Trust me, if you spray 100 hp at 1500 rpms, you will get 100 hp. If you spray it at 5000rpms, you will still only get 100hp. RPMS really dont dictate the amount of nitrous the motor will see, or make. The whole point of the story is.....how much TORQUE are you making with a 100 shot at 1500rpms, and how much TORQUE are you making with a 100 shot at 5000rpms.....Think about it. Yes I do know the answers, but since Im being bashed so hard, I figured the guys that REALLY know, would be able to answer them.

 

I am not bashing you or anyone. I really don`t think anyone is trying to bash anyone. I beleive they are all just stateing their opinions as far as what they think is true. I don`t know any of the answers on your questions. So, please enlighten me . The reason I posted this topic is to learn and I appreciate all help. Thanks.

 

The combination of added fuel and oxidizer and the physical resistance of the engine components. Basically you have the same resistance and more boom = more cylinder pressure. Now as rpms increase resistance decreases because of all kinds of physics that I forgot a long time ago( has to do with inertia and angular momentum and other black magic) and cylinder pressure decreases.

By the way...I never said dont spray out of the hole...just run a big stall or drop at 5000....use a window switch as a safty net incase your rpms fall below 3000 for some reason. If you hook your more likely to break something other than your engine anyway

 

Very true about the hooking issue. And I agree with the 5000 rpm launches as well. Im just trying to state that the NX kit is designed for STOCK motor, and I have never seen anything in the instructions, or otherwise, that says to only use it during a certain rpm band. Only at wide open throttle. 100 hp isnt very much. You are worried about 100 extra hp, but none of the people who run stroker motors, or beefed up motors are scared to be at full throttle during a shift. Is there any difference between a N/A motor running 450hp or a nitrous motor running 450hp? Does the tranny know any different?

 

Very good point. I don't think the tranny knows the difference.
Hmmm........

But why do I hear some users blow their tranny when spraying through shifts??

 

Not saying that this is the answer, but often times when things happen, it automatically gets blamed on the nitrous.....The tranny doesnt know anything but HOW MUCH HP is turning me. It doesnt care if its a blower, turbo, nitrous, or N/A. Like the deal with the guy whos car backfired through the intake, and he blamed it on too low of rpm, or sprayin while shifting.. He just assumed. When stuff like that happens, if is really important to look at everything and figure out WHY. Every mishap will tell a story, and if you figure out what went wrong, then you have a better chance of it not happening again, and you learn alot in the process. Dont be so quick to jump to the easy answer. Study what happened, and ask someone who is experienced in that area to help you. I have helped people with motors that blew up, and they automatically blamed the nitrous. After looking at the carnage, and studying what went on during the mishap, a malfunction elsewher in the motor caused the distruction.... I learn from every pass, and every mishap that I happen to see.

 

Here's Nitrous Express's direct quote: ( from http://www.nitrousexpress.com/welcome.htm)

"Q. How high must the RPM's before activating nitrous?
A. The RPM level is not as important as is the motors ability to rev freely when the nitrous is engaged, I.E. If the vehicle is in low gear, nitrous can be engaged at any time, but if the vehicle is in a higher gear moving at a slow speed when the nitrous is engaged the engine will detonate and damage will occur."

Here's another one - this one's kind of funny if you think about it.

"Q. Is there a trade off for engine reliability and power produced with nitrous?
A. When used according to factory recommendations, shortened engine life should not be a concern"

I do have a couple of questions though. In any wet kit, wouldnt a rich condition initially be present if the nitrous line was not previously purged, before the nitrous was activated? Woulnt a rich condition in the nitrous system, effect the motors overall a/f ratio more at lower rpms than at higher rpms, when the motor was receiving a higher volume of air and fuel from it's normal sources? Couldnt this rich condition at low rpm's cause backfires in cases where they would not occur at higher rpms?

Just curious...

 

If you dont purge the nitrous before a run, usually all that will happen is a cough, or hickup. The nitrous moves very fast at 900psi, so you may have a split second of being fat, but not enough to hurt anything. In a carbureted car, the fuel that is brought into the motor, is designated by the airflow around the boosters, so at a lower rpm, less air movement would be present, therefore, less fuel will be drawn through the booster. This is why it is so important to get the fuel curve correct on a carburetor. The "vacuum" created by the air blowing by the booster, is what draws the fuel into the manifold. If the curve is wrong, or bad, then the proper a/f ratio will never be had, and poor performance and or destruction could occur. Same thing with an injected car, however you have sensors to read this air movement, and translate to how much fuel to inject.......
And thanks for quoting the NX booklet for me. I couldnt find one. With the example they gave, you would probably hydraulic a rod in that situation.....Like I said before, wide open throttle, doesnt matter on RPM.

 

When I started using NOS, I was told not to spray before 2400 in second gear....then others told me that it is ok to spray in first, it's just kinda interesting... so now a days, it just kinda depends on how I feel!

