[Former_Boosted_IS]

For about 6 months now I have been running on FJO Wideband with high speed datalogging on my car. When i first starting logging I was really surprised to see about a 13.7 - 14.0:1 AFR in the mid range rpms on my car. Considering a lack of knock activity, it I accepted it because DI motor's incredible atomization allowing much leaner AFRs. As I continued to push my car harder and add nitrous to my car, I felt very uncomfortable with those high AFRs in the mid range, in particular because our peak torque occurs so early in the rpm range. Basically we are leanest at peak torque and that is really not ideal from a tuning perspective.

From here, I found out that Terry built his JB3 board around a future possibility that would allow users to easily dial in different air/fuel ratios (AFR). The JB3 was built with this exact fueling flexibility in mind. The JB3 has two "fueling resistors" soldered onto the board that limit the amount the O2 sensors can be biased. What this means is the JB3 limits how much fuel the tune can ask for at 100% fuel demand. The beauty is you can easily change those fueling resistors out from the standard 5.1k ohm resistors to anything you want. Recently, I posted some of my testing:

http://www.e90post.com/forums/showthread.php?t=386328

I have tested 5.1k ohm, 3.3 k ohm, 2.2k ohm, and 1k ohm. What I found is the 2.2k ohm had a very nice AFR up top, but still too lean in the mid rpms in my opinion.



The natural progression was to test the 1k ohm fueling resistor. The 1k ohm looked incredible in the mid rpms but was very rich up top. I could actually feel the car bog a bit at this high AFR.



This is a graph showing the difference in AFR between the 2.2k ohm and 1k ohm fueling resistors.



It should be noted, I was able to richen up the 4000 rpms from 14.0:1 up to around 12.7:1 going from the standard 5.5k ohm to 1k ohm fueling resistors. This brought up a problem, because I wanted the higher rpm range of the 2.2k ohm resistors but peak torque (~4000 rpms) AFR of the 1k ohm fueling resistors. Since I wanted to spray nitrous with as much headroom as possible this has been something I have been working on for a while. I added another methanol solenoid and nozzle to fire progressively with the nitrous to give more of an octane buffer when nitrous is spraying, but in my opinion that doesn't solve the lean mid range issue. My solution came as a result of emails at Terry from BMS. Terry offered to create a "fuel taper" option in the JB3 because I think he knew this wasn't just for me, but would be for all JB3 users. This would allow the JB3 users now to dial in the exact AFR they wanted! This is huge as we move forward to higher horsepower applications. For those that will be putting in larger turbos or nitrous, this is an absolute must. In my opinion, running 14.0:1 at peak torque is not a good idea whether it is a DI motor or not, if you want any room for safety.

Here is how the fuel taper option will work... the fuel taper will start to, and linearly, remove fuel from 4000 rpms to redline as defined by the user. The higher the fuel taper value, the more fuel will be taken away the closer you go to redline, but it will not affect your AFRs below 4000 rpms. In my opinion, this is a huge feature especially for anyone thinking of running nitrous. Now you can dial in a specific air/fuel ratio for many applications. You don't have to flood the car with so much methanol in the hope of richening up the AFRs. The problem with simply using tons of methanol is the car will still be trying to actively reach the target AFRs. As you are forcing in tons of methanol, the DME will be trying everything it can tolean things out. I feel I don't want the DME trying to lean out the AFRs when I am spraying nitrous.

I was fortunate enough to get some time for testing and wanted to share. Here is a run on the JB3 with a fuel taper setting of 5. Notice it doesn't make that much of a difference. Only leaned out the higher rpms by about 0.4 AFR.



Here is a run on the JB3 with a fuel taper setting of 10. Now this was getting very close and I felt I finally had a very good AFR to run my nitrous. I decided still I would prefer a touch leaner up top and settled on a fuel taper of 11.



Now this is the fuel taper setting of 11 on the JB3 running a 35 shot of nitrous. What is remarkable here is that a stock 5.1k ohm resistor runs an AFR of around 14.0:1 at 4k rpms or peak torque and now running higher boost and nitrous, my AFRs are much richer and in my opinion much safer.



