v8ter
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- Joined
- Nov 24, 2014
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- EL PASO , TX
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- MUSTANG GT 2015 50TH
Two questions? First, whats whipple recommendation on spraying meth through the blower because of the coatings of the rotors?As I pointed out earlier, stating that your lambda values in your logs are not changing pre and post install of the meth kit is not a good thing. I have tuned many 93 octane + straight methanol injection setups. you do NOT want to let your PCM pull back fuel once you start spraying, if you do the math of the "sum of the parts" of your fueling, you will find by letting the PCM pull fuel, the 93 octane part of your fuel, you are negating a good chunk of the benefit of the methanol injection.
There is almost NO difference in power potential, knock resistance, for methanol between about 0.65 to 0.75 lambda. Methanol cools cylinder temps even better than gasoline and e85, so running MORE methanol and giving up a tiny bit of power by running say a 0.70 lambda is a much better tune and will give much of the same benefits as a e85 setup if enough meth is run. There is a significant drop off in cooling ability and knock resistance going leaner than 0.75.
Lets work through a sum of the parts example. Setup is a 72lb injector whipple, with a single 12gph nozzle.
Injector duty cycles I typically see are mid 70's, so lets use 75% for this calculation
Meth duty cycle of the pump is very close to 100% unless you mess with the pump, so we will use 100%.
8 injectors, 72lb per hour each, converts to 12.24gph each, running at 75% duty cycle is a total of 73.44gph of 93 octane fuel to the engine.
A single 12gph meth nozzle is just that, 12gph of methanol fuel being delivered to the engine.
So based on 85.44gph of total fuel being delivered to the engine, that is 14% methanol and 86% 93 octane. You can now do math on octane, lambda, etc on that mix.
14% of 0.70 lambda (where I tune meth) and 86% of 0.80 lambda fuels means you should be targeting a lambda of 0.78.
Now if the tune is left alone, and commands 0.80 and sees 0.78 on the widebands, it will pull 2.5% of 93 octane out to move things back to commanded of 0.80. Now you are running a 93 octane lambda of 0.82 and methanol lambda of 0.70. That 0.82 is too lean for gasoline, and you are starting to negate some of the benefits of the methanol. Instead of having all the extra octane and cooling to run more timing, you are using some of the benefit just to suppress some of pre-ignition of running too lean of a gasoline lambda.
The issue becomes much more dramatic the more methanol you spray. I used to run dual 12gph nozzles on my last whipple setup, which was around 20% of my total fuel. For a 3-500ml single nozzle, this is probably a non issue, and especially if just being used as a bandaid for shitting 91 octane fuel. But for heavier users, I still recommend making your tune a flex fuel tune so that when it sees fuel trims go active it adjusts the stoich value in the tune and doesn't try to pull fuel out, and adding some safety items should the meth fail.
Easiest and best I have always used is the AEM flow gauge, which will record 10-15 flow sessions so it has a baseline of what your system flows, if it sees flow drop below the pre-recorded flow rates, it has 12v and ground triggers that can be used for any device. I plumb a on/off solenoid into the bypass vacuum line on the blower, and the ground for the solenoid is the trigger from the AEM gauge. If the meth flow rate drops, the solenoid goes to open position and all boost holding the bypass valve on the blower closed is let off, and you will loose all boost.
Second - If I want to use it for cooling purposes only and not taking advantage of the octane increase and not have it to add timing, is there any way safe to do this in case the system fails to spray?
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