Launch Control & Nitrous

[shaodome]

First off, thanks guys for a heck of a product. The supra clocked a 9.4 @ 150 last night right off the trailer. Not bad for low boost

I wanted to discuss using nitrous along with the transbrake. For this application, the torque converter is pretty tight (street car) and since it is a big turbo 3.0L it needs help to really get up on the stall to launch. For this purpose we use 100shot dry with the fuel being added by MS in the nitrous menu. The nitrous is only used to launch the car right now and it sprays at 2500rpm and stops at 4500rpm, which is about where we launch the car.

Ideally, I'd like to be able to ENABLE launch control on the transbrake and nitrous at the same time, but I noticed the firmware wouldn't allow the nitrous to spray if launch control was engaged? This makes it harder and more time consuming to launch the car. They are wired to their respective pins, so it isn't a conflict it just doesn't activate....looks more like design?

As a "work around" I was able to run the nitrous window switch style with the programmable outputs and leave launch on the launch input pin. This isn't great though as we lose the ability to add fuel or pull timing.

What I am trying to get to....

1. Burnout
2. Stage
3. Master Arm Nitrous ON
3. Engage transbrake (this is also wired to the launch input pin)
4. Full Throttle
5. Nitrous Sprays and adds additional fuel/pulls timing
6. Car builds boost and hangs on rev limiter specified in launch control

[jsmcortina]

Ideally, I'd like to be able to ENABLE launch control on the transbrake and nitrous at the same time, but I noticed the firmware wouldn't allow the nitrous to spray if launch control was engaged? This makes it harder and more time consuming to launch the car. They are wired to their respective pins, so it isn't a conflict it just doesn't activate....looks more like design?

Yes, it is by design. I'll have a think about your request.

James

[Matt Cramer]

I had another customer asking to be able to use nitrous while on the transbrake.

We may need to build a couple nitrous drag cars to better understand what these customers need.

[shaodome]

Here is a video of the car. Right now the nitrous is only a 75 shot, so it takes forever to come up on the stall. It needs a 125-150 shot, but I don't want spray it without any control:

https://www.youtube.com/watch?v=fO0uE-1 ... ata_player

[Barton]

well I know how to build boost on a manual transmission, in the video I can see that your launch is not agressive why?

please post your msq and explain to us why don't you use more agressive launch?

I suppose you cannot rev more your engine at launch because your torque converter does not allow you?

[shaodome]

well I know how to build boost on a manual transmission, in the video I can see that your launch is not agressive why?

please post your msq and explain to us why don't you use more agressive launch?

I suppose you cannot rev more your engine at launch because your torque converter does not allow you?

We lowered the nitrous shot prior to going to the track and as a result it takes way to long to get up on the stall. The 125 shot would just overshoot the hell out of what we need for a launch, but since I can't use Launch control and Nitrous at the same time we have to be careful. Until we have this feature we really can't use the nitrous settings in MS to launch the car competitively, which is unfortunate

As this is a street car, the coverter is pretty tight. When you have that coupled with a relatively small engine/large turbo combo you need nitrous to achieve stall speed.

[Barton]

ok, maybe I still don't understand what type of launch control is needed for a automatic transmission, if I'm wrong at any moment don't doubt to clarify it to me

but why don't you use a more agressive launch control?? in the video the engine does not sound to be cutting o retarding the spark (that is the concept of more agressive launch control)

[shaodome]

ok, maybe I still don't understand what type of launch control is needed for a automatic transmission, if I'm wrong at any moment don't doubt to clarify it to me

but why don't you use a more agressive launch control?? in the video the engine does not sound to be cutting o retarding the spark (that is the concept of more agressive launch control)

It's because you are not understanding how the torque converter works

The engine itself regardless of how aggressive I make the launch control will NOT make enough power to get up to the stall speed of the converter. This is a 3.2L engine that spins ~8500rpm with a 1200whp capable turbo on it, making it's power beyond 5500 RPM. It needs RPMs to generate enough exhaust flow to spool the turbo.

The most I have been able to get is 3400 rpm with a lot of retard (ATDC) and fuel in the exhaust. That is NOT enough power to leave with and will bog horribly. Most V8 guys don't have to deal with this as they make enough torque to leave with.

Nitrous fills the gap here.

If this was a track only car then the torque converter would be loose and not require as much power to get to stall speed, but then it would be horrible for street use.

[Barton]

I know everything you wrote there, there is something we both are missing, could you please post your msq to tell you if there is something you could inprove in your launch tuning for example:

normally I don't to add fuel to get boost.
In the video I don't hear launch rev limiter, that is the most important step to built boost.
Maybe I can tell you something that will make your engine built boost (this is while the programmers are working in your nitrous/launch simultaneosly)

[shaodome]

I know everything you wrote there, there is something we both are missing, could you please post your msq to tell you if there is something you could inprove in your launch tuning for example:

normally I don't to add fuel to get boost.
In the video I don't hear launch rev limiter, that is the most important step to built boost.
Maybe I can tell you something that will make your engine built boost (this is while the programmers are working in your nitrous/launch simultaneosly)

If you understood everything I wrote then I'm not sure why you still have questions , but I appreciate you wanting to contribute.

I'm very well versed in how to use launch control in MS and have used it successfully in a lot of customer cars over the years. With the transbrake engaged the engine just will NOT make enough HP to overcome the torque converter. We can make the 2step more aggressive, sure, but already at 10* ATDC is plenty and even so it is only like 1-2 psi of boost at that point. Extra fueling in the exhaust comes from the odd number of the spark cut rotation, which is necessary to explode the fuel hanging out in the exhaust in an effort to spin up the turbo. This already is causing EGTs to sky rocket and isn't very nice to the exhaust valves, especially since it isn't enough of a gain. Trust me...this is NOT enough on this application. What I am talking about doing is VERY common in small displacement drag racing applications.

