list your proceedures ???

how do you get it up on boost ?

 

Small shot of gas(nos) always helps.

smaller turbine A/R or smaller cam.

We always try to creep up to the lights on the "hump" then plant it.

 

I noticed RB's turbo pro mod with an auto had a tuff time staging and keeping in the beams at the gainsville race when he rolled through in 2nd or 3rd . He had some problems in vegas as well keepin it in the beams

 

If I'm the first to stage, I'll roll in at an idle, set the transbrake and wait for the other lane to stage. The moment they stage, I floor it and start spraying. Depending on how quickly the lights come down will determine whether the nitrous will shut down before I launch, or if I launch with the tail end of the hit. I've recently learned that, with my setup, if I launch with a little of the hit still to go, the car 60 foots better. So actually, the quicker the lights come down, the better, as far as the 60 foot goes.
This procedure protects me from being burned down at the starting line.

If I stage last, I have two options. I can start spraying as I transbrake-creep into final stage, or I can wait until I have staged, set the transbrake, and then start spraying. I'm still determining which yields the best 60 foot with this procedure.
It's always less tense if I can stage last. But, either way, I can't be burned down by the competition. And, spool up happens so quickly that concerns of hurting equipment is non-existent.

The new best 60' with my little 224 cid V6 and gigantic S510/91mm is 1.271. Leaving the line on the last .3 second of the hit. I've recently started to seriously work on the chassis setup to improve the 60' even more. My anti-squat was at 95%! Yikes!

I burn methanol. Also with the nitrous.

 

interesting thread, in the interests of helping me can you list some brief specifics about your combo such as engine size, turbo, fuel type and whether youre running a brake etc when you reply.

 

How are you guys creeping the car forward though, I have to hit the transbrake to spool, but I am considering some nitrous to help.


Would i brake boost at the first beams then bump till i get both beams and hit the transbrake and mat? Can u engage the TB under partial load or load?

 

we have got the converter selection right now, and can just roll in at idle...
jump on transbreak with 2 stage lights , and spool under 1.5 seconds

the stage proceedure , is directly related to converter , and ability to tune engine to be more agressive
igintion control is highly recommended, and some sort of boost controller

keep the ideas coming

 

I edited my last post to include more of the information you're asking for.

 

I use a DIY transbrake creep module. It helps me creep into final stage under power, automatically.
If I decide to start spraying before I've staged and set the transbrake, the procedure goes like this;

The nitrous system is on a WOT switch.
There is an ECM GPO function that allows the nitrous system to activate at a rpm higher than 2850 and map above 85 kPa (WOT).
There is an ECM GPO function that will activate the transbrake creep module at, and above 2400 rpm as long as the transbrake button is depressed, transbrake is activated, and a transbrake creep enable button is depressed.


The car is sitting pre-staged and idling.
If I decide I'm going to creep in under power, I'll set the transbrake first. I then press another button which enables transbrake creep.
I then go WOT.
The rest happens automatically. After going WOT the rpm passes 2400 rpm and the transbrake creep module will begin creeping the car into staged position. The creep module is activated for a preset amount of time to move the car into stage the proper distance. As the engine rpm passes 2850 rpm the nitrous system activates to begin bringing the engine to launch rpm (5,200+) and MAP (145 kPa+) level. Of course, all of this happens very quickly. The nitrous has started to spray before the car has finished staging on its own.
All that's left to do is release the transbrake button and launch the car. A delay box can also be used, if needed.

The nitrous system will shut off at a certain manifold boost tartget.

The boost controller launch setting, and the BOV launch setting are set to maintain the boost level just beyond the nitrous boost level shut off point, if I'm forced to wait for the lights to come down at the line for an appreciable amount of time.

The torque converter I use will stall at 3,200 rpm off the nitrous and no boost. With the nitrous system, if I clamp the wastegate and BOV shut, the TC stall can attain 6,200 rpm and 220 kPa MAP in 2 seconds. Even higher RPM and MAP, if allowed to stay on the system longer.

 

What's nice about using nitrous to help spool the turbo is, dialing in the torque converter and the turbine housing becomes less critical. I use a torque converter that is on the tight side, which helps with top end efficiency, and I use a large turbine housing, which again helps with top end efficiency.
I use an Airwerks S510 turbocharger frame with a small V6. You can't get much bigger on the exhaust side, yet I can be at launch rpm and boost level in just under 1.5 seconds, with a tight torque converter, and on methanol on top of all that. You don't see that successfully being done very often.

Exhaust back pressure to intake boost pressure ratio is better than 1:1 at 28 psi boost. Around 0.9:1, actually.

 

Nice combo AlkyV6,interesting read.

 

Another thing that comes to mind.
If the torque converter stall curve relative to engine torque input is well matched, controlling the boost level at the line becomes the only control needed in preparation for the launch. No staging rev control is needed.
For instance, with my car, the nitrous shuts off at about 11 psi. If I set the wastegate and BOV to keep the boost controlled to 12-13 psi in preparation for the launch, then the resulting stall speed/launch rpm ends up being around a steady 5,400. That combination of boost and rpm works very well for me. I have no need to separately control the rpm.
If I want to up the launch rpm and boost, I just kick the boost controller up a tad. Both come up at a nice predictable degree. Boost may come up 1 psi and the resulting stall rpm may be 5,450-5,475. Surprisingly sensitive, but not overly so.