I dropped the ramp time on my nitrous down a little to see if I could get a significant lean spike and all I was still able to get is a 12.8:1 AFR. In my opinion that is VERY safe on a DI motor. Keep in mind this is an addition of 92 rwhp, so this is a pretty big addition.

To see what the JB3 is doing, I was able to get a quick dyno run to show you the fuel taper in action on Map 7. Notice the black line up top. You can see how the "Fuel Taper" option is dialing in my ideal AFR through the run.



I will finish the dyno work soon and hope to give more information. In my opinion, this is the future of the JB3 tuning. If you all have a 1k resistor, then you dial in whatever AFR you want. The only disadvantage is that it could cause worse gas mileage during peak torque, but safer is better as I see it. Also, I cannot imagine this wouldn't result in lower EGTs too, but right now that is only a theory.

Where am I going from here? Well, first more nitrous soon, then bigger turbo or turbos later. I hope to get to over 538 rwhp soon with a little more nitrous. Remember that number was done of larger turbos at ~21 psi, race gas, and tons of methanol. What I have done so far is 526 rwhp (dynojet correction) on pump gas, 670 ml/min of methanol, a 35 NX nitrous shot, and 14 psi. I am planning on dynoing on MS109 soon, 1050 ml/min of methanol, 50 shot, and 14-16 psi.

[OpenFlash]

FIS-- Good info. You seem very interested in making your nitrous application as safe as possible. Have you considered a nitrous triggered ignition retard? Seems to me (as well as experts at NOS, NX, ZEX, etc.) that is the most important thing to have in a turbo-nitrous application. Especially in a DI engine where fuel dumping doesn't do anything to appreciably improve knock resistance.

Also, does the JB3 actually monitor AFR? Or does all the AFR adjustments you described required additional test equipment?

Shiv

[Former_Boosted_IS]

Originally Posted by shiv@vishnu

FIS-- Good info. You seem very interested in making your nitrous application as safe as possible. Have you considered a nitrous triggered ignition retard? Seems to me (as well as experts at NOS, NX, ZEX, etc.) that is the most important thing to have in a turbo-nitrous application. Especially in a DI engine where fuel dumping doesn't do anything to appreciably improve knock resistance.

Shiv

Shiv, thank you. I haven't seen any knock activity yet at the richer AFRs when progressively spraying the nitrous. My goal in adding fuel is that I am staying away from the leaner AFRs where I have seen knock activity at peak torque. 14.0:1 at peak torque is just too lean in my opinion and in the testing I have done. If I do start to see knock, then I would certainly look into whether that was necessary. I really am starting to think that progressively introducing the nitrous over a time ramps is the key to nitrous on this DME.

On a side note, I would LOVE to find a colder plug that works. Do you have any ideas here?

[Funkmob]

Isn't a wideband sensor calibrated for pump gas stoich? So when you have a mix of pump + meth mix the reading is off , cause meth has a total different stoich?

[Former_Boosted_IS]

Originally Posted by Funkmob

Isn't a wideband sensor calibrated for pump gas stoich? So when you have a mix of pump + meth mix the reading is off , cause meth has a total different stoich?

I am not sure that I know that answer there. I suspect the quantity of fuel versus methanol would affect things. I am at about 670 ml/min off nitrous and 1050 ml/min on nitrous.

[OpenFlash]

Originally Posted by Former_Boosted_IS

Shiv, thank you. I haven't seen any knock activity yet at the richer AFRs when progressively spraying the nitrous. My goal in adding fuel is that I am staying away from the leaner AFRs where I have seen knock activity at peak torque. 14.0:1 at peak torque is just too lean in my opinion and in the testing I have done. If I do start to see knock, then I would certainly look into whether that was necessary. I really am starting to think that progressively introducing the nitrous over a time ramps is the key to nitrous on this DME.

All the things you are doing (over-fueling and ramping up nitrous over a long period of time) is a band-aid for not being able to tune it conventionally. I think you will find that following conventional nitrous tuning methodology and simply applying a 1-3 degree ignition retard at nitrous onset along with a staged/secondary meth nozzle (to eliminate the need for fuel immediate adaption once nitrous is triggered) will address your concerns of knock and lean-run at nitrous onset. I'm not sure if you are doing that latter bit.

