i was wondering about doing a large dry setup
on my intake using 4 dry nozzles in the runners
( http://sethirdgen.org/personal/siameesedrunner.jpg )
and moving from my 22 lb injectors to a set of
30 lb injectors and using the air intake temp
table to provide a way to add the neccessary fuel
by bypassing the factory sensor with a relay and
switching to a resistor with a different value . that
way it would allow you to change the multiplier in
that table to add the fuel needed for the bottle .

whatcha think

mike

 

I've been looking into doing something for the S_aujp line for dry n2o. I already have an alternate PE table that is bit selectable.
It would be a small matter to add a little code to check for an arming switch and a few other quals to then use the alt PE table to add the extra fuel. The only other person I have interested is down for the winter.

I think the math for calcing the fuel would be a little easier if using the PE table as opposed to the MAT tables.
You also have to look at where the fuel would be added into the code calc sequence. All your math would go out the window if the extra PW is added early on and you max out at 255 for the calc.
Already happens on 400+ cid motors and stock code.

 

a couple of questions :
when you say max out at 255 are you refering
to a maf car because i am S/D

explain more on your thought of where in the
sequence in the calc's and how that effects
raising the pulse width by a fixed amount
in that table . i just didn't get it

thanxs for the response

mike

 

Look up in the 8D source code stickies for PW limit fix.

 

ok i read about the fix you spoke of
it makes me wonder though if you get
more of a ceiling by running a little
to large of an injector so that the intial
P/W will be smaller because of the changes
in V/E .

 

Nitrous comes in at a constant flowrate (at all RPMs). If you just increase the PW by X%, you won't be increasing fuel in a constant way, since it's frequency is determined by the RPM (thus total flow increases with RPM). You'd have to have an inverse table = More Multiplier at lower RPMs, Less Multiplier at high RPMs.

Cylinder bias in a dry setup may fry #5 or #7, so err on the rich side, and keep an eye on those plugs.

 

Correct, as soon as you get 255 in an accumulator.
You hit a "ceiling" on the PW.
That's why the fix worked. The bigger the injector, the smaller the value. So the farther away from 255 you are for that portion of the calculation.


Red, if PE were used, I think it would compensate for the RPM increase in fuel. Just need to do the math to find the afr you want at X n20 HP. Might run out of room.

Also, wouldn't X Hp = Y PW for n20. So a straight PW adder
might work. Some fuel will also be added by the MAT change.

I'd think a wet n20 setup would be worse for 5 & 7 distribution.

 

redngold 86z : by using 4 nozzles in my modified
runners i think i should be able to deal with
distribution. take a look at my pic above .

i would think that it would work because
whatever the right fuel curve is on motor
i am adding essentially _% more oxygen at
all activated rpms so i need to multiply by
_ % on the fuel to keep the balance .

one thing i have learned thru much testing
is on most street engines that are actually
driven the A/F works well at over a fairly
broad range . just don't detonate or load
too much at to low of an rpm and all's good

for reference one of my last kits had 41n 35 f
at 11 psi flowing fuel pressure in the fogger
and 61n 55f in the plate on a realitively mild
355 . ran 10.56 @ 131 on small valve factory
heads .

 

I have set up a few MPFI cars to work on a dry shot of nitrous. It's really easy too. Mount the bottle, run a single line and install the nossle right befor the throttle body. This works good for up to 200hp of nitrous. That 200 shot will do more than a 250hp direct port setup, it's a proven fact. That is another story though(related to air molecules).

At any rate, I just take the two PE tables and make them command a 10.0 a/f ratio naturally aspirated(retard a few * of PE timing too). Then do test hits with the nitrous on. If the a/f goes into the mid/high 12's, richen it up some. My testing indicates 36lb injectors should be ok for most LTR/TPI combos running a 100hp dry shot. 40lbers would be better though.
Using my method, you'll have two basic choices. One is to have a chip for nitrous and another for n/a. The other is to modify the coolant temp tables to add fuel and subtract timing in a higher area of the tables. Then use a resistor and toggle switch to bypass the actual coolant temp with the corrected value to "ride" in the modified table entries.

The only problem I have with the toggle switch method is that actual coolant temp will be bypassed. When making nitrous passes, coolant temp tends to rise as time goes on. The end of a run will usually result in a considerably different coolant temp reading than at the beginning. More than a N/A engine by far. It's possible to use the coolant temp tables to make adjustments of the burn rate as the coolant temp rises throught the run. Without actual coolant temp going to the ECM, that's not possible.


