Doug.  Thanks for making a new topic out of this as it’s definitely the ‘cleaner’ way to keep this topic going.  And here are the links to both pages of the original thread that started this particular train of thought which can bring those persons up to speed that missed it.

http://www.y-blocksforever.com/forums/Topic23177-3-1.aspx

http://www.y-blocksforever.com/forums/Topic23177-3-2.aspx

Lorena, Texas (South of Waco)

Along the lines of this thread, I just remembered my uncles E code bird had the factory hood scoop lengthened about a foot or so forward down the hood. I remember him saying the steel was brazed in  back in the day, and they hammered out the entire hood afterward due to  heat warping. Not sure how well it helped with getting air to the carbs, or if he did it for the looks, but it did look cool and very unique. I will try and get a picture sometime this year to share.

I'm glad my lack of knowledge and continuous curiosity has proved helpful.  I'm in constant pursuit of a fun, fast car!  I need a new handle...  I'm not as rebelious as I used to be, everyone can call me John 

I think I'm going to change my plan and try the reverse scoop myself (since I already have the hole cut).  I'll post pictures as I get it fabbed up.

John: Lake Forest, IL



'57 Fairlane 500 - Looking better every day.

Wow, first, thank you Newpunk for asking your original question including the hood scoop dilemma background.  Ted answered your question, then your thread morphed into something more technical to relate to your disappointment in hood scoop function.

Your question and excellent responses by Doug, Steve and others has helped me to better understand why I need to make some changes.  The final configuration is not clear in my mind yet, but I know it is headed to the base of the windshield.

And thanks to Doug, Roy and others who directed their replies to me.

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

Well that is a hard question to answer .  Seriously I think it might be the preception that when you stick your hand out a window of a car going say 100 mph it generates a lot of force.  of course the pressure isn't high but the area that it is acting on is more than you might think.  Also there is the aerodynamic drag acting on your hand that we haven't considered in any of this discussion.

Yeah, forgot that part,  In case anybody's interested, Doug spent a number of years dealing with this issue in an industrial setting. He's a reformed (But NOT rehabilatated)  Mechanical Engineer. Might spend some time explaining the "goofy" hood scoop shapes we saw in the past.

Frank/Rebop

Bristol, In ( by Elkhart) 

First of all I am hoping the part of the thread about Karol Miller that ended up about air pressure and flow can be moved here so that everybody can find it again.

 "Re Doug, Would seem as though the inertia of the air would have more effect than the formula gives. What am I missing?       Pegleg"                                                                                                                      

Well that is a hard question to answer .  Seriously I think it might be the preception that when you stick your hand out a window of a car going say 100 mph it generates a lot of force.  of course the pressure isn't high but the area that it is acting on is more than you might think.  Also there is the aerodynamic drag acting on your hand that we haven't considered in any of this discussion.

Charlie

I think that the idea of sourcing the air for the carb from the base of the windshield is the way to go because most of the relevant experience seems to say that this is the highest pressure area that you can find.  Also doesn't your truck have sort of a visor over the windshield?  This is likely to increase pressure at the base of the windshield even more.

You might be able to get an accurate reading in the carb bonnet with a sloping tube manometer mounted across the direction of travel so acceleration doesn't effect it.  I think the only way to read it safely would be to video it while you do the driving!

The idea of smaller openings in forward facing hood scoops it likely correct because strictly speaking the small opening allows for what is called "Static Regain" by allowing the air to slow down and convert its dynamic pressure into static pressure.  So as long as the air velocity through the carb venturi's is much higher than the velocity through the scoop's hole there will be efficient static regain. BTW I hope everyone notices that Ted Eaton's hood scope meets all these criteria.   For a discussion of static regain look in a New York Blower book which discusses this topic a part of the discharge velocity of industrial fans.

Finally sloping tube manometers are easy to make with clear plastic tubing.  If you have a rise:run ratio of say 1:4 then 1/2" movement of the water along the slope will be 1/8"wg which is a pretty low pressure!

Doug T

The Highlands, Louisville, Ky.