Using this approach on my car, when nitrous triggers, my AFR immediately goes to 12:1 and then tracks my AFR targets perfectly. This is using a m7 primary nozzle and an m10 secondary nozzle. Using an unstaged meth system, one will never achieve this AFR tracking response. The ignition retard amount, depending on boost when nitrous triggers, is 1-3 degrees which quickly tapers to 0 deg by redline (when running on race gas). Interestingly enough, the ignition retard doesn't reduce engine torque (on the dyno) which suggests that the combination of high octane and low IAT allows the engine to operate with excessive timing. Which clearly isn't good for the bottom (expensive) end of the engine. Basic tuning practices suggest running min advance required for best torque (assuming absence of detonation).

On a side note, I would LOVE to find a colder plug that works. Do you have any ideas here?

I've found that you can install M5 plugs in the N54. They fit and are definitely colder rated. You'll have to machine down a standard spark plug tool in order for it to fit in the n54's spark plug holes. But I never saw any improvements to knock resistance or power output during testing. Again, if you are battling knock retard issues, the real solution is to retard timing. That will have a MUCH greater impact that spark plug heat range selection.

Shiv

[OpenFlash]

Originally Posted by Funkmob

Isn't a wideband sensor calibrated for pump gas stoich? So when you have a mix of pump + meth mix the reading is off , cause meth has a total different stoich?

Widebands actually measure oxygen content, and back-calculate AFR assuming a given fuel (meth, ethanol, gasoline, etc,.). This is why most good widebands allow you to select the fuel being used. You'd still target the same nominal AFR (as displayed on the wideband) even when running straight methanol. You'd just find that you have to inject a lot more fuel in relation to air in order to achieve that nominal AFR value.

Shiv

[Former_Boosted_IS]

Originally Posted by shiv@vishnu

All the things you are doing (over-fueling and ramping up nitrous over a long period of time) is a band-aid for not being able to tune it conventionally. I think you will find that simply applying a 1-3 degree ignition retard at nitrous onset along with a staged/secondary meth nozzle (to eliminate the need for fuel immediate adaption once nitrous is triggered) will address your concerns of knock and lean-run at nitrous onset. On my car, when nitrous triggers, my AFR immediately goes to 12:1 and then tracks my AFR targets perfectly. This is using a m7 primary nozzle and an m10 secondary nozzle. The ignition retard amount, depending on boost when nitrous triggers, is 1-3 degrees which quickly tapers to 0 deg by redline (when running on race gas). Interestingly enough, the ignition retard doesn't reduce engine torque (on the dyno) which suggests that the combination of high octane and low IAT allows the engine to operate with excessive timing. Which clearly isn't good for the bottom (expensive) end of the engine. Basic tuning practices suggest running min advance required for best torque (assuming absence of detonation).

Shiv

Shiv, my results were a bit different for some reason? When I injected tons of methanol the car it was obvious the car didn't like it. I suspect if was the DME trying to lean out the AFR to hit the target. If you got down to an AFR of 12.1:0 at peak torque then you were a full 2 points below your target AFR. I am simply targeting the lower AFR rather than forcing it by flooding the car with methanol. Maybe just different means to the same result? Regardless you agree that an AFR below 14.0:1 is a good thing at peak torque when running nitrous?

For what it is worth, I don't think a timing retard when the nitrous triggers is a bad thing at all. I hope that comes across to you. I am just finding on a progressive nitrous setup it doesn't seem to be necessary from the timing logs I have collected.

[Funkmob]

Originally Posted by Former_Boosted_IS

I am not sure that I know that answer there. I suspect the quantity of fuel versus methanol would affect things. I am at about 670 ml/min off nitrous and 1050 ml/min on nitrous.

On this website there is some interesting reading regarding the stoich levels and AFR ratios for pump meth applications:

http://www.eng-tips.com/viewthread.c...=174777&page=1

[Former_Boosted_IS]

Originally Posted by Funkmob

On this website there is some interesting reading regarding the stoich levels and AFR ratios for pump meth applications:

http://www.eng-tips.com/viewthread.c...=174777&page=1

Funk, thanks for the link. I am not sure how that applies here though? I am running nearly 11 degrees at peak torque and nearly 14 at redline even on nitrous. That seems very attractive.

