Staggered H2O/Meth injection

[johnl]

Seems like it might be a good idea to beat the air to a high temp with a responsive small turbo but then, instead of using a big compressor to hold outlet temps down, do whatever other things it takes to make sure the charge air temp is low. For instance, I'm building an Air/Water IC system with short fat pipes and good heat exchanger capacity, with which I hope to get more IAT reduction with less charge air pressure loss than can be achieved with an Air/Air IC.


Now, to go farther - even lower IATs. How about what I read here? -

http://www.alcoholinjectionsystems.com/article_info.php?articles_id=40
at paragraph 7 that a "staggered" dual nozzle system, with one nozzle before the compressor in addition to one before the throttle body is better than a single pre TB, nozzle set up.

Then, another WA idea - why not cool the turbo with a dedicated/turbo only radiator and electric pump? Other than convenience, why do we pump 200* coolant into the turbo? For that matter, assuming an oil cooler that can handle the oil pressure, why not cool the turbo's oil too?

Here's links to a couple of pertinent posts in the A/W IC thread -
http://www.turbo-mopar.com/forums/showthread.php?70398-Going-to-upgrade-to-an-air-water-intercooler&p=1038089&viewfull=1#post1038089

http://www.turbo-mopar.com/forums/showthread.php?70398-Going-to-upgrade-to-an-air-water-intercooler&p=1043690&viewfull=1#post1043690

[johnl]

I should have referenced Paragraph 1 - from which the following:


"By cooling the air as it's being compressed within the turbocharger or centrifugal supercharger, the compressed air is now substantially cooler, more dense, taking less space and moves more efficiently through the compressor allowing us to pack and process more air through the turbocharger or centrifugal supercharger. This leads us to our second benefit. Improved compressor efficiency.

All of this results in improved compressor efficiency. Because of this improved efficiency the compressor does not have to work as hard to produce the same amount of boost as without the water methanol injection (http://www.alcoholinjectionsystems.com/index.html). In turn it raises the maximum mass air flow of the compressor. Thereby, making a smaller turbocharger . . . . perform like a larger turbocharger?

[Rrider]

I think its worth a try, makes a lot of sense. May not be so easy to get a decent temp reduction on ambient air though. Heat differential is what makes cooling happen!

[contraption22]

The water circulating through a turbo is to cool the bearing housing. It will have little or no effect on charge air temp.

[glhs875]

I think H2O/alcohol injection has great potential!!! I have been looking/thinking about ways to use it more effectively on my next combo! I was currently using a progressive set up before the TB.

[johnl]

The water circulating through a turbo is to cool the bearing housing. It will have little or no effect on charge air temp.

Yes Mike, I share that assumption - that there is little engine heat transferred to the compressor housing or to the inducer shaft/wheel by the use of engine coolant. Just questioning assumptions here.


I mean, how much heat can be pulled out of the center section and the compressor housing and shaft/inducer if it's coolant is ambient temperature?


Similarly, suppose an electric oil pump dedicated to the turbo with its own oil cooler, running a thin synthetic with no chance of engine debris? Easy peasy with a BB turbo. Why pre-heat the turbo with hot engine oil? And, why heat the engine with hot turbo oil?

Yeah, maybe the differences are minor. OK, but does anyone know? Or, are we all just following the OEM engineers' bean counter dictated choices?

[johnl]

I think its worth a try, makes a lot of sense. May not be so easy to get a decent temp reduction on ambient air though. Heat differential is what makes cooling happen!

Rider, what really hits me between the eyes is the possibility of making a small compressor perform like a bigger one by way of pre-compressor cooling.


I mean get a jump on it. We're all obsessed with big FMICs and hybrids with their point being to get quick boost with low IAC temps. Meanwhile we ignore the benefit to be obtained by cooling before the compressor.


And, of those few on this forum who use some kind of H2O/Alky injection, and who may even use staged or progressive systems with more than one nozzle, none of them (that I know of) has a nozzle ahead of the compressor.

[Rrider]

If you look at some of the old style drag bikes with suck-thru turbos, compressor wheel erosion shouldn't be that big of a deal. I guess it all depends on how much liquid you're pumping.

The AC setups on the 40's cars with the big hanging off the window devices is what I think of when you're talking trying to cool ambient air. That and swamp coolers neither of which work that great.

You can't use 50% alcohol in swamp coolers tho. :P

[contraption22]

I used a nozzle ahead of the compressor on an early TI setup. No ill effects that I can report.
I wouldn't use that method in conjunction with an intercooler though.

If I had time and money to spare, I would have liked to take that combination a few steps further. But the TII swap was the smarter move.

[johnl]

In the linked promo stuff it says that theoretically (1) the place to use 100% alcohol/meth is before the compressor because it evaporates/consumes heat better than 50/50 at that pre-compression point while (2) 100% water is better before the TB in order to control detonation by reducing combustion/EGT temperatures.

It also said that the alcohols erode the inducer less than H2O because they are less dense.


Of course, those two theoretical points are offset by the facts that 100% alcohol/meth is a fire hazard and pre-TB you may want to use 50/50 to richen the mixture.

[johnl]

Here's the part I referenced, said more precisely -


" . . . . .When done properly, very little of the water methanol mist (http://www.alcoholinjectionsystems.com/a10/Knock-Knock.-Who's-there...-Detonation!/article_info.html) injected into the inlet of the compressor survives the process. Thereby, discharging a much cooler air charge with a relativity high humidity with very little or no water methanol droplets present.

