Nitrous questions for my 99 Cobra

[daveshapellSVT]

Ok, i have always had some unanswered questions about nitrous... First off, should i use a dry or wet shot in my Cobra? and if so, how much of a shot can the engine take? Also, how is nitous used? i already have traction problems on the street so when is the right to to hit the Go button? I'm seriously considering running a 50 shot along with full exhaust and some other bolt ons this summer.. i figure a kit will run me 550? which is the best brand? sorry, i'm new at nitrous and i'm just not trying to blow my motor..i love my baby

[eillob]

The Zex kit is supposed to be the safest. There is no go button, once the system is armed the nitrous hits when you are at full throttle. There are no micro switches to deal with. There is a brain box that houses everything and makes for a clean look. I think you'd be real happy with a 50 or 75 hp shot. I love mine wouldn't trade it for anything.

[SikNingStang]

a dry shot is safer to run with your engine b/c you don't have to deal with the proper nitrous/fuel mixture... too much nitrous per amount of fuel will damage internals and with a dry shot you don't have to worry bout that. Also, Mustang's come stock with forged pistons which is required to handle more nitrous so it is safe for you to go with 125 - 150 shot but I'd stick with 125. Also it's better to use during mid to high rpm's. Don't do it off the line that'll make you spin and you probably wouldn't even want to do it in 1st gear... You just want it to push you through your RPM's better. You stang has enough torque for low end so use it around I'd say 3500 - 4k until you shift. You could get a button kit for a lot cheaper all you need is a bottle, the lines, jets and a button. I can get everything I need for 125$ from my friend.

[eillob]

Originally Posted by SikNingStang

a dry shot is safer to run with your engine b/c you don't have to deal with the proper nitrous/fuel mixture... too much nitrous per amount of fuel will damage internals and with a dry shot you don't have to worry bout that. Also, Mustang's come stock with forged pistons which is required to handle more nitrous so it is safe for you to go with 125 - 150 shot but I'd stick with 125. Also it's better to use during mid to high rpm's. Don't do it off the line that'll make you spin and you probably wouldn't even want to do it in 1st gear... You just want it to push you through your RPM's better. You stang has enough torque for low end so use it around I'd say 3500 - 4k until you shift. You could get a button kit for a lot cheaper all you need is a bottle, the lines, jets and a button. I can get everything I need for 125$ from my friend.

Im afraid I have to disagree with you a little bit. Stock mustangs don't come with forged pistons. And even with a dry system you still need to be concerned with your fuel ratio. Your nitrous system is going to use your fuel pressure regulator to increase the amount of fuel at the injectors. So your concern is going to be( is that going to be enough). You definately do not want to take on nitrous with a stock fuel pump I promise you. If you do you put yourself at risk of blowing your motor. Secondly if you are running 55-100 shot nitrous your stock injectors will probably do just fine but between 100-150 you may want to consider one size bigger. And remember this nitrous is a powerful substance but it will only do so much, it only enhances the underlying qualities of your engine. A stock engine will take up to 150hp but beyond that you need to consider a built bottom end.

The biggest difference between a wet and a dry system is that dry system is usually used on fuel injected motors and wet is usually but not limited to carburated engines. A wet system is going to spray nitrous and raw fuel into your intake plenum. Which IMO is a bad thing because fuel was not designed to be there. It can cause things like puddling in your intake which could lead to an explosion or backfires.
Dry systems are limited to about 150 hp but are much safer.

[eillob]

By the way Nitrous means that your days of getting by on 89 and lower octane gas are over. You have to use 91 or better octane gas at all times.

[daveshapellSVT]

thanks man.. that was helpfull.. i would deffinatly go with the dry shot and run 100 at the most.. there was this LT1 trans am at the beach the other night that was running 125 dry shot and states he ran 11's in the 1/4... my plan is to hit 12.5 with full exhaust, cold air intake,chip, and throttle body.. then i'd start running the shot.. 11's is where i'm gonna stop.. thats fast enough i think lol

[GTStang]

Ok I guess I'll have to start writing even though I have done the nitrous question a million times. There are basically 3 types of nitrous kits: Wet, Dry, Direct Injection.

Wet System: A wet system introduce both nitrous and fuel into the intake manifold. Now although this is perfectly fine for a carbed intake which is designed to have fuel into it this is not a great idea for a FI intake designed only to flow air. This could cause issues such as puddling.

