JW240
All idiot, no savant
- Joined
- Aug 15, 2004
- Location
- The Netherlands, Europe
Airbox mod for the 240
Why to remove the airbox restrictions and air preheat thermostat?
-more power, it made a noticeable difference on the butt-o-meter.
-better MPG (mine got a little jump better, but the thermostat in the airbox had failed on my 240 so it sucked hot air the whole time). I get 29 MPG now..
-If the engine gets hot air the AMM (Air Mass Meter) can be damaged and thats a very expensive part..
And on aside note, the engine has a bit more agressive sound when revving it
You start with this... completely remove the airbox. this is done by removing the battery, the battery tray and disconnecting the 45 degrees elbow that goes from the air box to the rest of the engine (amm). Removing it takes maybe 10 minutes..
Tools required: 13 mm socket for battery tray, 10 mm wrench for battery cables (watch out not the short the + to the body, so disconnect negative first!) and a 7 mm socket or flat screwdriver to remove hoseclamps.
To remove the thermostat flapper, there are 3 points where its held in place with little plastic thingies. They are visible when you look at the airbox from the air outlet side. Visible is one of the 3 mounting points. The thing releases when you press the 2 plastic tabs toward each other.
The next 2 steps can be left out if you completely remove the thermostat and valve. I didn't remove it because I didn't had a suitable way of closing the preheated air inlet and I wanted it to be reversible in case I would need it for a government emissions check. Untill now, this mod hasn't given any problems with emission checks.
This is the removed thermostat with flapper. I added maybe 10 small stainless steel washers, so that no matter what the thermostat does (mine was broken, so my engine got preheated air all the time), its always stuck in fully cold air position.
This is what it looks when fitted in the airbox again. It doesn't close all the way, so I added another washer to get it completely closed.
I still added a 50 mm cap on the hot air hose to prevent huge amounts water and dirt from getting in the airbox (the airbox has water drainage holes at the bottem so a bit water won't do much). Then, I connected the hot air hose again over the cap, so when I get a check, no one can see that it is not used..
The preheat hose fitted but if you look carefully, you can see a small red edge where the hose connects to the airbox. The cap is between the hose and the inlet. So the hose has no function, but its still there so they won't whine about it when they chack your car for emissions..
Here is a picture of the snorkel and 90 degree bend that volvo put in front of the air box. Notice the enormous decrease in diameter of the tube! the whole inlet system is at least 70-80 mm, and this is maybe 45 mm! so stupid. Only removing the snorkel gives some gain, but the bend is also very restricting.
The little piece of PVC tube next to it is what I replaced it with, but that was stupid. You have to replace the snorkle and bend with a single 90 degree PVC bend and a piece of pipe and point it upwards. a few water draining holes in the bend can be a good idea.
I want to point out that removing the snorkle and replacing it with a small pieze of tube is not smart! that way more dirt and water can be sucked into the air filter. not that that would hurt your engine immediately (well a lot of water would), but it reduces the lifetime of the air filter and it can damage it.
So a 90 degree bend should be used, but there isn't much space and when the airbox is back in place, its very very difficult to put the new bend in! I had to install the bend while the airbox was fitted and it was very difficult and it required some brute force...
This is where the 90 degree bend is fitted.. It fits barely in the small space behind the headlight and its a PITA to install with the airbox fitted.. Some zip ties can be used to calmp everything firmly against the bodywork.
The piping I used as a replacement of the snorkel. Its 75 mm outside diameter. about 3".
The next step is to remove one or bothe of the screens of the AMM. I would leave the first one in place to prevent any debry's from entering the engine and damaging the AMM if the airfilter would fail or a hose break.
What I did soon after the aibox mod was to clean the Throttle body and I checked for leaks past the AMM, and I found one in the thick hose between the AMM and the TB, just after the AMM, there the hose rubs over the battery cables that run to the starter. The car drove better after cleaning the TB and injectors.
I get almost 29 MPG with my 240, and I don't drive slow at all.. so I recon the upgrades are good
JW
BTW: during the winter, i use a extra 90 degree bend on the intake that points a bit to the rear to prevent rain and snow from entering the airbox...
