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-   -   Homemade CAI for 3.7? (http://www.jeepgarage.org/f5/homemade-cai-for-3-7-a-9285.html)

GR33N D3M0N 05-09-2010 06:40 PM

Homemade CAI for 3.7?
 
I was wondering if anybody has ever do a homemade CAI for the 3.7l's?? i was thinking about doing this myself, but i dont know where to start! thanks in advanced!

Megatron 05-09-2010 06:43 PM

Re: Homemade CAI for 3.7?
 
look up username :gcl06 he should have something.

welcome in advance.

GR33N D3M0N 05-09-2010 06:45 PM

Re: Homemade CAI for 3.7?
 
Quote:

Originally Posted by Father Paul (Post 204559)
look up username :gcl06 he should have something.

welcome in advance.

thank you very much!:D

Scottina06 05-09-2010 07:01 PM

Re: Homemade CAI for 3.7?
 
or you can go to airram.com and buy aluminum piping

08pretaco 05-09-2010 07:58 PM

Re: Homemade CAI for 3.7?
 
Ya that doesn't make much sense . Trying to make a cai for lower intake temps so why get a heat sink material...unless you plan on wrapping the tubing id say stay away from aluminum tubing otherwise you can make a cai and spend all the time to just have the same intake temp...that's my 2 cents. Good luck with whatever you decide

GR33N D3M0N 05-09-2010 08:13 PM

Re: Homemade CAI for 3.7?
 
at my dads gas station where i work at, we were getting rid of a countertop small refrigerator....maybe ill just integrate my intake with that:rolleyes: HAHA....but i might just have to stop by home depot this week!

08pretaco 05-09-2010 08:21 PM

Re: Homemade CAI for 3.7?
 
id say if you want to build your own and do not have access to a composite tubing or plastic tubing, you can always buy the section of tubing alone from say k&n or afe but just dont buy the rest of their intake. start off with that, it will give you the last section of where the ambient air will take into factor on your incoming air and at least that will be cooler. then from then on you can start doing thing with aluminum tubing (painting with heat resistant paint or some header wrap) and pick your own air filter and make you own box or whatever it is you have in mind!

08pretaco 05-09-2010 08:29 PM

Re: Homemade CAI for 3.7?
 
i dont know if you guys are to knowledged on the venturi effect.

this could be a great idea for an intake tubing: your only going to get a given amount of air into your cylinder given the size of the intake manifold and throttle body. get a larger diameter exterior tubing with a smaller diameter inner tubing ( say exterior 4" interior 2" with a silicone reducer into the throttle body).

what the two different diameters will do: first off- air flows quicker through a smaller diameter tubing. the inner diameter will draw the air into your manifold quick than just getting a large diameter tubed intake. the venturi effect will take into play by doing this- the inner, faster flowing air draws with it the slower air from outer section (between the small and large tubing) allowing the air to get through the throttle body and manifold faster due to its increased velocity and mass air flow.

so in conclusion what this does is this- get air flowing quicker through your intake into the manifold and ideally should get a larger volume of air to fill the cylinder. pair this up with a cold air charge and and good tune, you should be talking about some decent gains from something this simple.

GCL06 05-09-2010 09:13 PM

Re: Homemade CAI for 3.7?
 
Quote:

Originally Posted by 08pretaco (Post 204649)
i dont know if you guys are to knowledged on the venturi effect.

this could be a great idea for an intake tubing: your only going to get a given amount of air into your cylinder given the size of the intake manifold and throttle body. get a larger diameter exterior tubing with a smaller diameter inner tubing ( say exterior 4" interior 2" with a silicone reducer into the throttle body).

what the two different diameters will do: first off- air flows quicker through a smaller diameter tubing. the inner diameter will draw the air into your manifold quick than just getting a large diameter tubed intake. the venturi effect will take into play by doing this- the inner, faster flowing air draws with it the slower air from outer section (between the small and large tubing) allowing the air to get through the throttle body and manifold faster due to its increased velocity and mass air flow.

so in conclusion what this does is this- get air flowing quicker through your intake into the manifold and ideally should get a larger volume of air to fill the cylinder. pair this up with a cold air charge and and good tune, you should be talking about some decent gains from something this simple.

I'm not sure that the venturi effect would have enough impact to make up for the bottle-necking effect it would have. The throttle body on a 3.7 is about a 3" inlet (def get it ported/polished by FlyinRyan to increase air flow). So to go from a 3" inlet through a 2" bottleneck you'd be counting on the venturi effect speeding up the air a full 225% to make up for the lost area (∏3=~28.26in ∏2=~12.56in). I don't know how much of an effect is seen due to venturi but I highly doubt it will be a 225% difference.