[Funkmob]

Originally Posted by Former_Boosted_IS

Funk, thanks for the link. I am not sure how that applies here though? I am running nearly 11 degrees at peak torque and nearly 14 at redline even on nitrous. That seems very attractive.

I copied this from that page:

Hello,I have been running methanol injection in our supercharged and turbo charged 2.7L Hyundai V6 engines as an octane booster for higher boost levels on pump gas, 93 octane. I understand that gasoline is 14.7:1 stoich and methanol is 6.4:1 stoich. When supplementing approximately 20-30% of the gasoline with methanol and we look at a wideband that is calibrated for gasoline, the wideband shows extremely rich. If I tune the car to 12.2:1 A/F with the added methanol, how do I figure out what the actual A/F ratio is with the addition of the 25% methanol. I was told that even though I see 12.2:1 A/F on the wideband, the mixture is actually leaner than what I am seeing because of the difference in stoich between the two fuels and beacause the wideband is calibrated for gasoline. Can anyone help me understand this a little more cleary with some sort of formula that I can use to calculate the actual A/F? I would greatly appreciate it.Thanks T.C.Next Generation Motorsports


NCShane (Automotive) 24 Jan 07 16:34
The combined A/F is simply %A/F 1 + %A/F 2So for 20% methanol, .2(6.4) + .8(14.6)= 12.96This still doesn't help you since your A/F meter is calibrated for a stoich. ratio of 14.6. You can set your meter to read Lambda, then multiply by your combined A/F ratio to find your correct A/F.



The other stuff regarding timing on pure meth doesn't apply here

[Former_Boosted_IS]

Originally Posted by Funkmob

I copied this from that page:

Hello,I have been running methanol injection in our supercharged and turbo charged 2.7L Hyundai V6 engines as an octane booster for higher boost levels on pump gas, 93 octane. I understand that gasoline is 14.7:1 stoich and methanol is 6.4:1 stoich. When supplementing approximately 20-30% of the gasoline with methanol and we look at a wideband that is calibrated for gasoline, the wideband shows extremely rich. If I tune the car to 12.2:1 A/F with the added methanol, how do I figure out what the actual A/F ratio is with the addition of the 25% methanol. I was told that even though I see 12.2:1 A/F on the wideband, the mixture is actually leaner than what I am seeing because of the difference in stoich between the two fuels and beacause the wideband is calibrated for gasoline. Can anyone help me understand this a little more cleary with some sort of formula that I can use to calculate the actual A/F? I would greatly appreciate it.Thanks T.C.Next Generation Motorsports


NCShane (Automotive) 24 Jan 07 16:34
The combined A/F is simply %A/F 1 + %A/F 2So for 20% methanol, .2(6.4) + .8(14.6)= 12.96This still doesn't help you since your A/F meter is calibrated for a stoich. ratio of 14.6. You can set your meter to read Lambda, then multiply by your combined A/F ratio to find your correct A/F.



The other stuff regarding timing on pure meth doesn't apply here

I suspect these guys are running a whole lot more methanol than me as they are stating 30% methanol. The other issue is I am not running methanol all the time. It doesn't seem that we could do that unless we are running methanol all the time.

[OpenFlash]

Originally Posted by Former_Boosted_IS

Shiv, my results were a bit different for some reason? When I injected tons of methanol the car it was obvious the car didn't like it. I suspect if was the DME trying to lean out the AFR to hit the target. If you got down to an AFR of 12.1:0 at peak torque then you were a full 2 points below your target AFR. I am simply targeting the lower AFR rather than forcing it by flooding the car with methanol. Maybe just different means to the same result? ?

Actually, that is spot on the lambda target. I got it to the point there fuel trims wouldn't even budge when nitrous was triggered. Then again, I'm triggering nitrous at 4000rpm which is slightly higher than convention since I didn't want engine torque to exceed 500lbft due to engine integrity concerns. Somewhat arbitrary but I figured you'd never drop below 4000rpm if you were running the car hard (ie, drag strip).

Regardless you agree that an AFR below 14.0:1 is a good thing at peak torque when running nitrous?

It's certainly not a bad thing. But if you are solving your knock issue by simply running 2pts richer, you are a far gutsier tuner than I am.

