I am going to be installing a direct port nitrous system on my V3 sti and would like to know if there is any advantage to install one port for each cylinder intake or just a single port at the throttle boby entrance. I think the 4 port would be better but maybe it wont make any difference?.

 

Direct port is one on each inlet, usually used on higher powered installations. A single nozzle system will be fine for you I'd think. Good place for the nozzle would be in the under side of the intercooler at the outlet pipe. You want it as far away from the throttle body as poss but after the intercooler in order to give it time to mix thourghly with the inlet air.

 

Im also going to an FMIC so I can put it well back of the throttle body.

 

Why would you want it as far away from the throttle body as possible? Would this not give it more chance to liquidize before it get's into the inlet?

 

Not unless you're getting charge temps lower that -100 odd degrees celcius.... In that case i think you'd have other problems to deal with

 

recommended distance is 10" from the throttle body, which is very difficult unless you are running a frontmount...

i had mine set up in the throttle body hose and it worked fine, but i think it will be more effective when used a little further from the plenum..

 

From all the info I have gathered, I run a WON kit on one of my cars and it performs better mounted in the plenum directly above the throttle body.

Don't know if it is different on N/A engines though.

 

I rather have it as far away as possible given if it doesn't mix properly you'll have excessive charge going into certain cylinders and not enough into others

 

Neil, didn't your car expire after using the laughing gas? You could say it died laughing
F

 

never proven but if it did then it was due to doing a 1 minute+ burst where you should only do 15 seconds....(i.e. 1/4 mile type of duration)

and even then mine died 2 months later idling in traffic.....make of that what you will.

 

it took you 1 minute+ to hit your top speed?

 

Apologies I got it the wrong way around. The further away the more chance you have of it turning into a gas which you certainly don't want.

 

Nope, i took 1 minute (well actually about 45 seconds) to hit the electronic limiter at 157....

try it....

 

Did you hit the limiter whilst using nitrous?

 

yes, not the best idea id ever had but to be honest i didnt even realise the limiter was there!!

 

so four ports one at the entance to each cylinder plenum will work as will a single port but since I am going to a FMIC the four port may make more sence?. but there is no "right answer" but lots of ideas .
JOn

 

even with a FMIC i would still use a single port....the 4 port will work out quite expensive and tricky to fit, the single jet is very cost effective and easy....just get a boss welded to your intercooler pipework around 8-10" away from the throttle body, thats what i am doing.

 

If you've got the money and are serious about nitrous use, then a direct port system, with one separate nozzle at each inlet port, can't be beat. Inlet manifolds being what they are, you're bound to have some kind of slight imbalance between the flow rates along each runner, although from the looks of it, the Scooby manifold is less prone to this than most, not really having much in the way of a plenum, and it's right in the middle of the four runners rather than off at one end like many cars.

If I was personally doing a nitrous installation on my Scoob, best bang-per-buck would be from a single wet nozzle in the hose between TMIC and throttle body. IMHO you do want the nozzle as close to the TB as possible, but upstream of it so there's less danger of a nitrous backfire if the worst comes to the worst. And yes, I have experienced this - blew my entire inlet tract apart, cracked all four pistons, blew every gasket there was and a sheet of flame lifted the bonnet off its hinges. That's what happens when you use a single nozzle at the end of slightly unequal distribution inlet plenum but this was not on a Scoob.

If you've got a front mount on the way, then as Neilo says, weld in a boss but keep it in line with the TB if you can rather than round a harsh bend. You want the high velocity and turbulence entering the TB to be working on your wet mix to keep it atomised and even.