PVC is a relatively nice material for a CAI as it doesn't retain heat as much as metal does. It's also dirt cheap! As long as you connect the pipes tightly enough to where this is no gap between them it's also a very smooth pathway for the air. Throw a Spectre filter on there at less than half the price of the K&N for the same functionality without the brand name's accompanied price and you've got yourself off to a great start. Wrap it with some DEI header wrap or use another method to keep the heat out and you're almost set. I still haven't taken the time to make a heat shield around the filter but still plan to once I get a couple other little projects (CB, PA, antenna mounts, redoing wiring, etc...).

Some more detailed info and pics on the how to can be found here:
http://jeepgarage.org/showthread.php...hlight=project

GR33N D3M0N 05-09-2010 09:46 PM

Re: Homemade CAI for 3.7?
 
Thanks nick! i dont have enough money for a ported TB, but i did see ur thread...and thats possibly gonna happen this weekend, if not the next!

GCL06 05-09-2010 09:48 PM

Re: Homemade CAI for 3.7?
 
Working on the math as to whether or not the Venturi Effect makes up for the air loss due to the bottleneck effect. Just posting as I go and I'll edit to finish it up (assuming I can work through all the variables). I will be basing calculations on the Spectre P4 Cone Filter (Item#8132) at sea-level at 20C.


Bernoulli's Principle states that the faster a fluid is moving, the lower the pressure. Therefore, fluid in areas of higher pressure will move towards the lower pressure of the faster moving fluid, causing an increase in fluid velocity.

The standard density of air (p) at 20C is 1.2kg/m

Bernoulli's Principle Formula - (p₁-p₂) = [(p/2)(v₂-v₁)] where p=density of the fluid, v₁ is the slower velocity (before bottleneck), and v₂ is the faster velocity (into throttle body).

Replacing p with d to differentiate between pressure and density. p₀ becomes the pressure of 1 atmosphere.
(p₁-p₂) = [(d/2)(v₂-v₁)]

At the surface of the earth air pressure is equal to 1.01x10⁵ N/m

p₀ = 101000
d = 1.2
p₁ = [(101000-p₁) = (.6)(v₁-0)]
.......v₁ = velocity of incoming air at WOT
p₂ =
v₀ = 0
v₁ =
v₂ =


Difference In Pressure
(p₁-p₂) = (1.2/2)(v₂-v₁)
(p₁-p₂) = (.6)(v₂-v₁)


The formula for the Venturi Effect is - Q = (A₁)√{[(2)(p₁-p₂)]/[(p)(A₁/A₂)-1]} = (A₂)√{[(2)(p₁-p₂)]/[(p)(1-(A₂/A₁)]}
where A₁ is the area of the pipe before the bottleneck and A₂ is the area entering the throttle body, and Q is the volumetric flow rate.

A 3" PVC pipe (3.5" including sidewalls) is already a squeeze under the hood so I'll use that over a 4" pipe for the equations.


Non-Bottlenecked
Q₁ = (A₀)√{[(2)(p₀-p₁)]/[(d)(A₀/A₁)-1]} = (A₁)√{[(2)(p₀-p₁)]/[(d)(1-(A₁/A₀)]}

Q₁ = (A₀)√{[(2)(101000-p₁)]/[(1.2)(A₀/28.26)-1]} = (28.26)√{[(2)(101000-p₁)]/[(1.2)(1-(28.26/A₀)]}

A₀ = Area of the filter x % of air flowing through filter


Bottlenecked
Q₂ will represent the amount of air entering the throttle body using the bottleneck.

A₁ = 28.26
A₂ = 12.56
d = 1.2
p₁ =
p₂ =

Q₂ = (A₁)√{[(2)(p₁-p₂)]/[(d)(A₁/A₂)-1]} = (A₂)√{[(2)(p₁-p₂)]/[(d)(1-(A₂/A₁)]}

Q₂ = (28.26)√{[(2)(p₁-p₂)]/[(d)(28.26/12.56)-1]} = (12.56)√{[(2)(p₁-p₂)]/[(d)(1-(12.56/28.26)]}

Q₂ = (28.26)√{[(2)(p₁-p₂)]/[(d)(4.0625)]} = (12.56)√{[(2)(p₁-p₂)]/[(d)(.8025)]}

Q₂ = (28.26)√{[(2)(p₁-p₂)]/[(1.2)(4.0625)]} = (12.56)√{[(2)(p₁-p₂)]/[(1.2)(.8025)]}

Q₂ = (28.26)√{[(2)(p₁-p₂)]/(4.875)} = (12.56)√{[(2)(p₁-p₂)]/(.963)}

Scottina06 05-09-2010 09:54 PM

Re: Homemade CAI for 3.7?
 
thee only problem with the Flyin Ryan TB is the bore isnt increased all the way through the TB...so you still have a bottle neck at the blade. Get a Fastman with increased bore and larger blade to match. Do math on that one......

also...do a little research on the temp differences between aluminum and plastic......its almost funny


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