Originally Posted by
ZimbutheMonkey
Yeah, I know, however the reason my A/F ratios are that way with the water meth has to do mainly with the fact that I'm running right on the limits of what my 630 injectors can flow. So while the Methanol is richening things up a hair, my A/F ratios just happen to work out to 11.8:1 or so.
Regarding your second point, I don't know that there is any hard and fast rule that dictates that you need to be running richer w W/M. Like I said, I can run between 20-25 deg advance with little to no timing pull with my ratios the way they are.
I got ya. If you are running at the limits of your fuel system then I can understand why it is drifting lean on the top end.
In the tuning world there are and aren't some "hard and fast rules". While there is more than one way to properly approach a given situation, there are certain things that always hold true. For instance, my previous methanol stoichiometric burn point comparison. So, one given rule, so-to-speak, is that if you are sitting at x AFR value for x fuel, then when you inject y fuel that exhibits a lower stoich burn point, then your overall stoich point of your overall fuel mixture should drop accordingly, proportional to the extra percentage of y fuel injected. This is assuming that you are using a wideband AFR meter that has been calibrated for regular 14.64:1 gasoline stoich. It has to do with the way a wideband meter always first reads lambda and converts to AFR for whatever fuel you are using based upon how you configured the wideband.
To make things a little simpler and compare apples to apples, just think in lambda values instead of AFR. lambda 1.0 is stoich for any given fuel, even if the stated AFR value for each of those fuels is different. This has to do with the way a wideband (aka lambda meter) reads the resulting lambda value after air:fuel mixture burn has taken place. Usually a WOT lambda of around .75 - .80 will exhibit the best power vs safety attributes in most force induced vehicles. There are some few exceptions, but this covers 90%+ of them.
Originally Posted by
M-Hood
Well I think it depends on how you are using the w/m and where you are spraying it, if it is well before the TB it is mostly just being used to lower the IAT's and not much of it making to the cylinder to be burned. Whole different story if it is being sprayed in the runners near the injectors.
You are a bit mistaken. While the first part you mention is correct about it lowering IAT's. However, all of the methanol does in fact make it to the cylinders to be burned as part of the fuel mixture. The meth has nowhere else to go, and just because it evaporates into gaseous form does not mean it disappears whatsoever. It is still there, which is also why when you spray methanol on a car previously tuned for x WOT AFR, your WOT AFR's will enrichen quite a bit while just adding the meth while not having adjusted the tune to compensate yet. Meth injection adds power by lowering IAT's which assists in a more dense aircharge, lowering IAT's thus dropping cylinder temps and allowing additional spark advance like you mentioned, and by being a fuel with a higher AKI which also allows more spark advance to be run.
Originally Posted by
redline380
where the hell would it go? i can see the argument injecting it earlier helps cool the incoming air, whereas injecting it later would help cool the cylinder more. either way, its going to gassify almost instantly, thereby soaking up the heat. but i dont get why you say not much of it would make it to the cylinder to be burned. of course its making its way to the cylinder. it has no where else to go
You are correct.
Originally Posted by
M-Hood
Because when you spray it that far up stream it is not being used as a fuel and most of it is evaporating along with the water that is mixed in with it. Upstream it is pretty much 90% cooling 10% fueling, sprayed after the TB it becomes 90% fueling and 10% cooling. You are more then welcome to call up Scott at USRT and talk to him about it since that is where I get my info.
If Scott at USRT is saying this then he is mistaken. I am willing to bet it was just miscommunication though. Atomized or not, all of the methanol does make it to the cylinders as fuel and is all burned as a fuel. Unless you are spraying meth pre-BOV or something odd like that, then it is essentially in a fully closed loop system after being injected. It has nowhere to escape.
Evaporation does not equate to the fuel disappearing. Just because you cannot see it, does not mean it does not still exist as much as when it was in liquid form. Case in point would be gasoline in liquid form does not burn. This is because for it to burn it needs to be somewhat near the stoich burn rate that it exhibits. In that case 14.64:1. Until the gasoline does evaporate into gaseous form, it cannot burn. The same goes with methanol. In liquid form methanol cannot burn, or otherwise perform as a proper fuel. When it transforms from liquid to gaseous state through the process of evaporation, it can mix with the aircharge in a way that allows it to get close enough to its stoich burn point of 6.47:1 to serve as a fuel and thus ignite.
This liquid vs gaseous fuel burn stuff is not exactly up to any one person's opinion either; whether that be mine or anyone else's in the performance car arena. It is 100% cold hard factual physics.
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