Advancement of fuel delivery?

[Dusty Bradford]

Speaking of 2-step spooling pre-launch. I understand that the routine is different for sticks and automatics. The stick or no-load procedure is pretty well known. A local tuner told me that with an automatic you want to increase timing (50 degrees btdc with gas) and shoot for a power mixture, not particularly overly rich. As the turbo starts to spool timing is backed away. This sounds a bit dangerous to me. How close are people running to detonation limits with this routine? I would guess that the turbo/converter combination is such that spooling is not really a difficult problem to begin with.

I thought this way was the most common knowledge.

On gas I run as much as 46 degrees and 13.5-1. Some cars like 12.5-13.0 so I have to play with them a little to find what they respond to.

I run this timing below 100kpa. As the car builds boost I ramp the timing and fuel map closer to 12.5-1 when I launch. I do nor use a seperate map, I do it all on one map and just transition from boost building, to launch then to run. Since the boost is ever increasing, doing it all on one map is no problem.

 

[Alky V6]

I thought this way was the most common knowledge.

On gas I run as much as 46 degrees and 13.5-1. Some cars like 12.5-13.0 so I have to play with them a little to find what they respond to.

I run this timing below 100kpa. As the car builds boost I ramp the timing and fuel map closer to 12.5-1 when I launch. I do nor use a seperate map, I do it all on one map and just transition from boost building, to launch then to run. Since the boost is ever increasing, doing it all on one map is no problem.

Thanks Dusty. Believe it or not, it's not common knowledge. The spooling tricks for sticks is all over the place, but not for automatics. This is probably the only place on the internet where it's layed out so well now.

 

[Alky V6]

Turbo parts came in and she's going back together.

A big, gigantic THANK YOU to John (gnX405). B/W Turbo Systems specialist. He came up with the wheel in ONE day when others were saying 8 to 12 weeks from England. You are my hero, John.

 

[TurboTR]

Well, big increase in timing (and thus torque) is exactly the concept we argued for here like 7 years ago. Making torque seemed to work the best against the load of an automatic, and that's what this does. Making torque makes higher rpm against the load, the higher rpm raises the airflow, which spools the turbine, which.. Not considering the 2 step here of course.

The clutch cars, they use the bang bang method since they have no load to work against. Which is basically what pwr6kid is talking about, burning/exploding fuel in the exhaust.

Most (but not all) of us Buford guys just have autos though of course

TurboTR

 

[Alky V6]

Well, big increase in timing (and thus torque) is exactly the concept we argued for here like 7 years ago. Making torque seemed to work the best against the load of an automatic, and that's what this does. Making torque makes higher rpm against the load, the higher rpm raises the airflow, which spools the turbine, which.. Not considering the 2 step here of course.

The clutch cars, they use the bang bang method since they have no load to work against. Which is basically what pwr6kid is talking about, burning/exploding fuel in the exhaust.

Most (but not all) of us Buford guys just have autos though of course

TurboTR

LOL! Is this thread really that old? LOL. Funny guy.

I'll play with it again with the higher stall. Again, as I said 7 years ago? :biggrin: I tried 40 degrees and the rpm against the converter was less than it was at 30-32. I'll start out with 45 btdc with a mixture around 12.5 to 12.8 and see what it does.
I'm anxious to experiment with the 2 step also.
BBS- Going to start the engine now.

 

[Alky V6]

The new stator gave me about 340 more rpm off the juice.

In an effort to attain the highest rpm and map reading at T/C stall, I leaned the mixture at the new stall speed 16%. There was a little gain from this. I was amazed what little change there was within this wide range of mixture settings. Goes to show you how wide the tuning range is with methanol. From past tuning experiences, I figure I'm about 4% away from getting lean backfires throught the intake. One thing that changed as I leaned the mixture, the engine would respond crisper under load and when free reving.
After settling on a mixture which gave me the highest rpm and map reading at stall, I then tested different ignition timing settings at the new stall speed. The results follow.

datalog file/timing btdc/stall rpm
25r2 45 2600
25s 43 2753
25t 41 2772
25u 39 2777
25v 37 2775
25w 35 2778
25x 33 2783
25y 31 2780
25z 29 2694

I've found 33 degrees btdc to be the best timing before, and it looks like it still is. Isn't low ignition advance requirement a sign of good combustion efficiency?

