Turbo folks: Have some AFR questions

[dville_gt]

So I am going to spend some time getting my AFR as dialed in as I can on the street before I head to the dyno. Currently I just have 6lb springs in the gates. Due to a mistake in my AFR equation in my tuning software my tune is VERY VERY fat (read: bottoms out my w/b at 10:1 in boost).

So I am going to start pulling fuel out of it to get it where it needs to be. From what I have read you ideally want to richen the mix as you come into boost aiming for ~11:1 for boosted regions over say 8lbs.

Is this correct?

Should I modify my enrichment rate to not aim to go straight to 11:1, but rather feather it down to 11:1 as the boost comes up?

On a second note, I have all my stuff installed for meth/water injection (just going to try running washer fluid for now, might switch to pure meth or alcohol later).

Does the meth/water injection change the AFR?

If so should I get my fueling dialed in without the the meth, then add the meth, or try to do my tuning with the meth injection?

Is the ideal AFR for boost + meth still 11:1?

[FoxBodyNick]

i would say i agree with getting a progressive meth/water kit when applying it.

11:1 sounds good to aim for.

spraying it does drop the A/f ratio but how much, depends. If you are doing just a meth reliant tune then just tune it with the meth injection. Good luck if something happens and you lean out! If you are just adding meth as an insurance then I am not sure.

[majorownage]

If you are using a wideband, yes.

With the meth, you can shoot for 12s and make more power too.

A wideband is measuring lambda, which is based off the hydrocarbon content of the exhaust. Lambda is then multiplied by 14.7 for AFR.

So even if you are running pure alcohol, you still will be shooting for 11-12 afrs, even though your true AFR will be much richer.

[dville_gt]

Ideally I'd like to set the meth up as a bit of an insurance policy. I would really like the car to be able to live even with a failure, but I understand the further I push the boost levels the more I will need the meth injection (10:1 compression). So I think the best bet for me is to tune it on pump gas at least at the current boost levels, then as I raise the boost levels add the meth injection. Since the weather is cool right now I am more detonation resistant then I will be come summer time, so what works without meth now probably won't work w/out it later.

[dville_gt]

And yes, I always use a wideband for tuning.

[turbos66coupe]

Fist 11:1 is a little fat. 11.5-11.8 is a better start. With that said every car is different. Secondly meth injection is a fuel source and will most definetly change AF. Tunning for it is a must unless its a real small kit. Only problem is if you tune for it and it fails, runs out etc you are in for trouble. I don't care for it on a street car but I digrese. Question is why with only six lbs and a large intercooler do you need it. There is no way that turbo is heating any air at only six lbs. I would tune the car first get it dynoed and put a temp sensor on the intercooler outlet and see what actual intake temps are.

[turbos66coupe]

I just read your post two posts up and sounds like you've got the right thinking, except I dnt think the 10:1 compression makes a shit. boost changes effective compression ratio. So a car with 10:1 and 10lbs is no different than say a car with 8:1 and 15lbs. I used to have a sheet of paper that came from ford with effective compreeion ratios with x amount of boost. Ill look for it.

[dville_gt]

Fist 11:1 is a little fat. 11.5-11.8 is a better start. With that said every car is different. Secondly meth injection is a fuel source and will most definetly change AF. Tunning for it is a must unless its a real small kit. Only problem is if you tune for it and it fails, runs out etc you are in for trouble. I don't care for it on a street car but I digrese. Question is why with only six lbs and a large intercooler do you need it. There is no way that turbo is heating any air at only six lbs. I would tune the car first get it dynoed and put a temp sensor on the intercooler outlet and see what actual intake temps are.

My plans are to run it at 15psi. I have a fast acting IAT mounted right before the throttle body and have the IAT timing table pull timing starting at just over 100* IAT temps. I was planning to use the IAT timing tables to act as a fail safe for the meth injection not coming in for some reason. So 11.5:1 is a good afr? What is the consensus about AFR's across the range, should it be fatter or leaner in peak torque area's and fatter/leaner in higher hp/rpm areas?

[majorownage]

My plans are to run it at 15psi. I have a fast acting IAT mounted right before the throttle body and have the IAT timing table pull timing starting at just over 100* IAT temps. I was planning to use the IAT timing tables to act as a fail safe for the meth injection not coming in for some reason. So 11.5:1 is a good afr? What is the consensus about AFR's across the range, should it be fatter or leaner in peak torque area's and fatter/leaner in higher hp/rpm areas?

Y not just run C16 when you want high boost? Safer than meth injection.

[turbostang]

If the car is intercooled, I don't think I'd be looking into running meth injection - but thats just my take.

The higher compression just means you need to be more conservative on the timing table when running lower octane.