When injecting water, we can quickly over saturate the air charge and have an excess of fluid discharging the compressor. Water has a much higher latent heat of vaporization, nearly double that of methanol, and does not flash (instantly evaporate) like that of methanol or other alcohols when injected into a hot air stream. Therefore, a smaller nozzle must be used when spraying pure water.

http://www.alcoholinjectionsystems.com/images/methanol_injection_10.jpgA better choice for pre-compressor injection is a greater concentration of methanol vs. water or pure methanol. Methanol instantly flashes (evaporating) as soon as it enters into a hot compressor and meets the heat within it. By using an alcohol, this dramatically reduces the amount of actual fluid exiting the compressor due to it‘s fast evaporation. Additionally, methanol offers much greater cooling effect then water. Furthermore, methanol is also less dense then water thereby having a softer impact on the impeller. The specific gravity of pure methanol is .792 @ 68° F compared to water which is 1.00 @ 64° F.

One major concern associated with pre-compressor injection is erosion of the impeller. This is only likely to occur when injecting solid stream of water at the impeller of a turbocharger or using an excessively large nozzle .. . . . .."

[OG_SRT4]

I'll be watching this since I have a T1 suck thru setup and in that case pre TB is in front of the compressor. I've been thinking of getting a snow water injection kit and giving it a try.

[contraption22]

I would be concerned about the long term effects of exposure to methanol on the aluminum compressor blade. Maybe spray it down with fogging oil now and then if you're gonna let it sit.

[johnl]

Another idea, obviously not new - why not pressurize a sealed container of meth/water with boost? and then let boost drive a nozzle, fed from that container, ahead of the compressor? No need for a pump or a Hobbes switch or electrics. Completely progressive too.

To prevent vacuum from sucking the mix back into the intake during deceleration/off boost, place the boost barb connection well above the "water level," or put a one-way check valve in the boost line to the container.

If I was in the business of selling H2O/alky injection pumps and solenoids and switches at three to five fold markups, I wouldn't highlight this idea, and, (not to knock Mike) I'd exaggerate the inducer erosion problem.


Might be necessary to tune the boost to the container with sized orifices? or small diameter vacuum hose? to prevent too much volume of boost air and thence spray, or maybe use one or two small nozzles so that it has a staged delivery? or a small unrestricted nozzle followed by a second larger nozzle pressure switched by a two port (or flow through) pressure relief valve?

[wallace]

Are you intercooling this setup? I would be concerned with methanol puddling in the cooler and piping if spraying in the compressor inlet.

[johnl]

Are you intercooling this setup? I would be concerned with methanol puddling in the cooler and piping if spraying in the compressor inlet.

Yes, and yes, it is a concern.

Methanol flash evaporates so that's why they talk of pure or high % for pre-inducer and with low pressure boost driven nozzles, that would present a safety hazard. That is, with a boost driven nozzle, the "misting" is more likely to be a squirt or at least a squirt until higher boost is achieved.

So that brings us to the question of how to get boost driven nozzles to really atomize and effectively turn 50/50 into a misty near gaseosness (is there such a word?) . . . .

The difficulty of that problem brings me back to just a small pre-inducer high pressure nozzle, driven by a pump, that comes on early with 50/50 to get the superior marginal returns to be had from pre-inducer chemical cooling with (because it is a small low volume nozzle at high psi) little risk of puddling/condensation in the IC, followed by a second larger pre-TB/post IC nozzle that adds the conventional cooling/fueling benefits of H2O/Meth injection.

If the barb/take out point for the boost (in a boost driven system) was the bottom of the intercooler, then it would drain most if not all of any 50/50 mix that might condense in the intercooler and send it back to the pressurized tank from which it came for re-injection by the boost driven nozzle. I assume that the big risk with condensed 50/50 accumulating in the system is not fire/explosion but that at WOT a big gulp of liquid could hydro lock the engine.

[wallace]

You may not need an intercooler depending on how much you intend to inject.

[johnl]

Yeah, diminishing marginal returns; has anyone ever pushed IATs below ambient? Seems like with a combo mechanical IC and chemical IC you could.

[wallace]

I have heard of directing the spray directly at the compressor nut to help disperse the fluid and atomize it.

[johnl]

Here's thread at DSM Tuners -

http://www.dsmtuners.com/threads/pre-compressor-injection-test-results.363191/

[contraption22]

Another idea, obviously not new - why not pressurize a sealed container of meth/water with boost? and then let boost drive a nozzle, fed from that container, ahead of the compressor? No need for a pump or a Hobbes switch or electrics. Completely progressive too.

To prevent vacuum from sucking the mix back into the intake during deceleration/off boost, place the boost barb connection well above the "water level," or put a one-way check valve in the boost line to the container.

If I was in the business of selling H2O/alky injection pumps and solenoids and switches at three to five fold markups, I wouldn't highlight this idea, and, (not to knock Mike) I'd exaggerate the inducer erosion problem.


Might be necessary to tune the boost to the container with sized orifices? or small diameter vacuum hose? to prevent too much volume of boost air and thence spray, or maybe use one or two small nozzles so that it has a staged delivery? or a small unrestricted nozzle followed by a second larger nozzle pressure switched by a two port (or flow through) pressure relief valve?

This is how my old system worked. Boost pressurized the reservoir an it sprayed into throttle body ahead of the compressor. I still used a Hobbs switch and a solenoid to prevent siphoning.

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You may not need an intercooler depending on how much you intend to inject.

Many turbo and supercharged drag cars fueled with alcohol do not use intercoolers.

[wallace]

[QUOTE=contraption22;1048489]This is how my old system worked. Boost pressurized the reservoir an it sprayed into throttle body ahead of the compressor. I still used a Hobbs switch and a solenoid to prevent siphoning.

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Did you ever log the reduction when spraying the fluid? Did you see any erosion of the compressor wheel?

[Ondonti]

I didn't spray into the compressor because I used 100% methanol and that made me paranoid.

I have to redo my methanol system at some point and I was thinking about adding a boost barb to the lid of my tank simply because I had drilled a large hole in the top to allow the tank to not create vacuum when fluid moved out through the pump (was having priming issues that should be helped by running it upside down). I don't like having that hole open doing nothing. I had 34gph made up of 3 nozzles but I only have 3 ports for nozzles. Maybe I could run two 14's pre TB and run a 6gph nozzle pre compressor for better atomization and the same overall flow. I never had siphoning issues, just priming issues.

