problems with nitrous

[exciv2000]

I tried spraying a 35 dry shot the night of the red and jerry's meet while it was about 32 degrees out (don't know if that had anything to do with it). Bottle pressure was at around 750-800 psi after heating up. Also have a Cartech adjustable FMU. In my attempt at sleepiness I don't have any gauges like A/F or FP or boost in the car. Don't need them under boost, definitely need them under nitrous I discovered. It started on a race from a roll in 4th, squeezing at about 4000 RPM, everything seemed fine till about 5000 or 5500 rpm, then the engine just started to shudder (like you would when you're cold) so I backed off. Strange, a look back at the exhaust shows nothing but black and grey smoke, so maybe it's running too rich? I tried it a couple of other times in 3rd at 6000 rpm and up, immediately started to shudder so I backed off again. Car never had this problem on a 25 shot, but the last time I sprayed was back in July at IDRC. Only things done since were upgrading to a 35 shot. Plugs are NGK coppers gapped at .030, and I can't check them (it's too late) so don't even ask.

Any ideas?

I do have the Walbro high pressure GSS-342 255lph fuel pump, so it should have no problem with supply.

Another thought I had is this:
Since it is a dry shot and worked fine at a 25 shot with the vacuum line attached between my manifold and my cartech FMU, the combined boost of the JRSC + the air pressure from the solenoids was probably under the stock map sensor limit of 11 PSI... I'd usually see 9-10 PSI on the boost gauge at a 25 shot... so if a 35 shot puts more air pressure through the vacuum hose (I'm not clear how it would do this) then it's possible I was running at around 11-13 PSI of boost that the boost gauge would see and therefore the map sensor, possibly causing the shuddering that was happening. thoughts?

[stu]

Are you sure that Nitrous raises boost?

And even if it does, it would raise it in the cylinder, after the map sensor wouldn't it?

[Kellly]

do you have a 3 bar map?
i ve heard that stock honda map are only good to ~11 psi. maybe the map was seeing positive pressure?
any codes?

[stu]

But I don't think that the nitrous would raise the boost pressure, only the compression.

[Kellly]

yeah, not sure whats the deal?
good luck on it

[STIBungy]

Did the shuddering feel like the car was starting to hesitate?

[john]

What the heck do you mean that you don't need A/F and/or FP monitors under boost? Who have you been listening to? (Ok - it's a supercharger, not a turbo - maybe I'm being a bit harsh as I know nothing about supercharging.)

And please - never use the FPR/FMU/etc vac/pressure line as your reference line for anything besides the FPR/FMU/etc. That's just asking for trouble, IMNSHO.

What other monitors are on the car? Is .030 your normal gap? I'd try dropping the gap down to .028 or .026 to see if that eliminates the miss. If it does, perhaps you will need an ignition amplifier to spray.

Spraying can and will increase boost pressure on a turbo motor - not sure about supercharged setups.

[ryanman]

Or try more pressure in the bottle.

[ricewizard]

basic boys : grounds. do you have them? codes are there any? what is your rev limiter set at? changing from a 25to a 35 should not affect to much. check your basic.
^plug gap^

do you get more boost with better fuel? hope you said yes.

( hense nos is really good. ='s boost)

[HONDA GHANDI]

Heres a few things I see going on without having ever seen your setup. Dry NOS kit that you have sprays a tiny amount of N20 into the FPR line vacuum line to raise the pressure in that line. If you are seing a difference in the Boost gauge its because it is only raising the pressure in that line, not the manifold. If this vacuum line is also the line feeding your MAP which it shouldnt be then there is the posibility that you are reaching the limits of the map.

Observation #2. The ambient temp mixed with the intake manifold temps with N20 injected may be below the readable range for the intka eair temp sensor which will trick the ECU into thinking it is below -40 degrees in which case it will automatically go full rich with an almost 100% duty cycle on the injectors. Unfortunatly without a data log this cannot proven because it will not set a code.

#3: I had found on my old hatch that the N20 would run really well in cooler temps but in colder to 0 temps it would disrupt the air in the manifold by causing the moisture in the air to freeze. Everyone knows that cold air is not condusive to good fuel atomization. Your problem scott can be a combination of these things.

