Cold air intake for 850's

tessiev70 · Post by **tessiev70** » 19 Sep 2009, 18:12

Mck1 wrote:Hi,
I've just preformed the following air filter mods:

- Replacing the old air intake hose for a much larger one
- Closed the hot air intake flap to only let in cold air

Chris.

where is the hot air intake flap?

Post by **tjts1** » 21 Sep 2009, 10:35

The hot air intake flap is in lower half of the air box on non turbos.

Mck1 · Post by **Mck1** » 23 Sep 2009, 02:13

Hi,

Please find below a picture of the air intake hot/cold sensor which Is located at the bottom of the air filter box (picture found on this site posted by luketrash). By pushing the spring in this will close the hot air flap & only let in cold air, I used a bit of a cork to compress.

Good luck!

Chris.

volvoheader79295 · Post by **volvoheader79295** » 24 Sep 2009, 23:28

Hey guys. New to the forum. Old 240 guy with five of them and just bought an 850NA wagon last week. Right off I noticed the cold air intake had pull away from the radiator area and was just sort of sitting back there near the filter box. The hose was gone. I found a couple of old spare intake hoses from 240s and with a bit of cutting and splicing and some heavy duty black duct tape and zip ties I fashioned a new hose to the box. My, my what a difference! Now, after reading these excellent posts I want to find some of that large diameter flex hose and do a bit of cutting and routing. Where can I find that type of hose? I know a couple of fellas who somehow mounted an extra electric pusher fan closer to the grill and routed that air into a widened hose that narrowed down to the airbox. Huge difference apparently in HP. My guess is they wear out fans, but I dunno. Also, my car has the hot air routing from the exhaust header back to the airbox also. I live in central North Carolina with fairly temperate winters and on all my 240s I blocked that hose off and opened the cold air flow permanently. Can I do that on this car as well? Some posts seem to indicate they did that. Anyway, I still need to find that bigger silver flex hose. Love this site!!!

will bj robinson · Post by **will bj robinson** » 30 Sep 2009, 23:50

I added a KnN filter on a 3" steel tube (enough to take the filter too the inner fender)made a mount so that it sits the front of the cone too the gap between the battery and the fender(optima red top makes a bit more room). id say @ least 15hp fuel consumption down from 12.9l/100km to 10.3 and you get the added sound of the wastegate opening(for the ricer,not me).

Post by **charlyW** » 22 Nov 2009, 16:57

Easy way to prevent water getting sucked in is to fit a small drip loop [all you electrical experts will know what one is] with a selection of holes in it so the water gets trapped in the loop and drains out

BlackThunder · Post by **BlackThunder** » 28 Nov 2009, 09:13

charlyW wrote:Easy way to prevent water getting sucked in is to fit a small drip loop [all you electrical experts will know what one is] with a selection of holes in it so the water gets trapped in the loop and drains out

Man, this mod is really interesting. CharlyW, you're saying just put a downward bend in the tubing like a "U" with some wholes on the bottom so the water can drip out? Good idea. But would water still get sucked into the engine (at high speed)?

I'm going to have to check out where the air is coming in now to see how water doesn't already get into the airbox. Seems like with this mod that water or melted snow would get into the air system some how.

However, this is a cheap and easy modification that would be cool and fun to do. Just worried about the water.

Dustin

Post by **tjts1** » 29 Nov 2009, 14:00

The stock airbox already has a drain hole in the bottom. Its hard to improve on the stock air box. The only restriction is at the intake tube to the airbox.
cheers
Justin.

BlackThunder · Post by **BlackThunder** » 05 Dec 2009, 12:13

While looking for vacuum leaks today I saw that the hose running to the bottom of the airbox wasn't connected all of the way. Should there be a gap here?

This is the cold air intake right? Not the hot air. This is where the routing is going to the front of the car above the radiator.

Also, there is a plastic piece in the bottom of the air box. Does this plastic piece move? Or is it just restricting air flow to the air box?
(1997 850 NA)

I guess if there is this gap then I should go buy a hose clamp and some flexible tubing. I might get better cold air intake since there won't be a gap where hot air is getting into the air box.

Post by **tjts1** » 05 Dec 2009, 12:42

No, there shoudn't be a gap there and yes that plastic piece does move based on vacuum from the manifold to allow cold or hot air into the airbox. Your intake is stuck in the hot air side like every other one I've seen thus far. It needs to be fixed.
I took the whole thing apart, ripped out that plastic piece that restricts airflow and closed off the hot air side to make a permanent cold air intake. There is a noticeable increase in acceleration with this modification.

This is the vacuum port that powers the plastic flap to move from hot to cold air side. Under deep vacuum the intake breaths only cold air. When you open up the throttle vacuum drops and only allows cold air in.

Separating the 2 halves you can see the flap mechanism inside. The cold air intake which you can see in the previous post is at the top of the picture, hot air intake is on the left and all the air discharges into the airbox at the bottom.

Looking inside the cold air intake you can see a spring mechanism, pivot and air flap. All of this stuff can be ripped out to make a larger free flowing intake.

Here you can see the inside of the hot air intake.

And the flap that blocks off the hot air intake when vacuum colapses under WOT.

I cut off the circular flap and glued it on to the hot air intake to permanently block air coming in from near the hot exhaust. I completely removed the spring mechanism and pivoting flat to make an unobstructed cold air intake to the airbox. Then put it all back together. I made my own larger and less restrictive cold air tube.

Old intake tube on the left, new larger intake tube on the right.

You can see the new 3.5" flexible intake tube going over the top of the radiator in place of the old plastic tube.

The model pictured in this thread applies to 97 850 and 98 S70/V70. The earlier 850 hot/cold intake is slightly different.

This modification has been thoroughly tested by a lot of people. You can read the discussion here.
https://www.matthewsvolvosite.com/forums ... f=1&t=8830

Good luck
Justin

Cold air intake for 850's

Re: New air intake for 850's