttg35fort; May 31, 2010 at 01:24 PM.
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Old May 31, 2010 | 03:30 PM
  #105  
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Originally Posted by ttg35fort
Raj, with all due respect, I'm not sure that you have fully read the respective posts. Both Tony and I concur that there is a certain limit which you do not want to exceed with injection of water.

The issue we are discussing is whether injecting additional fuels is a potential problem. My contention is that additional fuel may be injected without serious adverse consequences so long as the AFR is maintained within a reasonable value. Tony appears to believe that that the total amount of liquid injected is an issue. I do not believe that this is an issue based on the information I provided in my post.
I don't mean to intrude on your conversation Terry so I will step out. I believe my post is spot on though - I believe that any amount of liquid is no longer in liquid phase at the end of the combustion cycle, whether it is a fuel or not (unless you have a misfire).

Anyway, I've been helping marcelz by PM so was really just completing my thoughts to him. Raj out.
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Old May 31, 2010 | 03:38 PM
  #106  
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I just thought of something even more simple that everyone can understand...

We have been discussing injecting a percentage of methanol with gasoline (e.g. 15% or so), and whether there is concern that, even if the AFR is OK, there is too much liquid in the cylinders so as to cause washing of the cylinders.

Now, E85 is 85% ethanol and 15% gasoline. I have never seen any issues whatsoever that E85 washes cylinders when an appropriate AFR is maintained. So, how can a 15%, 30%, or even 50% ratio of methonal/gasoline result in the washing of the cylinders when the appropriate AFR is maintained? Where is the basis for the concern that too much methanol will wash the cylinders when the AFR is still in check? I don't see it. If washing of the cylinders is an issue, then the guys running E85 certainly have a problem on their hands (although I suspect that this is not an issue and there is no problem).

EDIT: I'm assuming that the methanol is being sprayed with an adequate spray pattern.

Last edited by ttg35fort; May 31, 2010 at 05:33 PM.
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