Volkswagen Passat Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
24 Posts
Discussion Starter · #1 ·
Frustrated at what appeared to be a royal PITA to somehow convert our stock B5 airboxes to some sort of cone-filter setup, a buddy of mine and me decided to do our "own" version of an improved intake last weekend...

Basically, I had just gotten my K&N which I had planned to install anyway, but then when we had the box out of the car, decided that the bottom half wasn't serving much function at all. Took a Dremel, and literally just CUT OFF the bottom half of the airbox (leaving things like the clip-mounts and some of the plastic pieces needed to make it fit tightly back in place), but cut it off nontheless. So it's the square version of a cone filter, I guess you could say, and getting a LOT more airflow.

The end result? Heh, it's pretty cool--definitely a more aggressive intake sound (but not annoying) and I can hear my blow-off valve (diverter valve, or whatever) empty back into the intake if I turn my radio down now, something I was never able to hear before. I should have taken pics while doing it, but like I said, was more spur-of-the-moment :/
 

·
Banned
Joined
·
9,668 Posts
I dont know of anyone that has cut the whole bottom half of the airbox. What if you need to sell the car? People have cut 3" holes in the front of the airbox and used dryer ducts from the lower air grille to push air into the airbox. There have been a few that have created their own heatshields and just used a basic cone filter and some clamps, without the box itself.

Steve
 

·
Registered
Joined
·
4,011 Posts
Scuba2001 said:
I dont know of anyone that has cut the whole bottom half of the airbox. What if you need to sell the car? People have cut 3" holes in the front of the airbox and used dryer ducts from the lower air grille to push air into the airbox. There have been a few that have created their own heatshields and just used a basic cone filter and some clamps, without the box itself.

Steve
Good advice, go to search button and ask for "Colorado air box mod".

What you did is basicly lost all air pressure that was made by car moving forward.
Second, you are now sucking ALL hot air, (produced by: engine,turbo,exhaust, and air passed through cooler) instead "normal" fresh air from outside of car. Tests of of ClubB5 member Geri (Austria) with K&N cone filter installed on V6 B5 showed 15 degrees of C higher temps compared to fully stock airbox.

Good rule of thumb says that with each 3-4 degrees of C you will gain/loose(depends on raising or lowering temps) 1% of power. If we presume that your T-car is producing same heat like NA V6 (and your T-car produces more temps cause of turbo) 15 degrees of C higher than stock, will bring you down for 4-5% in power.
 

·
Registered
Joined
·
1,087 Posts
Nenad said:
Good advice, go to search button and ask for "Colorado air box mod".

What you did is basicly lost all air pressure that was made by car moving forward.
Second, you are now sucking ALL hot air, (produced by: engine,turbo,exhaust, and air passed through cooler) instead "normal" fresh air from outside of car. Tests of of ClubB5 member Geri (Austria) with K&N cone filter installed on V6 B5 showed 15 degrees of C higher temps compared to fully stock airbox.

Good rule of thumb says that with each 3-4 degrees of C you will gain/loose(depends on raising or lowering temps) 1% of power. If we presume that your T-car is producing same heat like NA V6 (and your T-car produces more temps cause of turbo) 15 degrees of C higher than stock, will bring you down for 4-5% in power.
What Nenad said. This has been beaten worse than any dead horse.

Simply put, for the most part, you take a step backwards removing the stock intake. Modifying the stock intake has helped a lot, as you still retain the intake of cooler outside air, and the slight over pressure from the car's forward movement.

Hope this works for you, but a lot of experience has shown that you want to keep the stock intake, and maybe just reduce a few restrictions in it.

Some of the guys here say their cone setups (removing or opening up the stock intake) are better, but I don't know. A lot of guys with the cone intakes have actually built heatshields to compensate for the "openess" of the design, and since learned that when it was all said and done, they more or less rebuilt a stock type intake system.

Doing the Minnesota and Colorado mods on a stock airbox work better than we expected. Even the stock airboxes are working good with heavily modified and chipped cars.

The key is to pull in as much outside air as you can to improve the airflow (turbo lag, high end breathing, etc.), without increasing the percentage of preheated air.

Mark
 

·
Registered
Joined
·
24 Posts
Discussion Starter · #8 ·
Wow...seems this *was* really discussed before, but I'm a relatively n00b to the forums, and haven't even had the car that long, so I hadn't seen it :nervous:

The air-temperature dissertation certainly makes sense from a scientific point of view--if this car was primarily for track use or running 1/4's etc., then I would definitely be concerned about a 4-5% "performance" loss. But as it stands, it's just my daily driver, probably for say the next 2 years, so to have something a little different in the way of an intake isn't a huge deal for me. Thanks for the input though, I really like this forum :D
 

·
Registered
Joined
·
4,011 Posts
It is general for all cars, not only for Passat. Point is that with warm air is increasing possibility of detonation in combustion chamber (I will not ealborate scientific point of this,unless you are interested) to prevent this your ECU will change timing and try to maintain normal A/F ratio, but on very hot days it can happen(hot air from outside+hot air under bonnet), and this is worst thing that can happen to car aside crash or timing belt failure (Passat have belt not chain). Severe detonations(knocking,pinging) are leading to craking of pistons , dammaging cilinders,burning valves.

It is not the point in preaching to you or 1/4 mile obssesity, only common sense for maintaining of car and not degrading any of performances if we/you do not want to improve them.Really hope that you will have no troubles caused with this modification.

cheers
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top