I had been reading some weird website based in the UK that talked forever about water injection and they got me back to thinking about preturbo injection.

[contraption22]

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Did you ever log the reduction when spraying the fluid? Did you see any erosion of the compressor wheel?


Nah man. We're going back..... omg... 20 years ago. I was just a kid playing with dirt cheap mods at the time. I'm not even sure I had a scanner back then.
Car went faster tho. Got into the 13's which was kind of a big deal for a T1 log car back in the day.

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- - - Updated - - -

Did you ever log the reduction when spraying the fluid? Did you see any erosion of the compressor wheel?


Nah man. We're going back..... omg... 20 years ago. I was just a kid playing with dirt cheap mods at the time. I'm not even sure I had a scanner back then.
Car went faster tho. Got into the 13's which was kind of a big deal for a T1 log car back in the day.

[johnl]

After reading about it, IMO, the only reason to inject pre-compressor is to trick the compressor into performing like a bigger compressor, to enable a small compressor, with it's low RPM CFM superiority, to extend itself farther into the higher CFM/RPM range where it is inferior. Ideal for a street car.

As I understand it, lower temperatures, at the tips of the inducer and through the compressor's snail, are enabled with a spray pre-compressor. Further, due to its lower flash point a higher percentage of methanol is preferred. And, the same reason, low flash point, makes it less likely that it will condense/puddle in the intercooler - it stays gaseous.

As for routing boost to the supply tank, I agree. Doing so will help priming but, more importantly, if it is taken from the lowest point of the intercooler, then it will drain/pump any condensate back to the supply tank. I wonder, however, how much of that boost pressure/signal will be seen at the nozzles though - we are dealing with diaphragm pumps - does their check valve attenuate/cut off that low side pressure signal from being transferred to the high side of the pump? and thereby killing any progression of nozzle PSI with boost?

- - - Updated - - -

After reading about it, IMO, the only reason to inject pre-compressor is to trick the compressor into performing like a bigger compressor, to enable a small compressor, with it's low RPM superiority, to extend itself farther into the higher RPM range where it is inferior. Ideal for a street car.

As I understand it, lower temperatures, at the tips of the inducer and through the compressor's snail, are enabled with a spray pre-compressor. Further, due to its lower flash point a higher percentage of methanol is preferred. And, the same reason, high flash point, makes it less likely that it will condense/puddle in the intercooler.

As for routing boost to the supply tank, I agree. Doing so will help priming but, more importantly, if it is taken from the lowest point of the intercooler, then it will drain/pump any condensate back to the supply tank. I wonder how much of that boost pressure/signal will be seen at the nozzles though - we are dealing with diaphragm pumps - does their check valve attenuate/cut off that pressure signal from the high side of the pump? and thereby killing any progression of nozzle PSI with boost?

[johnl]

How do I get rid of this double posting stuff? Must be something wrong with my computer. Just started for me but others on here have had the same bug for some time.

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How do I get rid of this double posting stuff? Must be something wrong with my computer. Just started for me but others on here have had the same bug for some time.

[Ondonti]

Server/software is having a problem so everything is freezing or double posting.


I just thought of an exciting terrible idea. Flaming BOV.

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Server/software is having a problem so everything is freezing or double posting.


I just thought of an exciting terrible idea. Flaming BOV.

[contraption22]

Yeah I'd never use methanol upstream of a BOV or intercooler.

[wallace]

I hadn't considered the bov...

[johnl]

Right, that's where one idea conflicts with another - greater than 50% methanol has a potential to ignite. Below that it won't yet chemical cooling is optimized with greater than 50%. Even at % well above 50% it's hard to light. But, with pressure and a BOV exploding a cloud of it into a hot engine bay . . . .

So, no one ever should run >50%

Besides, my assumption is closed loop - BOV routed back into the intake, NOT into the engine bay with its assorted ignition sources.

[Ondonti]

http://www.yellowbullet.com/forum/showthread.php?t=486039

Never read anything before about forced induction v8's running methanol but this was an interesting progression of a thread. A bit off track with the Mr freeze boost fed bottle setup (not much flow) but wear on the impeller does not seem to be anyone's issue.

Now I am thinking I might run three 14gph nozzles and put one preturbo. Then run my BOV with a hose that vents things in the right direction (maybe). I would think a dyno would be the most dangerous place (less airflow through the engine bay) and I did not find any flameup issues.

100% methanol of course. I wonder if methanol was able to backflow through the intercooler and through my BOV when I was running 34 GPH pre throttle body previously. 10:1 compression and probably running pump gas will like this I hope. I don't know how much power I can make simply by dialing back timing. Being stuck at very low boost would make me very slow. I had thought about running E85 again but Seattle is a real hassle to get creative with fuel unless you want to ship coal to China. I miss it being next door. Methanol on top of E85 is awesome.

[johnl]

Thanks Brent, that YellowBullet thread linked to an excellent thread at UK Aquamist

http://www.aquamist.co.uk/vbulletin/showthread.php?t=251


And yes, I'm thinking three nozzles, three stages, one pre-compressor, two pre-TB, controlled by three Hobbes switches, and three solenoids. One guy with a dual nozzle system had the pre-TB nozzle (under vacuum) pull the fluid out of the pre-compressor nozzle and supply line (backwards) - thereby sucking the pre-compressor nozzle dry. He fixed it with a check valve; in a staged system a NC solenoid valve ought to do the same thing though.

I also like the idea of an accumulator between the pump and the solenoid valves to ensure consistent pressure delivery and reduce demands on the pump.

Relating to boost driven pre-compressor nozzles, as one poster in that thread explained - if you have a pre-TB injector anyway, then use the same pump for both sides, pre and post compressor. Also, relating to inducer erosion, the mist of high psi, as opposed to the small drops of low psi, is preferred.

