First a little background:
I have a ZZ4 with HOT cam sitting in a '68 Camaro. I run consistent 13.0 @ 107/108 on the motor alone.

Now the nitrous system:
125HP NOS Powershot Kit
Jacobs Nitrous Mastermind
dedicated Holley Blue (filter just before pump and after regulator)
purge valve and safety valve
throttle switch and clutch switch
Hobbs switch
bottle heater

I calibrated the controller by building a small circuit using a couple 555 timers (all those years of engineering experience finally paid off with something useful). It corresponds well with empirical evidence gained by doing some live tests.

How I run:
Nitrous set to come on at 3k RPM
ignition retard of 5 degrees
nitrous cut-off/shift point at 6k RPM
fuel pressure set to 6 psi flowing

So now the problem:
The nitrous engages, but not as dramatically as I think it should. My best run was only 12.8@112.

Some ideas:
There is an obstruction somewhere in the nitrous path.
I hooked the fuel/nitrous the wrong sides of the plate. (I can't remember if it is labelled.)


So, any ideas what is going wrong?

Ed Bleich

Questions....

1. Bottle Pressure?
2. Total Timing?
3. Nitrous Jetting?
4. Purged o.k.?
5. How are your shifts?
6. Incremental Times?

Observations...

1. Your timing retard is high. For a 125HP kit (set at 125 HP) you really only need to retard by 2 degrees (32-34 degrees total would be very safe).

2. Your system is operating in a very narrow band with a 3,000 RPM range interupted with (I would assume) 2 shifts at least.

3. Your MPH increase is disproportionate to your ET reduction, suggesting that you were getting more bang for your buck at the top end but too late (ie. after your last shift).

4. You have several switches (WOT, clutch, hobbs) that could be checked.

All in all, it would be my opinion that you really are not getting much of a shot during your pass and that the nitrous is off as much as it is on. Another possibility would be an issue with your "safety valve" or the Jacobs piece.

I have a similar set up on an '89 vette - ZZ4, victor jr, 650 demon, NOS cheater set at 150HP - and it pulls very hard. I have been using nitrous for many (18+) years and have moved away from many of the redundant failsafes as they are typically the first point of failure in the system.

I would look at the WOT and clutch switches to verify that they engage/disengage quickly. You may find that the WOT throttle is a bit out and not engaging as quickly as you would like.

I would also try a pass short shifting through to high gear and see what happens on the top end. Listen for when the system disengages - yo may find that it is at 1000 feet with your high RPM limit at 6000.

Just my two bits. Good Luck.

I have run into typical issues which I hope to work out this year. I am using the edelbrock kit. I used a NOS fuel pressure cutoff switch and have had probs with it.

"I have a similar set up on an '89 vette - ZZ4, victor jr, 650 demon, NOS cheater set at 150HP - and it pulls very hard."

I have just purchased a Demon and Victor Jr to go with my ZZ4. Have you run it at the track? Have you made any jet changes in your Demon? Thanks!

I agree with James on all issues. I would check hose hook-up to be sure.

Another truobleshooting tool I would do is to wire the fuel & NOx solenoids to an IGN on supply through a push button switch and try a controlled run in second/third gear.

I would expect to see results like "Rat Fink" eyes when viewing your face in the rear view mirror after the run.

yipman64 has a very good point. I no longer run Hobbs switches for low fuel pressure because there is a momentary loss of pressure when the system is first actived (unless you are running a return line just in front of the fuel solenoid). This instant loss can cause the Hobbs switch to momentarily cut out or flutter on and off for your entire run. This is a very common and frustrating problem.

Did you clean the plate when you got it. I have seen several kits that came and had just a little debris in them that did exactly what you said. But you do also have alot of failsafes that could be wrong. Also i would run the nitrous cut off a little higher thatn your shift point, 100-200 rpm, so if you pull a gear a bit longer you still have nitrous.

On your mastermind, what do you have the "nitrous full" knob set to? If you have the "nitrous start" @3000 and the "nitrous full" @6000, it will come on @3000 and progressively ramp up to 125hp @6000. Set the "nitrous full" @4000 or so, so that the ramp is much quicker and you will hit 125 sooner. You could even set it @3000 if you think that you wont have any traction issues. Then your 125 will all come in at once and then im sure youll feel it. Hope this has been some help.

So here is an update and an answer to some of the questions posted:

I took the whole mess apart and checked things out. Everything seems to be fine electrically. Everything seems to be plumbed correctly. Admittedly, I did not look closely at the plate itself to look for manufacturing problems. Nitrous pressure is a bit over 900psi.
Full timing is 36 normally - I set the spray retard to 3 degrees.

