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What psi to turn on the meth?

 
Old 11-25-2018, 08:12 PM
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Default What psi to turn on the meth?

What psi should I turn the meth injection on? Hereís what Iím thinking. And give me your thoughts. The other night I got on it and it started clattering at 9.5psi. so I turned the timing down a couple degrees. I think it might have been lean but my wideband was inop. I was at 14 degrees and now im at 12 with 11.2-11.8afr. No clatter. Yea that scared the **** out of me but it happened and I immediately let off. I was gonna put a small nozzle (homemade kit with McMaster nozzles) and kick it on at 8psi. I can use my cortex boost controller to control it however I like. What your thoughts?
Car info is in my sig but 2004 ls1 gto, heads, cam, 7875 turbo.
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Old 11-25-2018, 08:19 PM
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I usually do somewhere in the 6-8 PSI range. Most of the time its tied into the 2nd fuel pump and powered through the same relay, so they both kick on at the same time.
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Old 11-25-2018, 08:38 PM
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mine is also turned on at 8psi.
i would imagine the "when'' to turn on would have something to do with ''when'' injector duty cycle is getting a little sketchy and needing a little assistance as the meth setups are a used as a ''supplement''
what size are your injectors?
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Old 11-25-2018, 08:40 PM
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Good info. So I guess I should have added. I have several maps on my controller. My lower map doesn’t go over 7 psi. So I’m not beating on it all the time. So I could set it for 8 psi so I’m not wasting meth all the time. I was thinknaboit using a windshield washer pump. Bad idea? I don’t really need much of a shot. I’m not gonna go over 12 psi with this motor. So I figure I’d get away with just a small nozzle
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Old 11-25-2018, 08:45 PM
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Originally Posted by slocaddy View Post
mine is also turned on at 8psi.
i would imagine the "when'' to turn on would have something to do with ''when'' injector duty cycle is getting a little sketchy and needing a little assistance as the meth setups are a used as a ''supplement''
what size are your injectors?
i have 60lb dekas. Duty cycle is at 75% at 6800 rpm with an afr of 11.31 so Iím getting a little close but I think I can squeeze anoth 80-100hp out of it. Iím upgrading the downpipe to a 3.5Ē oval from a smashed in my vice 3Ē pipe. I ordered a bigger airlter because the one I have is pretty small. It would choke an NA motor so I know this one isnít breathing. Probably gonna end up getting 80lb dekas when someone sells some and then Iíll do a boost a pump for now. I have an aeromotive 340 right now.
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Old 11-25-2018, 09:01 PM
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Here’s my afr and duty cycle from last night. Looks like 10psi on the 2-3 shift. But levels out right after.




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Old 11-26-2018, 02:45 PM
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Problems...

It seems clear you are just doing a very basic off/on system, rather than any type of progressive control.

Windscreen washer pump, very low output, low pressure and low flow. So not really an ideal candidate for a pump. At a lower level, a headlight washer pump will offer far more flow and pressure, so would be a better option.

But when proper methanol kit pumps can be bought for only $100 or so.....DIY stuff sort of seems pointless unless you have a selection of pumps.

Another cheap DIY option would be the pump/nozzle injecting pre-turbo into the compressor, which at least negates the pumps need to fight against boost pressure at the nozzle.
But then you could also do a pumpless setup, which with the right nozzle and setup, will inject pre-turbo using boost pressure alone.

Lots of options, although a "progressive" kit will cover you better for the future as things change than a simple off/on setup.
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Old 11-26-2018, 03:53 PM
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Originally Posted by stevieturbo View Post
Problems...

It seems clear you are just doing a very basic off/on system, rather than any type of progressive control.

Windscreen washer pump, very low output, low pressure and low flow. So not really an ideal candidate for a pump. At a lower level, a headlight washer pump will offer far more flow and pressure, so would be a better option.

But when proper methanol kit pumps can be bought for only $100 or so.....DIY stuff sort of seems pointless unless you have a selection of pumps.

Another cheap DIY option would be the pump/nozzle injecting pre-turbo into the compressor, which at least negates the pumps need to fight against boost pressure at the nozzle.
But then you could also do a pumpless setup, which with the right nozzle and setup, will inject pre-turbo using boost pressure alone.

Lots of options, although a "progressive" kit will cover you better for the future as things change than a simple off/on setup.

dang man. You gave me a good idea. Sealed tank. Boost routed to it. Check valve for vacuum. Use boost pressure to shoot meth into the turbo inlet side. . Hmmmm
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Old 11-26-2018, 04:12 PM
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If you do opt for that route, choice of nozzle is vital, it must be a proper low pressure atomising nozzle...so NO typical meth nozzle will do.

And the reservoir etc must be lower than the nozzle so it can never gravity drain out. But what you can do....is add say a windscreen washer pump to the reservoir as well, so it also has pump+boost

I believe such nozzles are common in agri industry, greenhouse type sprayers etc. But as you'll only have boost...in your case 8-9psi to spray, nozzle needs to be very good, high volume low pressure so to speak.
No real need for a check valve, I would be taking pressure directly from the compressor housing for such a system as pressure there will be highest. It would be silly to take boost from the intake manifold in this case.
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Old 11-26-2018, 04:36 PM
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Originally Posted by stevieturbo View Post
If you do opt for that route, choice of nozzle is vital, it must be a proper low pressure atomising nozzle...so NO typical meth nozzle will do.

