A very cool nitrous injection trick

[Alky V6]

Today during another test and tune session, I accidentally came across a very bitchin development involving the nitrous system. This is sooo cool.
I use a 400 shot of nitrous to spool a 91mm turbo. The turbo spools in 1.8 seconds. The timing is such that the turbo reaches launch readiness before the need to release the transbrake. Even on a pro light.
The nitrous shuts off with a map switch.
Today I started leaving on a 3 amber tree, which means more time between when the nitrous has shut down and the time when I need to release the transbrake.
When the nitrous shuts down, the rpm and map begin to drop to a lower level. Eventually, the map drops to a point that is below the turn off point of the nitrous map switch. When this happens the nitrous system is reactivated until the map level is again at or above the turnoff point of the map switch.

This is the cool part. Today, after final staging, the nitrous reached the turnoff point as expected. I sensed the rpm dropping, again as expected. The ambers began to come down. By the third amber, and the point where I needed to release the transbrake, the map had dropped below the nitrous turnoff point, and just before the transbrake released, for a fraction of a second, the nitrous reactivated and caused the car to YANK HARD off the line. It was extremely cool. The result was a 1.28 60'.
It's amazing what you can discover when you play around with things.

 

[buickbert]

accomplished at speedworld?

buickbert

 

[Alky V6]

accomplished at speedworld?

buickbert

No. This was at the local 1/8 mile track. I've got to get the blowby under control before I take the car to another 1/4 mile.

 

[tom j]

Doesn't this mean that you are still not leaving to the limits of your chassis yet? Time to turn up it up

 

[Alky V6]

Doesn't this mean that you are still not leaving to the limits of your chassis yet? Time to turn up it up

I suppose so. Small steps.
I had a few people come up to me in the pits asking what the heck I did. They were saying, "You used to roll out of the hole. Now you're yanking. What did you do?" "Did you change something?"
I told them, No. I just found the right nitrous tuneup to spool this monster.

 

[jasjamz]

So was the boost and rpm falling even though you were at wide open throttle and still on the transbrake? I thought once you hit say 15 psi the nitrous would shut off and the motor would spool from the 15 psi upward just slower.

 

[Alky V6]

So was the boost and rpm falling even though you were at wide open throttle and still on the transbrake? I thought once you hit say 15 psi the nitrous would shut off and the motor would spool from the 15 psi upward just slower.

It's how I happened to have the launch boost control setup during this test session. Wastegate and BOV. The initial nitrous shot causes the rpm and boost to overshoot the launch boost control point. When the nitrous shuts down, the rpm and boost are simply settling down to the launch boost control point. I've tried having the boost control point higher so that the nitrous isn't reactivated, but as you said, the boost too easily begins to build and overcome the boost controls, making for too much boost at the launch. Yes,... it is possible to have too much boost at the launch. Even with a 'slow spooling' 91mm. :biggrin: