Several people have written me asking about my comments concerning just rich of peak being very hard on an engine and a lambda of .85 to .86 generating lots of power.

The super simple answers are:

Just rich of peak, virtually all the O2 is being consumed and the 50% burn rate is such that a lot of heat is transferred.

Peak (lambda 1.0) is stoich, or the optimum chemical reaction. But our engines are not steam engines. We aren't just looking for optimum thermal release, but the most useful work. .85 to .86 lambda, which is typically something like 100-200 degrees ROP on an EGT gauge represents a very good balance of heat and exhaust gasses to expand. The flame front also moves at a different speed than at stoich, so more of the combustion can be converted to useful work instead of wasted heat.

For folks interested in some more details, I'm going to recommend a seemingly odd source. John Deakin is an aviation writer. His articles frequently appear in an online aviation magazine called AvWeb (www.Avweb.com). You have to sign up with an email address, but it is free. If you look through his column index ('Pelican's Perch'), you'll find a lot of articles on mixture management (the ECU is human in a small airplane) and engine basics.

The fundementals are the same, but the principles I've mentioned above are very visible in his logs and test data because he is working with large bore, fixed timing engines.

I'm going to have to wrap up my participation here. It is very difficult for me to talk about technicalities without relating it to our specific products. This appears to put me squarely into forbidden territory. Rather than make more work and grief for the moderators (they not only have to edit/delete my posts, but any references to them), I'll lay low.

I hope my participation to this point is perceived by most folks here in the spirit I truly intended it.

Best Regards,
-jjf

 

what you need as a failsafe is a system that will drop your boost (to wastegate spring pressure unless that happens to be like 19psi) the instant there is a problem, regardless of how that problem is detected.

A few good detection stratagies that come to mind are:
1. boost > x , AFR > y
2. boost >x , PumpFlow < Y

I will have to do some reasearch myself, but at this point I have no plans for meth or alky because I don't feel like it is safe enough for a daily driven car.

 

appreciate your posts...i little too much for most novice tuners but some very solid info

 

This is exactly what is possible with the ZEITRONIX wideband tuning system we sell and believe in.

Not only BOOST > AND AFR >,

but also IF EGT >

and combinations such as BOOST> + AFR> + TPS> programmable %

Basically, anything it logs including TPS, AUX 0-5v, RPM etc can be programmed to trip the AUDIO alarm, the VISUAL alarm AND trip the BOOST CUT SAFEGUARD to limit boost to 14psi.

We have tested this system to run our own meth injection tank dry in a customer car and continued WOT while monitoring and logging AFR, EGT, TPS, RPM, LAMBDA, BOOST concurrently with EVOSCAN and observed NO KNOCKSUMS AT WOT using just an ECU Reflash with meth injection and ZEITRONIX!

 

O.K. Scott, you got me very interested... I'll check out the info on your site then hit you up for some pricing info...

 

FWIW, the one I see programmed the most in customer units is a variation of number 1. Basically something along the lines of:

IF boost > x AND afr > y AND tps > n FOR at least .2 seconds, THEN alarm/failsafe

The time criteria is because of the legitimate lean spike you'll see on many setups, though if your wideband measurements are relatively slow (ex. a sensor tao of 100 mS and a 5 tao settle time), you'll miss the spike all together and can ignore it.

I've seen a few folks include EGT, but I'm not sure that makes sense. Absolute EGT readings aren't very meaningful. It is the temperature relative to peak that matters, and absolute peak changes with ambient conditions (especially atmospheric pressure).

Similiarly, absolute CHT does matter, but by the time you are there, the damage may well be done. Still, the biggest problem that I have seen is uneven fuel or meth distribution. Basically one cyl running way to hot. So multiple CHT probes are not a bad idea, even if the results are note factored into the failsafe system.

-jjf

 

What was your favorite candy as a kid? Skittles or M&M's? GOOD LORD CAPTAIN TECHNICOLOR!, you are burning your product sales into my CORNEAS with all those colors!!

Great and VERY INFORMATIVE POSTS GUYS!! AWESOME!

 

This post turned out very well.

I think I saw the vid that TTP has of them testing their kit's failsafe as well, was good stuff from what was shown.

 

I always looked at running meth and having an issue with the system as the equivalent to getting tuned solely for race gas and then one day someone fills your car with pump gas with out telling you.

 

And that is a darned accurate way of looking at it. Effectively, the octane of the fuel is changing. The change is coming in several ways (flame front speed and stability, lack of intercooling, etc.), but the net result is the same. With an aggressive tune, the sudden change is potentially a big problem - especially since the 'fuel switch' typically occurs at high power.

-jjf

 

Correct, it was using the same technology, but instead of boost cut, it was set up with MAP SWITCHING back to pumpgas boost, AFR and ignition timing in case of a fault.

This is the only TRUE way of a DUAL MAP SWITCHING setup on the stock ECU.

The difference with the non-MAFTPRO version of our meth injection-ZEITRONIX setup is that it remains on the same ECU MAP, cuts boost much lower and shifts the frequency to a load cell and cylinder pressure part of the ECU MAP which is "SAFE".

So basically there are 2 ways to achieve the safety net with our setup.

The less expensive "meth armed all the time" with boost cut safeguard.

and

The more expensive, "true dual maps" which uses one map and boost level when meth is switched off, and another map when meth is switched on and spraying. There is a physical toggle switch that allows one to switch between high boost and meth and pump gas boost and tune.

In case of a safeguard trigger, the meth map will default back to MAP #1 "pumpgas afr + boost level"

 

One thing I think people should consider is the cost of replacing a wideband. Those sensors are not cheap they are about 80 bucks and last nowhere near the time a narrowband does.

While it might be very safe it may not be very economical for your standard daily driver.

The failsafe I am incorperating is a flow sensor mounted right after the pump. That means that if you get any change in flow there is time for the failsafe to kick on and turn the boost down even before the stop in flow gets to the pipe. This will work in almost ever case other then if someone doesn't have it plumbed into the actual intake piece.

So if there is no flow there is no more boost the wastegate pressure.

While if I wanted to be even more safe I would hook up something like zeitronix when I am racing on the track so I have double the failsafe.

 

Keep in mind if the nozzle pops off, the line leaks or the meth somehow was flowing, but not into the intake, the motor is still at great risk.

The flow sensor at the nozzle end makes much more sense, but even so if AFR goes lean, or your wife puts wiper fluid in the meth bottle by accident, you're in trouble as there is no protection with a flow sensor.

BOSCH LSU wideband sensors can be picked up for $45-60 from the local VW dealer.

Compare that to the $250 OEM Mitsu narrowband.

 

The sensor can be setup for overflow protection as well. A leak in the line will allow more meth to flow. So the only way it will be tricked is if you have the line connected to the nozzle but not in the intake. Which should not be a issue as long as you make sure to install it correctly.

Interested in the sensor though. I thought VW sensors have a slower sample rate which I would not put on this just due to the speed I would want the system to react. Please correct me if I am wrong I would love to be able to buy cheaper widebands.

Also true on the meth mix if it is off it will change your tune so this is one thing you need to be very careful on.

250 for the OEM sensor is a rip off but true. But those do not need to be replaced for 60-90k miles unlike a wideband

 

I like the input you guys are giving, and it sure helped me understand it better. i will be contacting you soon. maybe I will keep the meth kit now.