The above explanation I gave on torque converter operation in a drag racing scenario and how it affects the rpm drop during shifts was a bit advanced. There was a lot of basics on torque converter operation that I didn't cover. For instance, getting more detailed on the exact nature of vortex vs. rotary flow inside a torque converter. Why you have torque multiplication during vortex flow, but not during rotary flow and how the stator plays a part in all that. That sort of basic information is readily available on the internet through some simple google searching. I would suggest that if you are still lost on the topic, that you study the basics of TC operation, then come back and study what I've laid out here. You might have a better chance of understanding it, if you go that route.
Time to go Stage II!
- Thread starter Alky V6
- Start date
Why would I want to go smaller? So far, everything is telling me to go to a 95mm.
What have you seen so far that tells you the 91mm is holding me back, in the sense that a smaller turbo would be better?
You're kidding me, right? You don't think I haven't already done that?
More torque at the lower RPM? Do you realize what RPM I will be leaving the line at? I will be launching the car at a RPM almost to the redline of your street machine.
the question is not WILL he be using it..... Its HOW MUCH he will be using and for how LONG it will be on for after the transbrake is released.
The question is not WILL he be using it..... Its HOW MUCH he will be using and for how LONG it will be on for after the transbrake is released.
Of course.
I'll be using the same amount that I was using with the Stage I setup. It will be shut off before releasing the transbrake and leaving the line.
Once the nitrous has pushed the MAP above 145 kPa, the engine can maintain any boost level on the engine alone.
So u didnt leave it on after the transbrake release with the stage 1 setup ?
Nope. The best 60' was with leaving the line at about 7 psi boost. The nitrous was shut off before releasing the transbrake.
There would have been no way to control the boost level, had I sat there staged at the line with the nitrous on the whole time. The nitrous was shut off once a target boost level was met. Then the engine alone was able to maintain a wastegate controlled boost level while I waited to release the transbrake.
I final stage (shallow), set transbrake, go WOT and the nitrous hits at 26.58 timeframe, 2836 rpm, 92.9 kPa MAP (no boost). Timing is retarded to 12 degrees BTDC.
In the above datalog views the cursor is at 28.08 timeframe, 5358 rpm, 148.2 kPa MAP (7 psi boost). The frame before driveshaft movement is first detected. So, the nitrous is activated 1.5 seconds before the car actually launches.
At the point where the car starts to move we have 28.14 timeframe, 5406 rpm, 151.4 kPa MAP (about 8 psi boost).
The nitrous is still on and won't shut off until we see 174-182 kPa MAP (about 11-12 psi boost). We are launching with boost and nitrous, AND IT FEELS LIKE IT!
Timeframe 28.54, the rpm has sharply ramped to 6,094 and 203.5 kPa MAP (15 psi boost) as the nitrous has just shut off and the timing has almost completely come back in. Timing at this point is 25.9 degrees BTDC.
DonnieIn the above datalog views the cursor is at 28.08 timeframe, 5358 rpm, 148.2 kPa MAP (7 psi boost). The frame before driveshaft movement is first detected. So, the nitrous is activated 1.5 seconds before the car actually launches.
At the point where the car starts to move we have 28.14 timeframe, 5406 rpm, 151.4 kPa MAP (about 8 psi boost).
The nitrous is still on and won't shut off until we see 174-182 kPa MAP (about 11-12 psi boost). We are launching with boost and nitrous, AND IT FEELS LIKE IT!
Timeframe 28.54, the rpm has sharply ramped to 6,094 and 203.5 kPa MAP (15 psi boost) as the nitrous has just shut off and the timing has almost completely come back in. Timing at this point is 25.9 degrees BTDC.
This was a strategy I was using early on in the testing of the nitrous system. Ended up being too slow and too complicated. As usual, you're quoting old news. Look up the more current strategies. I later abandoned using the nitrous during and after transbrake release. I found that the 60' improved when I didn't use the nitrous during the actual launch. The nitrous retard, when the nitrous was activated, slowed the rpm rise rate during the launch. RPM is what moves the car. Not nitrous, or boost.
What was the date on that post you quoted?
so ur best 60ft was not what you have in your signature 1.271 ?
Your right! Wow. I had forgotten what the best 60' tuneup was. Thanks for refreshing my memory. In that tuneup, the nitrous was still on for .40 second into the launch.
If you study the datalog graphs in that thread carefully, you will see the RPM jog higher as the nitrous is shut down. I later figured out that it was better to just leave the line at a higher MAP level right off the bat with no nitrous and full ignition timing. It didn't give me any better of a 60', but it was much simpler and netted the same sort of elapsed times.
Tony. Since you've lately read through that thread, maybe you can tell me if that was the same time that I performed the best ET with the car? I think the best ET was done before that point. Oh, the date's in my sig. The best ET was done earlier.
If you go to the link of the video in my sig, you will see a run using a later nitrous tuneup where the nitrous was shut down before the car left the line. You will hear the rpm jump up due to the nitrous, then the rpm level off after the nitrous is shut down, then the transbrake is released and the car launches. I believe there is a thread that explains the tuneup of that run, too. That was the run that netted the best 1/4 mile for the car. That is in my sig, also.
If you go to the link of the video in my sig, you will see a run using a later nitrous tuneup where the nitrous was shut down before the car left the line. You will hear the rpm jump up due to the nitrous, then the rpm level off after the nitrous is shut down, then the transbrake is released and the car launches. I believe there is a thread that explains the tuneup of that run, too. That was the run that netted the best 1/4 mile for the car. That is in my sig, also.