[Ondonti]

Another comparison they gave for compressor wheel erosion was of draw through carburated turbo setups. Those put a lot of fuel through the turbo and don't seem to have problems.

[johnl]

When staging, which nozzle should turn on 1st - Pre-compressor or pre throttle body?


Since the point of pre-compressor H2O/methanol spray is to enhance the efficiency of the compressor and since spraying too early may slow the wheel and therby impede spool up, I'm wondering if, on say a 20 pound system, maybe start spray pre-TB at for example 10 pounds, then spray pre-compressor at maybe 15 to cool and stretch the compressor map into the higher boost zones.

[Ondonti]

People were actually talking about it improving spool because of improved efficiency. Nothing really proven.

[Reaper1]

I'm pretty darn sure that I got my charge air to be below ambient in the intake. I wasn't even running that much GPH. I was in Florida at the time and the ambient temps were in the 90's and humidity was probably the same! LOL I'd make a pull and the intake would be cold to the touch and have condensation on it!

As long as the flow of alky before the compressor is very fine, then it will flash off into a gaseous state and reduce the temperature of the air as well as increase the density, basically making the turbo think it is at a lower altitude with cooler air. I'm not confident enough to say that this is the reason for the increased compressor efficiency and not their theory on making a better seal between the compressor and the housing, however this makes much more sense than the sealing thing. Methanol turns to vapor around 180-230F depending on ambient pressure (1-3 bar is what I am quoting here). The outlet temperature of the compressor is most likely going to be higher than this and the pressure is higher, so the vapor temperature is going to be higher. Now, another thing to keep in mind is velocity of the charge air in the pipes. Even though the charge air is going to be below the vapor temperature the methanol should still be atomized and the charge air should carry it along. Now, if you have an intercooler that has some dead spots in the end tanks I could see this maybe being a problem. However the charge is going to be so turbulent I just don't see it happening (YMMV). This is assuming that it is a very low flow that is being injected before the compressor.

Now, because we know that the vapor temperature is above 180F, I think it would be a good idea to know at what boost level the compressor is spitting out charge air that is higher than that. I would go so far as to make sure it is higher than the next bar(atmosphere) up from the boost you are running (that's my own opinion). Remember that the charge is going to cool off as the methanol evaporates and the pressure is increasing, so the temperature at which it will condense is going to be higher. You could use the compressor map and some math to figure it out, or a thermocouple in the exit side of the compressor will also tell you. Heck, using the thermocouple you could in theory make a controller that is temperature based (remember that it won't be a constant boost pressure where this temperature occurs because the ambient air the turbo is sucking in is going to change). You would certainly need a fast responding thermocouple, but because the temperature is relatively low an open tip thermocouple would probably be alright. The only worry here is if the tip of it were to break off...it could potentially be eaten by the engine. :(

Anyway, in my typical "engineer thinking" fashion I am probably overthinking and overcomplicating things, but hey...it's fun to think about...at least to me. :thumb:

[Ondonti]

Something I read elsewhere mentioned that a lot of extra heat added by the turbo beyond optimal is due to friction of the air against the housing at the tip of the wheel which is where the alky also travels too so those local spots will be hot enough to vaporize and also the friction heat would be toned down right away. Keeping the charge denser at the tips is a good thing.

[Reaper1]

The added heat is due to a few things.

First, we all know that when you compress something, it gets hotter.

The statement of the additional heat coming from friction of the air against the housing is also accurate. The air is more dense and is now "rubbing" against the housing walls. There's a lot of fluid dynamics that goes on, but that description is easy enough for most everyone to understand.

The other part to this is the compressor efficiency. Because the aerodynamics of the compressor is fixed, it is the most efficient and "happy" in a certain area. We see this as the "island" on the compressor map. What that is actually saying is that the compressor is using its designed in aerodynamics to the maximum. Now, if we go off to the right of the map, the "island" lines are indicating compressor wheel rpm. When we start trying to make the turbo move more air than it is designed for we have to spin the compressor faster.

Now, remember that the compressor blades are airfoils, just like wings. Now, I'm not 100% sure that they actually use airfoil cross sections or not due to the fact that centrifugal compressors work differently than axial. However, the same principle applies to what I'm heading toward.

We all know what the speed of sound is. I don't know how many of you all know about airplanes, but airplanes with propellers have a limit on how fast they can spin their prop. It's not that they couldn't spin it faster, it's that the prop becomes inefficient and can start vibrating because the very tips of the blades are breaking the sound barrier. They already get very close as it is (and do on occasion go supersonic for short bursts). Helicopters make the noise that they do because of the same thing...the tips of the rotors are supersonic. Now, the same happens with jet engine compressors in closed housings. If the tip speed goes supersonic the efficiency goes way down. Take this and translate it to our turbos. The faster we spin the compressor wheel, the closer it gets to having tip speeds at or above supersonic. Once that happens, this is when we tell people the compressor is doing nothing but blowing hot air. The tip speed has gone supersonic, and the air gets heated up even beyond what it would normally be. There's a bit more going on, but I think I got to where I needed to.

A denser charge will increase the speed of sound, so you could spin the compressor harder, but I wouldn't do it because it's not consistent.

[johnl]

People were actually talking about it improving spool because of improved efficiency. Nothing really proven.

But the question is, when or where on the compressor map does that improved efficiency occur? What I read, relating to pre-compressor spray delaying spool up, I took to reference the simple effect of the mass of the fluid hitting the inducer's blades at the very moment when they are just beginning to accelerate, and then . . . . any cooling effect at that critical moment also increases the mass (not to say density) of the gas, that the blades are trying to accelerate.


As Reaper points out, it is a dynamic question given that the flash point of the methanol changes with pressure. Yes, at the inducer's blade tips, the heat rise likely is so quick and high that it likely overwhelms any delay in flash point caused by pressure rise - but at what inducer speed is the tipping point? Where on the map does that overwhelming begin? And, yes, ideally a thermocouple (as Reaper says - as a measure of but one part of the two part temperature & pressure complex) could control when and how much pre-compressor spray.

