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Old 04-23-2004, 06:09 PM   #1
CitySubie
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Default Can NOS be safe?

I have stock internals on my 2003 2.5RS. I'm not looking to turbo charge my car, but would like to tap into some extra power when need be - for ex. NOS.

How many shots of NOS is safe for my car since I heard 5-6 psi of boost is safe IF I turbo. Or does that not matter?

I plan on getting Cobb Cams. Will that be a factor?
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Old 04-23-2004, 06:31 PM   #2
sidewayz
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go with a Zex dry shot...50hp..and you'll be fine.
or do a search
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Old 04-23-2004, 06:48 PM   #3
no-coast-punk
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Zex dry kits are scary. They work OK, but I've always been creeped out by things that simply clamp your fuel return line to increase fueling. Great for a rental car or project beater, but a bit iffy on something that has to get you to work everyday. Zex might not have instant icky effects, but it will take a TON of life off your motor and are basically a complete throwback from the days of carbeurated V8's running N20. I really don't like N20 but IF I were to use it I would definately use the VCN 2000 system by venom:

http://www.venom-performance.com/

it works by modulating your injector pulsewidth so the fueling is VERY accurate. It can also do a linear progressive of hit, where at 50% throttle you might be getting like a 5hp shot, but at full throttle you would be getting a 55 shot. It makes the car very easy to drive.

Since it modifies injector pulsewidth, you can also run it in conjunction with a turbo (but definately not both on a stock bottom end, or stock injectors)
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Old 04-23-2004, 07:05 PM   #4
CitySubie
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Do I have to change to a higher octane?
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Old 04-23-2004, 07:57 PM   #5
Hitokiri
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definitely

A nitrous system requires the same resisability to knock as a turbo system. You will need to upgrade many of the same things turbo people do.

fuel pump, injectors, fuel set up, ect. exaust matters less as you are not spinning a turbine but It is still extremely important.

A "safe" nitrous set up will require lots of upgrades just as a "safe" Turbo set up will. It is still FI, you are just going about it in a different way.

Todd
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Old 04-23-2004, 08:52 PM   #6
no-coast-punk
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You only need to move beyond the basics for nitrous systems larger than something near a 50 shot. Yes, larger exhausts, etc. will help with power, but the main thing is you don't overtax your fuel system. That's what I like about the venom kit, it has feedback on injector duty cycle, so you can tell if you are overtaxing your system. It all depends on your idea of safe, nitrous is VERY hard on motors, rings and bearings in particular, and even the best nitrous setup with extremely accurate fueling will take life off your motor, just not as much as a cheap dry kit.
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Old 04-24-2004, 01:52 AM   #7
squirrelmasta
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Agreed with the above. I plan on running N2O some day. meaning, when my engine is built and my drivetrain can hald it too. BUT that will be on a built proof engine or damn near it. STi block and what not.

Personally i wouldn't run a N2O set up on a stock car. i wouldn't run a Turbo set up on a Stock RS either. at least not for long. all it's doing is craming alot of air or heat into the motor and killing it. the motor can die pretty quick doing that.
-Eli
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Old 04-24-2004, 08:14 AM   #8
sidewayz
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Quote:
Originally posted by no-coast-punk
Zex dry kits are scary. They work OK, but I've always been creeped out by things that simply clamp your fuel return line to increase fueling. Great for a rental car or project beater, but a bit iffy on something that has to get you to work everyday. Zex might not have instant icky effects, but it will take a TON of life off your motor
since when did Zex "clamp" the fuel line?
I know people with kits that I've installed (one is an RS s/n Merc and he has been using it for over 50k) that have never EVER had a problem.
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Old 04-24-2004, 11:51 AM   #9
no-coast-punk
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Quote:
since when did Zex "clamp" the fuel line?
Read how the ZEX kits work. Their "brain" is simply a box that sits on the fuel return line and restricts the fuel return back to the tank increasing fuel rail pressure to get the extra fueling needed for the n20 hit. On their website they use lots of big pointless words and take a half page to describe that.... but it's still nothing more than a "clamp" on the return line. Now what is going to happen as that diaphraghm starts to fatigue over time? It won't be able to exert as much pressure and will not build as much fuel rail pressure, running your motor lean. I'm not denying it's a popular kit, and that some people out there have had good success with it, but many people out there are running dryer vent intakes and running car stereo power cables outside the car across the a-pillar and back into the car through the door sill.

Zex = hardcore rice IMHO
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Old 04-24-2004, 02:10 PM   #10
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Wet kits are the best. I had a friend with an old 83 GTi motor in his 82 Scirocco. he ran a 50cc shot and put more than $500 through his motor.


tore it down and found no more wear and tear than what is expected of normal use... course, putting NOS on a CIS car is way different than on a normal FI car with MAF or MAP.... but that's besides the point.

Wet is ALWAYS better. don't have to worry about your ECU trying to figure **** out.
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Old 04-26-2004, 12:43 PM   #11
MaK10
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You can check out our kit we offer progressive controllers that control every aspect of your nitrous, and our kits are a lot better quality that nos, nx, zex, etc.