I checked to see what happens to the fuel pressure on initial engagement - it chattered for a second or so. If I purge the line by manually engaging the solinoid prior to doing a run and dumping the gas into the engine, it doesn't chatter - I only seem to need to do this once before the first run of the day.

The purge seems to be working just fine.

I did a run with the "full" rpm set to 1k (so that when the system came on, it came on with the full blast instead of ramping progressively). No
difference. I wired a manual switch - the engagement of the spray was not at all dramatic.

I then removed the safety n20 solinoid and repeated the manual engagement test - no difference.

So I am exactly nowhere relative to my first post. The only thing I have not looked at it the plate itself, which I will do today. Clearly, I am not getting the bang I was expecting.

Anybody have any new ideas/suggestions to throw at me?

Ed

Could you have a bad N20 solenoid? I've heard that pregressive controllers like the Jacobs are hard on solenoids. Maybe you could test the solenoid with compressed air to make sure it comes on quickly and flows good when energized.

I had a problem similar to this at aSuper Chevy event. It turns out that the nos solenoid must be mounted above the plate and not below it. If it is below the plate reversion will cause fuel to enter the nos solenoid and destroy the seal. My luck this happened during first round eliminations.

The way I had (past tense) things plumbed was
that the line from the tank connected to the safety solenoid, which in turn connected to the main solenoid, which in turn connected to the plate. The safety solenoid was engaged by the WOT switch. The main solenoid was pulsed by the controller.

I have now removed the main solenoid and control both the remaining NOS solenoid and the fuel solenoid by connecting the positive side of a relay to the WOT switch and the negative side to the fuel control line of the Jacob's unit. This control line is just acting like an RPM switch. The relay turns the two solenoids on. Note that I no longer have a safety solenoid, but only two main solenoids. I do not use the progressive ability of the controller.

All that said, this does not mean that the n2o solenoid is not malfunctioning despite the fact that it is barely used and, as the old safety solenoid, was never pulsed like the fuel solenoid or like the now removed n20 solenoid.

Ed

chassisboy,

The n20 solenoid is above the plate.

Now a question: Given that the plate has two sprayer bars, one for n2o and one for fuel, and given that the two do not connect to each other, how can fuel get into the n20 line?

Ed

Sounds like an unusually complicated setup for a mere 125 shot. We ran a NX 100 hp system on a 355" 64 Nova that took it from 12.70/109 to 11.40/119 using just a full throttle actuator.

Maybe it is a bit overcomplicated - what do you want from an engineer.

Actually the reason I used the controller is that it does a lot of the little things I am too lazy to do manually once I get to the strip: retard timeing, rpm turn on switch and it has a rev limiter. (I drive the car to/from the strip.)

Ignoring for the moment the complexity, the fact remains that even when I bypass the controller, the system still does not deliver the bang I would expect.

Ed

What do the plugs look like after a pass?

MAT

The plugs look fine - as in no different than a non-nitrous pass.

My current thinking:
From my less than spectacular experiment with manual engagement, it seems to be the case that not enough juice is getting to the motor. The problem does not seem to be electrical and hence it must be mechanical. The potential sources are:
1) As suggested by Eric68, the solenoid could be bad.
2) There could be some obstruction in the line - a likely candidate is the 1/8 inch hardline that connects directly to the fitting in the plate.
3) The plate itself has an obstruction.


Ed

My two cents :-


i)
900 psi does not automatically mean that you are not out of or low on nitro - what does the plume look like when you purge - is it white ??

ii)
following on i) above, your engine is not getting 125 shot nitro - whatever is causing it - I don't know - but if you assume this, and have someone else go over it step by step with you, it usually turns up -

By the way have you tried to engage the system manually just in park/neutral- by bringing rpm up to 3000 rpm - squeezing briefly and observing the rpm responce - it should pop up to about 5000 and slightly over very quickly

If not - go back to my i) & ii)

Hope this helps

Trevor

Firstly, no disrespect inteded to Trevor but if you plan on engaging your nitrous system in park or neutral the results will be predictable and will lead to a whole new set of problems.

