VAP
07-28-2003, 06:47 AM
I had to open my yap a little prematurely last week and now of course I'm besieged with questions so I thought I'd use here as a way to eliminate the individual emails.
Stage 3 cold air intake for the A4/90 series 2.8 12V:
First there will be a full-width plastic intake with a 3" outlet cast/manufactured that fits the lower grill perfectly. It may or may not allow for the stock grill to be retained but it will be a perfect, sealed fit into that area.
Connected to the 3" outlet wil be a dual-walled 2 layer hose (silicone outer/neoprene inner) spiral wound wire hose assembly running from the intake outlet to the air box adjustable shutter/aperture assembly. This hose assembly was chosen for it's longevity due to location and it's inherent ability to flow consistently cold air that's unaffected by heat influences which it must pass as it transitions from lower grill to airbox, ie; radiator incoming air as well as reflected, radiated and convection heat influences.
On the airbox will be a mounted shutter aperture to regulate the amount of incoming air from the lower intake. My flow tests have shown I can get more CFM out of retaining the upper cold air intake in conjunction with the lower than just the lower will allow. However this creates an imbalance. Air under pressure will always seek the path of least resistance to relieve itself. Left unchecked the lower hose would simply overcome the lesser-pressure coming in the top (stock) intake and block any air coming in from that source or overcome it altogether if strong enough and vent out the front of the stock intakes inlet. To counter this I'm working on a "balanced system" with a slightly larger extension collector scoop for the original intake along with an adjustable aperture/shutter device for regulating air coming in the lower intake to match the CFM/psi air coming from the stock intake. The net affect is a balanced intake system that flows more air than either individual intake runner can alone. The end result is maximum airbox positive pressure at any/all RPM/MPH without either intake over-powering the other and relieving/exhausting itself.
The only way to do this and make it available to everyone and try to keep it a DIY project is to run a low pressure gauge in the bottom of the airbox while altering the size of the "scoop extension" used on the upper collector while also varying the aperture inlet size on the lower airbox inlet. A juggling act that will be governed by maximum psi readings on the airbox gauge. If I can find a CFM/psi that is near my maximum readings I should be able to design an inline restrictor for the lower line that will match it to the upper intakes maximum intake CFM. Some of this I can do on the flow bench however most of it will require test drives and real world conditions to dial in. The closer I can keep the new, lower hose's readings to stock upper CFM/airbox psi readings the easier it will be for me to make a "one-size-fits-all" application that works for everyone as engine mods won't affect the CFM or PSI differentials of intake air. Only MPH can determine that. As long as I keep more PSI in the airbox than the car requires to run efficiently F/A-wise.
If I can bypass/forego the adjustable aperture on everyones car that will decrease the price by almost $200 as good quality bore-adjustable shutter-type apertures are a spendy item requiring the airbox be milled to accomodate as well as internal/external flanges be attached to facilitate installation.
Another interesting aside is that there is definate benefit to an internal velocity stack being used at the lower hoses outlet into the airbox. I never knew they worked better in reverse than a simple hose cut-off but there it is. Probably more related to air dispersion/diffusion than anything else.
This piece could easily be 2-3 months out especially if I have to have the inlet ducts cast specifically for the lower grill cut-out.
My next big project is re-working a stock airbox so that it will hold a 4-5psi charge of air for an hour without leak-down. Likely more than I'll ever need but if I can achieve it I know it'll hold whatever I throw at it once the system is assembled.
Stage 3 cold air intake for the A4/90 series 2.8 12V:
First there will be a full-width plastic intake with a 3" outlet cast/manufactured that fits the lower grill perfectly. It may or may not allow for the stock grill to be retained but it will be a perfect, sealed fit into that area.
Connected to the 3" outlet wil be a dual-walled 2 layer hose (silicone outer/neoprene inner) spiral wound wire hose assembly running from the intake outlet to the air box adjustable shutter/aperture assembly. This hose assembly was chosen for it's longevity due to location and it's inherent ability to flow consistently cold air that's unaffected by heat influences which it must pass as it transitions from lower grill to airbox, ie; radiator incoming air as well as reflected, radiated and convection heat influences.
On the airbox will be a mounted shutter aperture to regulate the amount of incoming air from the lower intake. My flow tests have shown I can get more CFM out of retaining the upper cold air intake in conjunction with the lower than just the lower will allow. However this creates an imbalance. Air under pressure will always seek the path of least resistance to relieve itself. Left unchecked the lower hose would simply overcome the lesser-pressure coming in the top (stock) intake and block any air coming in from that source or overcome it altogether if strong enough and vent out the front of the stock intakes inlet. To counter this I'm working on a "balanced system" with a slightly larger extension collector scoop for the original intake along with an adjustable aperture/shutter device for regulating air coming in the lower intake to match the CFM/psi air coming from the stock intake. The net affect is a balanced intake system that flows more air than either individual intake runner can alone. The end result is maximum airbox positive pressure at any/all RPM/MPH without either intake over-powering the other and relieving/exhausting itself.
The only way to do this and make it available to everyone and try to keep it a DIY project is to run a low pressure gauge in the bottom of the airbox while altering the size of the "scoop extension" used on the upper collector while also varying the aperture inlet size on the lower airbox inlet. A juggling act that will be governed by maximum psi readings on the airbox gauge. If I can find a CFM/psi that is near my maximum readings I should be able to design an inline restrictor for the lower line that will match it to the upper intakes maximum intake CFM. Some of this I can do on the flow bench however most of it will require test drives and real world conditions to dial in. The closer I can keep the new, lower hose's readings to stock upper CFM/airbox psi readings the easier it will be for me to make a "one-size-fits-all" application that works for everyone as engine mods won't affect the CFM or PSI differentials of intake air. Only MPH can determine that. As long as I keep more PSI in the airbox than the car requires to run efficiently F/A-wise.
If I can bypass/forego the adjustable aperture on everyones car that will decrease the price by almost $200 as good quality bore-adjustable shutter-type apertures are a spendy item requiring the airbox be milled to accomodate as well as internal/external flanges be attached to facilitate installation.
Another interesting aside is that there is definate benefit to an internal velocity stack being used at the lower hoses outlet into the airbox. I never knew they worked better in reverse than a simple hose cut-off but there it is. Probably more related to air dispersion/diffusion than anything else.
This piece could easily be 2-3 months out especially if I have to have the inlet ducts cast specifically for the lower grill cut-out.
My next big project is re-working a stock airbox so that it will hold a 4-5psi charge of air for an hour without leak-down. Likely more than I'll ever need but if I can achieve it I know it'll hold whatever I throw at it once the system is assembled.