Juicedh22

iTrader: (6)

I was talking to Beer about this on PMs but thought it would make a good public conversation.

First off, my setup:
90mm plate dry shot (100 to start) DBW tb
purge, warmer, opener
Nitrous Outlet window switch w/ TPS Activation, older unit so dual stage

Beer informed me that I could trigger pcm multiplier tables (via pin56) with the window switch, instead of how I had just originally planned via the arm switch.

I got to thinking more about it, and talked with a friend and the first obvious question came up. What about time delays? vs just wiring to the arm switch?

Thought process is, if I wire cos5 to enable the n2o multipliers when the window switch is activated, this is the exact same time the nitrous solenoid will be enabled. So which happens 'faster'...

You have the time it takes for the solenoid to open and release the n2o (dry shot) and it travel to the throttebody plate and into the engine...

vs

The time it takes for the window switch to send the signal to the pcm, enable the n2o multiplier, then send hte signal to plugs + injectors and for them to pull timing and add fuel.

So if datalogged, you should be able to see how long it took for the timing to be pulled and fuel dropped in, vs the n2o hitting the engine.



On the other hand, with enabling the ve multipliers off of the arm switch, it is now prepared to add the fuel and takes the spark at the desired RPM regardless if the n20 has been activated or not. But if I have armed the n2o do I care? If the multiplier tables are modified at the same RPM as the window switch lies in, what's the difference?

Fbodyjunkie06

iTrader: (10)

It doesn't matter, there isn't enough cylinder pressure in that split second it takes for the timing to retard to hurt anything.

I don't start my timing retard until 3600rpm and I only pull 2* there. I don't have all my timing out of my car with my new timing I came up with until 5600rpm where my converter really locks up hard and cylinder pressure is nearing it's highest point. My converter doesn't fall under 6200rpm on my shifts so it has the full amount of timing pulled after 5600rpm so when I shift it falls back into the regions with max timing pulled.

The guys with msd 7 boxes or grids normally delay their timing retard .1-.3 after the transbrake is released so it gives the car a chance to plant the tire and hook.

On a street car though the ramping out really would just make it blow the tires off.

But to answer your question or concern it won't hurt anything if it doesn't pull it at the same time. Just as long as it retards soon after.

3fingas

iTrader: (16)

http://sherwood-performance.smugmug.com/

minytrker

iTrader: (13)

I always wire it so when the nitrous activates it grounds pin 56 and retards timing. Pulling timing when you arm it almost defeats the purpose of COS#5 IMO.

03EBZ06

Why ask the question? Just arm COS5 when the nitrous arming switch is turned on. You KNOW its first then. Why would you want to take a chance and see if COS5 beats the nitrous to the engine?

In my case, activation is at or greater than 3500rpm. I simply don't change fuel/spark until then in COS5. So even if activated, it just sits idle until my desired window RPM occurs.

Juicedh22

iTrader: (6)

The reason is, for when you're not at WOT, but with nitrous armed.... such as holding RPM while staging, or getting down on the street, if you do something silly like that.... you will be overly rich, since the VE multiplier is just RPM based.

ls2 bait

iTrader: (11)

I just put mine on its own switch. Then i know its on.

minytrker

iTrader: (13)

Its a computer, its way faster than your mechanical nitrous solenoids. I have all my cars pull timing when the nitrous solenoids cut on and never have an issue. If I had it pull timing when I armed the system I could never get up on the trans brake with that little timing.

03EBZ06

I know what your saying, but that is not true if you use the RPM and MAP enablers, at least for fuel. In my case, the RPM param is set less than launch and 90kpa. BOTH must occur to activate the fuel VE mods. My spark is really not affected either since none is reduced until window rpm.

There are different ways to do it thats for sure