And the reservoir etc must be lower than the nozzle so it can never gravity drain out. But what you can do....is add say a windscreen washer pump to the reservoir as well, so it also has pump+boost

I believe such nozzles are common in agri industry, greenhouse type sprayers etc. But as you'll only have boost...in your case 8-9psi to spray, nozzle needs to be very good, high volume low pressure so to speak.
No real need for a check valve, I would be taking pressure directly from the compressor housing for such a system as pressure there will be highest. It would be silly to take boost from the intake manifold in this case.
your pretty awesome, you know that? All of that is pretty doable and would be a cheap and simple setup. I have those nozzles you speak of already. I got three different sizes from McMaster. I got a 5, 10 and 15 full cone nozzles. Those numbers designate flow in gal per hour at 100psi.


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Old 11-26-2018, 04:47 PM
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But what happens at 10psi will be vastly different

But also fairly easy to test so you at least have some sort of visual of what will happen, and what they might flow. Strangely..and your nozzles might be similar, I'm nearly sure someone said the jet nozzles for home heating oil burners might be an option.

Whilst it is some 50 pages long, this is a good thread and there is some info about low pressure systems

http://www.aquamist.co.uk/forum2/vbu...read.php?t=251
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Old 11-26-2018, 04:50 PM
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Or another pre-turbo with some data, albeit a pumped system

http://www.aquamist.co.uk/forum2/vbu...read.php?t=531

Although I would probably add, that a low boost/pressure pre-turbo setup is probably not the best route to take, given charge temps etc will all be pretty low.

Pre turbo would be better suited to where the compressor is being pushed hard, charge temps are high etc

IMO as your temps will be fairly low, injecting fluid with the fluid mostly doing work in the chamber would make more sense...ie injection after the intercooler so a fine mist/spray can get into the chambers
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Old 11-27-2018, 06:39 AM
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I've never been a fan of spraying pre-turbo.
The water only has the ability to cool so much before it vaporizes.
Once it does, its ability to cool drops drastically, to the point of it taking a 1000 degree temperature rise of steam to absorb as much heat energy as water does just during the phase change to steam.

You want that water/meth to absorb as much heat as possible from the intake air.
Spraying pre-turbo means a huge portion of that available energy absorption is being used on the hot aluminum compressor housing instead of the air itself.
It might help the turbo efficiency a little, but you're losing a lot of cooling capacity. If you want to spray pre-turbo for efficiency, I'd still spray after the turbo for cooling and detonation resistance.
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Old 11-27-2018, 09:12 AM
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Thanks a bunch fellas for the information. Lots to consider. Initially I was thinking I could do something cheap and simple but that may not be the best route. The thing is I was only going to add it in for the last 4psi on my boost curve. So basically not use it under 8psi but after 8 and Up to 12 I’d use just a small shot for detonation insurance. Like I said the other night at 9.5psi and 14 degrees timing I did get some clatter. But turning the timing down (I can’t control the timing per boost, wish I could) for 9.5psi kills my power when I’m running lower boost. Just 2 degrees is enough to where my son even said something about it feeling slower without me even saying anything about it. I may be wrong on the timing thing but I don’t think I am, it goes by cylinder airmass and that table was maxed out at full throttle and it was taking the timing from the last row.

I guess i need to try lower boost and see if it still maxes it. If I could dial in my timing at lower boost it would be even stronger because I give it lower boost at lower speeds to keep tire spin down. I guess it’s going to be a balancing act. May have to substitute boost for the timing.

Last edited by Kfxguy; 11-27-2018 at 09:22 AM.
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Old 11-27-2018, 11:31 AM
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Of course you can control timing per boost....that's exactly how speed density tuning works,

And even with a MAF, more boost generally = more airflow, so again, shouldnt be too difficult to get tuning right for the boost used.
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Old 11-27-2018, 11:39 AM
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Originally Posted by Kfxguy View Post
I may be wrong on the timing thing but I donít think I am, it goes by cylinder airmass and that table was maxed out at full throttle and it was taking the timing from the last row.
Your air mass table shouldn't be maxed until you're making decent boost. It should go max as soon as you go wide open.
I max my air mass table out around 12 PSI. I just have 12 degrees of timing in that last row and it stays at 12 degrees from 12 PSI to 24 PSI. No real issues.
For you that might be a problem if you're maxing it at lower boost.

You can scale the entire tune by a %, which will give you more resolution on the airmass table. For example, scaling the tune 50% will cut your g/cyl in half, allowing you to use more of the table.
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Old 11-27-2018, 11:53 AM
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*It shouldn't go max as you go wide open*. I made a typo.
Rescaling might require you to do some retuning. There are actually 3 ways of doing it.
For the most common one, you basically rescale the tune by highlighting your injector flow rate row and multiplying by 0.5.
You'll go into the VE table and do the same thing. You'll also have to do cranking VE.

You'll cut your g/cyl in half, so you'll have to redo your spark tables. You'll pretty much start at the lower g/cyl values, and copy/paste the data from the row with double the g/cyl. So you'll work down to your 0.6 g/cyl and then copy the 1.2 g/cyl row and paste it into the 0.6 g/cyl, and everything after that will be ready for you to start tuning. ALWAYS start by copy/pasting data into the lowest g/cyl row or you'll mess everything up.
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Old 11-27-2018, 12:24 PM
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See my sticky for scaling a tune. It's geared towards MAF, but VE will be the same thing. There's more tables that need scaling than just the VE and injector flow.

https://ls1tech.com/forums/pcm-diagn...er-setups.html
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Old 11-27-2018, 12:26 PM
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Originally Posted by ddnspider View Post
See my sticky for scaling a tune. It's geared towards MAF, but VE will be the same thing. There's more tables that need scaling than just the VE and injector flow.

https://ls1tech.com/forums/pcm-diagn...er-setups.html
I got bored and cut my explanation short so I could find your link and come back with it.
Behold, you had already chimed in before I got back
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Old 11-27-2018, 12:40 PM
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Originally Posted by JoeNova View Post
I got bored and cut my explanation short so I could find your link and come back with it.
Behold, you had already chimed in before I got back
I got you
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