Further complicating it - we should consider that, for safety's sake, the spray ought to be half water with a much higher flash point and a different weight or mass.

[wallace]

If you lower the air inlet temperature with the same inlet pressure the air on the discharge will correspondingly drop in temp. The compressor efficiency is fixed by the physical design. The lowered discharge temperature means a denser charge for the same boost pressure taking away the amount of oxygen displaced by the fluid would give you the increase in oxygen. I pasted a link that has the formula for this as well as some other info.

http://www.gnttype.org/techarea/turbo/turboflow.html

[Ondonti]

If you lower the air inlet temperature with the same inlet pressure the air on the discharge will correspondingly drop in temp. The compressor efficiency is fixed by the physical design. The lowered discharge temperature means a denser charge for the same boost pressure taking away the amount of oxygen displaced by the fluid would give you the increase in oxygen. I pasted a link that has the formula for this as well as some other info.

http://www.gnttype.org/techarea/turbo/turboflow.html
Since I don't think we are using boost terminology correctly to describe the effects of alcohol injection:
When it comes to reaching full boost faster (boost threshold) I would say its simply denser air at the same compressor rpm creating more exhaust energy. Maybe on the onset of boost there is a slight lag but the idea would be that you overcome that slowdown or at least balance out. Boost response, what spool/lag really means, could be slower or probably the same if you are already in the rpm range where the turbo should be near lag free.

A lotta people talk about maximum compressor efficiency and staying in the island but almost nobody does it. We regularly see people on various platforms slapping recirculating compressor covers onto turbos when they chose a surging turbo (which not only lets you get away with being out of the proper map but distorts the map lowering efficiency across the board). We also see people running turbos that can't provide the flow needed at the demanded boost pressure. Since that seems to be how most people do things I don't see these imperfect situations as a reason not to bother with alky until the basics are fixed.... Let the people who choose a correct turbo enjoy the benefits of that while everyone enjoys the alcohol injection.

[johnl]

Thanks for that link Wallace, good stuff in there. Lots for me to digest.
And following on what Brent said, is my statement correct? - that alky, in effect, can fool the compressor?, can it extend the range of its map if alky is introduced at about the time it is overspun/pushed too far?

[black86glhs]

So let me ask this, "If The right mix of Meth/H2O is injected pre-compressor and it evaporates completely, thus lowering the pressure, will it cause a low pressure pre comp and a higher pressure post comp and help with spool?" This would only be for a short period, but could help offset the slow down of the turbo when injection first starts.

[wallace]

Remember the compressor map is just a guideline and derived in a controlled environment which includes a standard ambient temperature for testing. This is so you can compare apples to apples when selecting a compressor. Lowering the ambient temperature will provide more oxygen for a given PR I still believe you have the same efficiency set by the design of the compressor.

[Ondonti]

I would not overspin a compressor no matter what if you are looking for longevity. Its silly to even think about eroding your compressor wheel if you are overspinning the turbo. You will kill the turbo before it matters. I don't think any amount of injection will give you enough margin to punish your turbocharger physically. Better off selling your turbo and buying one you won't overspin than killing it and having to buy a new one while owning a worthless piece of junk. Overspin failures are nasty.

[johnl]

Yes, of course, "overspin" is a poor choice of words. More precisely, when the compressor is operating near the right or upper edges of its map, where it is about to cross over into inefficiency, or . . . . . if it is in its sweet spot but about to be pushed to the less efficient upper right, then, at that moment, the introduction of air at a lower temperature at the inducer, and through the snail, by way of alky, will move the map back toward the lower left - back toward or into the sweet spot, right?

[Reaper1]

Intorducing a higher density media into the compressor doesn't "move" anything on the map. The efficiency is rpm and pressure driven. The higher intake density only changes the numbers on the X-axis.

Just because the compressor map doesn't have information on either side doesn't mean there is "nothing" there. It just means that the manufacturer didn't publish that information. There is actually information to the left of the surge line. That line is arbitrarily "chosen" by an engineer to protect the compressor from being used in the "danger zone". The lack of information off to the right is there because the manufacturer determined that the compressor was not efficient enough to advertise it. It doesn't mean it can't do it.

Now, the turbo overall does have a "redline" for rpm. Within the rpm range that is published on the compressor map the turbo is supposed to be able to operate for the full intended life cycle of the part, and possibly more. Going outside of that range most likely will reduce that life as the number of cycles is multiplied (kinda like dog years as an example) over the same time period of use. The wheels are only capable of withstanding a certain load for a certain amount of time. When running over the "redline" there is possibilities of running into vibrational harmonics, and plain just overloading the wheel. Both can lead to catastrophic failure, which as Brent pointed out, is FUGLY!!

Anyway, point being is that for the most part, don't think about "moving" anything on the compressor map when introducing a different density substance into the compressor. Yes, temperature will affect efficiency, but this is a variable that, unless is super critical and can be controlled, needs to be ignored. If you are needing to know the exact effect on your engine, then you need to monitor your engine under operating conditions. This is an area where theory and math are pretty much a waste.

[wallace]

Lower the inlet temperature and for the same PR you've got more oxygen. So without increasing the boost you get more power....right?

[Reaper1]

Yup, but it has nothing to do with compressor efficiency. If you take a temperature reading across the inlet and outlet, as long as the compressor is spinning the same rpm and producing the same PR, the only thing that has changed is density.

[johnl]

Please forgive my elementary ignorance of physics - but . . . . . density = mass/volume. And temperature affects volume . . .. and it all goes to how many molecules of oxygen are pumped.

