Nmbr1GMfan - I called Jerald at FJO to ask him about what you and I had discussed. I've sent you a pm regarding his input.

Also, you might want to richen it up so that the lean condition during progression will lower as well as lower the a/f when it's at 100%.

 

Ok been looking at these problem for a while now. I think you are seeing nothing more than a lean spike that is normally there just carrying out a little longer caused by the on off on off. For every On causes some form of spike. The amount Of time that the car is lean is extremly important.
Ricky

 

I find this information interesting. I want to install a progressive controller on my truck but do not like the idea of lean spikes while the noid is pulsing. NXricky mentioned just upping the fuel jetting to help with this but will that not lower the total over nitrous HP added when the system reaches 100%?

Example: I have 150 shot that is jetted to rich..will that not lower the 150 down to 140 shot or lower?

 

The issue is likely the fuel system..not the controller. The controller will just stretch it out a lil longer.

 

Ricky is spot on, after the pulsing it stays at a reasonable a/f and the time here is minimal. The car does feel lean to me for the initial hit and then feels great, with the input so far from NX and Nitro Dave I will go up on the fuel jet and shorten the fuel solonoid to plate feed line. if that seems to not produce the results I feel comfortable with I will use the 1st stage for the nitrous and second stage for the fuel. Mirror the complete setup for both stages but pulse the solenoids at different Hz rates with the fuel pulsing faster to make up for pressure differences while pulsing. In my mind (however small that may be) this will work to increase fuel delivery while pulsing only as wide open the A/F is fine. Thanks for all the input guys. TODD

 

Can't you calculate out how long it takes the fuel to reach the nozzle for a given hit, taking into consideration the line size, the solenoid orifice size, the fuel pressure and the line length?

Then also calculate out the time it takes for the nitrous to hit the nozzle using the same methodology, take those two figures and calculate out a compensation value to use to activate the fuel and nitrous solenoids independantly to eliminate the 'lean' condition seen?

I mean this would apply to not only progressive (even though the pulse-rate could be used to compensate more than just time itself), but also to straight hits?

I mean I started working through the numbers myself, since I planned to do just this utilizing the two stages in the Max2 to make sure there wasn't a 'lean-area' in my curve, as I am running both nitrous and a supercharger... But with the flexibility of the Max2, I would figure it could be something that could be added to allow for this all within the program *hint hint, wink wink, nudge nudge*...

You could even take it a step further and once all of the conditions are calculated, you could basically determine how much time would be needed to syncronize the two, then adjust the activation based upon rpm ramping ( to calculate the pre-rpm activation time) and basically hit the 'on' point within a couple 100 rpm??? Or at teh very least, and simpler, you could calculate out the physical time needed and then give a 'time skew' value on the screen people could use to self-determine how they want to change the on points for given gears... Would make it much easier for the person setting it up without getting too fancy program wise...

 

There is an adjustable delay setting on the FJO box and Im sure you could use it to manage these issues, you would however have to operate two solenoids on different stages and run the delay between the two stages, with a mirror image of your ramp cycle. This is what I have introduced to NX, Nitro Dave, and FJO. All said it was uncharted waters but in theory would work. After my kit gets changed tomorrow I will determine weather or not to move to this option. I would like to say I have purchased from all of the above mentioned companies, their respective products have worked outstanding and have been nothing but helpfull. TODD

 

That is correct Todd, what I originally told you amount running the solenoids on different stages so you could control them independantly of each other should work to solve the issue that you have experienced, however we have never performed that type of test because we've never had an issue similar to what you are experiencing.

95 TA - This type of calculation has already been performed by a shop that works pretty closely with NX. In their testing they activated a single stage on a big block chevy and used various sensors to data log the amount of time it takes fuel to move from the solenoid to the exit of the nozzle/plate as well as log the same data for the nitrous side. What they found repeatedly was that the time difference between the fuel and the nitrous reaching the same point was very very minute. The time difference was so small that there's no way that the difference in pressures is the only reason for the lean spikes that we see with wet systems. I personally believe that it has more to do with the rest of the fuel system (pump, lines, fittings, return/returnless, etc..).

Also, IMHO, people see a lean spike and automatically flip out thinking that they are going to cause some horrific damage to the engine. When in most cases the spike is just that, a momentary rise and fall in the a/f that usually lasts less than 1000rpm and/or less than 1-1.5secs. These types of spikes do not cause engine failure, and if and engine fails at the same instant that the spike occurs then it already had some serious problems.

Just my .02

 

I noticed on the A/F on my car with the fjo was a little lean while pulsing as well. When not pulsing everything is fine.

 

Oh, I have no doubt that the fuel system itself and 'usually' the lack of proper volume for dynamic changes is a factor until everything 'stabilizes'... That is why my fuel system is way overengineered and errs on the side of excess volume, as I run a full -10AN feed, -6AN return system that should support over 1400hp, as well as the nitrous feed from the feed at the regulator to the nitrous solenoid is utilizing -6AN line as well, so any sort of instantaneous volume drain will not effect either the fuel rail or fuel solenoid feed points... But again, the system as a whole is far from 'stock'...

I don't doubt short lean periods don't pose any sort of threat if everyrthing is designed and setup properly, I would just rather err on the side of caution and have a nice even A/F that pretty much assures that any 'anomolies' that could cause major failure are readily apparent and visible... Call me overly meticulous, but shooting for perfection only assures fewer problems and headaches, ones that usually can get quite costly once corners are cut or abnormalities are just 'accepted' as the norm... All IMHO, of course...

 

Todd...did you dyno this at Rev Extreme...do you mind if I post your graph with AF?

 

Yes. Do you have access to a copy, I do not have one here at work. Post away if you have access. File is under Todd Greene (I think)

 

Looks like one graph is on/off
one progressive and one NA?
Is that correct? The AF looks like the whole thing needs to come down a bit too. Maybe up the fuel pill a bit.

 

Al, run 004 was after tune on motor, run 009 was 200hp jet progressive till 5500 and 010 was 150 jet progressive 3200 to 4200 (I think) but we were starting the wot runs later trying to see how the fuel reacted. As you can see the 200 jet run had lots of power late in the run after the 150 hp run had fallen way off, had I used the same progression it would have made nice power. Probably ought to get a fuel pump for 200. So Dave sent me a 40 fuel jet to replace my 38, a fuel line 6" shorter than the one currently in use and I may try to pulse at 12 or 13 Hz rather than 15. If I dont like that I will use both stages of the controller with mirror ramp times and pulse n2o at 15 and fuel at 13. I have lots of options and I thank all who are giving input, including RevX and Jeremy for the tune.

 

No problem. And your plan sounds good. I would recomend a fuel pump and if its possible on your car...incorporate a regulator closer to the rail with a return. I have not been following the GTOs so Im not sure how feesible that is. A good intank pump would probably help quite a bit.

And the difference in progressive rate between the 2 nitrous runs, but similair lean areas somehat confirms that its a fuel issue. If you did it in on/off and no progression it would probably have a very fast but sharp spike.

It looks very managable though. Few tweaks here and there and you should get her where it needs to be.

Jeremy was telling me your car is about bone stock? Very nice!!

 

Yea its completely stock other than 3.91 gears. I will make an n2o lap or two at the all GTO race at BMP this Sunday and see what happens. TODD