like you said before in the email “Getting bigger airline lets you run bigger fittings.” but i wonder if that graph applies at all to the air inlet on the base of the manifold while using 3/8 line??? 291 SCFM divided among 3 ports at 1/8," to me i guess your still over the recommended. which is good
Just a continuation from the emails ear2ear hahahaha ps like the orifices joke lol
So in a roundabout way Nathan is telling us is their airchimes have an orifice between 3/16" and 1/4", if they flow 75 cfm at 100psi.
Then all the folks that drill out their orifices to 1/4" would be flowing about 90 cfm at 100 psi. Maybe not a bad thing.
Oh wait a minute…
The flow through a 3/8" ID tube will NOT be 291 cfm@ 150psi. The chart you show is for orifices. Tubes are completely different due to choking.
I read a lot of engineering sites, and one I saw had a calculation showing the maximum flow with 100 psi through a 3/16" ID tube at 24" long will be somewhere around 30 cfm!!! The orifice chart shows 50cfm (through an orifice) so the drop through a tube is 40% AND THAT’S JUST A 24" TUBE!
The longer a tube is the more turbulence and friction you will get. The bigger it is, the less you get.
I would feel pretty confident saying bigger is better, but I don’t have the formula for figuring flow in a tube. And then you have to figure it will change with temperature and pressure…
Here’s a short snip of what you would be looking at to begin calculations (from a different site): And remember this is a 24" open ended tube…
[i]
At 2 ft, I’d roll the dice and use the choked-flow equations. They give you a result in lbm/hr that you can covert to CFM:
m(dot) = (pi/4)d^2 * C(m) * P * K(total) * [MW/(T*Z)]^0.5
where:
C(m) = 520 * {k * (2/(k+1))^[(k+1)/(k-1)]}^0.5
k = ratio of specific heats
d = orifice diameter (ft)
P = upstream pressure (psia)
K(total) is a stream of constants that is close to 1.0 for your application
MW = molecular weight
T = temp in Rankine
Z = compressibility (1.0 for air)
For this type of calculation I would assume isothermal flow, although in reality it will be more nearly adiabatic. But isothermal calcs are so much easier and the error, even in an extreme situation like this, is unlikely to be more than 20% (flow too high).
By my calc the flow is definitely choked. The good thing about choked flow is that as the assumed outlet pressure decreases towards the limit, the flowrate varies very little because the outlet density increases so rapidly. So you should get a reasonable number.
I assumed the air reservoir was at 60 F and 114.7 psia. This gives a flowrate of 160 lb/h or 35 scfm. I used a roughness of 5.0E-6 ft (drawn tubing). It is interesting to note that because the friction factor is a function of the roughness divided by the pipe diameter (e/d), and the diameter is small, the flow is very sensitive to the assumed roughness. If you used the usual value for commercial piping (1.6E-4 ft)you would get a flow of only 120 lb/h or 26 scfm.[/i]
WOW great charts and formulas guys! And thanks for the compliment Jeep!
Big Yella I hope you don’t mind a little extra tech in your thread…lol
The SHAPE of the orifice also affects flow.
Diagrams & formulas:
http://gasho.org/rotron%20pages/orifice%20flow%20calculation.htm
mmm flow dynamics. how I hate that class so much right now lol
Man I could give a poop less. I love all the details too. Go for it!
alphabet letters in math??? lol
Yes, variables are represented alphabetically. 
The real fun starts when you use greek letters haha
hahaha
Really nice install mate:D
Thanks man!
Your welcome… have you ever thought about doing this?? Except, do the writing in yellow & the shocker just in black outline? It would look the dogs danglies!
(I knocked this up real quick whilst getting ready to go to work)…
Hey that looks good! Yeah I’ve thought of doing something like that, probably with the Nathan Airchime saying. Thanks for the visual!
AMAZING JOB!!!
Looks great man, I’m impressed!
Thanks! I still need to update a couple pics with some of the wiring buttoned up, etc.
hey nice install! i have a 2006 f250 with upfitter switches do you think i could use one of them to switch from factory to train horn? also how complicated was it to wire up using the factory horn? thanks
Great job !!!
I know this is an old post, but I have to say that when I took my truck in I showed my service advisor where the button was just so he could scare the poo out of some of the techs.
He blew the horns and laughed his butt off… told me all about it later. I’m sure he woke up the neighbors in the apartment complex behind the dealership.