What kind of A/F ratios are best with water/meth?

[Mister T]

So I finally got my wideband installed and I've found that I'm running almost 11:1 on the nose. Would it be wise to lean it out to 12:1? I could probably pull it off with the W/M. However, I guess what I need to know is that would the potential gains (if any) be outweighed by the risk of detonation?

[The_Jerbel]

Re: What kind of A/F ratios are best with water/meth?

I shoot for 12:1.

[Mister T]

Re: What kind of A/F ratios are best with water/meth?

Although this is a pretty broad question, what kind of % gains do you tend to see between 11:1 and 12:1? Also, do the gains tend to be seen as more torque, HP or both? Again I know there's a ton of factors here so I'm just looking for a ballpark figure.

Also, if you tune for 12:1, how much of that proportion is the Methanol? In other words, how much headroom do you usually leave in case the W/M system fails and you're relying on straight fueling. I'm not saying that you would drive it for any length of time with the W/M not working. I'm talking more as a failsafe to give you time to notice something's wrong and take your foot off the gas before your engine does a meltdown.

Finally, what (if any) effect does our 3300ft elevation have on target A/F ratios? I've heard that Stoich is slightly lower (high 13's) than at sea level? Also, if there is a difference, is it a constant across the rev band or does it vary according to load, boost and RPM?

[Disturbo]

Re: What kind of A/F ratios are best with water/meth?

11.8 or bust, with or with out meth. you dont wanna have your meth fail and melt a motor. seen it happen to much. The car just has to work harder at our elevation vs sea level. keep the air fuel the same.

[aliencurv]

Re: What kind of A/F ratios are best with water/meth?

11.5 is a safe rule . but that solely depends on your compression ratio and ignition timing . since you seem to have control over fuel, i assume you can adjust timing also . that case, set yourself for 11.5 and add timing instead of leaning fuel.

also, your question regarding elevations: your computer will recognize the air volume . the computer adjusts fuel based on the maf/map values . a little bit of fuel is adjusted by ECT and IAT, however IAT is mostly used for timing .

to compensate for lower air pressure at our altitude, adding timing down low will get you into boost quicker. beware, the load is high at low rpm's and it's easy to detonate down there .

only problem with tuning ignition timing in calgary is when you drive to the coast.. you'll really feel the power difference on a calgary tuned car in vancouver, but at a potential price . too much timing and pop!

[Mister T]

Re: What kind of A/F ratios are best with water/meth?

Thanks for the tips. I should probably mention that I have an AEB series drive by cable. So I can't really do too much about the timing and fueling directly. What I was thinking of doing was getting my file revised and leaning it out that way. I could try and adjust the fuel pressure via my adjustable FPR. However, I've found that all that happens is the fuel trims change and I just end up chasing my tail.

That said, I do have some control over the fueling by adjusting the amount and concentration of Methanol. I'm wagering that it can change the ratios by about 1/2 a point +/-

[The_Jerbel]

Re: What kind of A/F ratios are best with water/meth?

I don't have time to answer your questions in detail right now, but I have seen an AFR enrichment of roughly 0.3-0.5 while using meth. The really depends on how much meth you're spraying, what meth/water ratio you're running, what volume of fuel you're injecting, and what kind of meth injection system you're running.

[aliencurv]

Re: What kind of A/F ratios are best with water/meth?

Thanks for the tips. I should probably mention that I have an AEB series drive by cable. So I can't really do too much about the timing and fueling directly. What I was thinking of doing was getting my file revised and leaning it out that way. I could try and adjust the fuel pressure via my adjustable FPR. However, I've found that all that happens is the fuel trims change and I just end up chasing my tail.

That said, I do have some control over the fueling by adjusting the amount and concentration of Methanol. I'm wagering that it can change the ratios by about 1/2 a point +/-

you're right about chasing your tail, and you're smart to recognize that . I have similar conversations where ppl don't respond well with why that happens. in a closed loop system, the o2 sensor is used to measure stoich and correct fuel trims to compensate for clogged fuel filters, dirty mafs, dirty air filters, etc... sounds like you already know this

to be honest, i'm not familuar with the all of the chips and tuning software out there. I only know what i've used, but the basic theory to not blow up your engine is all the same.

however, ordering files over the internet is hit and miss. it is nice that you have a wideband and you can send them a datalog. What wideband system did you go with? And does it log with rpm? that will surely help the company you order the tune from.

since i know your situation now and you don't have the software to tune yourself... i'm going to suggest simply turning the boost up a bit . avoid getting out of your turbos effeciency range of course. but if the fuel ratio responds well, and u don't experience detonation then you're golden! adding a bit of water/meth when u do that won't hurt either.

there's a few other things you can consider before retuning also. if you are running an airbox, i'd suggest replacing it with a very large k&n cone. If your only a foot or so away from having the cone in a cold air area, then mopac has overpriced alummininumunum bends, silicon couplars and homedepot has clamps.

in the s4 world, i have had discussions with people who have tried k&n filters and claimed poor results. one of the problems i have a hard time not getting upset over is their implementation of airflow. usually ppl try running ducting and leaving parts of the airbox combined with a k&n to "provide cold air" etc.. that just obstructs airflow in the congested engine bay. so take a look at your setup and see how you can free up airflow and obtain cold air without too much more pipe.

when dealing with forced induction, you can't beleive how important airflow is. more cfm means getting boost sooner which will exponentionally increase your top end.

so if you want more power, free up airflow first. make sure that pump (engine) isn't struggling to breath: intake and exhuast.

