Advancement of fuel delivery?

[Alky V6]

Light bulb time

When this stuff pops into my head, I have to write it down before I forget it.
The target boost level for the 1-2 shift is 200-215 kPa.
The nitrous system is pressure switched to shut off at around 200 kPa.
Presently, the nitrous system is shut down at 155-165 kPa into the run via a delay timer to hopefully have the map rise rate relax in time for the 1-2 shift. It appears that the shut down of the nitrous has absolutely no affect at all in the map rise rate. It does appear to momentarily have an affect on the rpm rise rate. The rpm noses over for .16 sec, then makes a sharp increase when the timing retard is cancelled.

 

[Alky V6]

So the nitrous shut down has a natural tendency to nose the engine rpm rise rate over when it shuts down at 200 kPa. The problem is the boost level by that point.
If I can just get the boost level to plateau at just over 200 kPa.
I'm going to start putting in a flat pressure number from launch to 1-2 shift, into the boost controller until I come up with the right number that will get me to that target. After the 1-2 shift, control pressure will quickly ramp to 29 and from there ramp to 31. That will give me 300-305 kPa MAP on the top end. The boost limit numbers I stated a few posts back were boost controller pressure limits, not actual MAP numbers. Sorry for the confusion. Welcome to my world.

The nitrous pressure switch has a hystersis of 15 kPa. Pressure would have to drop to 184.5 kPa to close the switch once it's changed to an open state at 198.7 kPa.

The boost level at the 1-2 shift is presently at 232-248 kPa depending on the shift point timing.

 

[Alky V6]

With a few intake backfires at launch from a few tuneups that I ran too close to the lean side (searching the limits), I decided to do a spark plug check. The intake poppet valve saved me again.
I was a little surprised. They all looked great with the plating burned off only the base surface above the threads. They're getting some time on them. They're ready to be changed out anyway.
This spark plug reading was with a top end a/f meter reading bouncing between 11.3-10.95:1 and a map of 300-305 kPa.

 

[Alky V6]

Here's something to contemplate.
The tuneup is such that the car is leaving the line at 4,140 rpm, 102 kPa MAP. By the 60 foot mark (1.48 sec), the rpm is only at 5,307 with 144 kPa MAP. I can't help but get the impression that this is one tight TC.

 

[charlief1]

The 60' is lookng better Donnie. Did you do it on the 1/8th or 1/4 track? As far as the car feeling squirrely you really need to get the suspension alignment done. This will help you quite a bit. It has to do with stability at high speeds after all.

 

[Alky V6]

The 60' is lookng better Donnie. Did you do it on the 1/8th or 1/4 track? As far as the car feeling squirrely you really need to get the suspension alignment done. This will help you quite a bit. It has to do with stability at high speeds after all.

The 1/8 mile.

 

[Alky V6]

I'm a little hesitant to mess with the alignment. The car rolls the easiest it ever has, the tires aren't showing any scuffing, and except for when the rearend is fishtailing when boost level limits are pushed, the car handles great. I will eventually get to it though.

I'm starting to prepare to up the nitrous level. The present book value of the nitrous jetting in the car now is 319 hp. The next step will be 31/31 jets which will yield a book hp rating of 346. I'm going to guess that will yield an initial hit equivalent to a 79-150 hp shot on gasoline.
My feeling is that the percentage of book value hp lost due to the nitrous/methanol combination is between 84 to 23 percent. Depending on the tuneup and the point examined within the timeline of the hit. It will be interesting to see how this jetting change messes with the current als tuneup.
This change will be done before the next T&T outing.

 

[Alky V6]

A delay box setting of .98 sec, staging the car at idle, and setting the transbrake while at idle to avoid excessive car position shift in the beams that can occur due to suspension wrap and unwrapping netted a .004 RT on a 3 amber tree.
The nitrous has this same amount of delay time to work on the engine before transbrake release. Highest rpm obtained by the time of transbrake release was obtained this last test session. 4140 rpm @ 100-103 kPa. The larger nitrous hit planned for the next test session should move this TC stall point by the launch to at least 4300-4350 rpm. This should also move the boost value by launch time up to at least 107-110 kPa. If this next test is successful, and the launch is still too tame for my liking, the move may be made to the maximum limit nitrous hit value planned for this project. Around a 400 hp hit. That would move the TC stall to around 4500-4600 rpm and the launch boost value to around 120-125 kPa. That rpm and boost level along with the nitrous hit will be quite enough to get the job done.

 

[Alky V6]

After measuring the weight of the nitrous bottle after the weekend, I found that the bottle was at the low limit (5 lbs left). Typically, as the nitrous bottle gets to the low limit point, the mixture during the hit is richer than you'd have with a fresh bottle. This is interesting considering that the last pass of the weekend netted the best 60 foot, the most noticeable seat of the pants yank, and only .02 sec off the best ET for the 91mm up to this point in my tuning adventure. I also sensed that the front tires were even carried for a very short distance. This no doubt adds to my suspicions that the system wants more fuel through the 103-145 kPa range. It's amazing to me since I've already been pumping up that region of the fuel map lately.

The number of passes on one 10 lb nitrous bottle until reaching the low limit of 5 lbs remaining, was 9 plus 2 thwarted runs. So about 10 runs per 10 lb bottle with the 319 hp shot. 1/2 lb of nitrous consumed per run.

