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.

[dieselgeek]

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.

that's pretty easy stuff to look up. the average guy is way oversized on the rails, there are things that some people get concerned about especially if you fire the injectors in groups versus individually/sequentially. Extruded rail is cheap so it's fine to go oversized on that.

[Bamfster]

Dumb Q time .... so when adding N2O w/EFI, does the WB02 act differently or do the same tuning principles apply? It seems to me that it would either go dead rich or dead lean at the initial hit ..... depending on which gets there 1st.

[Stich496]

that's pretty easy stuff to look up. the average guy is way oversized on the rails, there are things that some people get concerned about especially if you fire the injectors in groups versus individually/sequentially. Extruded rail is cheap so it's fine to go oversized on that.

looking stuff up while se'n double because of meds. isn't all that easy lol..
thank tho..
the 355 brodix track 1 headed/ bowtie intake all forged short block is going to be my test dummy.. for this..
it's got the best of what a mid 90's build could.. lutyna crank. olover rods.. cheapped out on pistons they are heavy trw forgings..
arp studs all around.. and zero seconds on it... the cam will need to be changed as the flat tap is a deathwish...
but this is what I'll use as I have it and it's sat and sat 1992 to 2011.. way to long..
start up will be on a stand.. to get it ironed out before I install it..
and I'd like to use the 2 stage nos I have.. but 2 less lines/selniods is a big + it be cleaner

[Stich496]

Dumb Q time .... so when adding N2O w/EFI, does the WB02 act differently or do the same tuning principles apply? It seems to me that it would either go dead rich or dead lean at the initial hit ..... depending on which gets there 1st.
I'd guess it depend on how far off you are on your fuel map

[dieselgeek]

Dumb Q time .... so when adding N2O w/EFI, does the WB02 act differently or do the same tuning principles apply? It seems to me that it would either go dead rich or dead lean at the initial hit ..... depending on which gets there 1st.

N2O tuning is just like tuning for boost. You aim for a certain AFR. If you observe dead lean or dead rich on your wideband O2 sensor, "you're doing it wrong" :-)

[Stich496]

N2O tuning is just like tuning for boost. You aim for a certain AFR. If you observe dead lean or dead rich on your wideband O2 sensor, "you're doing it wrong" :-)


ok says you.. but the nos kits you get pills/jets that are close.. the ms you have to map the fuel.. and how does one figure out that a 150 hit need x amount of fuel to get at least into the ballpark and not become the blue button blow torch

[dieselgeek]

ok says you.. but the nos kits you get pills/jets that are close.. the ms you have to map the fuel.. and how does one figure out that a 150 hit need x amount of fuel to get at least into the ballpark and not become the blue button blow torch

don't take my word for it, all I do is read the instructions. It's real simple to relate HP to fuel quantity if you know a rough AFR that you want to run.

I've also tuned a lot of wet systems and use a wideband O2 sensor. What the nitrous companies pick for you, is way way way overly rich. I'm guessing you haven't used a wideband O2 sensor for nitrous tuning so, in that case, you stick with what the nitrous hardware supplier sends you.

[Stich496]

oh I know they are rich.. but it's like i said a start.. no never used the o2 sensor..
used the et/mph and alot of blank pills, drilled every 5 thousands of an inch..

[TC]

From ZEX Nitrous Systems.....


Q: What is better, a wet or dry kit?
A: It all depends on the application. A wet kit is ideal for both normally aspirated applications as well as forced induction applications. It can require a little bit more installation time than a dry kit, but is easier to tune if greater than stock HP settings are to be experimented with. A dry kit is excellent for normally aspirated combinations that have a return style fuel system. They are very easy to install and are a great first time nitrous system. It is not recommended that dry systems be used on forced induction engines.

[Bob Holmes]

and how does one figure out that a 150 hit need x amount of fuel to get at least into the ballpark and not become the blue button blow torch

Its called "math."