[Mister T]

Re: What kind of A/F ratios are best with water/meth?

you're right about chasing your tail, and you're smart to recognize that . I have similar conversations where ppl don't respond well with why that happens. in a closed loop system, the o2 sensor is used to measure stoich and correct fuel trims to compensate for clogged fuel filters, dirty mafs, dirty air filters, etc... sounds like you already know this

Thanks for the endorsement. Although the AEB engine doesn't have closed loop under boost. The part throttle fuel trims you mention, do occur in closed loop conditions. As far as I know, those trim corrections are added to the WOT maps.

As for the file change, I'm not the one ordering it. I'd go through my Upsolute rep (Simon Lomas). However, I'd need to sens in some sort of logging. This is where it gets tricky. I have an Innovate LC-1 w Gauge. It can log, however I don't think it will pick up RPM along with the A/F ratios. What I think I may do is log VAG-COM and my LC-1 readings at the same time on two seperate laptops and then try and make an aggregate of the two.

I also realized I never told you what mods are already in place. So in the interest of saving you Carpal Tunnel Syndrome I'll list the relevant ones really quick:

-Airbox delete w partitioned CAI and K&N cone filter
-AEM e-boost controller
-LC-1 wideband
-Adjustable FPR
-034 exhaust manifold
-2.5 in exhaust w glasspack resonator and sport muffler
(I think that's all)

[aliencurv]

Re: What kind of A/F ratios are best with water/meth?

yah i don't think the lc-1 does it alone. u'll need to combine the controller with that gauge to do it. which is really too bad, because they have a large hold on the wideband market, but poor features for the base models.

someday i'll add vag-com to unity .. it does do lc-1 and a few other widebands + standalones and obdii. it is sadly still currently only being used by licensed tuners and not publically available yet, someday when/if i get time ..

[Mister T]

Re: What kind of A/F ratios are best with water/meth?

Saw the link, that's cool man. Is this something you made yourself? How does it work, what does it do? Fill me in please. I'm always down for something that allows me to tweak things.

As for the LC-1, yeah it is pretty bare bones. But then again it's also $220 (US). The only wideband that I've seen for a comparable price is the AEM one. And from what I've heard it's not as responsive as the LC-1, nor does it have any modular expansion capabilities.

On another note. I had some time to do a little more testing and I decided to downsize my W/M nozzles. With the weather getting colder I seemed to be getting a little richer (around 10.5:1). Went down a couple of sizes and now I'm seeing more in the 11:1 range again. What I'm wondering is if the W/M is fooling the intake temp sensor and ECU into selecting fueling values that are richer than they should be? I asked Darren at Snow Performance if he thought this may be the case but he didn't think so. However, with the temps getting colder, any misting effect is probably exaggerated. I guess I'll have to see what happens when things drop below 0. Oh well cold air = more air

[aliencurv]

Re: What kind of A/F ratios are best with water/meth?

yah i am the developer of a lot of automotive hardware and software.... as side projects for my company. but mostly i work in some other fields .

the one that is the best bang for the buck is actually the WMS Wideband, but it's not available right now.

is your w/m spraying before the iat?

if it is, then the iat will recognize the temperature change. also, you mentioned that the computer doesn't run in closed loop in boost? or do you mean it runs open loop at wot?

the fuel trim is still used in open loop, but only calibrated in closed loop. the fuel trim compensation is applied to the open loop map at wot.

the water meth will affect the fuel trims. so if the nozzles are changed, pressure isn't consistent, or it's on/off often... the fuel trims need time to recognize the drastic changes of the o2 sensors. you may experience different afr's if parameters keep changing.

also, your final afr is based on a Load reference map. so different gears, road grade, air temp, etc will have different calculated load values which will result in varying afr's. but, i imagine your afr logging is done on the same road, same gear, same rpm range, same start speed, etc... to get accurate values.

[Mister T]

Re: What kind of A/F ratios are best with water/meth?

Yes, the W/M is spraying before the IAT sensor

Yes, the AEB drive by cable doesn't have closed loop controls at WOT. That's one of the advantages of tuning it. It doesn't have a MAP sensor and consequently no limp mode. This also means that you can blow it up if you don't know what you're doing. Which is why I've educated myself to the best of my abilities. From what I've been able to gather the AEB ECU uses a combination of MAF, TPS and engine load data to determine fueling and N75 valve duty cycle (mine however, is deleted).

Now, as far as I know the closed loop part throttle trims are applied to the WOT open loop maps. What I'm not sure of is whether of not O2 sensor readings during open loop operation are applied to the fueling maps. If I had to hazard a guess, I'd say that open loop readings are not applied to the long term maps. So I don't think that the W/M will influence the trims.

As for my testing conditions, I tend to have a route that I'll do pulls on. So there is some consistency. However, being in the city means that I'm limited to 2nd gear pulls. I'll usually short shift into second, let the TC load up (it's a tip) and then pull from around 2500-3000 to redline. Most of the pulls are done at 80% duty cycle (EBC). Obviously the ambient temps have been a changing variable. So I'm trying to draw a bead on it's effects. As far as I've been able to tell, cooler temps seem to result in more PSI/airflow and richer mixtures.

It may also bear mentioning that the turbo I'm running is a one off experiment from the good folks at G-popshop. They mated the turbine section from my blown K04-015 to a completely new turbine, CHRA, compressor and comp housing. The turbine has a 10.5 deg clip to free up some flow in the tiny K04-015 housing. Also, the comp wheel is rated at 32 lb/min. I'm using an off the shelf Upsolute GT-28r file w 415 Genesis injectors. So it's taken a while to dial it in. I think I'm close though, as the wideband should let me fine tune it a little more. But then again, tuning is never done, is it?

PS: If you have the time I'd like to see some of the stuff you've done. Shoot me a PM if you have the chance.