ChuckP

iTrader: (7)

So im tuned on 91oct running 50/50 meth/water w/ an aquamist hfs-6 kit.

28psi, 11.5afr, 18deg up top

About 10min into my sessions i start to get some nasty knock. (verified by my CEL flashing)

Can i add more methanol as a safety buffer in my mixture? How would that impact my AFRs?

Or should i just pull a degree of timing?

I'd love to lower the boost a little but its ecu controlled and im not too familiar with that. My tuner is extremely busy and this is last minute, hence why i am asking you guys for advice.
thanks

Richard L

iTrader: (5)

This is something I hope others will chime in and help. It is all about trimming the system to work best for your set up.

I think changing a higher % of methanol is a first thing you should do. How many nozzles are you using?

Richard

ChuckP

iTrader: (7)

2 nozzles .08 and .09mm. I hope others have the time to chime in.

If i add 10-15% more methanol to my mix, how will that impact my AFRs?

NS@AEM

What kind of engine management are you using? Do you have a data log that verifies the knock? Obviously I'm more acquainted with the AEM EMS so I'm not as familiar with some of the chip tuning or flash tuning knock control strategies out there today but I do know that in some instances a flasing CEL can also indicate misfire. Do you have additional evidence that shows you're knocking and not misfiring? Just want to be doubly sure...

One question I have is what happened after 10 minutes to induce this problem? If you were succesfully tuned on 50/50 previously then I would be led to think that there is either a problem in the injection system or in the tune. Increasing the concentration of methanol may only mask a bigger problem elsewhere. Again, a datalog would be very helpful in this kind of situation.

I would personally check over the injection system to verify that everything is working correctly. Start by checking the most obvious: fluid in tank, all lines connected, fluid actually coming out of nozzles, make sure failsafe is working correctly, etc. If you really are seeing knock and everything with the injection system checks out to be okay then it might simply be a tuning issues. Perhaps after 10 minutes you're getting enough heat built up that the knock threshold is greatly reduced.

Adding in more methanol would decrease your AFR but by how much is hard to say. The way I tune, adding in 10-15% more methanol would decrease the AFR by a couple of tenths but how your tuner tunes may be totally different from how I do things. Even if you can't get in to see your tuner I highly suggest trying to communicate the problem with him to see if he can offer any insight.

Hope this helps. Good luck!

05blue8

iTrader: (28)

Good point NS, something like a leaking connection or leaking hose would not be resolved by adding in more methanol. The biggest issue with running a 50/50 ratio is making absolutely 100000% sure that you add in the exact amount of water to methanol ratio and keeping it spot on. My tuner said that a variation can cause the whole tune to be off so he doesn't recommend doing it, I've personally just always loved 100%

Mad_SB

iTrader: (8)

Upping the meth % will increase octane but decrease in cylinder cooling / charge stabilization. Check your plugs. My bet would be that you have toasted a plug and as a result it is not igniting the mixuture properly. Maybe gap the plugs down a tiny bit.

ChuckP

iTrader: (7)

NS@AEM- No datalogs available as im not allowed my laptop in the car during sessions with the group i run with. All i know is about halfway through my sessions, she gets knock happy. (CEL flashing). Stock ECU. No problems whatsoever with the injection system. I believe its the heat as you explained in your post.

MadVII- Plugs look fine and are gaped at .020. I wil try upping the methanol content this weekend to 60/40 meth/water and see if that helps.

Thanks guys.

Richard L

iTrader: (5)

On the HFS-6, you can increase the flow by either setting the offset or gain of the system to allow more incylinder cooling. The meth te fuel ratio is still relatively small, increase your flow will not affect your AFR too much.

For track work, the engine can do with more cooling anyway.

ChuckP

iTrader: (7)

Thanks Richard

esevo

iTrader: (11)

Try leaning it out more and reducing timing some. Make sure your HFS-6 is set up correctly like Richard said. With H20 power will come more from leaning it out more not with timing as much. 12.0's - 12.4's are more than safe on 91 with 2 jets.

Hope that helps a bit.


Evan Smith

ChuckP

iTrader: (7)

Much appreciated man. I road race, so im prefer to stay on the rich side. 12afr's scare the crap out of me. I'll mention going leaner next time i visit my tuner and see what he has to say.

As far as adding more meth to mixture, it worked perfectly on the track this past weekend. thanks to everyone who offered advice.

EvoTio

iTrader: (10)

Good to hear that you solved your problem. How much more methanol did you end up adding?

NS@AEM

Interesting that you'd have a "heat soak" issue with water/methanol injection. I don't know exactly what you're combined flow rate is with the two nozzles you mentioned but it must not be enough if your IATs are still high enough to lower the detonation threshold enough to have knock after ten minutes of track time. Personally, I will say that I'm still not entirely convinced this wasn't a misfire issue. Increasing the concentration of methanol will reduce the occurrence of misfire if you're injecting too much water/methanol overall because more of what you're injecting is actually combustible.

Anyways, I'm sure your tuner will get your squared away.

shaman

iTrader: (2)

I would like to know what the tuner says too. heatsoak on WMi seems a little strange, unless you aren't spraying much, or you are spraying too much and losing spark.

rommel6.5tme

only purified water,