During this recent testing of dialing in the nitrous tune, picking just one point in the fuel map (3680 rpm/100 kPa map), the range of fueling that was explored was around 11%. They were right. Methanol has a very wide tuning range. Even when paired with nitrous.

Time to clean up the ignition timing setting when on the system.

 

Turns out the timing setting when on the system is much more critical than I thought. I tried to level out the timing curve to give a nice straight timing value during NOS activation and got an interesting result. It looks like I'll be working up a varying timing curve for when on the system. Why can't anything be easy.

 

I would have expected the timing to be sensitive when using the system. It would be interesting to see the changes with and without timing control.

 

After I finish the upcoming testing with the nitrous timing, I'll post some results.

 

Just to organize my thoughts.
I seem to have become lax with the importance of the timing while on the system. In the beginning of my experimenting with using nitrous to help spool the turbo I understood that a certain shot of nitrous was much more potent at low rpm than at high rpm. A larger volume of nitrous mixture allowed to enter the cylinder due to more time available with an open intake valve during low rpm operation. Back then I understood that and set up the timing table to give me more nitrous retard at initial hit, with less retard as rpm increased. As I increased the shot size throughout the years, I have pretty much ignored the timing and simply set up a straight timing retard value with no regard to making sure I had a little more retard during initial activation.
In the recent datalogs, you can see that there is a dip in the timing at initial activation of the nitrous system. That was the straight nitrous retard working with the timing table. There was no special or conscious effort made to create that dip in timing for the nitrous system. Also notice that the dip doesn't last very long. The timing quickly jumps to a more or less straight line value during the rest of the nitrous activation.
I recently thought it might be nice to level out that timing retard value for no other reason than it would look more pleasant on the datalog. I massaged the main timing table so that when the straight value nitrous retard came in it would result in a nice straight line timing value during the duration of the hit. It only amounted to about 2 degrees more timing at the start of the hit to remove the initial dip in timing.

 

It turned out that little 2 degree change at the beginning of the hit made all the difference in the world. When the nitrous activated, the engine acted as if it was on a low rpm rev limiter (2850 rpm!) and the rpm and map both stayed level for the duration of the hit. The change was so extreme that I was looking over the controls to see if maybe I had forgotten to arm the nitrous system or open the nitrous bottle or something. It took me awhile to even realize that maybe that little 2 degree change might have something to do with it. Maybe a nitrous solenoid was sticking?
Well, I simply went back to the past timing strategy, and all was back to normal. Wow. It made me realize that maybe I was missing out on something with my simple nitrous timing retard strategy. If 2 degrees at the start of the hit can make that much difference. Hmmm.

 

My first test is going to involve carrying out that intial dip in timing longer into the hit, instead of having the timing jump back up so quickly. Maybe the timing jumping up that 2 degrees or so is what's causing the rpm and map rise to stall at around 3900 rpm during the first portion of the hit.

 

I would think you could use normal ignition timing usin ghte nitrous after it gets above @4500rpm. At that point, with the small shot you're using, the total nitrous injested would be relatively small in comparison to the incoming charge and the cooling effect of the nitrous would offset some of the timing retard needs of the boosted charge.

Am I making any sense here?

 

I understand where you're coming from. Part of the testing will involve slowly working up the timing during the last half of the hit. Actually, I'll be playing with the timing in both directions in the later part of the hit, just to see what the characteristics are like. But first, I'll be concentrating on the first half of the hit. Small steps.

I feel, ultimately throughout the hit, there will need to be a balance with the timing, allowing enough crankshaft power to have the rpm ramp up at an acceptable level, but also allowing enough energy to be expelled into the exhaust system to help quickly spool the turbo. After all, the main idea is to get off the nitrous as quickly as possible and rely on the turbo.

edit: I wouldn't exactly consider a 360 shot small for a V6.

 

When I first discovered the nitrous/methanol ALS, I was working with a smaller shot. The trigger point for the ALS affect was 14 degrees btdc. What I have failed to realize is that with the larger shot sizes, that ignition trigger point could very well be different. I've been concentrating too much on the mixture strength alone, and not on both mixture strength and the ignition timing.

 

Ahhhhh..... For some reason I had it in my mind that you were using a 75 shot... 360 changes things!! lol

You may have said it, but what size nitrous jet are you using? 90+?

 

The primary system is port injected. With that large of a shot, you really want to port inject it.
The jetting per intake port is square at 32/32. The fuel side is using main fuel rail pressure, 45 psi at idle, MAP referenced.

 

First attempt with the smoothed, ramped timing with the nitrous,... SUCCESS!!!
Smooth rpm and map rise.
Time from nitrous activation to the target 150 kPa MAP, 1.6 seconds, with the current light WG and BOV settings. A new best.
I'll get the datalog posted soon.

 

Beautiful!
Next, I'm going to ramp in one more degree of timing by the end of the hit, having the extra degree start to ramp in at 4600 rpm.

#ad

 

Holy cow! What the heck happened here!?
I think the engine is trying to tell me something. "Less timing, dummy!"
It looks like I'm on the edge of finding the ALS trigger point of a 360 shot!
This one scared the beejeebees out of me.

This test brought some new fuel and timing table cells into the picture that I'm going to need to massage to get the timing retard back to a smooth ramp.

#ad

 

I just love finding gobs of horsepower.
The exhaust tone during the nitrous activation was back to perfectly smooth. No missing or popping with this test.

 

Today with bin file 15p, the time from nitrous activation to 150 kPa MAP, 1.54 seconds. The ALS trigger parameters are becoming clearer. Still, a little more work to do on both the fuel and timing tables. Very close.
The ALS is lighting off, but looks to be a little on the rich side during the first half of the hit.

 

The timing while on the nitrous is much more sensitive than I had imagined. One third of a degree of timing makes a noticeable difference in rpm and boost climb rate.
It's a delicate balancing act between having enough timing to make for a smooth rpm rise, but not so much as to slow the boost rise rate.
The ramp up of timing is also steeper than I would have thought from the point of activation at 2500 rpm to the turn off point of around 5400 rpm.
I'm still working on it. I just had to post to share how adjustable the rpm and map rise rates are using tiny fuel and timing changes.

 

Holy shit a third ? Is it linear or are you having to find that 1/3 of a degree through the whole transition into boost ? How sensitive to weather and altitude is going to be now ? You're gonna have to bring the transmission by yourself. See the candy on this car, and the new one coming,too.

 

Not sure if it's linear yet. Haven't got that far yet. I'm up to about 4500 rpm at the moment.
When I started, the rpm was stalling for a moment at 4050 rpm. I leaned the fuel map 1% and increased the timing .7 degree. The result was surprising. The rpm did not stall through that range. When the rpm reached 4500 rpm, the timing began to level out, and the rpm rise rate did the same, while the boost continued to climb at a steady rate. Very interesting.
I'm going to continue to add timing in as I work up the rpm ramp up. Hopefully I'll be able to end up with a transition when the nitrous turns off where the rpm will show very little change when the full timing comes back in.