To: Volvo303@yahoogroups.com From: "David Touitou" Date: Tue, 01 Nov 2005 09:17:52 -0000 Subject: [Volvo303] Hot vs Cold air intake Reply-To: Volvo303@yahoogroups.com Hello all. I don't know if this as allready been talked about here but I could not found any data on it (either here or in the PDF documentation in english or in my swedish printed doc). On my Vattenfall C303, I have the plastic box containing the airfilter (no aluminium box). This airbox is connected to a square plastic box. From the square plastic box are two aluminium tube (about 10 cm diamater) to get air. One goes to the exhaust manifold (to get very hot air), the other goes in front of the engine (to get air, still warm but less). There a switch on the square box saying "hot" and "cold". So here are the questions : . is the square box an automatic switch (depending on heat) that will switch between the two possible intakes ? . does "hot" on the square box mean "get hot air" (from the exhaust manifold) or "it's hot outside" (so get fresher air) ? . at which outside temperature should the switch be set to "hot" and "cold" ? Thanks a lot, David. PS : if "hot" means "get hot air from the exhaust manifold", my C303 has spent it whole summer running on _very_ hot air 8-( To: Volvo303@yahoogroups.com From: "David Touitou" Date: Tue, 01 Nov 2005 10:20:30 -0000 Subject: [Volvo303] Re: Hot vs Cold air intake Reply-To: Volvo303@yahoogroups.com I've removed the box to see what's inside 8)) > So here are the questions :=20 > . is the square box an automatic switch (depending on heat) that will > switch between the two possible intakes ? Yes it is. There's a "temperature sensor" in the tube going into the air filter, which dilate when air gets hotter. While dilatating, it pushes a plastic plate that closes the tube coming from the exhaust and opens the tube coming from the "front of the engine". > . does "hot" on the square box mean "get hot air" (from the exhaust > manifold) or "it's hot outside" (so get fresher air) ? The switch on the outside is not a switch, just and indicator of the position of the internal plate. > . at which outside temperature should the switch be set to "hot" and > "cold" ? No clue 8) I put the temperature sensor under hot water, it does dilate but not enough to close completely the "from exhaust" tube (I don't know if it is supposed to). On the other end, once put under cold water, it retracts really nicely and closes completely the frech air tube. And now the new question : what would happen if I removed the square box completely and connect the fresh air tube to the air box ? I know having hotter air to start is nice (engine runs smoother) but I live in a countryside were we did not went under 0=B0C for years. So I wonder if forcing fresh air (maybe with a longer tube than current) would not be a very good thing for the engine (even if I put back the whole system on if I go in the mountains or very cold places). David. To: Volvo303@yahoogroups.com From: =?ISO-8859-1?Q?Gr=F8nntass?= Date: Tue, 01 Nov 2005 12:16:31 +0100 (CET) Subject: Re: [Volvo303] Re: Hot vs Cold air intake Reply-To: Volvo303@yahoogroups.com David Touitou : > And now the new question : what would happen if I removed the square > box completely and connect the fresh air tube to the air box ? I think you might get problems in high humidity, even if the temperature is above 0C. The carburettor will not feel well, and in worst case the engine might stop or run very bad. Christian To: Volvo303@yahoogroups.com From: "David Touitou" Date: Tue, 01 Nov 2005 11:43:46 -0000 Subject: [Volvo303] Re: Hot vs Cold air intake Reply-To: Volvo303@yahoogroups.com --- In Volvo303@yahoogroups.com, Gr=F8nntass wrote: > > David Touitou : > > And now the new question : what would happen if I removed the square > > box completely and connect the fresh air tube to the air box ? > > I think you might get problems in high humidity, even if the temperature is > above 0C. The carburettor will not feel well, and in worst case the engine > might stop or run very bad. I agree on the humidity problem, but : . there's not this square box in any of the documentations I found, only a direct tube to the air cleaner . even a direct tube get _very_ hot because is stands by the engine . the carburetors get _very_ hot too (got myself burnt after a 5km trip last week) just because there's fitted to the intake manifold metal to metal (and the intake manifold gets heat from the exhaust manifold) I guess the whole system depends on the civil vs militerian version of the C303, plus the differences between years (with/without the box, watercooled or not intake manifold, second aluminium air filter box or not, etc).