water/meth based on injector duty cycle - Cobalt SS Network



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Old 10-11-2017, 03:22 AM   #1
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water/meth based on injector duty cycle

anyone ever play around with water meth injection based off injector duty cycle? my current devils own stage 1 kit (pressure switch based) is starting to have issues. its old, it actually predates the cobalt (was originally on a friends supercharged 2.4 cavalier in the early 2000s). im planning to put a new aem kit in soon, ive installed a number of the boost referenced kits on various cars, as well as i have one on my turbo l61 944, and ive had great luck with them.

so ive noticed a number of things im not happy with on boost based systems when it comes to roots/screw blowers, and thats mainly driveability. my cobalt has a pressure switch, it works fine for heavy throttle, although on the dyno we noticed the car would tend to knock right after a gear change, and as a result we had to have the meth turn on as 3psi to help with this. the problem with that is under light load i can easily pass above 3psi boost, as a result sucking back the meth like a good thing. also had a similar thing with a trailblazer ss with a magnuson blower, it had an aem boost referenced kit in it, although it only made 7psi so the meth was set to start at 2 psi and in fully at 6 psi. again, the meth could start spraying at lighter loads, and at lower rpm when you stab the throttle it would build boost instantly and spray far too much meth and it would go way rich, however it was the appropriate amount of water/meth for higher rpm. the end result of the issue with both vehicles stems from boost referencing.

ive never played around with water meth using maf or injector duty cycle. i know some people here have run maf based systems, ive yet to read of anyone using injector duty cycle. has anyone tried it? im looking at the aem multi input system (maf, 0-5 volt and idc) so i can run it off anything.
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Old 10-11-2017, 08:22 AM   #2
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Not trying to get off topic too much but I also have a DevilsOwn kit and was wondering what kind of issues you are starting to see because of it's age? Also is your pressure switch progressive? It sounded like you did have a progressive controller on your trailblazer but I didn't know if you had one on your Cobalt? I had similar experience as you with the tip-in knock. So I start spraying at 2psi and am on full spray by 10psi. When we first started tuning for pulls I did have tip-in knock if I would be say around 4k rpm and then hammer down in 2nd or third gear. However we were able to pull timing out of that boost vs. MAF area of the table (I'm not the tuner so bear with me if my reference isn't 100% correct) and now my tip-in knock has been completely eliminated. I think the problem with going rich under light throttle becomes more of a problem when you are spraying proportionally more meth. What flowrate nozzle(s) are you using? I also still go rich under light throttle, it may get down to around 10.5-10.8 if I am boosting under 5 psi. I really just try to avoid that area of load. I'll either keep it right at or under 2psi for light acceleration or above 7 psi and then it only enriches to about 11 AFR. AFR at WOT is right around 12. How did you adjust for pulling fueling to compensate for the meth? My tuner told me that we do it by adjusting stoich in those areas which he said is also the way you adjust for E85. Interested in seeing what you figure out for this.
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Old 10-11-2017, 11:11 AM   #3
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Good ole tip in knock during gear changes

What size methanol jet are you running?
Pump pressure? Assuming 100 PSI, since it's an old kit.

Two ways to eliminate tip-in knock on methanol without having to create a massive dip in your timing table, or always having to roll into the throttle.

1) Purchase a new progressive controller and solenoid(s).

- Dual stage is preferred, allowing you to run a very small jet to begin spraying just as you get into positive pressure.

2) Purchase 2 solenoids, 2 boost switches, 2 relays. (Popular with the diesel crowd)

- First injection needs to be a small nozzle .5 gph - 1.5 gph, preset to come on just as you begin building positive pressure.

- Second injection will be your larger nozzle, set to turn on near full boost.

Selfishly I recommend Prometh, previously known as Alcohol Injection Systems.
American made product, robust, solid warranty, and the owner himself provides the technical support on the phone 5 days a week.
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Old 10-11-2017, 01:28 PM   #4
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Quote:
Originally Posted by 100% METH View Post
Good ole tip in knock during gear changes

What size methanol jet are you running?
Pump pressure? Assuming 100 PSI, since it's an old kit.

