genII nitrous.... any good or bad experiences?

[FTMFW]

i need to come up with a few spare and well hidden hp's for next year. any kits you guys recommend? any kits to stay away from?

max jetting for pumpgas?
dry or wet shot?
would like to do 2 stages, one "giveaway", and one hidden, or tee them both in together to one solenoid instead, not sure. wouldnt mind a 30 and another 25 on top of that one

any comments or help appreciated!

also, anything have to change with an mps air shifter as far as nitrous tuning, kill time, window switches or anything?

 

[Draco1340]

Kind of an open ended post. There are lots of good posts here with more detail, but in general:
40 HP is about what you can do on 93 pump gas. More than that requires pulled timing and better fuel.
40 HP is also about what the lower injectors can handle on a gen II if you tune with PCIII. You need to flash the ECU or get a Bazzaz, or many other options.
50 HP is at or above the limit of what the stock valves / springs were intended for.
2 stage systems are less common than just using a controller. I don't know how you would do a 2 stage dry system. Lots of info on the board on how to do a dry setup.

 

[ogre]

just do a 50 shot with a reflash

 

[GPW]

Properly mapped you can spray all day.

 

[FTMFW]

so what brand would you guys go with? ive been looking at schnitz' kit as well as mps, the other question ive got is related to the lines. obviously my experience has been with ss braided lines, ive seen installs done with 1/8 clear plastic stuff, i dont know how confident i would be in that, does anyone have any feedback on using that? what about spraybars, and the 'spyder' setup?

 

[Draco1340]

so what brand would you guys go with? ive been looking at schnitz' kit as well as mps, the other question ive got is related to the lines. obviously my experience has been with ss braided lines, ive seen installs done with 1/8 clear plastic stuff, i dont know how confident i would be in that, does anyone have any feedback on using that? what about spraybars, and the 'spyder' setup?

Plastic lines after the solenoid are fine. Braided lines before the solenoid are required.

Spraybar or spyder setup vs. airbox fogging is highly disputed, but just to stir things up, this is my perspective based on the typical comparisons:

1. Spraybars make about 10% more HP than just fogging airbox for the same size shot. This is true, and its due to the 3 different ways nitrrous makes power. It makes power through a) latent heat of evaporation (super cooling), b) 12% higher oxygen content than air, and c) liquid to gas volume change. What I mean by c) is that spray bars can get a small percentage of the nitrous into the combustion chamber as liquid before it completely goes through phase change, where air box fogging will always have gas phase nitrous going into combustion. This allows for a small difference in power. Of course with nitrous, if you want more, just put in a bigger jet, so I don't see this as a big advantage.

2. Spraybars give a bigger "hit". Well depending on how this is set up, thats true also, but keep in mind for racing, you want the system to be smooth; not violent. Smooth keeps the front down and the wheel hooked. Smooth wins races. Violent messes your shorts and sometimes breaks parts. Placing spray way forward towards the ram air tubes responds more slowly and tends to soften the blow. Depends what you whant. Progressive systems on both a spraybar system and a fogger system can damp most of this out.

3. Spraybars give a more even distribution of nitrous to each cylinder. I don't believe this to be true, but my opinion is different from most. While it is true that a spray bar more or less garantees that each cylinder sees the same "average" amount of nitrous, this isn't necessarily true during a progressive ramp. At wide open throttle, the intake valve is opening about 100 times a second. Your nitrous solenoid is opening about 5 times a second (depending on controller). The pressure and flow at the exit of the spray bar varies during this cyling. Sometimes the cylinder gets lots. Sometimes it doesn't. On "average" the nitrous is the same across all cylinders, but there can be huge variation between cycles. This doesn't show up on dyno testing, so nobody complains about it. A properly designed air box fogging system can create a well mixed air/nitrous blend that is the same from cycle to cycle and cylinder to cylinder. I have used thermocouples to verify that each cylinder sees the same amount with a fogged air box, so it can be done.

I'm interested to hear what others have to say. Keep in mind the other two things that are important in any nitrous system that you haven't asked about yet is pressure control, and progressive ramping.

 

[FTMFW]

Plastic lines after the solenoid are fine. Braided lines before the solenoid are required.