 

[Alky V6]

After the weekend I had a couple of racers I've known for quite some time now come up to me at different times over the next few days with big smiles on their faces. They know the trials and tribulations I've been going through with this turbo swap and it worked out that I lined up with each of them over the weekend. They both had about the same story. "I knew I got you out of the hole real good, but knew you'd be passing me soon. But man, when you did, it was as if I was sittin' in the coffee shop, sipping away at my coffee, watching you drive past." One added that the pass he made against me was the quickest to date for his car, yet he was still amazed by how fast I blew past him.

 

[Alky V6]

A circus ride note. Driving these things can be like being on a circus ride for the first time. A new sensation that catches you by surprise. I had a new one this past weekend.
On one of the passes, the timing of the wastegate control pressure cutback lagged after the start of the 1-2 shift by a little bit which allowed the boost level at the start of the 1-2 shift to be too high. About halfway through the shift, the WG control pressure cutback was catching up and prevented the tires from completely blowing away on the last part of the 1-2 shift change. What resulted was the tires slipping through the complete shift change only slightly. It allowed me to get a taste of what the 1-2 shift could feel like if I didn't have to limit the boost level through the shift. THE SUCKER YANKED HARD!!! It was as if someone threw 5 psi more boost at it ON the shift. Very impressive it was.

 

[Alky V6]

Nitrous jetting choices.

900 psi bottle pressure, 45 psi fuel pressure. 1.68 n/f ratio.

30/30 319 hp (presently in the car)
31/31 346 hp
32/32 364 hp
33/33 393 hp

I'm going to try the 32/32 jetting. Small steps.

 

[Alky V6]

I'm at a point in the progress of the tune where it's time to either play with T/C stall speed, or the nitrous jetting. I'm sure you're all getting the impression by now that I've decided to play with the nitrous jetting, and for a very good reason. Let me explain.

Playing with the T/C stall alone will allow a higher stall speed at launch which will put the engine higher in the torque curve and also give a little more boost at launch as a consequence of the higher engine speed and exhaust energy being created. The problem with playing with stall speeds is that you can never be sure of the amount of stall increase you might end up with when changing the T/C. If the target is to increase the present stall speed say 200 rpm, it might require a few tries with different T/C configurations to get to that target. It would be easy to undershoot or overshoot the target stall speed. That means a tedious transmission r&r and wait to get the T/C back from the converter shop.
Now granted, a person's combination may not be that critical about getting the stall speed right on, but what if you could simply dial in a 100-200 rpm increase or decrease in the stall speed, and a small increase or decrease in boost level to dial in your car for that certain launch attitude you might be searching for. That certain 60 foot you might be searching for.

 

[Alky V6]

That's where a simple nitrous jetting change comes in.
With the time that it takes to change a set of jets, you can accomplish all of the following:

Instantly raise the torque level of the engine throughout the launch.

Raise the stall rating of the T/C due to the higher torque level that you're inputing into the T/C. This makes a physical T/C stall change unnecessary and puts you in complete and simple control of the resulting stall speed.

Raise the amount of extra exhaust energy available to help spool the turbo quicker.

May even require you to change the turbine housing out for a larger one. This will reduce choking exhaust back pressure and help the engine BREATHE for better top end performance.

Allow a more instant launch strategy. No more sitting at the lights, burning down your T/C, waiting for the darn turbo to spool up. Presently, I am idling into the staging beam, setting the transbrake and not even going WOT until the other racer finishes staging. AND I"M SPOOLING A 91MM! How much easier can a launch routine get?
The other racer stages, I go WOT, I release the transbrake button on the first amber and hold on.

Much easier control of the complete launch for a more consistent run.

 

[Alky V6]

The latest fuel map, 3.2 29h.
You can see that the fuel delivery peaks at 5700 rpm. That is where the peak torque of the engine is. The fuel delivery actually drops slightly after peak torque. After getting the fueling at peak torque squared away, the burnouts improved dramatically.
The black dots outline the boost curve from the latest datalog 29d. 146 kPa by 5300 rpm. Very nice. The plan is not to have 146 kPa reached any sooner than 5000 rpm.
The first lower left dot shows the rpm and MAP level obtained by transbrake release at the launch.

 

[Alky V6]

A view of the wall. Almost gone.

 

[charlief1]

Looks like you've just about got it where it needs to be Donnie. Congrats. Just a little more tuning and I think you'll have it squared away.

 

[Alky V6]

Looks like you've just about got it where it needs to be Donnie. Congrats. Just a little more tuning and I think you'll have it squared away.

There are a few small areas to still explore. Most of it is in the high rpm/mid boost region. The engine won't see that area, so that is not real important. The other area covers the boost ramp trail from 103 kPa to 146 kPa. Improvements are being made there, but I still need to explore more fuel in that area. Up to this point, it has shown a thirst there.

 

[Alky V6]

In case some have forgotten or are wondering, I'm using an Electromotive TEC3r upgraded to WinTEC4 for engine management. I use the Motec software to render the tables. The table rendering with the Electromotive software is lacking to say the least.

 

[Alky V6]

I posted this datalog tracing in another section and thought it might be interesting to those that are following this thread. This is the run where the boost controller pressure cutback was a little late in timing with the 1-2 shift (see post 891). It resulted in an awesome feeling 1-2 shift pull. If anyone has any questions, feel free to ask.