With respect to the soft shot, I would:

1. Double check your jetting for the system. Is it possible that you have to small a nitrous jet?
2. Does your bottle have a high flow valve? Is it open all the way? Basic questions but I will often tune on the street by only opening the bottle half way.
3. Is 900 psi your maximum pressure with the bottle heated? If so you are probably low on nitrous. It could also be that your nitrous is bad (long shot).
4. Have you made a "pass" with the bottle closed? Obviously the car should bog when the system engages and you should slow down but it will also answer some other questions (although it may kill a set of plugs)...
a) if you do not feel the extra fuel hit with the system, you probably have a problem with the controller.
b) if you are not sure if you feel the extra fuel, you probably have a problem with the controller.
c) if it feels the same as every other nitrous pass you have made, you have a problem with the nitrous flow and your carburetor is too lean.
d) if the car bogs and slows down the fuel system (and most likely the controller) is working properly.
5. Try a pass without the controller. Your an engineer for crying out loud, you can do it man!

Good luck
James
PEng

Originally posted by Ed Bleich:
The plugs look fine - as in no different than a non-nitrous pass.

My current thinking:
From my less than spectacular experiment with manual engagement, it seems to be the case that not enough juice is getting to the motor. The problem does not seem to be electrical and hence it must be mechanical. The potential sources are:
1) As suggested by Eric68, the solenoid could be bad.
2) There could be some obstruction in the line - a likely candidate is the 1/8 inch hardline that connects directly to the fitting in the plate.
3) The plate itself has an obstruction.


Ed If you have a restriction on the nitrous side it would seem to me that the motor would go very rich, unless you have a restriction on the fuel side also. Having well colored plugs would indicate that whatever mixture is getting in the cylinder is close but not the volume you would expect. Are you sure it's a 125 kit and not a 12.5 kit?

Addressing a number of inputs:

In one of my posts I said something about "purging" the fuel side. I did this by engaging the nitrous system with the nitrous bottle closed (this done on the road enroute to the strip). This meant that only fuel was dumping in - the car slowed very noticeably. This would mean that the controller and fuel system are working.

The 900psi somtimes goes to 950 or so and that with the bottle heater on and the bottle full. When the bottle empties the pressure drops into the low 800s.

The fact that the plugs look good after a run is curious indeed. This would imply, as was stated by onovakind67, that the mixture seems to be good. I have the non-adjustable powershot, as opposed to the adjustable super powershot. This plate just has one set of "jets" which really are just fittings that thread directly into the plate. Could there be a problem there and how would I know?

Ed

Maybe a lower gear ratio will allow the extra hp to have something to show it's stuff with. You know. Your previous gearing was being set up for ideal with what you had. Now you have some whoop aaaaaas added that needs something bigger to deal with. Like some other guys might of mentioned like shift points for what ever gearing changes you want for ideal G forces. Saw a guys duce venting nitrous out the hoods top a few times so it seems he had a way to ram nitrous into the engine and the stuff would vent at too high of a preasure. I was wondering if he had an extra resevoir for the nirous under the hood that would raise preasures higher due to heat if he was using a one way valve at the tanks entrance.
Happy launchs to you.

Hey, Go easy on us engineers. If it wasn't for us, you wouldn't have the wheel, hence, Camaro, to tool around in.

You also wouldn't have the stick-on-the-dash coffee cup or cup holders.............

And yet another update:

The nitrous solenoid definitely works. I pulled the braided line connecting it to the plate off, charge the system and used a jury rigged switch to turn it on - it opened and closed just fine.

I took the plate off and checked it out. Everything looked fine except maybe the connection between the 1/8" hardline and the restrictor fitting on the plate. The hardline uses a compression fitting to seal the connection and there was a possibility that the end of the hardline was too close to the restriction in the fitting leading to a potential registration error. This is, I will admit, a stretch. After "fixing" this up, I connected the plate to the solenoid, charged the system and used the above switch to see if anything was coming out of the plate. All four holes seem to be spraying just fine.

So, I put everything back together and will now have to wait for the rain to end and the roads to dry to see if I have done any good.

With respect to a comment made about my gearing, I used to top out in 3rd gear. I have gone to slightly shorter tires and now expect to top out in fourth gear. In short, the effects of the added HP have been accounted for.

Ed

didn't read the whole thread, not enough time

how close are your solenoids to your plate, closer = harder hit
3k rpm is plenty rpm to use
what are cam specs? stall or manual?

times does seem low
'94 Z ran 11.13 @ 120+ on a 150 NX shot

agree could be solenoid, might just be all the car is gonna do :(

try losing the mastermind and just running off the WOT switch, keep close eye on bottle pressure also

Nothing for Nothing E=mc2.

Check the NO2 bottle contents.

Is it N02 or INERT?

:confused: