the way the output relays are drawn in i cant tell if there are 4 relays for the soilinoids or not.

it apears theres just extra 12v+ lines drawn to the nitrous noids but im not sure

thanks

 

think i got it
does this look right/better to u guys ?

 

Just 2 relays.

 

so the way i have the second drawing is correct ?

 

No, the top one is correct.

 

i dont understand the 12v+ lines comming off the master arm/presure switch that comes over to the noids.

i see were it says relay1/2 contacts.but i would think those lines should come directly off the relays. and have nothing to do with the arm/safety switch as those are on the input side

 

A relay is just a switch, but it's operated by an electromagnet instead of a lever. When the relay coil (green square) is energized, it closes the contacts of the switch (Relan 1/2 contact). The switch connects the solenoid to the power source through the hobbs, WOT and master arm switches.

 

The dashed line is from the coil (green box) pulling the contact (solenoids).
There is what appears to be a diode(?) in line with the coil +/-.

 

Internal or external, the diode is to shunt the back EMF when the coil is deenergized.

 

I should learn to type faster, I only repeated what you said and less techy at that, lol.

 

ahh i get it now the lines comming from the arm and saftey switches is just showing what the circut looks like when its completed. the dotted lines on the diagram are the actual connections from the relays to the noids.

i actually wont be using a presure switch or wot switch, as the ecm will not fire the nitrous unless the tps sensor is above whatever i set it in the tune

ill also be doing a dry shot and using the injectors for the addtional fuel



im going to do a 25 shot that comes in 1/4 second after i release the antilag/launch button, which will spray the entire lenght of the track, then ill time the second stage( additional 75hp) to start spraying in high gear down track

 

No, the dotted lines show which contacts are associated with which coils. They're not circuit paths.

Using a pressure switch is still probably a good idea.

 

while a fuel presure switch would prolly be a good idea space is starting to become a premium, the only place i could see fitting one would be were the shrader valve is in the fuel rail, which i have to see what the threads are were it screws in.

though with the amount of power this thing is going to be making i do belive the motor would come apart long before the low presure switch on the fuel system shut the nitrous off.

im using this system on a 355 tpi with twin 57mm turbos with the system set on kill 20-23 psi this thing should be making around 900rwhp with the nitrous, any loss in fuel presure even under boost alone would probably destroy the engine.

im just hoping the dual areomotive 340lph pumps dont turn out to be like the walbro 255 pumps that seem to die all the time

 

I suppose it would depend on what kind of a safety margin you have on your mixture, and where you set the pressure switch. You could easily have it shut down at a pressure that still yielded a rich mixture.

 

the problem i see is i run 43psi base fp im expecting launch to be around 8 psi of boost so minimal fuel presure will be 51 psi to keep the nitrous system activated.at max boost fuel presure will be about 65psi

that would leave me 14 psi worth of fuel presure drop before the nitrous deactivates. id have to do some math and see how much a 14psi presure drop would lean out the mixture on boost alone, but im willing to bet it would take me from a safe 11.0 afr to the mid 14's or higher before the nitrous even shut off


edit
actually i need to look threw the nitrous settings a bit more there may actually be a setting to kill the nitrous system based on afr from the wideband

 

Do they make a boost-referenced hobbs switch?

The wideband definitely would respond too slowly.

 

http://www.atpturbo.com/mm5/merchant...egory_Code=BCS

 

That's not boost-referenced.

 

???

 

It's boost activated... so just a regular pressure switch that turns on at a fixed setpoint.

It would be interesting if there was a pressure switch that referenced the setpoint against manifold pressure.

 

Hey, for $25.00 freaking dollars whaddya want....

 

i dont believe anyone makes a boost refrenced hobbs switch
the afr safety feature is only available in megasquirt 3 i just found out.

teh afr setup would give me a much closer tolerance for shutting the system down over the hobbs switch.
the hobbs switch would take around a 14psi pressure drop to deactivate the system, with the afr system even though slower to react would still shut down the system faster

say i should be running an afr of 11.2-1 i could set the wideband cuttoff to be around 11.8-12.1 which would still kill the nitrous long before the fuel presure switch would


my other option would be to run a base presure of 65 psi and trim back my fuel maps in the non boost sections and low boost sections and then use a fuel presure switch set to 62psi nitrous shutoff

actually being as i have a megasquirt 2 setup the last option is my only option at this time.

next spring i will be upgrading my ms unit to ms3 with the ms3x expansion board so i can switch to sequential injection and cop ignition system with the ability to adjust each individual cyls fuel and ignition settings

id do it now but the priority atm is getting the car torn back down and preped to go out for paint soon

 

Then just get a nitrous window switch then....

 

thats not the issue thats all bu9ilt into the mega squirt looking for a way to shut down the system due to a fuel presure drop or other issue

 

It would be nice if someone did make such a switch. You could set it a few PSI below your static fuel pressure and the setpoint would track.

 

It appears you'd have to make your own. Spark cut would be faster either way no...?