 

[Alky V6]

I started playing with the 2 step again. With the 2 step set at 2350 rpm and the fuel enriched 15%, I got the highest map reading. Not much higher than at 10% and 20% enrichment, but it was better. Approach rpm set at 15.
At 15% enrichment there was a noticeable change in exhaust energy at the tail pipe. Enough to move the fume pickup box. This effect didn't occur with 10 or 20% enrichment.

 

[Alky V6]

When I started tuning in the new stall speed, I started where I left off with the fuel map I used with the old stall speed (2440 rpm). 2440 is a low fueling spot in the fuel map.
The new stall speed, 2780, is smack dab in the middle of the large bump of fueling in the fuel map. An interesting chance to load that spot real good and play with the fueling on that bump.
During initial stall tests the O2 read 10.2 to 10.9. Spending much more time laying on 10.2. The reading doesn't really get much lower with my O2 system. The plan was to lean the mixture at this spot until I got a reading of 11.4:1.
I would say that during the first 10% of leaning, the O2 reading changed very slowly towards the new target. It was only the last 3% or so that the changes became more sensitive as the new target was coming up. Stall rpm slowly increasing with each change.
The worst stall speed recorded during this leaning process was in the 2600s. So the power within this wide 16% swing in the fuel mixture was really pretty close. I wonder what the hp is at the extremes of this 16% swing? That would be intersting to know. How much hp does it take to change the stall speed 100 rpm? 200 rpm?
I ended up with a mixture at stall speed that ranged from 11.7 to 12.4:1.
The bump of fueling in the fuel map looks more trimmed down, but is still a very noticeable bump.
Fueling ended up being trimmed down at the following rpm breakpoints:
2440 - Trimmed much less than the other breakpoints.
2550, 3000 - These two points were trimmed the most, and were trimmed very close to equally.
The trimming of the rpm breakpoints included map breakpoints from 83 to 125 kPa. The 3000 rpm breakpoint included trimming the 72 map breakpoint.
The 3440 rpm breakpoint was also trimmed, only enough to maintain the already established fuel slope between 3000 and 3750 rpm breakpoints.

 

[charlief1]

This sounds good Donnie. How's she feel now?

 

[Alky V6]

The 2 step is very interesting.
After some adjusting, I got the rpm fluctuating closer together in the sense of timeline. If I move the aux rev limit closer to converter stall, the rpm fluctuating widens. I settled on 2350 for the moment. 430 rpm below the new stall speed.
When the engine hits the aux rev limit, timing goes to 0. As rpm drops, timing comes back (27 btdc). Rpm rises again to the aux rev limit and 0 degrees again. So the timing datalog looks like a square sine wave.
The map reading seems to follow the timing wave. When the engine goes to 0 timing, the map jumps up after a short delay. So the turbo is spooling with this. The problem is, when timing comes back after the short drop in rpm, the map also drops back down. The map reading also looks like a square sine wave. As the timeline progresses while being on the 2 step, the map readings in general (high and low spots) do ramp up a little. I'm sure a lot of it has to do with the low aux rev limit and the associated amount of exhaust energy at that low rpm.
The mission is to find a 2 step setting where map rise is more stable. A smoother rise in map while on the 2 step rather than the roller coaster effect. Add nitrous to this picture? Hmmm. Nitrous on the 2 step. A higher aux rev limit would be used, of course.

The next step is to find out what the new stall speed is on the juice.

 

[Alky V6]

This sounds good Donnie. How's she feel now?

I haven't done any testing other than on the rack so far. Next weekend I'll be taking her to the track.

