djm_e22

iTrader: (2)

LT1 nitrous tuner gurus, the below message is the way 383LQ4SS explained how you use torque to tune your timing. It makes perfect since. So after reading it, it also seems as if the 1 to 2 degrees retard needed per 50 shot is not always true. It kind of depends at what rpm you shoot the nitrous at. A 150 shot at 6000rpms has no where near as much torque(cylinder pressure) compared to a 150 shot at 3500rpms. So it seems a good tuner would retard the timing at lower rpms but slowly add timing(within reason) as rpms rise. You would obviously need a pcm dedicated specifically for nitrous if you did it this way and another one if you decide to race motor only. What do you think? Is this right? Also read below.


Thanks to 383LQ4SS
"And one other thing about the dual stage and timing. If you set it it so the shots are near the same size and space the shots out in the rpm range correctly...youll only need to pull timing once.

The TQ line is what you are looking at for retarding timing since it is a direct measure of cylinder pressure. So if you hit the car with a 100 shot at say 3200 rpm and the Tq clims to say 575 ft/lbs you can retard the timing for that amount...maybe pull 2-3 degrees...not much. Then the rpms climb...but tq begins to fall quickly with rpm due to the nature of nitrous until it reaches your second stage rpm activation point at say 5000 rpm. By 5000 rpm the TQ is down to probably 500 rwtq right before the second stage activates. The engine is ready to have more timing back at that point....or more nitrous. So we give it more nitrous....and TQ then shoots up again to say....610 rwtq. The timing requirements are going to be nearly the same to cover both peaks. So just retard timing once with the duals stage.

Taking that approach is the safest simplist path. When you dyno....keep the TQ peaks relatively the SAME PEAK number. IOW dont have the first stage come one and make 700 ft lbs and then die off rapidly and hit it with a tiny second stage so that TQ is 575. And Vice versa...dont hit the first stage with a 50 shot and the second stage with a 150. The second stage TQ would be much higher than first and make things less manageable from a driving and tuning standpoint

You want a nice avg TQ across the rpm range. Guys like Robert even throw a third satge in there and then decrease the shot of each so there is three tq peaks thru the engine rpm range.

With three Tq peaks you can barely feel each stage coming on as they hey hit. And if the shot sizes and rpms are setup correctly the car feels like a roots blower car with a WIDE FLAT TQ curve...and the ngine stays happy. Why does the engine stay happy?

Take the 200 shot and hit the engine with it all at once at 3200....youll blow the tires away there is so much TQ. Its could be as much as 650-750 rwtq. Thats stressing pistons and rods with that cylinder pressure...AND timing must be pulled to cover that 750 rwtq. That might be 4-8 degrees. Then as rpm climbs TQ falls off rapidly and you would really need to start adding timing as TQ falls with rpm. Thats not too easy unless you dedicate your tune to a nitrous tune.

The total HP between the two setups will be the same...but the TQ of the single stage will reach critical levels for stock parts and be much more detonation prone which can take out forged parts as well.

The dual stage is all about Tq management. The benifits of tuning, drivability and less engine wear is readily apparent"

djm_e22

iTrader: (2)

So I guess this above message is correct?

Tony Shepherd

iTrader: (4)

A quick scan though the thread but yes it is correct.