The reason you don't hear the pop/bang of the 2step in the video is because we had to turn it off due to the way the code currently is. The nitrous is setup as a dry shot and extra fuel controlled by the MS. So it was either have nitrous on a "window switch" type output with no additional fueling or timing being pulled or disable the launch control for the moment (wired to the transbrake).

[Scottie-GNZ]

The most I have been able to get is 3400 rpm with a lot of retard (ATDC) and fuel in the exhaust. That is NOT enough power to leave with and will bog horribly.

You are using the spoolup technique for a manual transmission. For the automatic, you want to pull fuel and add timing.

This is what I am doing with my turbo LS Mustang and also what I did when I ran a 2JZ in an RX7 and also the Mustang. I ran a 3.0L with stock heads, HKS 280s and a 76GTS with the big .96 exh housing and a 100-shot. Launch Control was set for 4700 and while foot braking into the lights, I leaned it out to about 13.0:1 and bumped the timing to about 34*. Once I engaged the t-brake and went full throttle, the nitrous would come on. At that stage you are now pulling back the timing and adding fuel and at 4500, I had launch Control pull timing and I would shut off the nitrous (did want to spray while on the 2-step). After the car launched I would delay the nitrous for .5 sec and ramp in back in.

Now, I used an FJO nitrous controller (already had it installed) independent of the MS and it gave me great flexibility. I am sure MS/TS could do the same thing if you can get the requested change. In a nutshell, what I did was use RPM control in stage-1 to turn on the nitrous at a specific RPM + t-brake engagement, turn it off just before the 2-step, then use time control in stage-2 to delay turn on for .5 sec then ramp as traction allowed. The FJO allowed me to use both stages on one solenoid.

Here is a test launch and you can hear the engine going through the spoolup/launch progressions. Ramped the nitrous in a little too aggressive.

http://www.youtube.com/watch?v=hj82ZW4msLY

[shaodome]

Hey Scottie..Looks like a fun ride down the track

I've tried all kinds of combos and the converter is just to tight. If I get the requested change I plan to use booth stages of nitrous in the software with a diode in the harness so I can use Nitrous Stage 1 to uh....stage....and Stage 2 to haul ass down the track after the launch.

This car is running a 1.20 backhousing on the Big Borg. All said and done should make ~1200whp through the TH400 with the 150 shot.

[Barton]

very good idea from scottie playing with the torque.

[shaodome]

Just bumping this back up. I would like to take this car back to the track on Wednesday for some more test/n/tune and there are some good events coming up in the next few weeks. It'll be difficult to race in the current config.

[kaeman]

I had another customer asking to be able to use nitrous while on the transbrake.

We may need to build a couple nitrous drag cars to better understand what these customers need.

I like the way you think Matt.

If you had the converter reworked couldn't you get good track and street performance in this vehicle. I have friends that are running 4500 stall converters on their street/strip cars and they don't have any complaints with the street drivability. I understand the you have a small 6 cylinder and my buddies are running v8's and turbo'd v8s. But you still might be able to loosen the converter just a smidge and get happy performance both on the street and the track. BTW enjoyed the video of your supra.

[shaodome]

the stall on this converter is actually pretty high, but it is tight otherwise you would blow through it more on the big end and eat up power. There are plenty of JZ guys running well into the 7.60s with the SAME converter.

[jsmcortina]

How about users who want to use nitrous during the run as well as to spool the turbo during launch?

Would it make sense to have max RPM / MAP settings for launch + nitrous ?

James

[roadracer4life]

Yes I agree with the above that you will need to be able to use the NO2 on the 2step/transbrake to help improve spool time and launch setup.. I am currently on a V1 AEM and its setup this way and works great..
On my car I use the TPS to trigger the NO2 above 90% throttle.. I activate the 2step on the transbrake button.. And with the AEM I can setup launch rpm on the 2step and can dial in the launch boost with the internal boost control settings..
Launching with a transbrake and 2step is great because you dont want to launch right up on the converters stall.. Lets say you have a 5000rpm stall then you would want to set your 2step to limit rpm to 4500rpm so you have a 500rpm gap.. That gap will give the engine enough momentum to flash the converter hard when you come off the transbrake and launch extra hard..

hope some of this was helpful and I look forward to selling my AEM and going with an MS Pro soon..
-Sam

[shaodome]

How about users who want to use nitrous during the run as well as to spool the turbo during launch?

Would it make sense to have max RPM / MAP settings for launch + nitrous ?

James

I was talking about this a little with Ben @ DIY yesterday....

Lots of us have two stages....one to launch and a second that is direct port. Depending on the user, some opt to spray both stages once the launch is complete. So to answer your question it would be nice to have the ability to spray on the two step, after the launch and the second stage as well.

Wouldn't the max RPM be handled by the 2step settings as is? As for the map....with a target boost set for launch (that already exists in the code) I was wondering how fast the algorithm would be capable of adjusting on the spray? If you tune the PID loop without the use of nitrous and then hit the car with spray on the transbrake it will make the boost ramping in different from rolling down the track. Using the set duty cycle number for launch is what a lot of people do instead of having to fuss with a PID loop in this case.

[jsmcortina]

Lots of us have two stages....one to launch and a second that is direct port. Depending on the user, some opt to spray both stages once the launch is complete. So to answer your question it would be nice to have the ability to spray on the two step, after the launch and the second stage as well.

How would you see the settings working? I've not got a clear picture of how to configure this logically.

James