The only downside I have in having the torque converter and turbine housing so delicately matched is that the boost is very closely tied to engine rpm during the initial rpm and boost ramp up during the launching of the car. There is not very much being lost through the wastegate that would allow say a controller commanded sudden jump in boost level at about 30 feet out, if the tuner felt it was needed. That could easily be fixed by going to just a slightly smaller turbine side or smaller overall turbo in general. My particular situation is pretty extreme. But then, I wanted to see just what could be done with an extreme situation. I was pleasently surprised.

 

you've touched on a very important subject, about turbos being slightly small..
most racers think they have a bigger dick, by having a bigger turbos..
think about where the car spends the most time in each section of the track...
then work out where the MOST gains can be found.. due to how much time is spent in that section..

 

Well, in my case, it had nothing to do with the size of my Johnson. Knowing ahead of time that I was going to use nitrous to spool the turbo that I would eventually choose, I was able to pay much less consideration to the age old compromise in turbo selection. Spooling quality.
Instead, I decided to pick a turbo where the airflow needed throughout the majority of the run would be spent smack dab in the middle of the highest efficiency island of the turbo's compressor map. Not at the edge of the 65% range. People have told me, the consideration of running the turbo in a high efficiency zone was not really that important. I thought it was.
If a pro top fuel engine tuner found out about a blower that was one half of one percent more efficient than anything ever seen before, I'm willing to bet he'd want that blower on his engine, like right now.

You're absolutely right. Look to see what sort of airflow the engine is going to see in each section of the track. And if you don't have to worry about spool up woes, it's not a bad idea to pick a turbo that will give you the most time in as efficient a compressor zone as possible.

On the other side of the fence, if a person picks a large turbo just because it's big and bitchin, without taking into consideration how he's going to get it spooled up, well then, I would have to completely agree with you.

 

yes, many ways to skin a cat..

 

Yeah Phil Thomas (ODR LSx car) is downsizing his turbo a little bit (from a 106), yet his LSx single turbo car is looking to keep up with twin BBC cars....

 

One other option that is open to me, since the nitrous is already onboard, and that I haven't explored because I haven't felt the need to, is injecting nitrous right at the launch.
The car has already given me a clue as to the effectiveness of this idea. As I've already mentioned, I'm getting better 60 foots by launching the car at a lower rpm, MAP level, and with a small bit of the nitrous hit still left to go before it hits the shut off point of 11 psi. And, when I say just a small bit of the hit left, I'm talking about a mere fraction of a second.

Here's a launch scenario I've been imagining. I go through my normal staging procedure and the car is sitting on the line, already at launch rpm and MAP level, and the nitrous system has already reached the shut off point of 11 psi. I can imagine a wild performance increase if the nitrous system was again activated right at the launch of the car. Kinda like a booster kick in the pants to get the car past the 60'. Of course, the chassis would have to be there to handle it, but I thought it would be interesting to see how it would work out.
Once the nitrous system is reactivated at the moment of releasing the transbrake and launching the car, an adjustable timer would keep it activated for as long as needed, or as long as the chassis and/or engine was able to handle it. There would be a lot of boost and nitrous working together there for a moment.

 

You guys are going to get me in trouble thinking about this stuff.
Here's another option for me.

My particular nitrous system is a two stage setup. The main stage is a large hit, port injected wet system. The smaller 2nd stage is a single wet fogger nozzle injecting just before the turbine housing.

Due to the way the boost ramp up is closely tied to the engine rpm ramp up, a few things could be changed to give me a little more capacity to have a wastegate commanded boost rise step up during the launch.
A smaller turbine housing
A smaller turbo in general
Hitting the nitrous system again
Increasing engine size relative to the existing turbo.

The last two choices are grabbing my fancy. First off, hitting the nitrous system is pretty much the same as increasing the engine size, but without the trouble of doing it. The nitrous hit will, of course, increase engine performance immediately, but that's not what I'm really concerned about. It's the added exhaust energy that I'm looking for.
More exhaust volume will push the turbo more, giving me some extra wastegate capacity to work with at the launch.
Activating the whole nitrous system seems to be a bit of an overkill, though.
What about only re-activating, or leaving activated at the line, the much smaller 2nd stage to help supply a small amount of extra exhaust energy? Would that be enough extra exhaust energy to push the turbo beyond the present rpm/boost ramp up relationship, making the boost controller more of a player at the launch?

I've never activated the second stage on its own. Would it even light off?

 

Another thing we did with the escort is used the nitrous to spool up the compressor using a fine nozzle drilled into the compressor at the angle of the direction of the wheel. We even tested without the engine running and it spooled up the turbo real fast.
That plus the extra power it gives once it's ingested into the engine really gets the boost up.

 

lots of things to think about in this thread!