MS2 and nitrous

[Orange65]

Will Megasquirt 2 support nitrous as a dry system? Or does nitrous have to be a stand alone system from the MS?

[dieselgeek]

If you run the MS2-Extra firmware, there's a stage of dry nitrous available. You tell it how much fuel to add, feed it an "Armed" input, and let it trigger the nitrous solenoid relay directly. You then can use all kinds of safeguards to make sure it's only spraying when you really want it to (i.e., set RPM and TPS windows, minimum coolant temp, etc.).

[CDMBill]

Obviously there are injector sizing issues with a dry shot setup, which may mean new injectors and appropriate non-spray tune. The software can also switch the spark map to compliment the other safeguard settings.

[dieselgeek]

WAs reading today and noticed I made a mistake. With MSII, you get TWO stages of nitrous - progressive if you like. They stepped it up since MSI apparently.

[Bamfster]

WAs reading today and noticed I made a mistake. With MSII, you get TWO stages of nitrous - progressive if you like. They stepped it up since MSI apparently.

Another reason I changed my mind and am going w/ MS2

[TC]

I'd go with a wet system, than try to have the EFI compensate for ALL the added fuel needed to run the nitrous.........

Also and this should have been ask first, how much of a nitrous hit are you looking at running??

[dieselgeek]

I'd go with a wet system, than try to have the EFI compensate for ALL the added fuel needed to run the nitrous.........

That's because you never tried it with the EFI system. Dry nitrous is a shitload safer than wet nitrous, as it eliminates the *dangerous* half of things that can go wrong. With dry nitrous, and the computer doing the extra fuel, worst case scenario the nitrous doesn't fire and you run rich. No chance, ever, of having the nitrous "on" and the fuel "not"

And that goes ONLY for speed density EFI systems, not spraying through the MAF on an OEM installation (which I think is a bad idea).

[Stich496]

That's because you never tried it with the EFI system. Dry nitrous is a shitload safer than wet nitrous, as it eliminates the *dangerous* half of things that can go wrong. With dry nitrous, and the computer doing the extra fuel, worst case scenario the nitrous doesn't fire and you run rich. No chance, ever, of having the nitrous "on" and the fuel "not"

And that goes ONLY for speed density EFI systems, not spraying through the MAF on an OEM installation (which I think is a bad idea).

ok.. got that, but how much does sizing the injectors to be able to feed two stages of nos , kill the off nos spray pattern and fuel control, or would it just make the duty cycle of those injectors just very short when off the happy gas.. as I'm guess'n you'd be use'n bigger injectors than normally would

for exp.. a progressive 150 shot and a 175-200 on top of that.
I'd think moving that much VOLUME of fuel through the injectors because of rail size would limit this..

[TC]

That's because you never tried it with the EFI system. Dry nitrous is a shitload safer than wet nitrous, as it eliminates the *dangerous* half of things that can go wrong. With dry nitrous, and the computer doing the extra fuel, worst case scenario the nitrous doesn't fire and you run rich. No chance, ever, of having the nitrous "on" and the fuel "not"

And that goes ONLY for speed density EFI systems, not spraying through the MAF on an OEM installation (which I think is a bad idea).

So your saying that the EFI system can handle a 500hp dry hit??, or lets be a little more realistic and say a 300hp shot, you know like what a NOS Big Shot system will give you........

The thing I like about a wet system is the EFI only has to compensate for a small variance in AFR's, where as with a dry system it's got to compensate for huge variances........

Then comes injectors, lets say you have a 400hp motor and your hitting it with a dry 300 shot, what kind of havoc is that going to play on the duty cycle of the injector?? I mean your going to have to run a large enough injector to handle 700+hp........But then use that same injector to drive around town with at a much lower power level.....and a way lower duty cycle....And if I get this right, the lower the duty cycle the longer the injector stays closed and more of a chance of lean pockets in the intake charge........

[TC]

And how about tuning it.......I can just see a lean Nitrous backfire as a possibility in the early stages of tuning............ especially with some guy trying to do it himself, without the use of a dyno..........

[Stich496]

I wanna know how that tiny fuel rail is gonna flow that much fuel to keep up.. no matter if the injectors can
my last 2 stage set up had a 1/2" fuel line to keep the volume high enough
the fuel pump can only push so much fuel through a 3/8 line no matter if the pressure is 58 psi or 200

[TheSilverBuick]

What's the difference between running a Turbo engine that peaks at 1200HP and running a 500 shot on a 700HP engine? People run EFI'd 1500hp, 2000hp, ect all the time an apparently have no issues idling or flowing fuel through fuel rails. Hell you cite 700+HP, CDMBILL runs more than that, as does seered, and I'm sure Jeff. The EFI seems okay with those HP levels, don't be retarded, you know this.

How many people have melted pistons down with carbs and nitrous trying to tune it? I'm sure lots.

[Bamfster]

How many people have melted pistons down with carbs and nitrous trying to tune it? I'm sure lots.

Sheepishly, I raise my hand ......

[dieselgeek]

Randal is spot on.

An EFI combo that can handle a large shot of nitrous is no different than one capable of supporting a large turbo. It needs to have enough injector for idling and full loaded WOT. The bigger you go on injectors, there is no "lean pockets" (or Hot Pockets - yum!) concern - the problem you run into is controlling idle because injectors start to have non-linear fuel flow with extremely lowering pulse widths under 1.0 milliseconds...

TC, once again, commenting without experience: when you run a dry shot with EFI, there is no "compensating" (most tuners choose to disable closed loop corrections when spraying) of the EFI system. You simply tell the EFI system how much extra fuel to add when the nitrous is triggered, either with a HP number, or an Additional Pulsewidth number. It's the same thing as selecting Fuel jets only using the computer. You start out on the slightly rich side and go from there. I'm quite confident I could tune a dry nitrous setup safely and more quickly than the average or above average carb tuner. It's even easier than tuning for a big turbo.

CDMBill has largely oversized injectors, I think they're 120 lb/hr and good for like 1600hp on gas? he's yet to run the dry shot, instead choosing the more difficult path of finding that 4 digit number on motor alone.

[Stich496]

What's the difference between running a Turbo engine that peaks at 1200HP and running a 500 shot on a 700HP engine? People run EFI'd 1500hp, 2000hp, ect all the time an apparently have no issues idling or flowing fuel through fuel rails. Hell you cite 700+HP, CDMBILL runs more than that, as does seered, and I'm sure Jeff. The EFI seems okay with those HP levels, don't be retarded, you know this.

How many people have melted pistons down with carbs and nitrous trying to tune it? I'm sure lots.

ARE THEY ALL THE SAME SIZED RAILS or do larger injectors use/require bigger rails.. I have no idea..
so I'm not being a retard.. I have no idea if docs car rial i.d. is the same as a tpi rail i.d.