For what it is worth, I don't think a timing retard when the nitrous triggers is a bad thing at all. I hope that comes across to you. I am just finding on a progressive nitrous setup it doesn't seem to be necessary from the timing logs I have collected.

If you try implementing a retard system, you will likely find that you don't have to rely on the other band-aids (over-fueling and slow nitrous ramp up). At this point, we are pushing these engines to nearly 200/liter. Doing so while targeting the factory timing curve (regardless of octane) is questionable IMHO.

Shiv

[OpenFlash]

Originally Posted by Former_Boosted_IS

Funk, thanks for the link. I am not sure how that applies here though? I am running nearly 11 degrees at peak torque and nearly 14 at redline even on nitrous. That seems very attractive.

No, it's not attractive. Because running 8-9 deg of timing at peak torque will give you the same peak torque as running the 11 deg which you have no control over. That advance was mapped, by bmw calibration engineers, for a stock n54 running 5-7psi on pump gas. Not a fully modded n54, running 14psi with nitrous and methanol on pump gas. This 2-3 degree delta is, by all definitions, OVER-advance and is unnecessary stressful to the engine. The goal is to achieve the most conservative timing curve while not sacrificing much (or, in this case, any) torque output. I'm not trying to give you a lecture by any means. But you what you are doing doesn't follow basic engine theory.

Shiv

[Former_Boosted_IS]

Originally Posted by shiv@vishnu

Actually, that is spot on the lambda target. I got it to the point there fuel trims wouldn't even budge when nitrous was triggered. Then again, I'm triggering nitrous at 4000rpm which is slightly higher than convention since I didn't want engine torque to exceed 500lbft due to engine integrity concerns. Somewhat arbitrary but I figured you'd never drop below 4000rpm if you were running the car hard (ie, drag strip).



It's certainly not a bad thing. But if you are solving your knock issue by simply running 2pts richer, you are a far gutsier tuner than I am.



If you try implementing a retard system, you will likely find that you don't have to rely on the other band-aids (over-fueling and slow nitrous ramp up). At this point, we are pushing these engines to nearly 200/liter. Doing so while targeting the factory timing curve (regardless of octane) is questionable IMHO.

Shiv

I don't disagree a timing retard would be a bad thing with nitrous. I do want to emphacize that.

I am confused when you say I am running two points richer to solve a knock issue? I don't have a knock issue that I have logged. I am simply stating I think that is a much safer A/F to be spraying nitrous at when using a dry system. That gives quite a bit of buffer from going lean. Would I be correct in saying you agree the richer A/F is wise for that exact same reason?

[OpenFlash]

Originally Posted by Former_Boosted_IS

I don't disagree a timing retard would be a bad thing with nitrous. I do want to emphacize that.

I am confused when you say I am running two points richer to solve a knock issue? I don't have a knock issue that I have logged. I am simply stating I think that is a much safer A/F to be spraying nitrous at when using a dry system. That gives quite a bit of buffer from going lean. Would I be correct in saying you agree the richer A/F is wise for that exact same reason?

I read this:

My goal in adding fuel is that I am staying away from the leaner AFRs where I have seen knock activity at peak torque.

And interpreted as you saying that you were seeing knock activity at the leaner AFR. Sorry if I misunderstood you. Lots of info in this thread so it's easy to get a mixed up. FWIW, I targeted rich as possible at first just to be conservative at first. I actually found out that it was too rich when running at the track. The car would rich bog slightly at the onset of nitrous/meth. Which actually gave me some much needed emotional comfort Next time out, I'm going to swap the nozzles (run m10 primary and m7 staged). Should still be conservative but will probably run better.

Shiv

[Former_Boosted_IS]

Originally Posted by shiv@vishnu

No, it's not attractive. Because running 8-9 deg of timing at peak torque will give you the same peak torque as running the 11 deg which you have no control over. That advance was mapped, by bmw calibration engineers, for a stock n54 running 5-7psi on pump gas. Not a fully modded n54, running 14psi with nitrous and methanol on pump gas. This 2-3 degree delta is, by all definitions, OVER-advance and is unnecessary stressful to the engine. The goal is to achieve the most conservative timing curve while not sacrificing much (or, in this case, any) torque output. I'm not trying to give you a lecture by any means. But you what you are doing doesn't follow basic engine theory.