 

[Alky V6]

I did a little more testing today and found that there is little difference in performance from 11.0:1 to 12.5:1.

That would actually be 4.84:1 to 5.7:1. A 17% spread.

I settled on 11.0:1 - 11.7:1 (4.84 - 5.15) and 34 degrees btdc at T/C stall off the juice.

This pretty much matches published best a/f ratios for a naturally aspirated alcohol burning engine.

 

[gnX405]

Turbo parts came in and she's going back together.

A big, gigantic THANK YOU to John (gnX405). B/W Turbo Systems specialist. He came up with the wheel in ONE day when others were saying 8 to 12 weeks from England. You are my hero, John.

You are welcome Don, I'm Glad I could help.

You've got an interesting thread here.

 

[TurboTR]

Joila- and once again, max torque against the stall has won the day (for now).

Don, about your 2 step strategy- how about trying it w/o the timing retard feature and just let it run a straight cylinder cut approach? Seems like passing unburned a/f charge into the exh (because of cyl cut) might get your turbine energy up and thus MAP higher? Have you experimented with that yet?

TurboTR

 

[Alky V6]

Forget the 2 step stuff for now. I just finished some testing on the nitrous and transbrake.

HOLY COW!!! What a difference a few 100 rpm in stall makes. Now, I am truly scared for my life!

Details coming up next.

 

[Alky V6]

Same 305 hp nitrous shot, on the transbrake for .70 seconds.

Using the delay box it went like this:

Go WOT while on the transbrake.
Release transbrake button. Transbrake was programmed to stay activated throughout these nitrous rack tests.
After a .315 second delay, the nitrous system activates.
The nitrous was on for .70 seconds before I lifted. Started to sound pretty native. Different than what I was used to.

The timeline on the last of three nitrous tests went like this:
Went WOT
0.000 sec - Transbrake released
.315 sec - 2715 rpm @ 95.941 kPa. This is the point just before the nitrous turns on.
.815 sec - 3708 rpm @ 99.636 kPa. This is basically the tail end of the hump. The turbo speed has caught up to the engine and the map is starting to take off to the moon. This is .500 second after nitrous activation.
1.015 sec - 3962 rpm @ 102.099 kPa. This is where I got off the throttle. 2 tenths of a second after getting past the hump.

Total time from nitrous activation to getting off the throttle - .700 sec.

When I get to the track, the delay box will initially be setup to give me .7 seconds on the nitrous before transbrake release, and I'll progress from there.

This last test, I stayed on the throttle the longest. A split second before I got off the throttle, the a/f ratio readout started to shoot from 10.12:1 to the moon. I think it was getting ready to go into the afterburn we talked about earlier in the thread where the a/f ratio goes to perfect burn (14.64:1).
I'm not going to do that on the rack, so I'll wait for track time before I do anymore extensive nitrous testing.
Taking into account a slight delay in the readout of the O2 sensor, I would guess that the fuel went into afterburn at the point where the map began to skyrocket. This would be my very smooth ALS in action. Wow.

Another turbo anti-lag system for automatics has just been discovered, folks.

Timing during the nitrous hit was 16 degrees btdc. Very conservative, but I think it helps get that afterburner affect going.

All this testing was done without the spool valve being used!!!

I'll try to get some pics of the datalog so you can see the traces taking off to the moon. Very cool stuff. We're getting closer, people.

 

[Alky V6]

This is the MAP trace of the last nitrous rack test. The red trace line is at the point where the nitrous was activated.

 

[Alky V6]

The is the EGO voltage trace. The detail line is at the point of nitrous activation.

 

[Alky V6]

This is the EGO voltage trace again. The detail line is at the point where the throttle was released.

 

[Alky V6]

If you take into consideration that the O2 reading is actually about .2 of a second delayed, then this is where the detail line should really be at, at the time the throttle was released.
You can see that the reading was beginning to go for the stars just as I got off the throttle. Exhaust tone also got much louder which is the reason why I was quick to get off the throttle. The afterburner affect had begun.