Spraybar or spyder setup vs. airbox fogging is highly disputed, but just to stir things up, this is my perspective based on the typical comparisons:

1. Spraybars make about 10% more HP than just fogging airbox for the same size shot. This is true, and its due to the 3 different ways nitrrous makes power. It makes power through a) latent heat of evaporation (super cooling), b) 12% higher oxygen content than air, and c) liquid to gas volume change. What I mean by c) is that spray bars can get a small percentage of the nitrous into the combustion chamber as liquid before it completely goes through phase change, where air box fogging will always have gas phase nitrous going into combustion. This allows for a small difference in power. Of course with nitrous, if you want more, just put in a bigger jet, so I don't see this as a big advantage.

2. Spraybars give a bigger "hit". Well depending on how this is set up, thats true also, but keep in mind for racing, you want the system to be smooth; not violent. Smooth keeps the front down and the wheel hooked. Smooth wins races. Violent messes your shorts and sometimes breaks parts. Placing spray way forward towards the ram air tubes responds more slowly and tends to soften the blow. Depends what you whant. Progressive systems on both a spraybar system and a fogger system can damp most of this out.

3. Spraybars give a more even distribution of nitrous to each cylinder. I don't believe this to be true, but my opinion is different from most. While it is true that a spray bar more or less garantees that each cylinder sees the same "average" amount of nitrous, this isn't necessarily true during a progressive ramp. At wide open throttle, the intake valve is opening about 100 times a second. Your nitrous solenoid is opening about 5 times a second (depending on controller). The pressure and flow at the exit of the spray bar varies during this cyling. Sometimes the cylinder gets lots. Sometimes it doesn't. On "average" the nitrous is the same across all cylinders, but there can be huge variation between cycles. This doesn't show up on dyno testing, so nobody complains about it. A properly designed air box fogging system can create a well mixed air/nitrous blend that is the same from cycle to cycle and cylinder to cylinder. I have used thermocouples to verify that each cylinder sees the same amount with a fogged air box, so it can be done.

I'm interested to hear what others have to say. Keep in mind the other two things that are important in any nitrous system that you haven't asked about yet is pressure control, and progressive ramping.

well, pressure control i havent really thought about yet. i want to use 2 1lb bottles, im not sure i want to use bottle heaters or just insulate the hell out of them.

progressive ramping....do you think its necessary for a 40-50 shot? i never break the tire loose and rarely lift the front more than a few inches, and thats getting 1.51 60's.

what do you think of zex's system, and do you think a purge is necessary? i want this kit dead hidden.

 

[Draco1340]

FTMFW,
If your tire is starting to come up on motor, it will absolutely flip you over with an extra 50. I would recomend a progressive. Used on Ebay?
A purge is necessary if you are bracket racing and you need consistency, but the effect is minimize if your lines from the bottle to the solenoid are short.

 

[kingofdacoast]

40 is where you want to stay with a completly stock engine and then you still want to stay out of the rev limit. As Draco said there are way too many opinions on nitrous to say which is better for your application. I always prefered fogging over spraybars but there are a few new spraybars out that are doing really well when it comes to tuning and efficiency. I've actually been using one for the past 7 months (its not available to public yet) and I'm up to 315hp with no issues or engine damage as of yet. I did have to put a high volume pump in it to keep up at higher rpms but other than that still stock fuel system. Just check out the post here on the board and ask questions when you have them and you should come up with something that will work for you.

 

[Draco1340]

Pressure Control is important if your running for consistency, and if you whant your parts to last. I notice at AMA events that the guys in Real Street (SICK fast class) just carry around torches and heat the bottles before staging. That works, and God knows they go scarey fast, but many venues will kick you out for that. The more traditional approach is bottle heaters and blankets, but a bike battery is so small that problems arise with not being able to start. Carting around a car battery for this is a big pain if your a one person operation. Also, bottle heaters can only regulate withing about 1500 psi. What works for me is running low pressure (600 psi) through a regulator and running twice the jet size to compensate for the lower pressure. two 40 HP jets at 600 psi gives you about 40 HP. The added advantage is that the pressure never drops over the course of a run. I used to map bottle pressure and was shocked to find how quickly N2O pressure drops over the course of 10 seconds during a land speed run. You may be tuned for 1000 psi, but by the end of the run your only pushing 600 psi. If you regulate down to 600 you don't have that problem, plus you never have to heat the bottle unless it gets really cold out.