If you want the benifits of meth, use E85 and tune accordingly.

What exactly is 15psi going to do?

[dville_gt]

If the car is intercooled, I don't think I'd be looking into running meth injection - but thats just my take.

The higher compression just means you need to be more conservative on the timing table when running lower octane.

If you want the benifits of meth, use E85 and tune accordingly.

What exactly is 15psi going to do?

Not sure I understand the question exactly. I have the 6psi springs in the gates right now. I'd like to move up to the 1 bar springs for more power obviously? What is the problem with meth/water injection on an intercooled application? I have the meth bung welded about 6 inches before my fast acting IAT. My plan has been to run the meth/water as a bit of an insurance policy against detonation in the hotter months. I have a pressure switch to activate it and use the devilsown calculator to figure out the nozzle size (14 gallons per hour). I already have everything hooked up (pump, lines, nozzle, pressure switch, tank, etc.), so if it'd provide me with a bit more leniency in the learning curve it'd be worth it, especially when washer fluid is $2 a gallon. Problem with e85 is dealing with the scarcity (especially since they ended the subsidy), not to mention I don't have the fuel system to handle it (eliminator pump/90lb injectors). Since the meth/water is self enriching (and apparently even enriching), I figure it will even buy me more room within my current fuel system. Am I way off base here?

[dville_gt]

And as I stated earlier, I plan to using my IAT vs timing tables to pull timing as the IAT's start to rise, I figure this will act as a bit of a fail safe in the case that my meth/water system fails for some reason, have it aggressively pull out the timing if IAT's get over xxx degrees, I figure I'll have to revisit this number as the weather gets hotter since the IAT's will undoubtedly be higher in summer months vs. winter months all other things equal.

[turbostang]

Not sure I understand the question exactly. I have the 6psi springs in the gates right now. I'd like to move up to the 1 bar springs for more power obviously? What is the problem with meth/water injection on an intercooled application? I have the meth bung welded about 6 inches before my fast acting IAT. My plan has been to run the meth/water as a bit of an insurance policy against detonation in the hotter months. I have a pressure switch to activate it and use the devilsown calculator to figure out the nozzle size (14 gallons per hour). I already have everything hooked up (pump, lines, nozzle, pressure switch, tank, etc.), so if it'd provide me with a bit more leniency in the learning curve it'd be worth it, especially when washer fluid is $2 a gallon. Problem with e85 is dealing with the scarcity (especially since they ended the subsidy), not to mention I don't have the fuel system to handle it (eliminator pump/90lb injectors). Since the meth/water is self enriching (and apparently even enriching), I figure it will even buy me more room within my current fuel system. Am I way off base here?

You're missing the point of the question - What are you looking for 15psi to do exactly? What if 15 psi doesn't do what you expected?

In other words, don't settle on a boost number, but rather a power level or an ET.

I don't think there's any leniency at all, if anything it will add a new level of difficulty to something you're already unfamiliar with.

I don't know that the IAT vs. timing is fast acting enough to be able to catch the meth failure.. I'd think you'd have to drop the timing much sooner than you 'wanted' to - which would probably end up in your 'normal' running conditions.

All in all, i'm not a fan of adding complexity where it's not needed

[dville_gt]

Okay, I see what you are asking now. Based on a very similar combo (lq9/t6 s475 @ 15psi) there is an s10 truck that is doing bottom 10's. I'd really like this car to go 9's so I figure my coupe will probably be pretty close to that @ 15psi. Granted the s10 isn't running meth injection and is using the more restrictive truck intake, so possibly I can pull those goals off without the meth injection at all.

You're missing the point of the question - What are you looking for 15psi to do exactly? What if 15 psi doesn't do what you expected?

In other words, don't settle on a boost number, but rather a power level or an ET.

I don't think there's any leniency at all, if anything it will add a new level of difficulty to something you're already unfamiliar with.

I don't know that the IAT vs. timing is fast acting enough to be able to catch the meth failure.. I'd think you'd have to drop the timing much sooner than you 'wanted' to - which would probably end up in your 'normal' running conditions.

All in all, i'm not a fan of adding complexity where it's not needed

[turbos66coupe]

Like brooks said water/meth does add complexity to the whole thing. That combo should runs 9's falling out of a tree. Shoot for an et and go from there. You may be surprised how well t does. Start with the 6lb spring as you have it. Get dialed in and ge the chassis stuff under control because 9's is no fun in an unsafe car. Then turn up the whick! As far as afr stuff like I said I would as farshoot for somewhere around 11.5:1. As far as load scaling and when you want to richen it up well that depends on a lot of variables. I generally leave that to more experienced tuners so sorry no help