I've always heard that intake tubes to the front at least get air that has not been heated in the engine compartment. I have been told that the cooler air charge simply makes horsepower! My 56 has a large K&N filter piped from in front of the radiator. I'm sure there is some specific science involved but I'll leave that up to you guys. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I was able to promote a low pressure manometer from a buddy. 3/16 id tubing inlet. Since my car is a heater delete, I pulled the cap on the original heater fan duct, capped it with cardboard, and taped the tube in the middle. On the inH2O scale, I got about .5 inches at 30mph, .75 at 40, and 2.0 at 65. That was down in a little valley, when I crested the hill and caught a little breeze, it spiked to 3. Not very scientific, and I'm not really sure how I should do this. Given its water, it's not much pressure at street speeds, but maybe cooler air? And it doesn't look linear to me.



With the tube poked thru the triangler hole next to the hood hinge, I got about the same on the trip home. Electric fan off.



Steve, if you want to try it with your scoop set up, let me know and I'll send it down. I know you know more about testing and engineering than I do.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

John's HH is ducted from the heater plenum, ala NASCAR.

Frank/Rebop

Bristol, In ( by Elkhart) 

Yeah - and I was thinking of the double ducted set-up on the '56 T-bird of Speedpro56 too. The front bulkhead where the radiator mounts must build a bit of speed "air compression". The two snorkle inlets attach to the front - and the top seals to the hood? That's how it appears in the photos I've seen.

 
 Steve Metzger       Tucson, Arizona

Check the intake arrangement on the Hoosier Hurricane some time.

Frank/Rebop

Bristol, In ( by Elkhart) 

There is an anecdote from Smokey Yunick's autobiography re: high speed testing of one of his stockcar racers. They used to tape a cover over the heater duct outlet under the dash (fed from the intake behind the windshield). Once, at top speed, that panel blew out with explosive force.

Seems like plumbing THAT duct to the aircleaner should have a noticeable effect?

6 VOLTS/POS. GRD. NW INDIANA

Many years ago someone, I think Hot Rod, did an article on that. The "engineeringtoolbox" site gives 1 lb pressure as 27.7 inches of water. They had a 3 foot board propped up from the tunnel to the dash, and had the passenger take readings as they taped the end of the tube in various places around the car, outside. As I recall (after 35 years or so, ha), they confirmed the use of air intakes around the base of the windshield, facing aft, or a scoop as you describe with an intake above the hood boundary layer/turbulence, etc. Couldn't really find a pressure effect, so much as clean, undisturbed, air flow. Most air scoops seemed to end up in disturbed, or negative pressure flow. I don't have the engineering knowledge to evaluate any of this.



After removing the supercharger I resurrected an old 55 repop air cleaner that was made as a dry element. I had cut the whole bottom out of it, and attached the top to the body, converting it to a cover for an open element air cleaner ( I had an old base to set the small dry element on the carb). What little I can find seems to indicate that these have about half the filter area required for a 312 at 5000 rpm. I'm still working on that for a solution.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Daniel - I've got a device my outfit used to use to check inlet and outlet temps of big mill motors. It has a pair of thermocouples that are designed to be used in an air-stream situation and I dangled one right down in the carb throat. It has some interesting uses - but doesn't have a way to make a paper or electronic record (the reason its been replaced with a better instrument). Holley publishes data that says the HP goes up one for every ten degrees the inlet air temperature drops so I became interested in feeding my motor something besides air from the radiator.

I don't have a manometer but a guy could probably make one with a "U" tube and distilled water to check out the pressure situation. I have a sneaking suspicion that the only gain the T-bird scoop can give you is a temp drop (in ordinary use) - and not too much in the way of pressure. There is a photo around of a Bonneville bird where they put an extension on the scoop that led clear out over the leading edge of the car - it probably reaches higher pressure there when the ground speed gets "up there". 

 
 Steve Metzger       Tucson, Arizona

Steve,



Interesting setup. Since you have obviously managed to measure the air temp in the scoop-fed airtight space you have created, I wonder how hard would it be to measure air pressure also? I'm thinking there must be a minor supercharging effect at high speed (?).

6 VOLTS/POS. GRD. NW INDIANA

Yeah Al - I was thinking about that rubber substitute myself. My intentions for the dry airfilter are mostly to put on the car when its static. The air pan intake version (sealed to the hood scoop) that I use for driving around drops the inlet air temperature by 60°-80°. It goes on (and off) with a single fastener and is easily exchanged for the "right" part when she's stopped with the hood up.

 

Arizona being the location it is, you can imagine the temp in the carb throat on a 106° day like today.....sometimes I'll swear the radiator is cooling the air passing through it rather than heating it.

 
 Steve Metzger       Tucson, Arizona