Sure there are a million ways to run a dry nitrous setup . The best ideas involve modifying GM's code to recognize when nitrous is present. The information I have posted is the most basic way to have a dry setup NOW. My friends have sprayed a ton of nitrous using the described dry system. I know it works, I helped some of the guys do it.. The slowest car ran about 118mph in the quarter, the fastest was in the 139mph range.

Using a dry system on a LS1 is even more simple. Just spray the MAF sensor. My buddy does that to stock cars all the time. They tend to run low 11's @ 127mph. Thats on street tires, stock fuel system and good tuning[edit:+headers]. Sure the injector DC is at 156%, but the cars make a ton of reliable HP (through repeated runs at the track and on the street).

 

Thanks Tim,
I need to figure the math behind the 10.0 in the pe tables.

I'm making N20 code for aujp as time permits.
What else do you think might be needed?

My thinking is for N20 is all it will need is a constant to add to the pw plus some quals to use it.

 

What size nozzle for the single N2O fitting at the intake?

Since you guys are talking dry N2O I was wondering if anyone knows the freq. & duty cycle a NOS soleoid can be pulsed at. What I am really after is the inductance of the solenoid. It would be nice to have the ECM do a pulse width modulation to roll on the HP like boost comes in.

 

I think using a toggle switch to activate "nitrous mode" would be easy. That mode could use a TPS X RPM X retard (amount) table . Even an existing 2d table could work.. Then add/use an existing table for PE fuel adder (nitrous mode) VS rpms. DFI has a fuel delay to compensate for latency issues when spraying a dry shot before the throttle body.
Using an output to activate the nitrous solenoid (based on TPS and RPM) would be great too. Automatically controlling a bottle warmer would be sweet.
Hopefully I'll have time soon to get back into assembly.

 

In anothre post I asked for if someone had any logs showing N20 coming on using an aftermarket ecm. No takers....

I wonder if the fuel delay is blended or just off/on for x milliseconds.

The quals are easy, I'm trying to make this so it could be for other uses besides N20. So far I have
External arm
TPS
MAP
Rpm window
The external arm can be skipped if desired.
And any of the quals can be eliminated by setting to the appropriate number.

The fuel portion is the only real difficult part.
Need to be able to start with some hard data and work backwards to get the PW right.

 

In case you do the PWM. I have come across 30Hz-100Hz.
0-100% DC. All seemed to recommend using two N2O solenoids, one to PWM and one as an On/Off switch.

Are you serious about the N2O entering the intake later than the fuel that a delay is necessary? I would be more worried about the N2O getting the go signal before the injectors dump enough fuel.
Sure they don't do it for unequal N2O & fuel line lengths....to bias the fuel?

 

You'll need an input for a fuel pressure switch.
Don't want that going low on you at the wrong moment.
D2, D3, or D4 running from U10 are candidates.
Could just run the enable "button" through the fuel switch hardwired to make it easier.

 

It's not needed, decent idea though...

 

Sorry I didn't see that. What type of log file do you want, from the wideband or DFI diagnostic software? Want the matching calibration file? I'm sure there is something I can dig up for you. If you want to give me some time, I can send you detailed information on the test vehicle and conditions. PM you email address, I can't find it on my computer anymore. The DFI files are from an LT1 w/ 13:1 CR, 92 octane fuel and 100hp shot. I also did some testing with a 200hp shot on pump gas. FYI, It's trapping over 130mph. I also have some test data from a 730 running a dry shot. Just LMK what you need...


I had it backwards, it's a delay to activate the N2O solenoid.

 

Would need to verify the n2o solenoid current load to see if the 730 ecm driver could handle it. Well, ask someone who might know.

For logs, if it's a TP,DM, or TC log I can get the data extracted.
I only have TP, but I know people that would put the other data into excel for me.
What I need to see is the PW change during n2o activation.
An excel sheet with DFI data would tell me how the high $$ stuff does it. Any wb info during the run will help.
And I'd need the size of the N2O hit. Best I can tell, The hp won't change much from engine to engine. Will just have to make sure the initial calcs come up with a rich pw adder.
I'd like to see what cal settings a DFI or similar have for n2o setup too. Any n2o info is appreciated.

 

Give me a couple of days and I'll put something together. This package will include DFI log, calibration and stand alone wideband files from the same test. You'll just need to download DFI's calmap software to go through everything. here is a link to the correct version...
http://go.mrgasket.com/ftp/calmap/Ca..._7+_v4_0_2.zip

Then you'll need LM-1's software to view the wideband log..

 

BTW, calmap's help file is a good thing to read...