Here's a vid of me spraying a 50shot outta the hole at about 1200rpm in 1st....fun fun fun....


http:www.quake-eternal.com/blown_L98_vs_KASR2.asf

KASR

 

"Trust me, if you spray 100 hp at 1500 rpms, you will get 100 hp. If you spray it at 5000rpms, you will still only get 100hp. RPMS really dont dictate the amount of nitrous the motor will see, or make. The whole point of the story is.....how much TORQUE are you making with a 100 shot at 1500rpms, and how much TORQUE are you making with a 100 shot at 5000rpms.....Think about it. Yes I do know the answers, but since Im being bashed so hard, I figured the guys that REALLY know, would be able to answer them."

Yes, more torque exerted on the rotating assembly (and more usuable torque). I've got 95k on my motor. Would you insure my motor for 10 runs engaging a 150 shot at 1500 rpms if I was at full throttle? It still is going to decrease engine life, so I don't know why NX says that. But it is sort of starting to sway me that they qouted to use it at any RPM. hmmmmmm

"When I started using NOS, I was told not to spray before 2400 in second gear....then others told me that it is ok to spray in first, it's just kinda interesting... so now a days, it just kinda depends on how I feel!"

I'm thinking they meant don't engage it in first due to traction issues. Maybe not, but that's just my take on it.

 

Yea, traction is an issue - that video, I have my comp ta BFG drags on - but they aren't warmed up, so that may account for the nasty burnout (but then again, notice I am burning the tires, while still keeping up with him!! hehehe)

But there have been times where the tires were nice and roasted and I hooked up almost immediately, of course that was at about 1800rpm.

Yes, nitrous is responsible for some enormous torque gains and remember, torque isn't how fast you can go, it's how fast it gets you there!

There's an equation that you can whip and see what kinda torque gains you get - if I find it I'll post it later.


KASR

 

Sprayin through shifts WILL hurt the transmssion.... I can smell my clutches burning sometimes after a run...

 

I want to make this perfectly clear in case there is still any misunderstanding. The above statement is correct and contains the basis for understanding the effect of nitrous on cylinder pressure. A generally accepted formula for estimating mean cylinder pressure (MEP) is below:

MEP = (HP X 792,000) / (displacement X rpm)

So MEP varies inversely with rpm at the same hp level. Obviously, in a typical LT1 setup hp increases as revs increase. But if you isolate the contribution of nitrous it's easy to see what happens. If you take HP to mean the HP contributed by N2O, Custom is right. The HP added by the N2O will be the same no matter what the rpm. So if you double the rpm, you cut the pressure in half!.

That's why N2O can be dangerous at low rpm. Using a hypothetical motor as an example. This motor has a (hypothetical) 200hp nitrous "shot".

4,000rpm, no nitrous:
MEP = (300hp*792K)/(385*4,000) = 154psi

4,000rpm with N2O:
MEP = (500hp*792K)/(385*4,000) = 257psi

2,000rpm, no nitrous:
MEP = (100hp*792K)/(385*2,000) = 103psi

2,000rpm with N2O (I don't run it this way):
MEP = (300hp*792K)/(385*2,000) = 309psi

Note that MEP is higher at 2,000rpm with N2O than at 4,000rpm with N2O. Also, I think that peak pressures have more of an effect on breaking parts than mean pressures. But you get the point. N2O can produce very high cylinder pressures when activated at low rpm. This can break parts. Will a given nitrous shot break parts in a given combo at a given rpm? There may be ways to estimate this a prioi, but I don't know them. That's where experience comes in. Custom N2O seems very experienced with nitrous, so I am not going to argue with him. I am also not going to activate my nitrous below ~4,000rpm There would be no point with my setup anyway as this is what works best at the strip. On the street, for the rare occasions when I spray in that environment, it's not a problem either. That's what the gear shifter is for!

Rich Krause

 

In my 96 Impy my car WON"T SHIFT if I have the 150 shot activated. Also my window switch takes out the idiot and makes my kit idiot proof. I don't know about you guys but I still get a little adrenaline when I get up to the line and I wouldn't want to manually turn on the nitrous but that's just me. I have a 2500 rpm stall and engage the nitrous at 2700 rpm and turn it off at 5400 rpm to shift at 5700 rpm. It may just be the extra weight in the car that causes this but most Impy's won't shift with the nitrous engaged FYI.

Mike
www.azsupersport.com

 

Come on guys, let's use some common sense. If you spray at too low of an rpm, you BMEP will go through the roof and you WILL bend rods/break pistons/split blocks and all the other ugly stuff, especially if you have a nearly stock converter.

There is absolutely NO question about this.

As far as spraying through the shifts, not a good idea with a 4L60E, which of course, is why I changed to a TH400.

If you have a high stall converter, (mine is at 3800), it really doesn't matter when you spray for the simple reason that as soon as it hits, your RPM jumps dramatically, so from that standpoint it's hard to hurt the motor.

You also need to consider the relative speed of the fluids and line lengths. You want the N2O solenoid to be as far away from the nozzle as possible, and the fuel solenoid right on top of the nozzle. This helps prevent lean tip-in and also will help with backfires.

Don't forget the #1 reason people break their motor on N2O, and that is LACK OF FUEL. I would never consider running ANY kind of shot on a stock fuel system, for example, or a stock rev limiter.

If you do it right, the nitrous is just plain wonderful

My LT1 is 100% stock bottom, cast crank, cast pistons, etc., yet i've been running a 200 shot for 2 1/2 years and the car is just getting faster........