 

[kingofdacoast]

Pressure Control is important if your running for consistency, and if you whant your parts to last. I notice at AMA events that the guys in Real Street (SICK fast class) just carry around torches and heat the bottles before staging. That works, and God knows they go scarey fast, but many venues will kick you out for that. The more traditional approach is bottle heaters and blankets, but a bike battery is so small that problems arise with not being able to start. Carting around a car battery for this is a big pain if your a one person operation. Also, bottle heaters can only regulate withing about 1500 psi. What works for me is running low pressure (600 psi) through a regulator and running twice the jet size to compensate for the lower pressure. two 40 HP jets at 600 psi gives you about 40 HP. The added advantage is that the pressure never drops over the course of a run. I used to map bottle pressure and was shocked to find how quickly N2O pressure drops over the course of 10 seconds during a land speed run. You may be tuned for 1000 psi, but by the end of the run your only pushing 600 psi. If you regulate down to 600 you don't have that problem, plus you never have to heat the bottle unless it gets really cold out.

That is some good info there Draco. Real good.

On my big bike nitrous setup bottle pressure isn't important. Doesn't matter if I got 1000lbs or 400lbs I still have the same HP and fuel. All I do is turn the bottle on before a run and whatever the bottle pressure is, is where I run it at.

 

[Ft Campbell Busa]

Love reading your posts Draco!

 

[tegbusa]

Love reading your posts Draco!

+1

 

[Draco1340]

Thanks for the input.

Here is a graph from the days when I was logging pressure during landspeed runs. At that time a buddy of mine and I were experimenting with a nitrogen push system that we had seen on cars with huge nitrous systems. As you can see, the pressure of a typical 2# bottle drops like a stone. How can you tune a motor in these conditions. The higher the pressure, the faster it drops. The bigger the shot, the faster it drops. Multiple bottles or bigger bottles help a little, but adds weight and complexity. The push system was nice, but very complicated. The regulator gave me the same results, and was smaller and much less maintanence.

My personal opinion on Nitrous is that it gets a bad rap for being tough on motors because its difficult to accuratly dispense. I could be wrong, but I believe its no tougher on a motor than turbos or even similar power normally aspirated motors if done well. Of course I've got my share of shredded motors in the past to prove me wrong.

 

[202mphbusa]

Makes me wanna yank my turbo off and go back to motor and nitrous..
Maybe my thoughts will change with more seat time and sorting of my setup

 

[moody]

On my 08 I got a NX wet system 4 nozzle with ss breaded line. Now, I custom mounted my system inside my airbox, running my fuel and nitrous lines into airbox via bulkhead connectors. I would suggest to anyone running poly line on their nitrous setup to NOT run poly line into airbox. Trust me when i say this, its not if ploy line will break its when and when it does that means unmetered amount of nitrous going into combustion chamber. "And that aint good for no body!"... I started out with approx. 50hp shot on 91pump gas tuned via wideband contoller, fyi thats a completely stock engine including air filter and foot shifting. (Keep in mind I weigh in at around 285 pounds) I went from running 10.01 @ 137 mph to a 9.54 @ 150 mph. With my jockey on the bike, he ran a 9.29 but whats important about my jockeys pass was that at the top end of 3rd gear it hit a weird sounding rev limiter so he let off the nitrous button and finished the pass with no problems. I was confused at that point. No problems appeared on the wideband, plugs looked fine, bore scope showed nothing. The only thing I would come up with is that we were floating valves, due to the weight difference I am making the engine rev slower cause Im fat and my 150 pound jockey was allowing to engine to rev quick enough to start the floating process. Assuming this, I think we just got luck enough valves didnt make contact with piston/s. Also according the the busa shop manual, the gen II has only 30 lb at seat pressure valve springs due to the light tit. valves. Shortly thereafter, I installed the ape 52 lb valve spings (with the spacers installed) and a thin head gasket and bumped my pills up to approx. 80hp shot still stock pistons. The very first pass with my 285 butt I floated valves and bent 2.... In short, I advise to stay well below 50 hp shot (especially if your light) on the gen II because there is simply not enough valve spring pressure for much more than factory hp output. And I know 'THEY' might say this and 'THEY' might say that, but what do 'THEY' know?