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Methanol/Water injection in GM 3800 SC engines--may not be a good idea. by kgoodyear
Started on: 07-03-2015 07:54 PM
Replies: 15 (560 views)
Last post by: Slammed on 07-06-2015 10:12 AM
kgoodyear
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Report this Post07-03-2015 07:54 PM Click Here to See the Profile for kgoodyearClick Here to Email kgoodyearSend a Private Message to kgoodyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
I’ve been doing a lot of research on methanol/water (aka MWI) injection system.
I think it comes down to whether you are selling MWI or if you are looking for chinks in the hype.
Here is what I’ve learned:
MWI is a double edged sword. One edge gives you more power, pretty sparkplugs and clean cylinders; the other slowly dissolves the aluminum intake chambers of the upper engine.
Al is very reactive with O2 and in fact this reaction coats the aluminum and actually protects the Al below.
The throttle body, super charger, intercooler, intercooler core and intake heads are all Al on the 3800 SC

Methanol dissolves this crystalline structure from the surface thus exposing the pure Al. Exposing the pure Al causes it to combine with O2 netting a recursive reaction. (I wonder where all the AlO is going. Perhaps cycling this through the oil?)

Keep in mind, the sand paper I use out in my shop is coated with aluminum oxide (AlO). This is because it is a crystalline structure and has many fascists (edges) to abrade the surface of whatever I am sanding.

http://en.wikipedia.org/wiki/Methanol
Quote
One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminum. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminum from corrosion:

6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O

The resulting methoxide salts are soluble in methanol, resulting in clean aluminum surface, which is readily oxidized by some dissolved oxygen. Also the methanol can act as an oxidizer:

6 CH3OH + 2 Al → 2 Al(OCH3)3 + 3 H2

This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH3OH is negligible. Concerns with methanol's corrosivity have been addressed by using methanol compatible materials, and fuel additives that serve as corrosion inhibitors.

------------------
Goody

The beauty of a solution lies in its simplicity

[This message has been edited by kgoodyear (edited 07-03-2015).]

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Xyster
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Report this Post07-04-2015 10:19 AM Click Here to See the Profile for XysterSend a Private Message to XysterEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the info. My only question is, what about just water injection (skip the meth) ?
Water (pure water) is pH 7 and obviously not an acid. This won't readily react to the Al, but what drawbacks do we see?

I quick search yielded no results.
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kgoodyear
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Report this Post07-04-2015 10:42 AM Click Here to See the Profile for kgoodyearClick Here to Email kgoodyearSend a Private Message to kgoodyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
Keep in mind I am not a chemist or a mechanic so one might want to proof my answers. It is my understanding that DISTILLED water will cool the air and therefore the chamber. It is this steam cleaning that makes the chamber so clean and helps absorb heat from the air chamber. The methane increases the octane to around 118 and this, combined with the "cooler" air provides for more fuel and therefore more power on ignition.

I don't know yet what happens to the mixture once it hits a saturated IC core. I'm still working on that one. One could lose benefits just from that.

So here is what I am going to experiment with:

The idea is to cool the air before it gets to the combustion chamber. We have that with the IC. One can delay heat saturation by cooling the IC coolant as much as practical. I make a small insulated tank (adding some needed weight) in the front compartment and design it in such a way I can surround an old heater core in ice and top off the water ice with dry ice. (Not a new concept.) As the water exits the IC radiator I run it through this bath, cool it more and call it good. Once the water is saturated, bypass the ice box or drain and add more ice. You won't have the advantage of a higher octane but I believe this method will simplify the system and adds no risk.

[This message has been edited by kgoodyear (edited 07-04-2015).]

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Slammed
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Report this Post07-04-2015 10:48 AM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
People have been using water/meth on aluminum motors for decades

But, the 3800SC does not take water injection well at all. Nearly zero benefit. You have to spray it pre-supercharger and that just ruins any benefit. You may also destroy the teflon coating on the rotors

You could build a fogger plate and spray it post-SC, but you might as well go intercooled then
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Report this Post07-05-2015 06:05 AM Click Here to See the Profile for bmwguruClick Here to visit bmwguru's HomePageClick Here to Email bmwguruSend a Private Message to bmwguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
I used to run the meth in my 3800s/c. It was good at first, but became unpredictable and the fueling was not always consistent when the nozzle would get dirty. I wound up switching to a cam and wound up with the same power and consistent fueling.
Dave

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Joseph Upson
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Report this Post07-05-2015 08:41 AM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by kgoodyear:

I’ve been doing a lot of research on methanol/water (aka MWI) injection system.
I think it comes down to whether you are selling MWI or if you are looking for chinks in the hype.
Here is what I’ve learned:
MWI is a double edged sword. One edge gives you more power, pretty sparkplugs and clean cylinders; the other slowly dissolves the aluminum intake chambers of the upper engine.
Al is very reactive with O2 and in fact this reaction coats the aluminum and actually protects the Al below.
The throttle body, super charger, intercooler, intercooler core and intake heads are all Al on the 3800 SC

Methanol dissolves this crystalline structure from the surface thus exposing the pure Al. Exposing the pure Al causes it to combine with O2 netting a recursive reaction. (I wonder where all the AlO is going. Perhaps cycling this through the oil?)

