Knock with meth injection -> more meth or water?

[imagine3163]

So I have been reading non stop for the last couple of weeks about methanol injection as I recently bought and installed the Devil's Own base kit in my DSM a couple days ago. The question I have that I cannot seem to get a straight answer/explanation for is if you are getting knock with methanol injection, should you up the amount of water you are injecting (like a 70-water/30-meth mixture) or should you up the amount of methanol (70-meth/30-water)? So, what is a better knock preventer: Methanol or water?

Thanks!

 

[lowexpectations]

Go straight meth and be done with it.

 

[imagine3163]

I do not want to go straight meth for multiple reasons, but are you saying that Meth is a better knock preventer? I am confused because on the Devil's Own message board, they hint that adding a higher water concentration will be a better knock suppressant. Due to its cooling nature, the water can do a better job of slowing the burn respectively raising the octane of the fuel in the combustion chamber. However, this seems counter intuitive to me because what is the purpose of meth then?

 

[ApexVIII]

i believe it is the methanol that is the knock suppressant
but im not sure

i run 50/50 mix

 

[imagine3163]

I run a 50/50 mix as well, but I am getting a little knock and was wondering if I should add more water or more meth to get that to go away.

 

[eder-loco]

I use your local autozone washer fluid -0 degree. and get no knock running a 35r(27psi) flowing @ 45-50 LB/Mnt

most knock i've gotten is 0.4Deg

 

[imagine3163]

Thanks, but that doesn't answer my question.

 

[broads72]

I use washer fluid as well.

 

[silvreclips]

Adding more meth with raise the octane rating of the gas. More octane = less knock. However meth will not cool the air charge anywhere near as good as water will. So more water = colder AITs which will also help fight knock. So either may help. Detepending on your intercooler setup you may want to run more meth if your intercooler can cooler the air charge enough. You may also want to look in upgrading to a bigger nozzel.

 

[mattdev]

How much boost are you on? I see you have 650 injectors. That is waaayyy too small for that setup. If you are missing fuel you will still knock no matter what octane you throw at it. And the most common meth/water mix is -0* Washer Fluid (50/50).

 

[imagine3163]

I am currently running 25 psi with an 80% idc for my injectors, so I am assuming fuel is not the problem. The nozzle calculator recommended a 5.4 gph and I am currently using a 7 gph. I have a pretty efficient intercooler so I will try adding some more meth into the mixture and see if that helps.

 

[Burnett03]

You can add 2x the meth if you want but if the tune is bad it is still going to knock. Ever think that maybe you are running to lean?

 

[ApexVIII]

how much knock are you getting? post a few logs

 

[Killa_dsm]

Yeah a log would be nice. I would say play with the mix and see what works for you. You could always try more meth because it seems like you are running a good size fmic. Maybe even upgrade to a larger nozzle? Like I said it all depends. I run a 50trim on denatured alcohol m14 nozzle and soon will be installed another nozzle pre-turbo.

 

[imagine3163]

Here are a couple of logs. The first one gets the usual .4/.7 blurps of knock, but when I try to run stock timing in the second log, I get over 3 degrees of knock. My afrs are 11.1 to redline which is extremely safe on meth so I know I am not running too lean.

 

[crimsondragon]

If you truly are running 80% IDC, 11.1 AFR on meth, and still knocking, I would look into checking valves and piston for any irregularities and/or carbon deposits that could be causing hot spots. Although I have to agree, 650cc injectors on a 3052 at 25psi sounds risky.

 

[Burnett03]

You need to start by calibrating your airflow system/ or fixing boost leaks. At 5,500rpm (100% VE) Your actual boost should make with you boostest, and well yours doesn't. So you need to calibrate a bit.

 

[turboglenn]

Before I went E85 i was running an M10 nozzle and then added an M5 on top of it, it allowed me to use barely iany injector but when tuning for knock (something i dont really try and do) I noticed that 70/30 was good, but pure methanol was way better in my car. Everyone's car is diffferent. So experiment, try pure meth, try pure water...up your nozzle size, just see what your car wants. Meth doesn't stop knock al together it simply aids in the prevention of it. Are you sure none of your lines for the meth are kinked or that your nozzles aren't plugged? I plugged a nozzle up so bad on one gallon of "blue juice" that i will never run it again. I buy my methanol by the gallon (2.45 here) and just pour it in pure most of the time for when i have to fill up with pump when i cna't find the good corn juice

 

[imagine3163]

You need to start by calibrating your airflow system/ or fixing boost leaks. At 5,500rpm (100% VE) Your actual boost should make with you boostest, and well yours doesn't. So you need to calibrate a bit.

Thanks for noticing that. The 2400hz slider was off by about 8%. After I fixed that knock hasn't been an issue. Here is another log I did. Thanks for all the help guys!

 

[Joesmoke]

Water and meth will do different things at different times in the combustion process.

You will find a lot of comments about water being a better knock suppressant. You of course, will find the opposite spoken as well.

I am currently leaning towards the thought that water will make a better knock suppressant.


I run straight meth but I think I will be trying more water this year.

Heres a link with a lot of info on mixtures and theories.

water injection

 

[mattdev]

Mark the thread as resolved

 

[kawboy]

Thanks for noticing that. The 2400hz slider was off by about 8%. After I fixed that knock hasn't been an issue. Here is another log I did. Thanks for all the help guys!

Any idea why this would get rid of knock?

Just curious

 

[imagine3163]

Any idea why this would get rid of knock?

Just curious

No idea, it could have been something else too. Its the beauty of a DSM.

 

[Devilsown]

One of the main things to remember with methanol injection is it will not always remove all of the kr you are getting. You can get Kr from many of differnt reasons. I have seen some cars that will get KR from the transmissions while shifting. Noisy valve trains, pistion slap are afew other things that can happen inside the motors.

Now how to know whats going on. Best rule of thumb is if you can run 100 octane gas and have No kr you run water-methanol injection and not produce any kr. If your getting kr on the 100 octane gas there is something else going on.

This would be the first thing to test, if your getting the kr from something else playing with the mixtures is not going to fix anything.

Now if 100 octane gas does fix the kr issue then general running higher % or a larger nozzle can help with this. But you should also look to see whats going on with your O2 and your intake air temp.

I like o2 to be around 12.0 on most applications and have the intake air temps to under 100 degs.