Two ways to eliminate tip-in knock on methanol without having to create a massive dip in your timing table, or always having to roll into the throttle.

1) Purchase a new progressive controller and solenoid(s).

- Dual stage is preferred, allowing you to run a very small jet to begin spraying just as you get into positive pressure.

2) Purchase 2 solenoids, 2 boost switches, 2 relays. (Popular with the diesel crowd)

- First injection needs to be a small nozzle .5 gph - 1.5 gph, preset to come on just as you begin building positive pressure.

- Second injection will be your larger nozzle, set to turn on near full boost.

Selfishly I recommend Prometh, previously known as Alcohol Injection Systems.
American made product, robust, solid warranty, and the owner himself provides the technical support on the phone 5 days a week.
X2 on prometh
also running a maf based controller(such as snow there like $200) can help as it reads off maf hz instead of the quick and rapid boost of a roots blower
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Old 10-11-2017, 03:11 PM   #5
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the most recent thing with the devils own kit is the check valve failed again. i know the pump sometimes leaks as well. there is nothing i cant fix by changing a few parts, but the whole kit is so old id like to change it out for piece of mind. its a stage 1 kit with an adjustable pressure switch, so its not progressive. i cant remember what nozzle i have in it, i think its a d07, or 650cc.

my tip in knock at the time was solved by reducing timing and drop the meth on point down to 2 psi. in the end i still lost 10ft/lb of torque from what the car was happy with on a 4th gear pull. its a band aid fix but i know it can be solved with a better water/meth system, we have done it before. had a supercharged s2000 with a snow progressive water/meth kit and lots of tip in knock problems. after swapping the system out for an aem boost referenced system the tip in knock was gone.

for tuning, the p12 pcm in the ss/sc doesnt have the tables for flex fuel, it has a single box for setting stoich. my tuning for the meth is essentially just calibrating the maf table with the meth on. right or wrong, its worked 8 years, albeit not perfectly. like i said before, meth coming on outside of power enrichment, it makes for some interesting things. fuel trims tend to get thrown for a loop in some areas because the meth comes on and all the sudden its running around 12.5:1 afr when the ecm is commanding stoich. next time in those trim cells you might be not have the meth spraying, and now your at 16:1afr as the ecm tried to correct for the previous rich condition.

this sort of brings me back to maf or injector duty cycle referenced. with a maf system you should be able to accurately calibrate the maf tables for the water/meth, as at X maf frequency you will always have a set about of water/meth spraying. with injector duty cycle reference it would be essentially like the injectors are larger.

ill have to look into the prometh stuff a little more, their website seems to be lacking info and instructions on their kits. ill be honest though, ill likely end up putting an aem kit in. at my shop we have put in literally hundreds of them over the years and always been happy with the way the kits perform, and only once had a problem with a bad controller.
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Old 10-11-2017, 04:12 PM   #6
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Quote:
Originally Posted by Sharkey View Post
the most recent thing with the devils own kit is the check valve failed again. i know the pump sometimes leaks as well. there is nothing i cant fix by changing a few parts, but the whole kit is so old id like to change it out for piece of mind. its a stage 1 kit with an adjustable pressure switch, so its not progressive. i cant remember what nozzle i have in it, i think its a d07, or 650cc.

my tip in knock at the time was solved by reducing timing and drop the meth on point down to 2 psi. in the end i still lost 10ft/lb of torque from what the car was happy with on a 4th gear pull. its a band aid fix but i know it can be solved with a better water/meth system, we have done it before. had a supercharged s2000 with a snow progressive water/meth kit and lots of tip in knock problems. after swapping the system out for an aem boost referenced system the tip in knock was gone.

for tuning, the p12 pcm in the ss/sc doesnt have the tables for flex fuel, it has a single box for setting stoich. my tuning for the meth is essentially just calibrating the maf table with the meth on. right or wrong, its worked 8 years, albeit not perfectly. like i said before, meth coming on outside of power enrichment, it makes for some interesting things. fuel trims tend to get thrown for a loop in some areas because the meth comes on and all the sudden its running around 12.5:1 afr when the ecm is commanding stoich. next time in those trim cells you might be not have the meth spraying, and now your at 16:1afr as the ecm tried to correct for the previous rich condition.