Keep in mind, the sand paper I use out in my shop is coated with aluminum oxide (AlO). This is because it is a crystalline structure and has many fascists (edges) to abrade the surface of whatever I am sanding.

http://en.wikipedia.org/wiki/Methanol
Quote
One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminum. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminum from corrosion:

6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O

The resulting methoxide salts are soluble in methanol, resulting in clean aluminum surface, which is readily oxidized by some dissolved oxygen. Also the methanol can act as an oxidizer:

6 CH3OH + 2 Al → 2 Al(OCH3)3 + 3 H2

This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH3OH is negligible. Concerns with methanol's corrosivity have been addressed by using methanol compatible materials, and fuel additives that serve as corrosion inhibitors.


What you mention doesn't happen unless you store methanol in your intake manifold. First it's partially diluted with the addition of water, second it evaporates long before it has time to cause corrosion in the intake system. I've been running it for years now and haven't seen any corrosion and imagine if it were a problem it would have been well documented as so many are using it.

It is not a power adder, it is a power enabler so you gain nothing by just adding it. If you have no problem with spark knock, you shouldn't use it unless you suspect the potential for it and would like a little added safety. As mentioned already, supercharged engines tend to be a little complicated with its use from what I've read, but turbos have no problem pre and post nozzle location as long as the nozzles are properly sized and placed.

Your quote refers to Methanol being used as a fuel, not an octane booster.

[This message has been edited by Joseph Upson (edited 07-05-2015).]

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Blacktree
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Report this Post07-05-2015 09:12 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yeah, I'd think a water/methanol mist would take quite a long time to eat away enough material from the intake ports to even be measurable. The bigger concern, as mentioned above, would be how to effectively integrate it into the 3800SC engine. You might be better off using an intercooler and squirting N2O instead of water/methanol. Or maybe switch to E85.

[This message has been edited by Blacktree (edited 07-05-2015).]

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kgoodyear
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Report this Post07-05-2015 11:39 AM Click Here to See the Profile for kgoodyearClick Here to Email kgoodyearSend a Private Message to kgoodyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ultimately, I suspect the reason most people who use mwi are doing it for an increase in power. Snow, a leading builder of MWI clearly shows increases in performance says

"Proven to deliver 20-35 HP and 45 FTLB of torque on all naturally aspirated applications and 50-80 HP increases and up to 150 degree drop in air temps for all positive displacement superchargers and small fast spooling turbos!"

This is certainly impressive.

Conversely http://www.eng-tips.com/viewthread.cfm?qid=39643 says

"Aluminum loses its passivity at pH levels exceeding ~ 8.5 At a pH of 10-12 substantial corrosion can take place. Aluminum and its alloys resist most alcohols, however, some alcohols like methanol can be very corrosive when extremely dry, especially at elevated temperatures. "

It may be all moot if one were to inject pre SC. I am running an IC so I think the pre IC injection is not going to cause any appreciable increases.

Perhaps we might hear from some of the forum's members that actually run MWI in the 3800 SC with or without IC.
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Xyster
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Report this Post07-05-2015 11:50 AM Click Here to See the Profile for XysterSend a Private Message to XysterEdit/Delete MessageReply w/QuoteDirect Link to This Post
Perhaps I was looking at this wrong...

If you're looking into MWI with a turbo and race cam and etc (and using a 3800) why not? Fe heads are safe. Cylinder sleeves are safe too. Valves aren't Al.
So, now you're probably ready to start in with "but what about the manifold?" How about a custom sheet metal unit? If you're already this invested then why not?
The only problem I can't answer for is the pistons. Will there erosion on the piston (especially near the rings)? Will the time in the cylinder be brief enough for it to not be an issue?
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Joseph Upson
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Report this Post07-05-2015 01:41 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Xyster:

Perhaps I was looking at this wrong...

If you're looking into MWI with a turbo and race cam and etc (and using a 3800) why not? Fe heads are safe. Cylinder sleeves are safe too. Valves aren't Al.
So, now you're probably ready to start in with "but what about the manifold?" How about a custom sheet metal unit? If you're already this invested then why not?
The only problem I can't answer for is the pistons. Will there erosion on the piston (especially near the rings)? Will the time in the cylinder be brief enough for it to not be an issue?