This guy, on you tube is good

Boyle's Law - Pressure & Volume
https://www.youtube.com/watch?v=11BkIYy4rf0

Charles's Law - Volume & Temperature
https://www.youtube.com/watch?v=HgcVglzGl7M


Avogadro's Law- Moles & Volume
https://www.youtube.com/watch?v=Nk8pPH9eh6o


Dalton's Law - Gas Mixtures
https://www.youtube.com/watch?v=tEIpukK8CKM


Gas Density & Molar Mass
https://www.youtube.com/watch?v=wlpvFWxY0x0

[Reaper1]

Please forgive my elementary ignorance of physics - but . . . . . density = mass/volume. And temperature affects pressure and volume . . .. and it all goes to how many molecules of oxygen are pumped.



Fixed :thumb:

Ideal gas law: PV=nRT
P= pressure
V= volume
n= molar mass of the substance
R= universal gas constant
T= temperature

You can not change one factor without it directly affecting another. In our case we aren't changing the pressure or the volume. The temperature gets lower, so the only thing that can change in order to keep everything balanced is "n", the molar mass. This makes perfect sense since we are no longer ingesting only air. We have now added another substance to what the compressor is dealing with.

Because of this, you are now dealing with a more dense substance (there is more mass for the same volume) going in and coming out of the compressor. The only thing that changes on the compressor map graph is the numbers on the X-axis because the mass is higher than what is tested, so the mass flow goes up as well. You are not running a different pressure ratio, so the rpm doesn't change.

I suppose you could think about it as shifting the entire map over to the corrected mass flow, but then that makes your graph dynamic simply because you don't inject the methanol all the time.

[wallace]

Not all of that density increase is the fluid that's been introduced some portion is more of the denser air that's a result of the temperature drop at the inlet.

[johnl]

LOL. Reaper 1, thanks for that correction - it goes precisely to my blind spot.
That admitted, as happens often in the Politics & Religion sub forum, I now seize upon the one part of what you said for vindication -

"I suppose you could think about it as shifting the entire map over to the corrected mass flow, but then that makes your graph dynamic simply because you don't inject the methanol all the time. "

and that is the point of my question - going to how to stage the injection. Staging IS dynamic, it's OK to be dynamic. That is, would you all agree that injection pre-compressor should be secondary, delayed until the compressor is well into the sweet spot of its map, and then, at that moment, give the boost curve a second life by shifting the entire map to the northeast, with a spray of 50/50?

Further, post-IC/pre-TB is where the primary 1st stage spray would begin and at a lower boost level.

In other words, the Hobbes switch for the pre-compressor nozzle would be set to turn on at a higher boost pressure than is the boost point setting of the Hobbes switch that turns on the pre-TB nozzle.

[wallace]

If you do set this up I would really like to know if spraying in the inlet has any affect on spoolup. It would require spraying before the spoolup has occurred.

[johnl]

Actually, the idea is to spray into the compressor well after spool up, for two reasons, first, as you say, to minimize any loss of inducer speed from the additional mass of the colder air caused by the 50/50, and second, in Reaper1's phrase to "shift the map" of the compressor, at the point where it needs to be shifted, dynamically, again, with the increased mass of the colder air created by the 50/50's evaporation. If you hit the compressor with 50/50 down low, before it is spooled, before it is making any heat, then you aren't optimizing. Hit it later, after its spooled, when heat is a problem. Meanwhile, hit the TB and plenum with 50/50 to lower combustion temps/suppress detonation, and most importantly - allow more timing. As a bonus, you can pull some of that fuel you otherwise are using for combustion coolant.

[Reaper1]

Not all of that density increase is the fluid that's been introduced some portion is more of the denser air that's a result of the temperature drop at the inlet.

I'm going to agree with you somewhat. The reason I say "somewhat" is because yes, we are cooling the air down and that will cause the air to condense. However, we are introducing another substance into the volume and that will take up most (I'm going to stay away from the absolute "all") of the displaced volume of the condensed air.

Also remember that the molar mass of the gas is now higher. I'm not a chemist (I hate chemistry, but I understand the basics), but in order to know what that change is you would have to know the molar mass of the injected compound and then use the percentage (I think based on volume?) to calculate the new molar mass. I'm going to take a stab at it and say the difference isn't going to be extreme.


LOL. Reaper 1, thanks for that correction - it goes precisely to my blind spot.
That admitted, as happens often in the Politics & Religion sub forum, I now seize upon the one part of what you said for vindication -

:thumb: We are all in this together. I'm just trying to help, that's all. I don't mean to come off as a d*ck or anything. I just want to throw that out there. :thumb: (hooray for intarwebz misunderstandings!!)


"I suppose you could think about it as shifting the entire map over to the corrected mass flow, but then that makes your graph dynamic simply because you don't inject the methanol all the time. "

and that is the point of my question - going to how to stage the injection. Staging IS dynamic, it's OK to be dynamic. That is, would you all agree that injection pre-compressor should be secondary, delayed until the compressor is well into the sweet spot of its map, and then, at that moment, give the boost curve a second life by shifting the entire map to the northeast, with a spray of 50/50?

You are correct, there is absolutely nothing wrong with dynamic. It's just harder to picture and to explain.

[johnl]

No problems, never were any; you're posts are valuable, instructive.

I read somewhere that the ratio is 3:1; that is, for alky injection, for each three parts of intake air volume reduction from decreased temps due to vaporization of the alky/water, there is one part of offset - of increase in volume - derived from the water/alky's vaporization. To restate it, as the fluid vaporizes, yes, it expands when it is transformed from liquid to gas, BUT the heat it sucks out of that hot compressed air as it vaporizes, reduces the volume of that hot air by an offsetting 3:1 ratio. This fact, after all, is why we are interested in it. I'll try to find the reference to see if I'm re-stating it correctly.


On delaying pre-compressor spray until well into/after spool up, another way of thinking about it is that the ratio of the inertia of the mass of the spray (the weight of the gas/fog/mist) to the inertia of the spinning inducer is more favorable. That is, at or near full inducer speed, the inertia of the spray is totally overpowered by the inertia of the inducer where at low boost/beginning of spool, the spray, reportedly, does slow spool.