Dry System: A dry system is one that introduces nitrous into the intake manifold but not fuel. The extra fuel needed is introuduced into the engine by the stock injectos. What you do is overdrive the fuel pump and injectors to work at say 110%. Not exactly a safe feeling when you think about it huh? This set-up is the best for a FI car but I would not dare run it without changing injectors and the fuel pump to larger ones.

Direct Injection(Fogger system): This is where the nitrous and extra fuel is introduced right into the combustion chamber. This is the absolute best set-up but thier are two draw backs. A lot of companies fogger's start at the 300hp range. Also machine work needs to be done to the intake manifold or you need the nozzle-like system. Either is an expensive proposition.

Lil bits of info: General rule of thumb is a stock V-8 can take a 125hp shot. Most kits you will be looking at will have a arm switch and then it will only spray nitrous when you have the pedal at WOT. Zex's NMU(nitrous management unit) is pretty neat and helps to prevent a lean condition. People think nitrous is cheap about $500 but figure more like a $1000 cause you really need a purge kit($100), bottle warmer($150-200), bottle psi & fuel guage($150-200) to run it effectively. Then there is the $40 to fill a 10lb bottle. Lastly if I had a 4.6 and wanted nitrous I would spring for the uber-expensive Nozzle system by NOS. It sucks that it is $1200 but it is by far the best nitrous set-up for the 4.6.

[HiFlow5 0]

Here's a result of puddling and backfiring.

[eillob]

Damn thats ugly.

[daveshapellSVT]

shit.. dry system it is lol

[GTStang]

Originally Posted by HiFlow5 0

Here's a result of puddling and backfiring.

Nice pic man!!!! I'm gonna have to keep that one.

[daveshapellSVT]

i was talking to a friend last night over the whole wet vs. dry deal and his thoughts on it were that the wet system is much safer.. he says that the dry system doesn't distribute the nitrous evenly to all the cylinders and thats not good for the motor.. And he likes the wet system because its directly injected into the manifold along with fuel.. another bad thing about the dry is that you have to manually add fuel to the motor through like injectors or a fuel pressure regulator.. so i guess i'm kinda torn now.. how about tuning? what kind of changes need to take place when running a wet or dry shot... don't you have to retard the timing any, get different spark plugs, and cold wires special for nitrous use?

[GTStang]

Originally Posted by daveshapellSVT

i was talking to a friend last night over the whole wet vs. dry deal and his thoughts on it were that the wet system is much safer.. he says that the dry system doesn't distribute the nitrous evenly to all the cylinders and thats not good for the motor.. And he likes the wet system because its directly injected into the manifold along with fuel.. another bad thing about the dry is that you have to manually add fuel to the motor through like injectors or a fuel pressure regulator.. so i guess i'm kinda torn now.. how about tuning? what kind of changes need to take place when running a wet or dry shot... don't you have to retard the timing any, get different spark plugs, and cold wires special for nitrous use?

Ok well ya friend is wrong. If a wet and dry system both spray nitrous into the intake manifold right before the TB how is either going to distribute the nitrous more evenly than the intake manifold allows. The answer is niether they both do it exactly the same.

Also what he likes about the wet system is what is bad about it on a FI car. Spraying the fuel into the intake manifold is bad on a FI car. You have to understand a FI intake was never designed to have anything in it but air. Unlike a carbed manifold which is designed to help atomize fuel and air as it heads to the cylinders. Look at those pics of the blown Cobra intake, those are long runners with mad bends and plenty of places for fuel to puddle. Samething but even worse on a 4.6 4v Cobra intake manifold.

As far as the dry yes there is a danger with running lean because you are overdriving your pump. This is why I recommend getting a larger fuel pump.

[daveshapellSVT]

ok, sweet thanks for your info.. i learn more and more about nitrous the more i talk to you... the thing i'm thinking about now is the tunning part... so i get a heavy duty fuel pump.. do i need different spark plugs with a certain gap along with "colder" wires.. running a 50 shot will i need to retard the timing or anything? i heard somewhere that when you run a 75 shot u need to retard 2 degrees..

[eillob]

GTstang is right. It is never a good idea to spray raw fuel into the intake. And I think your what your friend is describing is a direct injection or fogger, which is the best but like GTstang said earlier it is also the most expensive and the biggest pain.

You need to get colder plugs two stage colder to be exact. Autolite 23 work great. As far as fuel pump goes if your staying around 100hp shot of nitrous 190lgh is fine.

Retard should be about 2 degrees for 50 or 75hp.