Shiv

Shiv, without just guessing at my timing curve, I grabbed one for you.



It shows I am very close to the 9 degrees at peak torque you mention.

I do want to make it clear that I am not even in the same league as you in terms of tuning and understanding. I have no illusions that my wisdom exceeds yours and I do appreciate your input.

[OpenFlash]

Originally Posted by Former_Boosted_IS

Shiv, without just guessing at my timing curve, I grabbed one for you.



It shows I am very close to the 9 degrees at peak torque you mention.

I do want to make it clear that I am not even in the same league as you in terms of tuning and understanding. I have no illusions that my wisdom exceeds yours and I do appreciate your input.

It's cool man... I'm somewhat of a n00b when it comes to nitrous. So I'm learning here myself. So please don't take anything I'm saying as another other than constructive suggestions. Mistakes when running nitrous are plentiful and really costly. No one wants to see anyone else swallow the price of a new engine.

That said, the area of concern for me (and remember than I'm spraying at 4000rpm which means my peak torque is at 4000-4500rpm) is the 10-11 degrees of timing the DME is stubbornly targeting in that RPM zone. That's just too much timing when running ~500lbft of torque. You'll make the same engine output with a little ignition retard.

Nitrous tuning is a funny thing because it drops the IAT so much which works as a great knock suppressing agent. The downside is that you can run (esp when you add secondary agents like methanol and/or race gas) MORE advance than is necessary to make that peak torque. And that is not something you would want to play with when running twice factory engine output.

Shiv

[Former_Boosted_IS]

Originally Posted by shiv@vishnu

It's cool man... I'm somewhat of a n00b when it comes to nitrous. So I'm learning here myself. So please don't take anything I'm saying as another other than constructive suggestions. Mistakes when running nitrous are plentiful and really costly. No one wants to see anyone else swallow the price of a new engine.

That said, the area of concern for me (and remember than I'm spraying at 4000rpm which means my peak torque is at 4000-4500rpm) is the 10-11 degrees of timing the DME is stubbornly targeting in that RPM zone. That's just too much timing when running ~500lbft of torque. You'll make the same engine output with a little ignition retard.

Nitrous tuning is a funny thing because it drops the IAT so much which works as a great knock suppressing agent. The downside is that you can run (esp when you add secondary agents like methanol and/or race gas) MORE advance than is necessary to make that peak torque. And that is not something you would want to play with when running twice factory engine output.

Shiv

Thanks for taking the time to respond in these threads. Remember you are running a straight shot where I am progressive on a 2 second ramp. I am also using a 1 second delay. My window is about 3500 rpms to 6400 rpms I think. After the first ramp, the car will not ramp again but fire the shot for subsequential gears. That means I will not have the torque spikes down low either.

[Clap135]

Former

Thanks for posting the timing/af logs. I must say your timing for the power you are making looks very nice. I'm glad to see you got a proper af ratio figured out. Sweet information posted for future nitrous users.

[Mike@N54Tuning.com]

Great info! That external wideband air/fuel log of "taper 10" is the nicest piggyback air/fuel ratio I've ever seen. Timing curve looks solid also. And if I read this right you're still using pump gas? That's amazing and just goes to show what proper fueling can do. Being able to swap out those fueling resistors and dial in your air/fuel curve is a very nice addition to the JB3.

Now that you have the air/fuel ratios perfectly dialed in I'd suggest taking advantage of the JB3's user adjustable fuel pressure safety system. Here is your CSV log with fuel pressure added. Notice that the lowest it goes under full load/nitrous is around 13. I would set the safety to 11-12. That way if you ever run leaner than you are now it will trigger the JB3 to revert to a safety map.

I know this doesn't apply to you as you're using the NX controller but for those not using a controller the JB3 also can control the nitrous turn on/off, reduce nitrous during shifts, ensure nitrous only turns on when meth is flowing, etc. BMS is testing all that now but its setup in the latest 4/22 interface under the methanol/nitrous tab.

Mike

[mwahlert]

my god the PROcede user software needs an overhaul.... the jb3 user software is laid out VERY nicely.