[wallace]

Isnt the whole idea of injecting pre compressor to actually get more air in? You can inject after and lower the charge temp....but you're not packing more air molecules in just lowering the temp of what's been compressed.....just like an intercooler. I agree the air mass would increase with the fluid introduced. Think about the difference in power in summer vs winter...way more power since the air is denser and drier. I would think the pre compressor injection should fall somewhere in between...the fluid if completely vaporized would be similar to the humidity in the air. Some % of the power increase in winter would be due to lower humidity and some because the air is denser? Great discussion btw.

[johnl]

Thanks Wallace, your participation is appreciated. This subforum should be more active, the possibilities for our cars, especially T1 cars, are too cheap/simple and too great to be neglected. And, with an intercooler and pre turbo and post IC injection, I wonder "how low can we go?"



Re 3:1 expansion ratio, look at the last post here -
http://www.eng-tips.com/viewthread.cfm?qid=283133

(http://www.eng-tips.com/viewthread.cfm?qid=283133)

And this is a really good discussion too -
http://www.eng-tips.com/viewthread.cfm?qid=314358

(http://www.eng-tips.com/viewthread.cfm?qid=314358)

Injection after the turbo/after the IC/before theTB does more than just lower IAT, the water when it is in the combustion chamber absorbs heat and in doing so delays the pressure spike that results in detonation. It can do a better job of that than a too rich mixture of gasoline. It also enables more ignition advance. Meanwhile, the pre-turbo injection mimics a bigger turbo and allows more total air/oxygen.

[johnl]

Ordered one of these with a jet - goes in front of the turbo compressor inlet.

[wallace]

Neat where did you source that?

[Rrider]

Off the hood of a benz right? :P

I want one of those too..

[johnl]

http://howertonengineering.com/howerton-engineering-partsspecialty-aquamist-items/


Jeff Howerton, here in CA, is a dealer for Aquamist. Not that I have hands on experience or complete knowledge, but so far, to me, the Aquamist systems - controllers & redundant ECU interfaced fail safes - appear to be the best in the industry.


As for these rings, I ordered the 2" size because that's the inlet size I have but I am concerned about its effect on the flow into the turbo inlet. The angle of the available jets' spray is also a part of the size selection.


IIRC, there were tests done by contributors to this site that concluded that one "cork" in a T2 system was the stock airbox and perhaps the diameter of the pipe leading to the turbo inlet.


This ring, in order to ensure that the spray hits the roots of the inducer's blades, must sit tight, right on the face of the inlet, and obviously the ring's three supports and the jet holder assembly, in that position will impede inlet air flow. The answer to this is to obtain a jet with a narrower spray angle/cone and then locate it and its holder ring farther out, in the throat of a 3" or 4" inlet pipe transition, where the ring's area is a smaller percentage of the inlet's total area. That is for later. For now, I'll experiment with the jet angles that come with the rings. The ring's threading is metric so you have to buy an Aquamist jet for it, you can't use the more common 1/8 NPT threaded jets.

[Ondonti]

I wonder if there are any race class turbo cars with turbo inlet limitations that are allowed to run pre turbo injection. That would be some good data. I sorta assume its illegal since the outlaw classes mentioned in a thread I posted were sketchy/secretive on its use. I said above that its a bad idea to overspin but it would be kinda fun to have a car at its flow limits (way off the map to the right) and make more power because you are able to knock down heat.

When I was searching and found this thread
http://www.yellowbullet.com/forum/showthread.php?t=547335
Interesting setup with a nozzle right over the shaft nut!

I also found this.. Had heard of the Fopar before but these were some fun pics.

http://www.fullboost.com.au/forum/showthread.php?8160-Twin-Turbo-4-6L-1991-Dodge-Daytona/page14
http://www.performanceforums.com/forums/showthread.php?67259394-The-FOPAR-Twin-Turbo-Ford-281ci-V8-powered-Dodge-Daytona/page4

[johnl]

Yeah, now you're talkin.

This just arrived, tiny filter too.

Can't upload the pic. Maybe I need to delete some pics from "manage attachments?" How do I do that?

[johnl]

If you do set this up I would really like to know if spraying in the inlet has any affect on spoolup. It would require spraying before the spoolup has occurred.

http://www.yellowbullet.com/forum/showthread.php?t=1603034

See that thread, great stuff. First 16 pages are great. Pre-turbo meth or 50/50 helps spool, creates gains in shaft power.

Best posts in the thread are by Kjewer1, for example :

" . . . The difference with injection pre-compressor (as far as

temps go) is that the cooler the inlet temp of the air, the

cooler the outlet temp, and the difference is greater than

the difference at the inlet. In other words, a 20 degree drop

in inlet temp is worth more than 20 degree drop at the

compressor outlet. Cooler air is easier to compress. So if

you're going to inject, pre-turbo is worth a look. . . . "

[contraption22]

Are any of these guys injecting pre-turbo using intercoolers? I dislike the idea of having a large vessel of pressurized air and fuel under the hood.

[shadow88]

Are any of these guys injecting pre-turbo using intercoolers? I dislike the idea of having a large vessel of pressurized air and fuel under the hood.

Some of us cold start injector guys with fogger systems don't worry about it. Once you've blown an intake manifold apart, and realize the fire goes out on its own, you don't think about it much..

[contraption22]

Those are all injected downstream of the intercooler, greatly reducing the size of the bomb


Sent from my iPhone using Tapatalk

[shadow88]

I'd say by the condition of the charge pipes and air filter, it's not too different.

[johnl]

Mike, the way it is done is with at least two high PSI sprays, 100 PSI or better, one before the turbo and another one or two before the throttle body. The pre turbo nozzle is perhaps 3 gallon per minute, beginning at maybe 5 pounds of boost, with the other two being 5s and coming on later. So, they're staggered.

