B 21 FT Air Box Modification For Cold Air...
Username
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    Welcome to SwedeSpeed
    You're currently browsing Swedespeed as a guest. Please sign up or sign in and take part in the conversation with other Volvo owners and enthusiasts. With more 2 million posts our community is one of the most active groups of Volvo owners in the world. Take a moment to sign up and enjoy all of the features our forums have to offer.
    Results 1 to 6 of 6
    1. #1
      Junior Member JBLasVegas's Avatar
      Join Date
      Nov 2006
      Location
      Las Vegas, Sin City, Nevada.
      Posts
      371

      B 21 FT Air Box Modification For Cold Air...

      I just have one question regarding the air box modification that I've been seeing for the last few years. What is so much better about it then using the original, big snorkel that comes through the radiator support and angles over to right behind the grille, and just removing the hot air thermostat and blocking off the hot air intake side of the box while removing the hot air pipe from the manifold shield? I don't get it. I just did the above mod this afternoon, and even with temps over 100 degrees, I could really feel the "pull" in a gear that I would have downshifted from into a lower gear. The difference is really phenomenal. After I removed the thermostat, all I did was to place a little spot of epoxy on the hot / cold air flap to keep it in the cold-air mode, removed the heat tube, and capped the hot air inlet to keep any under hood air from being sucked in. Then, I painted the cap that I used black so that the smog guy wouldn't see it. What could be simpler? Volvo already put a big molded pipe angled over right behind the grille for atmospheric temp air.
      Any input? George?

    2. #2
      Global Moderator
      Join Date
      Aug 2004
      Location
      Temple, Texas, USA
      Posts
      19,094

      Re: B 21 FT Air Box Modification For Cold Air... (JBLasVegas)

      Here is my easily reversed air box mod on a stock 240 B230F non-turbo...

      (modify as needed for B21, etc)

      Materials: New or used good exhaust manifold pre-heat flex DUCT/HOSE just like on the car.

      1. Remove and save: fresh air box thermo and flap (snaps out/in), mass air meter screens (2) and stock air filter.

      2. Disconnect the pre-heat duct from the heat collector at the exhaust manifold. Re-route this end under the fan shroud to a point just above and behind the front air dam near the RF corner of the car - secure.

      3. Connect one end of the new/used duct to the heat collector and follow the stock route to the fresh air box but do not connect - just dummy under the fan shroud and secure.

      4. Re-install stock air filter or aftermarket as desired (if re-usable aftermarket filter do not over-oil).

      5. Inspect the ENTIRE intake system for leaks and repair as needed (including the flex hose between the mass air meter and throttle body).

      Now the fresh air box has TWO sources of cool air - the original snorkel and the duct at the air dam.

      Next would be a free-flow exhaust and a test of the cat for no flow restrictions and proper Ox readings at the tailpipe.

      George Dill


    3. #3
      I'm running similar to George's.

      * Took out airbox flap/solenoid, trashed.

      * Kept AMM screens in place.

      * Preheater hose rerouted to air dam.

      * Second preheater hose routed from exhaust header to under bumper for "emissions" reasons.

      Pat
      '12 S60 T5, '92 245DL

    4. #4
      Junior Member
      Join Date
      Oct 2012
      Location
      Amherst NY
      Posts
      17
      Im goin to have to read more into this or just call ya Mr.Dill haha... and removing the thermostat doesnt cause heat issues? pretty dumb question i guess. but i will learn... quikley
      Drive Like You Mean it Friends...

    5. #5
      Member
      Join Date
      Mar 2008
      Location
      Sarsfield, ON
      Posts
      3,113
      Where I live we still have real winters. All of my 240s (now three since two days ago) run with no pre-heat hose and the gubbins in the air box, and I've never had any problems firing them up in the cold. You live in a warmer climate, so remove the pre-heat hose for some other use, remove the whole pre-heat thermostat and door assembly, and seal off the pre-heat hole in the air box. And the latter is important as you don't want the air intake sucking in hot air from the engine compartment as that could eventually fry the MAF.
      '88 244 auto (parts car), '89 244 5 spd. (daily driver), '92 245 5 spd. (my car) '80 Holiday Rambler/Ford E350 (tow vehicle and track crash pad), '95 GMC K2500 (local hauler/back-up tow vehicle), '83 Mazda RX7 (race car when I have the funds), '99 Miska 20' car hauler.

      The man's prayer: "I'm a man, but I can change, ... if I have to, ... I guess."

    6. #6
      Global Moderator
      Join Date
      Aug 2004
      Location
      Temple, Texas, USA
      Posts
      19,094
      Quote Originally Posted by John2x240 View Post
      Where I live we still have real winters. All of my 240s (now three since two days ago) run with no pre-heat hose and the gubbins in the air box, and I've never had any problems firing them up in the cold. You live in a warmer climate, so remove the pre-heat hose for some other use, remove the whole pre-heat thermostat and door assembly, and seal off the pre-heat hole in the air box. And the latter is important as you don't want the air intake sucking in hot air from the engine compartment as that could eventually fry the MAF.
      Rather than disconnect the pre-heat hose from the air box just re-route the other end along the bottom edge of the radiator, out the engine compartment below the side sheet metal and then tie it up just above and behind the front air dam. Be sure the hose has a downhill run somewhere away from the air box. If you run on gravel/mud a lot slap a piece of 1/4" mesh over the open end of the hose. The air box will draw fresh air from both the hose and the existing snorkel. For inspection just run a dummy hose from the pre-heat chamber on the exhaust manifold along the same route as the original hose then hide the loose end under the air box but not near the snorkel.

      During extended periods of very cold weather this mod can hurt mpg and may cause engine wear.

      George Dill
      Last edited by gdill2; 10-05-2012 at 05:44 PM.