And unlike any of the big name kits, we offera lifetime warranty on our kits. We are so confident in our quality, we don't even sell rebuild kits for our solenoids because they will not require one, unlike the other brands.

if you wanna check it out, www.racetested.com

-Tom
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Old 04-27-2004, 02:39 AM   #12
mybluesubi
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NOS works fine in the chair at your local dentists office, otherwise say bye bye to what you know as your engine and drivetrain
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Old 04-27-2004, 02:22 PM   #13
no-coast-punk
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Mak10, your product sounds pretty interesting. It would be nice to see a competitor to the venom 2000 system, but your website SUCKS. There is absolutely no real info on there other than marketing fluff, I can't even really tell how the kit works, if it's a basic wet system (which we can't use on DIS cars) or what. More info would be good.
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Old 04-27-2004, 05:30 PM   #14
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Quote:
Originally posted by mybluesubi
NOS works fine in the chair at your local dentists office, otherwise say bye bye to what you know as your engine and drivetrain
i love reading pointless posts by uninformed.
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Old 04-27-2004, 08:41 PM   #15
no-coast-punk
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*warning, pretty long but I'm trying to clear up a few misconceptions floating around out there*


Quote:
Originally posted by awd4ever
i love reading pointless posts by uninformed.
Ugh... I love reading pointless posts worshipping a technological throwback from the days of carbeurated V8's.

Like everything in life, N20 has it's drawbacks and benefits. Personally I think Drag racing = teh SuX0P\3 = n20

The first thing you have to ask is "why are people screwing around with n20 when they could just be shooting straight pure oxygen into their motor". The reason for this is that we need inert gases in the combustion process in order to act as a buffer against a combustion rate that is TOO fast.

If you were to run straight oxygen through a conventional motor you would powder your rod bearings and then shove a connecting rod through the oil pan, and then promptly melt the block, all with the same power gains as a pretty well built turbo motor. This catastrophy would happen because the fuel/air mix would have an INSANE burn rate, this super fast burn rate would cause a massive shock load on the motor as soon as the spark plug fired, compared to the relatively slow and gentle rise in cylinder pressure and fall in cylinder pressure of normal combustion. When you add more inert gas (the N2 part of N20) your burn rate goes down and things become a bit more livable.

This gradual rise and fall allows the bearings and oil between the bearings to do their thing, which is be elastic and absorb this shock of combustion. When you have faster burn rates you don't give your bearings and oil as much time to be elastic like they were designed to be and wears things out much quicker. (you can bend a paperclip many times if you go very slowly, but the faster and faster you bend it the quicker it fatigues).

The other thing that N20 eats up quickly are your rings. The piston rings have to absorb and release a TON of heat all the time. They are designed to absorb heat at a certain rate and release it at a certain rate. The problem with N20 is that the piston rings now have to absorb alot more heat in a shorter period of time, and this puts them above the threshold of being able to release heat at the same rate it is taken in right after the combustion event. Heat devours rings VERY quickly.

There are a few other nasty little things that N20 does such as release trace amounts of nitric acid into your motor under certain situations, and as you may have guessed.... nitric acid is bad for metal parts.

If you don't believe what I'm saying, look at some of the nitrous breathing NHRA motors that are running 1500 shots (yes you read that right). They run really HUGE bearing clearances to allow a thicker oil cushion, and some really crazy ring spacing to keep the rings away from heat. A proper nitrous motor is quite different from a race built forced induction or NA motor.

If you are worried about N20 suddenly blowing up your motor and leaving you stranded, it is pretty unlikely given the build quality of most kits out there. The only catastrophic failure of N20 systems is when something doesn't work the way it should and your motor runs lean. This is about as likely as your OEM fuel pressure regulator failing under WOT, not very. Of course this is assuming a high quality system that has been PROPERLY installed. However ANY nitrous system out there will vastly increase wear on the moving parts in your motor regardless of how safely it is tuned (good tuning does get rid of some of the nitric acid problem though). If you plan on keeping this car to drive to your grandkids wedding day, I highly recomend against the stuff, but if you are looking for a cheap way to go fast in a car you plan on getting rid of after 100,000 miles, or you have a long term rental car *shrug* why not.

I realize this was my usual excessively long post that few people probably read all the way through, but just giving you all the angles. I'm sure this will piss a few people off, oh well.

Engineering world aside, my personal thoughts on the issue: Don't even think about a wet system on a car with an ignition system like ours. And the only nitrous system that I would personally trust on one of my motors is a direct port system, because that is the only system that ensures perfect distribution of N20 across all cylinders. Every non direct port system out there will run some cylinders too lean and some cylinders too rich.

Ultimately I think N20 on 4 cylinders is REALLY pointless, because once you move past a 50 shot, building the motors gets just as expensive as a good purposebuilt turbo motor, and you will never see the power gains of true forced induction out of N20.
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