[dieselgeek]

From ZEX Nitrous Systems.....


sure it's easier to tune a wet system if you're not running a tune-able EFI computer. I'm sure that's how they're answering the question because 99.9% of their customer calls (and guys like you) are asking "can I put a 900 shot on my bone stock camaro and how do I do it??"

When tuning a standalone EFI system - custom - dry nitrous is better for many reasons.

[CDMBill]

Quite a few related questions here.

First, you can run a dry or wet system with an MSII or MSIII.

Second, fuel rails are one part of the overall fuel volume and pressure supply question. On the single four barrel throttle body build I used blank .5" ID rails from Aeromotive supplied by #8 lines split off a #10 supply line from the pump in the back by the tank. The stock motor systems sold by ZEX and others are for safe, basic installs and have little or nothing to do with custom installations.

For the dual four barrel throttle body setup I used Wislon Manifolds .625" ID "D" shaped rails. Both use the same 96 lb/hr RCI Bosch style injectors. They were choosen for the original build because they would support 800 HP N/A and up to an addtional 400 dry shot. 1200 total agianst the 43 PSI regulator. The dry nozzles were supplied and plumbed by Nitrous Express, Mike Thermos's new company after he sold NOS to Holley. They are installed so that the nitrous plume engulfs the spray from the injector nozzle and are aimed at the intake valve throat from about 3" up into the manifold.

Drivability with the 'oversized' injectors hasn't been an issue as they are disk style and were engineered for this kind of application.

The new combination N/A makes just over 1000HP with the same 96 lb/hr injectors, obviuosly the duty cycle has changed somewhat mostly at WOT or close to WOT.

The N2O on the dual TB setup is a wet system from Wilson's Nitrous Pro Flo shop. Its sized for 150-500HP and was designed to be used with their dedicated progressive controller. It uses dedicated N2O and Fuel solenoids on each bank. As a heavy, tire limted drag radial car I need to run either a progressive or multi stage system and the progressive is worlds easier to plumb. What we can't do affordably at the moment is manage a progressive N2O system with EFI. It could and is being done but with far more expensive systems and mucho dyno time neither of which I have the money for.

I'll disagree a bit with Scott here as I'd much prefer to tune the wet N2O system on top of an EFI tuned N/A platform because we can optimise perfomance for both N/A and sprayed tune-ups so much easier.

The EFI controlled wet N2O still has all the safety advantages of the EFI wet system including TPS driven full throttle control, RPM windows and the feedback of the WB 02's should we decide to run closed loop as a trim function. I doubt howver that we ill run closed loop but we do keep the datalogging capacity of the MSII.

We will sneak up on the N2O set-up after the N/A set-up is optomised. Unsurprizingly the chassis tuning and optimal converter/tire/gear selection for a 1000 HP n/a combo is differnt than a 1000 plus 400 porgressive N2O set-up so while the engine can be changed with a mouse click or on the fly almost with an MSIII the mechanical elements require more time and attention.

BTW, we'll be using a new MSIII box as data logging supplement as we work though the eventual cut over to the new box from the MS II software and hardware. I can't say enough how b nice it will be to be able to see fuel pressure on both systems as well as wheel speed, drive shaft speed, fuel temp etc. etc.. This stuff sounds crazy but it is so helpful to have.

[Stich496]

thanks...

[chevy3100truck]

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

not to be a pain in the ass, but that is completely wrong..... a 3/8" line with 50psi and a 3/8" line with 100 psi will flow extremely different volumes of liquid.

[Stich496]

to a point, but double the psi don't mean double the flow.. and fluid stall is a real issue

[chevy3100truck]

A rough conversion for increasing flow within the same size tube is 2x pressure = 1.5 times flow capacity, 4x pressure = 2x flow capacity.

[A/Fuel]

Don Jackson has a handy chart to get GPM's from area and pressure for nitro, it depends on the percentage though. I have one for alcohol too, so I imagine there is one for gas. There is usually a small difference when compared to a Racepak flow meter, but's it's better than the shot in the dark.
The main thing to remember is to convert the jet size into area though.