Progressive Nitrous control setup

[M800]

Ok here is the plan

Setup the inlet with some 250 hp jets (fogger NOS flares x4). The fuel will be supplied by the injectors (8x) that are currently running at 50% duty cycle so there is plenty of fuel for this hit.

The problem is 250 hp is a sizeable hit on the drivetrain (Aspen 6 speed and Torsen diff) so I want to pulse the relay that drives the n2o noid so as the 250 shot comes on gradually rather than all at once.

The N2O setup at the moment (100 shot) uses and AUX into the ARM switch and then a DIG from the noid. It also has an AUX to an AT so we have not only RPM vs TP but also Ground Speed vs TP (I only shoot in 4th gear or higher and only above 5k RPM).

My tuner is unfamiliar with the new Nitrous setup in the software and I'd like to help out as much as possible while still looking after my machinery.

My question is how do I set up the MXXX to provide this gradual hit.

Cheers,
Bazz

[IDP]

Pulsing a regular relay is not ideal. It can be much better to use a Solid State relay.

What type of Nitrous solenoid are you using? Many aren't suitable for pulsing, not at a decent frequency anyway.

The M800 Nitrous setup doesn't allow for PWM control of Nitrous solenoids, it just does 3 fixed stages.

The way around this is to set it up as a single fixed hit but with the nitrous output set up on a spare aux output that isn't connected to anything.
Then set up an Aux Table on the Aux Output that your solenoid relay is connected to Using 'Nitrous stage' as 1 axis of this table and possibly 'RPM' as the other.
You can then setup the PWM ouput characteristics to suit your solenoid in the aux table parameters.

Hope that helps.

[M800]

Yes, I agree that a SSR is required The noid is a 10 month old NOS (Holley) Cheater with teflon seats suitable for their progressive system, so pulsing shouldn't be a drama.

I understand what your saying but don't seem to be able to setup the PWM output characteristics in the AUX. I'm actually using a spare IGN, would this matter?

So what I have so far is a RPM based, PWM (if I can get that input) controlled noid. This is 3/4 of what I was after, but I still have a few questions.

Do I still require a DIG from the noid?
How can I make it Ground speed based as well? Was I on the right track with the AUX to the AT ?

Thanks for your help
Cheers,
Bazz

[IDP]

If you set your spare ign output to function 3, Aux table.
you should then have the PWM frequency etc under the parameters box.

Not sure what you mean by a dig from the noid?

The std Nitrous setup can be set to use ground speed with a minimum throttle also.
Use this and then the output from this will be in your AUX Table.
So now you have Throttle position, Ground speed and RPM based output

Your Aux table would then look something like this.

_________________1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 Rpm
Nitrous stage___1. __0___ 0___0____0___50___60___70__80__100__100____0
Nitrous stage___0 .__0____0___0____0___0____0____0___0____0____0_____0

[M800]

This looks the business, thanks. I'll look into it later today and formulate my next series of questions

The DIG input is required to allow a compensation to be made for fuel (extra) and timing (2* per 50 hp shot) as far as I'm aware (I'm new to this ).

However, with the AUX to the solenoid now being pulsed the DIG will be pulsed too. I'm assuming because of the reduced N2O at the beginning of the hit that the "pulsing" of the compensations for timing and fuel will be proportional to the amount of N2O. Does that sound right?

Cheers, very helpful as I'm now starting to understand this better.

Bazz

[IDP]

I don't see that you'll need a dig input from the solenoid.

You map the fuel increase and ignition retard in the standard nitrous setup.
There's a 2D table and a 3D table for both fuel and ignition so that should be all you'll need to map the extra fuel and retard.

[Martin]

Why not give this a try? This is out of the M800 Helpfile.


2: Coded

As the Ground Speed (or Throttle Position) increases above the levels
set in the Stage Levels table the outputs are requested as follows:

Stage 1: Outputs 1
Stage 2: Outputs 2
Stage 3: Outputs 2 & 1
Stage 4: Outputs 3
Stage 5: Outputs 3 & 1
Stage 6: Outputs 3 & 2
Stage 7: Outputs 3 & 2 & 1

When using this method output 2 should have twice the nitrous flow of
output 1, similarly output 3 should have twice the flow of output 2.
This gives even steps between each stage.

[M800]

IDP, wouldn't you need to tell the gold box that the N2O is armed? Hence the digital in from the Arm switch. I can't think of another way the ECU would know that "Yes, I want to go ballistic this time"

I spoke with the tuner today and have come to the conclusion that rather than a Digital in we can use a AT more effectively. The AT's have a threshold that we can set so that as the PWM changes the AT will have a constant supply (not pulsing). 0%=12v, 100%=0v so if the threshold is set to say 10v then the Aux wont turn the AT off

Martin, the scenerio that the helpfile gives is for multiple stages, each with their own bank of solenoids and jets. Beautiful setup if you can afford it. Consider what I'm trying to do is use one stage to be progressive, rather than multiple stages being multiple gear breaking hits.

Cheers guys, I really believe we're getting on top of this one

Bazz

[IDP]

Yes, Digital in from the arm switch is correct.

The ECU already knows what the solenoid is doing as it is controlling it, simply use the aux out duty cycle channel for that output.

It really shouldn't be neccesary though. If you map the amount of nitrous duty cycle you want and then map the fuel/ ignition to suit, as long as you don't change the nitrous duty cycle without retuning the fuel all will be good.

However you could use the Aux out duty cycle channel as a comp in the fuel comp table.
Map the fuel for 100% nitrous and then use Aux out duty cycle as a comp to reduce fuel for the reduced nitrous flow.

No easier to do initially but maybe useful if you wish to adjust the nitrous flow at the track.

Also worth noting with the solenoids I've pulsed (WON) they work nicely at around 25 - 30hz but be aware that duty cycles of less than around 30% are fairly inaccurate and above around 80% they stay open so worth operating in the 30 -75% area for progression and jumping straight to 100% for full and 0% for off.

[M800]

Excellent, of course the ECU is already taking care of the AUX (why didn't I think of that ) that means I don't even have have to worry about changing the wiring on the ECU from the DIG to the AT, just AUX I have going through the ARM.

There probably isn't much need to do changes at the track but I'll suggest the AUX into comp of the fuel setup to my tuner (are you listening Lee ) and see what he says. The jets are difficult to get to as it's a stealth install, so even if we run at 50% DC having the AUX into comp of the Fuel would allow on-the-fly increases, nice

Thanks for the heads up on the solenoid duty cycles too
Much indebted for your help IDP

Cheers
Bazz