Now then kiddies I'm at a point where i really need to get a cold air feed for my 1.6 driver. The original hose the connected the airbox to the inside of the offside wheelarch has been missing for donkeys and i know this aint good for the motor as very quickly it sucks in the hot air given off from the engine. Would a standard replacement of the original suffice or could i go better and get hold of one of them badboys that attach to the back of a chin spoiler with a funky-lookin funnel?? I'm after the best possible air suckage, of the cold variety, available. The engine is fitted with a new Weber carb if it helps. IIII thankyou
Not sure you'll gain much by fitting a replacement for the hose going to the wing fitting. I bought one a while back as the original had perished to the point that it was chucking little shreds of foam at the air filter. Then I fitted a temperature sensor in the airbox as a diagnostic aid to solve carb icing probs. With and without the foam hose I see very little difference in intake air temp, though it has to be said I do very little sitting in traffic. I'll do another with/without test now that the weather's much warmer, but TBH the 'trumpet' just beyond the warm/cold flap is quite a way from the engine's heat, and pointing at least partly into the 'wind', although I've no idea how the air might be swirling around under the bonnet. Best bet probably is a hose going to the front of the car, if you want the coolest air possible. Maybe a fine spray of clean water across it for a bit of evaporative cooling, and a 'whiff' of water injection.
My hose is wrapped in duct tape (it was falling apart whwn I got the car) and is currently poked through that circular hole on the chassis leg (it has a plate welded over it but mine came off without much of a fight by accident when I was de-rusting).
I do have the hose from the manifold...although its an aftermarket one...and made out of what can only be described as the same as those things you get Mr Kipling Bramley Apple Pies in!!! with extra duct tape!! Dont get me wrong though; the trumpet is positioned fortunately away from the engines heat but going by my pigeon physics in air dynamics i'm sure the air in that void would eventually start dragging in hot air, especially when in traffic. Stuff the original type hose then; especially if its gonna start falling to bits over time. Aint the foam hoses design to avoid excessive noise?? if so, stuff it even more. If all else fails and i become desperate i can stick with the pie theme and fashion a heat shield from some Fray Bentos cans!! I like the sound of the water injection i could use some of that Volvic with a hint of lemon!! The engine bay would smell lovely!! super!!
D'you know, I hadn't even thought that the foam on the cold-air feed pipe might be for sound insulation rather than thermal? Guess there's no reason it couldn't be doing both... Will have a good listen, as well as looking at my temperature readout when I do my next with/without comparison, see if I can hear any difference. I just realised how confusing my first reply might look, what with me talking about carb icing, and the air temperature with different cold air feed pipes. It wasn't connected, I solved the carb icing prob by cleaning out the airbox thermostat. My warm-air Mr Kipling pipe was/is in reasonable condition. Only after that did I notice that the 'steady state' air temperature didn't seem very different with/without the foam-insulated cold air feed pipe. This was on a day when the ambient air was maybe around 18C; as far as I recall, I was rather surprised to find that without the foam pipe I was seeing 20C air going into the carb, with foam pipe it was a degree or two higher. I can't explain this, so am keen to repeat the experiment to see if I get the same result. Like the idea of a ducting system made from Fray Bentos tins, mmmm, love 'em, but they must be sinfully unhealthy .
With regards to the cold air feed being designed for both noise and thermal insulation it wouldnt surprise me...it would have been in VWs best interests to make the engine as quiet as possible. Unsure why the pipe didnt have an internal layer to protect the foam from deterioration...maybe because a smoother surface causes more noise than a surface with more air resistance...this could assist with the effects to induction noise...ah, my head hurts!!! also, would it be possible that the air sucked in from the wheel arch/chassis leg could have higher air temps than say front of the grille or chin spoiler due to friction heat from the brakes? How did the experiment go EZ? any conclusions? No Fray Bentos heat shield yet.
As far as I can recall, there's a wire mesh designed to keep the foam where it is, until it degrades into really lickle bits... Didn't get round to the experiment, had lots of family business on this weekend, will do soon though. I'll try not to brake much, though I rarely drive in a 'heavy brake usage' mode, being an old fart 'n'all.
A wire mesh!!...Cant say i've ever seen one of those pipes in good enough nick to have one!! I dont think i'm the anchor slammin type either but i dont drive like an old fart yet
leave it all standard. just replace the dodgy bit, poss from scrappy if your lucky enough. if you must then just spin the trumpet 180 so its facing away from the wing and jubilee clip some hose to it down towards the grill at the bottom of the bumper or something like that. wont make no difference though mate. it just makes people think theyve got the extra power imo. but its your car at the end of the day
So... Temperature-wise, barely a gnat's cock in it. With engine fully up to temp, straight flat 5 mile run at 70, minimum airbox air temp 20.3C without airpipe to wing. Coming back after a quick fitting of the pipe, minimum temp 20.7C. I went to the next junction to see if this diff was just the heatsoak up from the engine during the changeover, but it didn't go any lower. Soundwise, quite a difference. I suppose no surprises there, noticeably quieter with the foam insulated pipe. Guess it's sound insulation then. Unfortunate exhaust odour in engine bay during the changeover leads me to think it's time I tracked down the exhaust leak...bugger.
Ah the clips from hell beckon maybe I don't have the pipe into the inner wing - one those 'if i find one cheap enough' jobs. Pete's right that the air in the corner of the engine bay probably isn't that hot so it shouldn't affect performance. The fact that it's quieter is probably more to do with why it's there, possibly to help with noise regs. Barkstar
I didn't realise there were so many cars out there without that pipe. When I bought my car it had some tape around it hiding what was actually underneath. When I had initial carb problems a local mechanic ripped it all off saying it didn't do anything anyway. Seems he was right. Mind you, he ripped off the hot air feed pipe as well.....
Going by the general consensus it seems the pipe's just for noise control rather than temperature. I've had this car for about a year now and it didnt have the pipe since i got it and it runs like a beaute...but i always had it at the back of my mind whether the pipe would be of benefit if fitted. I also found a baffle plate on the back of the grille next to the o/s headlamp. Removing this could help with more cold air...who knows!!