Why to remove the airbox restrictions and air preheat thermostat?
-more power, it made a noticeable difference on the butt-o-meter.
-better MPG (mine got a little jump better, but the thermostat in the airbox had failed on my 240 so it sucked hot air the whole time). I get 29 MPG now..
-If the engine gets hot air the AMM (Air Mass Meter) can be damaged and thats a very expensive part..
And on aside note, the engine has a bit more agressive sound when revving it
You start with this... completely remove the airbox. this is done by removing the battery, the battery tray and disconnecting the 45 degrees elbow that goes from the air box to the rest of the engine (amm). Removing it takes maybe 10 minutes..
Tools required: 13 mm socket for battery tray, 10 mm wrench for battery cables (watch out not the short the + to the body, so disconnect negative first!) and a 7 mm socket or flat screwdriver to remove hoseclamps.
To remove the thermostat flapper, there are 3 points where its held in place with little plastic thingies. They are visible when you look at the airbox from the air outlet side. Visible is one of the 3 mounting points. The thing releases when you press the 2 plastic tabs toward each other.
The next 2 steps can be left out if you completely remove the thermostat and valve. I didn't remove it because I didn't had a suitable way of closing the preheated air inlet and I wanted it to be reversible in case I would need it for a government emissions check. Untill now, this mod hasn't given any problems with emission checks.
This is the removed thermostat with flapper. I added maybe 10 small stainless steel washers, so that no matter what the thermostat does (mine was broken, so my engine got preheated air all the time), its always stuck in fully cold air position.
This is what it looks when fitted in the airbox again. It doesn't close all the way, so I added another washer to get it completely closed.
I still added a 50 mm cap on the hot air hose to prevent huge amounts water and dirt from getting in the airbox (the airbox has water drainage holes at the bottem so a bit water won't do much). Then, I connected the hot air hose again over the cap, so when I get a check, no one can see that it is not used..
The preheat hose fitted but if you look carefully, you can see a small red edge where the hose connects to the airbox. The cap is between the hose and the inlet. So the hose has no function, but its still there so they won't whine about it when they chack your car for emissions..
Here is a picture of the snorkel and 90 degree bend that volvo put in front of the air box. Notice the enormous decrease in diameter of the tube! the whole inlet system is at least 70-80 mm, and this is maybe 45 mm! so stupid. Only removing the snorkel gives some gain, but the bend is also very restricting.
The little piece of PVC tube next to it is what I replaced it with, but that was stupid. You have to replace the snorkle and bend with a single 90 degree PVC bend and a piece of pipe and point it upwards. a few water draining holes in the bend can be a good idea.
I want to point out that removing the snorkle and replacing it with a small pieze of tube is not smart! that way more dirt and water can be sucked into the air filter. not that that would hurt your engine immediately (well a lot of water would), but it reduces the lifetime of the air filter and it can damage it.
So a 90 degree bend should be used, but there isn't much space and when the airbox is back in place, its very very difficult to put the new bend in! I had to install the bend while the airbox was fitted and it was very difficult and it required some brute force...
This is where the 90 degree bend is fitted.. It fits barely in the small space behind the headlight and its a PITA to install with the airbox fitted.. Some zip ties can be used to calmp everything firmly against the bodywork.
The piping I used as a replacement of the snorkel. Its 75 mm outside diameter. about 3".
The next step is to remove one or bothe of the screens of the AMM. I would leave the first one in place to prevent any debry's from entering the engine and damaging the AMM if the airfilter would fail or a hose break.
What I did soon after the aibox mod was to clean the Throttle body and I checked for leaks past the AMM, and I found one in the thick hose between the AMM and the TB, just after the AMM, there the hose rubs over the battery cables that run to the starter. The car drove better after cleaning the TB and injectors.
I get almost 29 MPG with my 240, and I don't drive slow at all.. so I recon the upgrades are good
JW
BTW: during the winter, i use a extra 90 degree bend on the intake that points a bit to the rear to prevent rain and snow from entering the airbox...
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