this sort of brings me back to maf or injector duty cycle referenced. with a maf system you should be able to accurately calibrate the maf tables for the water/meth, as at X maf frequency you will always have a set about of water/meth spraying. with injector duty cycle reference it would be essentially like the injectors are larger.

ill have to look into the prometh stuff a little more, their website seems to be lacking info and instructions on their kits. ill be honest though, ill likely end up putting an aem kit in. at my shop we have put in literally hundreds of them over the years and always been happy with the way the kits perform, and only once had a problem with a bad controller.
There's a multiplier (0 - 2.0) below the PE table.
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Old 10-11-2017, 10:26 PM   #7
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Originally Posted by 100% METH View Post
There's a multiplier (0 - 2.0) below the PE table.
are you refering to the power enrich ramp in? in the statement you have highlighted in red i was talking about light to medium throttle opening when it gets 2-4 psi of boost with not a lot of load, a situation where its not in power enrichment mode and the ecm is commanding 14.7 afr.
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Old 10-12-2017, 06:39 AM   #8
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With my car, 2psi is about the limit before it goes into PE. With the progressive controller set at two and if I do get a little overlap my AFR may dip to 13.5 but that's about it. Where I go rich is light throttle power enrichment plus methanol around 5 psi.
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Old 10-12-2017, 11:08 AM   #9
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Quote:
Originally Posted by Sharkey View Post
are you refering to the power enrich ramp in? in the statement you have highlighted in red i was talking about light to medium throttle opening when it gets 2-4 psi of boost with not a lot of load, a situation where its not in power enrichment mode and the ecm is commanding 14.7 afr.
There are threshold boxes above, that will help you with that.

But this is where you should be spraying a .5gph-1gph jet, during light throttle.
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Old 10-13-2017, 01:26 AM   #10
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But this is where you should be spraying a .5gph-1gph jet, during light throttle.
would a progressive meth controller not do the same thing as a 2 stage system based off pressure switches, but in a more linear fashion? set the controller to start injecting at 2 psi and spraying 100% at say 15 psi.

im really looking for some info on progressive water/meth systems that use a MAF or injector duty cycle based reference instead of using boost.
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Old 10-13-2017, 11:24 AM   #11
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Quote:
Originally Posted by Sharkey View Post
would a progressive meth controller not do the same thing as a 2 stage system based off pressure switches, but in a more linear fashion? set the controller to start injecting at 2 psi and spraying 100% at say 15 psi.

im really looking for some info on progressive water/meth systems that use a MAF or injector duty cycle based reference instead of using boost.
A progressive, sure...

But you'll have better atomization on smaller jets.

Better results with two jets spraying progressively (dual stage progressive controller).
Prometh is working on releasing theirs
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Old 10-17-2017, 08:48 AM   #12
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Water injection based on duty cycle load seems more a European thing and most use an Aquamist set-up for that => Progressive system with a fixed pump pressure and a fast acting valve near the jet(s).
But this set-up is expensive compared to the simple pump controlled "progressive" systems.

Looking into this too, as inj. duty cycle is a good parameter to base WI on in a Supercharger set-up where boost is almost constant.
Recently found this controller that can program a 3D map for WI, based on rpm and boost pressure, and can control a fast acting valve => https://torqbyte.com/products/torqbyte-cm5-lt
Has lots of other goodies, but also a bit expensive...
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Old 10-17-2017, 02:52 PM   #13
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im going to have a better look at that system when i have time. it looks like something ive been thinking about for a while.

ive always thought a water meth system should function like a normal fuel system, constant pressure, an electronic injector and a 3d table to properly tune it. really relying on a pump to build pressure and varying the flow based off pump pressure is a bad way to do things. having it start and vary based off one input alone is just as bad. ive been looking at a megasquirt ms3x for another project and it has built in water meth control with rpm vs map tables, and it can be configured to a pwm output.
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Old 10-17-2017, 03:14 PM   #14
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Might as well just use a split second controller and a 5th injector lol
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Old 10-18-2017, 02:04 AM   #15
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Might as well just use a split second controller and a 5th injector lol
thats not actually a terrible idea.
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