If you road race I would be realllllly careful about an alky system. You need to be careful about tank slosh. A baffled tank or cell with the alky coupled with proven failsafes would be the best option. That is the only way I would run alky on a road course, also, you need to look into the groups you run with as many tracks mihgt not allow alky injection equipped cars on the course.

 

Ask yourself what AFR you run on 93 alone. Then ask yourself why you would tune even richer on meth.

 

Every wideband used in a car for tuning reads lambda. This lambda reading goes into the magic controller and gets converted to AFR by a simple calculation and is independent of the fuel used. The magic controller then sends out a signal based on the lambda of gasoline.

Lambda is the same for every fuel.

If you tune for 11.3:1 on gasoline you will still tune to 11.3:1 with meth injection. You could tune for a higher AFR with less timing like the guy that likes to argue with everyone, or you could do what damn near everyone does and tune to the mid 11s and bump up the timing.

 

LOL.... Even NJ should get a kick out of that.

 

This is incorrect.

Furthermore you can both LEAN AFR AND RAISE TIMING with meth injection.

There is a reason there are experts in the field of tuning.

 

I don't see how low to mid 11's AFR using meth provides any margin of safety if the system fails at WOT. Assuming a 50/50 mix of alky/gas, if the meth were to fail, then it is my understanding that the AFRs would suddenly go very lean, since you're now missing half the fuel. What you would really need is a way to cut fuel immediately and completely in the event of a system failure.

As was explained by coolnick, the AFR readings are actually calculated based off the lambda. So if your wideband is reading 11.3 with 50/50 meth injection, then in reality it is showing you a lambda of .768 based on a stoich ratio of 14.7 for gasoline instead of a stoich ratio of ~10.55:1 for a 50/50 meth/gas mixture. The _actual_air_to_fuel_ratio_ in this case would really be ~8.10:1 (i.e., 10.55 * .768).

As was explained by TTP, you should be able to tune for a higher lambda with Meth than on straight pump gas. However it would be inaccurate to say that you can tune for a higher AFR, since a higher lambda value for a 50/50 mix would actually still result in an overall richer (i.e., lower AFR) fuel mixture due to the lower stoich ratio for the mix as opposed to pure gasoline.

l8r)

 

Assuming a 50/50 mix of alky/gas is a bad assumption.

I go through about 1 1/2 QT. Meth in a 20 minute lapping session and about 5 Gals Gasoline. Do the math on that for me please.

 

You mean cut boost. Last thing you need is to cut fuel when you are already lean.

The zeitronix / meth injection systems we sell and install/tune do exactly this based on MANY single alarms parameters as well as combination parameters.

 

Sorry, I was using bigger numbers to show the effects of mixing fuels on stoich ratios and AFR. In your case it looks like you're injecting somewhere between 10% to 15% methanol.

So if I pick a flow rate of 10% methanol, tuned to a lambda of .768 (11.3 AFR as shown by a gasoline calibrated wideband), it would result in an actual AFR of ~10.66:1. At that rate, if the meth stops flowing, the AFR will jump by at least one point, probably more. IMO, not really a good situation to suddenly go to an AFR in the upper 11's on 93 octane, especially considering that timing was most likely also advanced to take full advantage of the methanol. If you're injecting 15%, then the effects of a system failure would be even worse. Again my only point being that relying on a "conservative" AFR to save the car from a methanol injection system failure seems like a risky proposition.

TTP, I should have said cut the ignition. Boost cut would work, although I'm not sure how that would work if you had an MBC.

l8r)

 

If you cut 100% of the fuel you would still be safe.

In all honesty if the system craps out on you in the heat of the moment you are probably gonna take some damage. During a lapping day I check gauges about once every 30 seconds. I'm so into pushing the limits that I wouldn't notice a green LED turning red. During a drag race that is a different story. Then again if I was into drag racing I would be injecting nitrous not alchy and I wouldn't be worried about the cost of race gas for a measly 11 seconds of action.

That being said I don't mind taking chances because the odds are in my favor. I want to run alchy to run 26 psi daily or if I go with a bigger turbo to compensate for the lack of bigger than stock injectors. During a lapping day I would turn down the boost and use alchy only as a chemical intercooler.

 

You can bypass the MBC with a solenoid that is normally closed and have it trigger open and you will be on WG pressure. You can do this with the Snow Performance Safe Injection and you can use the ZT-2 to do it too. The Snow kit simply works by low flow, the ZT-2 works by different parameters ie you set boost, AFR, EGT, TPS what ever you want.

I have the R-500 from PLX Devices and it uses an LED to warn of set conditions. All i have to do is tap into the LED and wire in a relay to open the solenoid bypassing the MBC.

 

That flow sensor mentioned is a poor failsafe by itself. The flow sensors slowcar uses in conjunction with the zeitronix is a bulletproof system.

 

^^ I totally agree with the flow sensor by itself not being totally reliable. I can wire the LED on my R-500 to a relay and when the warning condition exists it lights up the LED and activates the the relay which in turn opens the solenoid to bypass the MBC to run wastegate pressure. It will essentially work like the ZT-2 and it will have the flow sensor.

 

the snow safeinject is a fixed low limit flow switch, not a flow sensor

flow sensor (aquamist dds3) outputs a VDC proportional to flow rate.

 

ding ding ding