Educate Me On Hood Scoops

[71GSSDemon]

So, I was looking into hood scoops for my Charger build. Currently running a 383ci NA.   Rules say 11" high, can start at the leading edge of my hood at stop short of the windshield (distance depends on whether it is forward facing scoop (1/2") or rear facing (2"))).  If a cowl induction style scoop would be used, rule state it has to be completely open at the back.  This is a tremendous amount of air getting forced into the engine compartment.  The engine alone would not likely consume all of the air at speed and bunch up, causing high drag.  For a forward facing scoop it doesn't mention inlet size.  It seems to me, an 11" tall, hybrid cowl style scoop with a forward facing inlet, sealed to the intake pan, would be the best of all styles, seeing that I can then size the inlet and be within 1/2" of the windshield.... yes?

[deepindebt]

This is a subject that will make your head hurt, lots of black magic on inlet size. Also the air box and what takes place in it will also make your head explode. Lots of smart guys that will be willing to help out. Good luck!

[Rex Schimmer]

After building several scoops that "looked right" but didn't work we hired Dave Woodward, Woody, at Design Dreams to design one for us. It took me a month to build it but It works! and with some better sealing to the engine air box it should be better. You can find Woody's contact info on the Landracing web site.

Rex

[71GSSDemon]

This is a subject that will make your head hurt, lots of black magic on inlet size. Also the air box and what takes place in it will also make your head explode. Lots of smart guys that will be willing to help out. Good luck!

I know all of the aero is black magic.  It hurt my head typing it... 

[71GSSDemon]

After building several scoops that "looked right" but didn't work we hired Dave Woodward, Woody, at Design Dreams to design one for us. It took me a month to build it but It works! and with some better sealing to the engine air box it should be better. You can find Woody's contact info on the Landracing web site.

Rex

Thank you for the reply.  I will check it out.

[panic]

What top speed do you anticipate reaching?
As the speed goes up, the inlet size goes down, but may be inadequate for launch.

[71GSSDemon]

What top speed do you anticipate reaching?
As the speed goes up, the inlet size goes down, but may be inadequate for launch.

For me, the ultimate goal will be 200mph, but I was more looking right now for thoughts on forward facing vs cowl induction vs the rules.  Like in my original post (below) is the added air (close to 5x what my engine can consume) worth any aero advantage of getting air up over the windshield.  I did a mock up and it appears the scoop would be a few inches short of the roof which makes me think air will make a sudden change, likely increasing downforce at the top of the windshield but then may be very dirty over the roof, back window and rear spoiler.  This to me would be a disadvantage over a lower scoop.

Rules say 11" high, can start at the leading edge of my hood at stop short of the windshield (distance depends on whether it is forward facing scoop (1/2") or rear facing (2"))).  If a cowl induction style scoop would be used, rule state it has to be completely open at the back.  This is a tremendous amount of air getting forced into the engine compartment.  The engine alone would not likely consume all of the air at speed and bunch up, causing high drag.  For a forward facing scoop it doesn't mention inlet size.  It seems to me, an 11" tall, hybrid cowl style scoop with a forward facing inlet, sealed to the intake pan, would be the best of all styles, seeing that I can then size the inlet and be within 1/2" of the windshield.... yes?

[Sumner]

Some more thoughts....

https://purplesagetradingpost.com/sumner/bvillecar/bville-scoop%20info-1.html

...and a spreadsheet here....

https://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html

It is also where that inlet is in the approaching air stream.

Sumner

[71GSSDemon]

Some more thoughts....

https://purplesagetradingpost.com/sumner/bvillecar/bville-scoop%20info-1.html

...and a spreadsheet here....

https://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html

It is also where that inlet is in the approaching air stream.

Sumner

Thank you sir, I will check it out

[John Burk]

An air inlet on the nose of a streamliner or lakester sees peak air pressure for that speed at all speeds and doesn't need to be a certain size . On the leading edge of a wing or a body with that shape it's a line rather than a point . A little away from that point the it's a percentage of peak pressure so a big inlet on a small body wouldn't get 100% pressure .

[John Burk]

Not having any luck copying and pasting with my new laptop . If somebody went to -Bonneville Motorsportsinnovations.com and scrolled down 11 lines they could post a photo of my air inlet like I described .

[WOODY@DDLLC]

For some unknown reason my webpage is down but here is a link to an article I did on scoops a few years back.
Scoops are simple: Pg 22 https://engineprofessional.com/2014EPQ2/
This one turned out pretty well....

[71GSSDemon]

Thanks guys. This is all great stuff