Hood scoop/ pressure question

Shocks, Springs, Brakes, Frame, Body Work, etc

Moderator: Team

sgcuda
New Member
New Member
Posts: 5
Joined: Sat Feb 10, 2007 10:14 pm

Hood scoop/ pressure question

Postby sgcuda » Sat Jul 08, 2017 3:35 pm

Running a dual 850 setup on a tunnel ram 500 cid Mopar. Planning on running low 8's. I put an old school snorkel on top that has 2 1" tall half moon baffles, 1 in front of each carb. Snorkle opening is 2 x 13. I have been told that a couple of pressure relief holes on the backside of the snorkel would help the airflow into the carbs. I have seen this done on street engines, but never on a full drag race car. Opinions?

Greenlight
Pro
Pro
Posts: 377
Joined: Wed Feb 16, 2005 10:37 pm

Re: Hood scoop/ pressure question

Postby Greenlight » Thu Jul 27, 2017 2:47 pm

A properly designed air scoop will always perform the best when it is sealed and the pressure inside is the highest possible. A properly designed air inlet system converts high velocity low pressure air to low velocity high pressure air (a very small supercharger). Proper sizing of the inlet and shape of the scoop, will determine whether or not the air scoop provides an overall ET gain.

An improperly designed air scoop MAY perform better with reduced pressure (i.e. add holes in the back).
Project Greenlight

User avatar
panic
Guru
Guru
Posts: 1874
Joined: Sat Dec 11, 2004 12:04 pm
Location: Ecbatana
Contact:

Re: Hood scoop/ pressure question

Postby panic » Fri Jul 28, 2017 3:24 pm

X2
The pressure/speed conversion is simply the X-area of the entry vs. the X-area directly above the air-horn, and enough distance from A to B and volume for the conversion to take place.
Remember that terminal speed determines entry size: faster = smaller.
There's probably a ratio for both, but I don't have them. The SCTA site does: http://www.landracing.com/forum/index.p ... 718.0.html
Ideally, the air entry would resemble the dynamic cone retraction mask used on the SR71, which restricts the area at speed while retaining a streamlined shape.

BirdMan
Expert
Expert
Posts: 600
Joined: Mon Jan 19, 2009 11:19 am
Location: Topeka, KS

Re: Hood scoop/ pressure question

Postby BirdMan » Wed Aug 16, 2017 3:14 pm

My son and I used small clear tubing attached to hood at various locations and heights. We had several at a time and the tubing faced forward on the hood and inside the car made vertical manometers with colored alcohol/water mix. We taped the tubing onto a board/cardboard and after positioning/attaching the board we marked 0 (where the level was at rest, like the flow bench ones) and drove the car on the interstate at varying speeds and with/against the wind to determine the location for the scoop opening of our handmade thin alum scoops, my car still has it on it and will be on it when I convert to street driving but with an air filter somewhere to get clean air.
Rich in Dads2 41605.jpg
Dale C.


Return to “Chassis / Suspension / Body”

Who is online

Users browsing this forum: No registered users and 2 guests