external intake duct

[Tango Charlie]

A coworker of mine years ago rigged a funnel sticking out the front of his grille and ran a length of SCAT tube to the air cleaner. A mid 80's Tercel, if memory serves. He claimed it had more oomph for passing at highway speeds. Neither he or I had any interest in FE back then. He got the idea from the old Mooney M20 we used at the time for flight instruction. It had a knob on the instrument panel labeled "boost" or some such. It opened a door on the front of the cowling behind the prop and bypassed the air cleaner.

[Tesla]

Did a bit of a run checking pressures with my "special" home made U tube, the intake duct vacuum between filter & turbo is more than twice the magnitude than the positive pressure at the front of vehicle when cruising, and under hard acceleration it goes off my scale, so no real concerns about pressurizing the crankcase, there just won't be quite as much vacuum.
Just got to finalize the pathway and get some materials to do a proper trial.
Is anyone out there curremntly running a "Ram" air set up?
I have an external snorkle with a larger head on it and thought it may have given a better result than I discovered.
Obviously volume flow is the issue, you need a big supply of pressurized air to feed the intake system.

[bandit86]

Read abou a guy on the net who ran several 2 or 3 inc intakes into a Dodd spirit turbo. He claims 2 large pipes by the airdam were the most efficient, any more did not make a difference.

My thought. Get a 6 inch PVC pipe. Cut in half. Mount to front of car under bumper facing forward like a snowplow. Will act like a airdam. On the ends have them blocked, drill a 4 inch hole and duct both 4 inch hoses into the airbox.

[Tesla]

Have completed the external ducted intake, so now air to the filter is from the pressure area at front of vehicle, cruising at around 95km/hr on a flat road the filter box is basically at cabin pressure, when accelerating it goes to slight vacuum and when coasting it is slightly pressurized.
Don't know if it will help fuel economy figures, but it definately has improved accelerator response, the vehicle had distinct turbo lag, which emphasised the truck like lurching when going through the gears, i.e push pedal down, count to three, feel the kick, this has nearly gone and accelerator response is almost immediate. It also seems like less pedal is needed to do the same job, the vehicle just feels a lot more drivable.
I have read a lot of the old threads on intakes here so it will be interesting to see if there is an improvement in economy or if it will just be a gain in power and response.

[Tesla]

Over the last 150 L fuel usage has gone down from 11.4 to 10.7l/100km, just over 6% improvement, that's a pretty good result I think & I suspect the actual will be even greater as I was doing quite a bit of eratic testing over the period.
The above figure does also include some other mods as well, which have been going on before & during the 150L period, front airdam, some undertray work, and some on front wheel arch covers, but I think at least 1/2 can go to the air intake.