The parts have to bathe in the stuff to cause a problem and that doesn't happen with a properly functioning system. Google is your friend and if you can't find an intake manifold, piston, etc damaged by intended use of WMI, you can be pretty sure it's because it is not happening. The only thing WMI can do to boost power by itself on an N/A engine is restore power already available but inaccessible due to spark knock. The more up to date threads and demos usually admit that you must do something in addition to it's application to reap a benefit; add additional timing advance, or turn up the boost. If you don't you'll be guaranteed to lose performance as the mixture by nature absorbs heat from the combustion process which reduces expansion gasses which reduces the amount of force on the piston and ultimately the net output.

If you increase boost and or timing, those two changes each add heat to the combustion mix and the WMI offsets that and that's why it works so well. It has the ability to allow you to make more power with manipulating settings than it takes away when you leave all else the same.

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kgoodyear
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Report this Post07-05-2015 01:50 PM Click Here to See the Profile for kgoodyearClick Here to Email kgoodyearSend a Private Message to kgoodyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
One of the things I didn't make clear (but vaguely implied) earlier was that I am running a big intercooler. From further observations I think washing diluted methanol over this huge surface area is going to negate much benefit as well as inject more AlO from this into the air wash. I am becoming more convinced I can accomplish more by trying to bringing the COMPRESSED air down to a lower temperature.

Another thing I didn't really make clear was my application/observations were referring to aggressive driving over a shorter periods of time.

I still think however while most of the AlO may go out the exhaust, some has to get into the oil. No doubt, the size of the crystals may be on the molecular size though still abrasive. Is the trade off worth the additional horsepower side of the sword?

Ultimately, injecting methane and water after the TC/IC would be advantageous-as suggested before via a plate between the IC and the aluminum intake manifold. So I may explore that solution.
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Report this Post07-05-2015 03:21 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Honestly, I do believe you're over thinking it in regards to aluminum oxide particles and plenum erosion. Switch from the technical side of it over to real life and follow the results from those actually using it effectively in those scenarios. I wouldn't spray it before the intercooler because it is an obstacle and interferes with atomization although thermodynamically it maybe beneficial. The ratio of meth to water is also important and directly affects what type of advantage you gain. Some builds do well with water only although it gets tricky due to the increased risk of quenching the combustion mix. When mostly meth is used everything gets very cold but it may not be as effective against spark knock as using closer to 50/50 water/meth.

A variable injection controller also has its advantages but is not used as often for the benefits it offers.

It's trial and era the closer you get to the "edge".
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kgoodyear
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Report this Post07-05-2015 03:57 PM Click Here to See the Profile for kgoodyearClick Here to Email kgoodyearSend a Private Message to kgoodyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
Joseph,

You make a good point. I don't know who said it, " There are facts and then there is the truth. " I think MWI after the IC in a plate between the SC and the intake manifold might be a solution. A spacer with injectors within the port. This, of course, adds caveats like lengthening SC/IC bolts, belt and so on.

[This message has been edited by kgoodyear (edited 07-05-2015).]

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kgoodyear
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Report this Post07-05-2015 05:05 PM Click Here to See the Profile for kgoodyearClick Here to Email kgoodyearSend a Private Message to kgoodyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here is yet another option one might consider. The arrows show places in an old unported aluminum intake where one could place MWI nozzles. This positioning avoids the current intercooler and also cools the air just before the combustion chambers. This minimizes exposure to Al and cools--even further the air coming through the super charger or the intercooler. Aiming the nozzles slightly down would encourage the mist to flow more evenly to all cylinders.

Even better, the air wash will force the methanol and water away from the IC and there are no changes necessary to belts or bolts.

[This message has been edited by kgoodyear (edited 07-05-2015).]

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sardonyx247
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Report this Post07-06-2015 05:46 AM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
It would have to be after the SC/turbo as that is where the heat is at you want to bring down, compressing water vapor will heat it up too, thus more heat for your IC to bring down.


Edit to add:
Adding that much to any NA engine is just tottal BS.
Take a 50hp geo metro for instance....

Beyond that I am intrigued by the meth eating aluminum.

[This message has been edited by sardonyx247 (edited 07-06-2015).]

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Slammed
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Report this Post07-06-2015 10:12 AM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
I wasn't just talking out my bum when I first posted.

Go take a look over on clubgp. Tons of those guys went through this exact thing AND with a fogger plate or post SC injection. Incredibly hard to tune and not worth the effort.
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