Questions from a novice nitrous jets

[marT350T]

How easy is it to change the jets on my nitrous fogger system.

Do you put the same size jets in both the nitrous and fuel sides ?

TIA

[russell_ram]

No offence, but if you don't already know the answers to those questions I would respectfully suggest that you don't mess with it. If you do, and get it wrong, you will destroy your engine in seconds.

Thae actual answers are:-

Very easy.

and

No, they are sized to provide NOS and fuel in the correct ratio. No-one can easily tell you the sizes you require for a given HP shot on your installation. The sizes will depend on things like fuel and bottle pressure etc. Your system manufacturer will be able to provide you with guideline sizes but that is all they will be - you need to optimise from there for your own application.

I would suggest you buy yourself a good book BEFORE you start messing.

Russ

[twistedsanity]

http://www.robietherobot.com/nitrousjetcalculator....

the fuel jet size will depend on weather you are fi or carb, carb is 5 psi and injection is 45psi(assumed), as the post above suggests contact the manufacturer as they all have there own calculations which may vary slightly, if you have a single fogger then the jets will be sandwiched between the fogger and fuel/nitrous hoses(american kits), as a rough guide you shouldnt go above 50% of your engines standard rated factory bhp, over a 50bhp shot you need to retard the ignition timing a few degrees, a progressive controller would be a wise investment depending on the application,
most engine failures where nitrous is concerned are due to either wrong jetting, a blockage in the nitrous system fuel su[pply(creating a lean condition) or greed, to much or too long and itll go pop, the fuel pressure will remain constant but the nitrous bottle pressure can vary between 1200psi and about 600 after a run so the whole "jet size" calculation is a bit hit and miss really(nitrous pressure is dependant upon temperature which drops off as you vent/use the nitrous)
have fun!!

[marT350T]

I will only be using a small jets as it is just to reduce my turbo lag.

I will want to run the system slighly rich and have been told to run a 2:1 ratio of nitrous to fuel.

[v8 jago]

You will be better of calling up to see dar. He is well clued up on nitrous and everything that goes with it. You have to get it right or your engine could be no more..

[twistedsanity]

if your just trying to loose the lag provided you dont have a huge turbo 15-25bhp should be sufficient, dont forget on a turbo motor the effect is much more pronounced because of the charge cooling effect from the gas, the engine is not relevant to the ratio of nitrous/fuel jets, the relevance is the fuel pressure you are running, the nitrous although relevant is less controllable, you start the run with a warm bottle at at about 1200psi then as you vent the bottle cools and the pressure can drop to as little as 800psi, so no matter how exact your jet calculations you will run richer towards the end of the run due to the nitrous pressure loss, its all abit hit and miss really, you can use a second bottle of nitrogen to maintain a constant pressure in the nitrous cylinder throughout the run but obviously this isnt really practical for street applications, another way would be to use a nitrous controller to vary the fuel input in relation to the nitrous bottle pressure decline, provided you started with a known cylinder pressure the dropoff in pressure would be linear and therefore calculable, i dont know of anyone who makes a controller like this yet though, but i could be talked into it.....

[chuntington101]

alright mate. go for something like a 25shot. should net you upto 50bhp on your setup!

have you forged the bottom end yet mate??

Chris.

[marT350T]

No, well I dont think so. I plan over the winter to get the engine stripped and upgrade to forge items if they aren't already.

Was just going to get the bottom end balanced as I have been told there is no need to do anything else to it.