Then, the spray is NOT flammable - pure water, or at most 50/50 meth/water, is sprayed so zero bomb effect.

In that thread there is back and forth, on pure water vs 100% meth, with a conclusion - water or mix for street, pure meth for track. Mix and 100%, of course, add fuel.

Also discussed, best bang for buck is to use pre-turbo injection to enable a small stock turbos to pump more weight of air across their entire map, and also to substitute/avoid need for big/bigger intercoolers, and lastly to improve a big turbo's spool.

[GLHS60]

The other part to this is the compressor efficiency. Because the aerodynamics of the compressor is fixed, it is the most efficient and "happy" in a certain area. We see this as the "island" on the compressor map. What that is actually saying is that the compressor is using its designed in aerodynamics to the maximum. Now, if we go off to the right of the map, the "island" lines are indicating compressor wheel rpm. When we start trying to make the turbo move more air than it is designed for we have to spin the compressor faster.


We all know what the speed of sound is. I don't know how many of you all know about airplanes, but airplanes with propellers have a limit on how fast they can spin their prop. It's not that they couldn't spin it faster, it's that the prop becomes inefficient and can start vibrating because the very tips of the blades are breaking the sound barrier. They already get very close as it is (and do on occasion go supersonic for short bursts)..

Interesting, is this the sound when say WW-II planes make when diving or even going down...

I'm only going by old movies, news reels etc. but the sound of propeller planes in distress is usually the same...

Asked with deep respect to those who served, past and present.

Thanks
Randy

[johnl]

115 PSI Chinese pump and Jabsco accumulator, both rated for methanol. They fit in center of the GLHT's stock compact spare tire. 50/50 H20/methanol feeds from rear window washer reservoir into low side of the pump by way of 50 feet of 1/2" poly hose coiled around the outside of the compact spare.

Methanol rated 3/8 line runs forward; it snakes around perimeter of GLHT's cargo area, enters the unibody frame rail under the driver's side seat and emerges in the front of the driver's side front wheel well. Amazingly, the stock jack still fits next to the pump, under the fiberboard wheel cover.

[Vigo]

That's clever. What's the reasoning with the 50ft of hose and the accumulator?

[zin]

Those fountain parts there John.?

Love the use of space. What do you have triggering it?

Mike

[johnl]

50 foot of hose substitutes for a tank and it fits in the place that I have available - the wheel well.

The pump is pressure actuated; it should automatically turn on every time the pressure drops below 115 pounds, or whatever minimum pressure I set it at.

The job of the accumulator is to take a load off the pump. It's a pressure and volume reservoir with a bladder (see the Schrader valve?) such that it will reduce on/off/on again cycling of the pump every time boost demands fluid and drops line pressure. It also ensures that the two sequentially triggered nozzles cannot outrun the pump with surge demand for more fluid than the pump's capacity to deliver both sufficient pressure and volume.

Triggered by two Hobbes switches activating two meth compatible high pressure solenoid valves. One nozzle will fire at the compressor nut and a second will fire at the throttle body butterfly. I haven't decided which will fire first or at what points in the boost curve. Starting with 3 GPM at the compressor nut and 5 GPM at the TB.

Not fountain parts but RV parts; this sort of accumulator and pump set up does the same thing - pressure and volume assurance - for surge demands for potable water in motor homes.

[zin]

Neat! Link to where you got the parts?... :-)

Mike

[contraption22]

Any info on the effects of exposing an aluminum intercooler core to methanol?

[Rrider]

This isnt specific to intercoolers, but heres a linke to test data on 6061-

http://www.dtic.mil/dtic/tr/fulltext/u2/a193978.pdf

I've seen it eat holes thru aluminum floatbowls so its def a valid worry. I get the impression from speaking to peeps who had problems that when you dilute it in water it gets worse not better.

[contraption22]

Looks like many racers that use meth for fuel are also adding "Top End Lube" to their fuel to prevent corrosion of aluminum fuel and intake system components. I guess that would do the same in this instance, but then you would undoubtedly be collecting oil in your intercooler.

[johnl]

Zin, I'll post part numbers or pics of parts with their boxes with numbers; both the pump and accumulator are off of ebay; the other parts too for that matter.

Great question Mike M, and Rider thanks for that pdf where at the end it says "Pure methanol displays a much more moderate behavior" as compared to diluted methanol. Out of safety, with the pump and reservoir inside the car, I was not going to run any mix greater than 50%. So . . . . . after Marra's input, now I'm rethinking the precompressor spray. Maybe limit it to distilled water? Straight water, after all, is far better than methanol at heat absorbtion/charge cooling but it IS nice to add fuel via methanol.

I've been dreaming of running tests with the twin probe pyrometer that I bought from Asa Cannell's to see how much temp reduction each jet does or does not provide, especially to see how much/whether the pre-turbo jet is worthwhile. I've drilled and tapped the Ramerati intake manifold and the high side its A/W intercooler to see what it does too. I also want to use those 1/8th NPT ports to check pressure differential in that intercooler and to compare it to the giant Spearco A/A that's in this GLHT.

Maybe there's a water soluble top end lube - Castor? - that can inhibit intercooler corrosion? I sent an email asking that question to a racing fuel/castor oil dealer that I know. Probably good for the pump, solenoid valves, and the engine too. But castor is tricky stuff, don't want a clogged jet!

Pics - Two solenoids, tank, 100 feet of poly hose with .6" ID - not 50 feet - .6" x100 feet = 1.45 gallons so system total at least 2 gallons, jet holders, and poly tube label.

[Ondonti]

I just bought 5 gallons in an old race can from a methanol Sprint car team. They have top end lube mixed in so the stuff is pink. I don't know that I would keep mixing that stuff in as I would probably get refills from a larger supplier. I am running Pre turbo right now on my daily :D