sorry for not contributing to this earlier, been real busy
anywho, I got my airbox from a '92 Buick Century (I think) with the 3300 engine. I also grabbed some airbox tubing from another buick (a regal of the same era). Both sides of the box are 3" diameter which is actually too large for a 2.5L Jeep imo (more on this later).
From the TB, I used the stock 2.5" rubber flex piece which is about 4" long, then connect to a 2" to a 3" PVC converter. Then a 3" 90' corner. Then a 18" piece of 3" PVC pipe, then a piece of that Regal flex hose, then the airbox.
From the airbox, I put another flex piece on, then a 6" piece of PVC that goes through the firewall, then a sharp 90' and now a 3" to 2" reducer.
Now what I did wrong;
1) 3" is too large for the 2.5L as it just doesn't need that much air and it causes the air to slow down too much, thus allowing too much sound to escape the air intake system. That is why I now have the reducer on the end. Before the reducer the sound was extreme! At 1/3rd throttle there was a deep rumble that was like a V8, at 2/3rds the whole Jeep started vibrating badly. The reducer removed most of the vibration, the sound has grown on me
2) This maybe related to the 3" as well, but every once in a while, I'll have a small backfire. Doesn't cause any CEL or other problems, but it started right after the install.
Things, I'd change ;
Obviously, I'd use 2.5" plumbing and have enlargers just at the airbox. I'd also increase the length of pipe used in case that's the reason for the backfires. (no too sure about that one)
- Watch the height coming off the TB
- after the firewall, I made a hard right turn to turn the air flow towards the vent opening, but that can interfere with the wiper arms if you're not careful.
- At the end of the tube in the cowl, I cut the pipe at a 45' so it made a overhang at the top, just in case water came straight down onto the pipe it would have less chance of getting into the airstream. BTW, I live near Vancouver B.C., a MAJOR rain belt... I have driven through SERIOUS rain storms with this setup and never had any problems. Water does NOT get in... period.
post here for addtional questions,... I'll follow this thread.