[exciv2000]

As mentioned above, stock honda map sensor. No guages while boosting john because I don't need them for the SC since it's tuned. SC's don't get boost spikes, etc. like turbos, so there is no way to overboost other than spraying. Yes spraying through an SC can and will increase boost pressure. Normal plug gap is .046 I believe, so .030 it has been at for the longest time. No codes were thrown. I was on 100 octane at the time. As far as it shuddering, it wasn't going any quicker, but I wouldn't call it hesitation since I consider hesitation to be something brief, this was much longer. The map sensor is seeing positive pressure through use of a JR Map Controller. Rev limiter is set at 7200 but shouldn't matter since I never hit it on spray and I know what it sounds like off the spray so it's not related.

[ryanman]

Or try more pressure in the bottle.

[exciv2000]

Ghandi comes through again! #2 moreso, and #3 sound reasonable. My setup is such that the map sensor has one vaccuum/boost line, the dry kit and the Cartech FMU share another line, so it can rise the fuel pressure off the FMU vs. the 1:1 stock FPR.
The third vac/boost line goes from the manifold to the 1:1 stock FPR and any other accessories like boost gauge if I connect them in. Then there is the brake line booster but I never play with that, and it's quite a bit larger.

[travis sertic]

WHAT NITROUS KIT.DID YOU USE THE RIGHT CALIBRATED JETS?I HAD NITROUS ON MY SHO AND HAD NO PROBLEMS WITH A 75 SHOT.

[stu]

No caps please.

[stu]

Can someone please explain to me how exactly nitrous raises boost pressure? I can see how it could raise compression, but not boost pressure.

[ryanman]

Can someone please explain to me how exactly nitrous raises boost pressure? I can see how it could raise compression, but not boost pressure.
I'm thinking it has something to do with the air molecules and expanding them???????????????? I dunno exactly but I'm sure someone will post.

[ryanman]

I was just thinking about it and it seems to me cause the air is already under pressure and then your shooting MORE air/nitrous into the manifold and therefor makes the pressure rise do to the more forced air. Wait that was a run-on sentence. I'm sure you know what I'm talkin about.

[HONDA GHANDI]

In an NA car Nitrous will displace lots of air in themanifold making the flow actually decrease. In a turbo car the wastegate is in charge of keeping the boost level even so N20 wont cause any abnormal boost fluctuations.

Now on to SC cars, the N20 makes the air charge much more dense as well as taking up more of the manifolds space. Since the blower is mechanical it compresses the regular air as well as the more dense n20 air together resulting in higher boost numbers. Small but definatly worth it.

On a side note Chris Dye talked to JR today and we are now JR dealers. JR also said I should have no problem with a 50 shot on my B16. All the same I thinkI will wait until I have a backup motor before squeezing a 50 shot. (and a cage for sea level hehe)

[djet820]

In an NA car Nitrous will displace lots of air in themanifold making the flow actually decrease. In a turbo car the wastegate is in charge of keeping the boost level even so N20 wont cause any abnormal boost fluctuations.

Now on to SC cars, the N20 makes the air charge much more dense as well as taking up more of the manifolds space. Since the blower is mechanical it compresses the regular air as well as the more dense n20 air together resulting in higher boost numbers. Small but definatly worth it.

On a side note Chris Dye talked to JR today and we are now JR dealers. JR also said I should have no problem with a 50 shot on my B16. All the same I thinkI will wait until I have a backup motor before squeezing a 50 shot. (and a cage for sea level hehe)

I learn soemthing new everyday...

And as for your car, what're you hopin to get when you do install the 50 shot?
I want to see the 4 cyl beast run.

[exciv2000]

ouch, 50 shot plus 10 PSI? Eh, I don't think that will last long. Mark my words bud. I know you're the ghandi and all but no no no. 25 shot, yes.

[HONDA GHANDI]

If I do a 50 it will be a wet direct port. I have much faith in the B16 but not that much. Hence the "backup" motor waiting in the garage. If tuned right it will last, but the pistons wont. I know this already. If I had a decent set of coated pistons and rods, and maybe a block gaurd there would no way you could talk me out of it. :D

[exciv2000]

OK, now your talking. So would the map controller throw a code if it was over 11PSI or just stuter like mine did? I'll hafta try it when it's warmer out and give a second report sometime.

[HONDA GHANDI]

It dependson how high it goes on the actual voltage side of the map. If it hovers at like 4.8 to 4.85 volts it might throw a code, if it is a full 5 volts then yes. If you are in the 11.5 PSI range the car wont run too terrible but may throw a code.

[exciv2000]

hmm, probably either the injector duty cycle or cold temps then. It sure was a blast for that split second that it wasn't stuttering tho. :D

[travis sertic]

oh sorry.dose it bother you that i type in CAPS!