I have seen way too many post about buying or wondering how someone can make a CAI. Well first off, the vaunted HD CAI is now officially more expensive than a real aluminum tubing CAI. Believe it or not, it will be cheaper to go on eBay and buy a Prelude CAI than it is to make one from HD. This setup is for the 2.5 MTX only. The 2.0 FS-03 MTX is even easier; just buy a GSR intake and put it on as is.
So it is now official that any Home Depot CAI is obsolete due to price. I got the 97+ prelude 2 piece CAI for $5.
This write up excludes the removal of the airbox since that is a pretty basic step. If you can’t take the airbox off and take the VAF out of the airbox than this write up is not for you.
This is what you should get from your Prelude CAI, with the exception of one extra coupling and 2 extra clamps
All the stuff you will need is as follows -
(1) Two Pieces Prelude CAI (From 97+ Preludes)
(1) 1” silicon tubing
(7) 3” hose clamps (5 is provided with Prelude CAI)
(1) 1” hose clamp
(2) 2.5” to 3” silicon couplers (1 is provided with the Prelude CAI)
(1) 3” silicon coupler
(1) Computer IDE ribbon or other strong, flexible material
Cutting the Tube
Use a hack saw ($10-$19 at Home Depot) to cut the upper tube (the tube with the nipple) approximately 1.5” from the nipple.
Put everything in it’s place. As you can see the elbow with the nipple will mate to the Throttle Body, than mate to the VAF, Which mates to the down tube, that ends with the filter.
Attatching the Filter
Simply clamp your filter onto the bottom of your downtube (the one you didn’t cut.)
Attach first coupling to VAF
Take one of the 2.5” to 3” silicon coupling and place the small end onto the intake of the VAF. You can’t mess this step up since the other end of the VAF is 4” in diameter and no way can you get the coupling onto that end.
Put 3” coupling on elbow
As the tittle saids put the 3” silicon coupling on the elbow, the end you cut in #2.
The coupling prvides a step up in size and will slide into the big end of the VAF with no problem. If you can find a 3” to 4” coupling it will be way better; but since this is a project anything will do for now. Air flow will not be affected. I did a flow test and the coupling inserts did nothing to the airflow patter (primarily because the VAF is so restrictive.)
Attach elbow to VAF
I use an IDE ribbon for this task as I have a bunch on hand. They are readily available and is pretty reliable due to their construction.
A test fitting
This is than how your intake should look. The only thing not attatch is the down tube to the VAF and the elbow to the TB.
Installing 2.5” to 3” coupling onto TB
Well as the title suggests, this step involve putting the smaller end of the coupling onto the TB. Use a clamp and tighten it till you can’t tighten it no more.
Attach elbow and VAF piece to TB
Once again, as the title saids. Put the end of your elbow into the silicon tubing but DO NOT TIGHTEN. The VAF should sit comfortably in the engine bay.
Insert down tube
The only way to insert the downtube with the filter is through the bottom of the car. Fairly easy to do, just put the tube up and than reach from above to pull the tube up.
After you have everything in place, start tightening the final clamps. You want to tighten the downtube to the VAF first to place everything just right. The filter should be sitting right below your battery in the corner. After that is nice and tight, clamp your elbow to the throttle body. Make sure you tighten everything and double check every single clamping point. You don’t want nothing falling out as your driving along. After everything is nice and tight, attach the vacuum hose to the tube and plug your VAF back in.
That’s it, your DONE!
The filter sits perfectly on the splash guard and will not fall out of the engine bay. I did a stress check of all components and nothing is being stressed. The top portion is being supported by the various accessories in the engine bay so no stress is placed on the VAF or the TB couplings. The down tube is supported by the splash guard so again no stress s placed on the intake system. You do not need to tie anything down as far as the intake is concern since the chances of this system ever falling out is highly unlikely.
To address the concern about the airflow pattern being affected by the 3” coupling inserted into the VAF I checked the airflow pattern. It is definitely better if you can find a 3” to 4” silicon adapter but the setup as is does not do any damage to the system
Well I hope everyone will go out and make their own intake and drive happy.