> The Nitrous FEED line:  From storage bottle to solenoid. Is bigger better? Is braided better?

THAT argument again. Nitrous Feed line size & material.

Is bigger better? err no... Not this time. No matter what the "expert" racer/tuner tells you.

4mm O/D Nylon (internal bore 1.7mm to 2.5mm) Nitrous line, Versus the Stainless Steel Braided 3.7mm ID Nitrous line argument... Which is the best one to use with your system. This pipe feeds Liquid Nitrous Oxide to your Nitrous Solenoid in the cars / bikes engine bay / area...

The facts... These are the two "normal" obvious possibilities. At least here in the UK.

One is basically the nylon pipe that air specialists use in factories and machinery. Just pure nylon. Comes in any colour you want! Great stuff for nitrous Oxide as well.

The other is Brake pipe. Or that's one of its uses. Its a P.T.F.E. core with a braided stainless steel protective outer casing. There are generic brands, and big names like Earls, Aeroquip and Goodridge. Many Nitrous companies make up their own. On the face of it it looks like a simple question - but its really not! Which is best simple 4mm nylon or expensive braided?

• The first common type - The "brake pipe" type of line, in braided stainless steel with a fairly big internal bore, and relatively high thermal mass.
  

• The second commonly used type (at least here in the UK) is the 4mm NYLON Outside Diameter or O/D with quite small internal bore inside, and very low thermal mass "cheap" unprotected (no stainless armour sleeve) Nitrous line...

The Nitrous lines job is to deliver a constant flow of LIQUID Nitrous Oxide to the solenoid valve.

Advantages of the Braided stuff...

RED = DISADVANTAGE
GREEN = ADVANTAGE

• Its pretty to look at!
  

• Cost
  

• It STAYS pretty to look at after its been disconnected and re-connected hundreds of times with quality stainless steel fittings!
  

• Its tougher, and more abrasion resistant because its coated with stainless steel braiding.
  

• Can withstand very high pressures safely

• it has low "gassing" of the Nitrous (and stays in dense liquid form) as flow increases due to less pressure drop over the length of the tubing.   If the line happens to be full and cool... Generally its not though.  So some of these advantages turn into inconsistencies in practical use at least for the first few seconds of operation.
  

• It has more internal volume, which is its largest problem. So a short period of time goes by when activated, where all the "gas" that may be sat in the line (not THE REQUIRED liquid) gets pushed out  through the Nitrous solenoid and Jet. This effect is worse with small Nitrous jets and long pipe runs. In racing use a "purge" valve can be used to ensure that the air/gaseous Nitrous is vented to atmosphere before the run, which is wasteful and of little use in a street type system. A small bore nylon tube almost removes this problem and is therefore more consistent in use.
  

• It looks more "professional" and quality.
  

• High thermal mass means it will cause gassing or boiling for longer wherever the pipe is hotter than the Nitrous leaving the bottle. Again a small volume nylon only feed pipe doesn't suffer this problem.
  

• Its more difficult to cut and fit the end fittings for if you have never done it before! But not too difficult.

Advantages of the 4mm O/D Nylon stuff...

RED = DISADVANTAGE
GREEN = ADVANTAGE

• Its not as pretty to look at
  

• Cost
  

• Its nuts and olives, and the pipe itself begins to look tatty after it is undone and redone lots of times!
  

• Its not as tough and abrasion resistant.
  

• Its cheap! and can easily be replaced in minutes.
  

• Not actually designed to stand very high pressures safely. But is "ok" for nitrous usually!
  

• It has MORE gassing of the nitrous as flow increases. This is due to the pressure drop over the length which increases with the flow rate. This means less dense Nitrous Oxide delivered as the jet sizes go up or the pipe gets longer. This makes it more difficult to estimate the correct jets without individual testing. Although once correct it is more consistent than Braided pipe due to low thermal mass.
  

• It has less internal volume, so it "purges" the line of gas and air faster giving faster and smother "hit" of Nitrous. Little or no need for a "purge" valve.
  

• Its easier to cut and fit the end fittings
  

• It is small so can be run in side wiring looms, under carpets inside the car more easily.

Conclusion

There may be a few other minor considerations but basically this is what happens. If you are running a low power system (UP TO SAY 70BHP) in a street car, a nylon line is adequate. It will perform better than braided and be more consistent.

If you REALLY want pretty stainless braided pipe here, with its bigger internal volume then it will work, but there will sometimes be a short delay between hitting the button and go! This matters less with bigger hitting systems (70bhp upwards) because higher power system purges the line much times faster than low power system! There is no "yes" or "no" answer.

Horses for courses I am afraid... Personally for 70BHP and above I would use Braided, routed carefully away from heat... And on a bike where the line is short, I would ALSO use braided for 35BHP and above. For all the rest I would use 4mm OD nylon.