How well does a Cowl Induction system work?

[Andrew McBride]

You know this may be a dumb question to ask but I really have always wondered how great the benefits are to using a cowl induction system like the old DZ 302 Z's. What kind of benifits does this allow. Any pro's and con's. Was it a system that was designed more for looks and had a little to no effect? Just curious.

Andrew

[MrQuick]

Well its cheap, no cowl hood needed, and its the best air you can get. That area has very high pressure and its all clean air.
The bad...combustion/fuel smell with ac or vents on.
Loss of vent pressure in car.
Cuting a hole in your fire wall might be a down side for some.
Nascar still uses this style set up, Im not sure why GM didn't use it more.I guess they liked the look of the hood??

[rocketrod]

Check out CarlC website he has some info on a homegrown cowl setup. You may also want to look into a Ram Air Box, http://www.ramairbox.com/ It basically use is sits on the base plate of your existing air cleaner and you have two inlet tubes feeding it cool air from the front of the car. While this setup does not require you to cut holes in the firewall the inlet tubes do take up quite a bit of space. As for performance you will increase with either, but it will vary depending upon your application.

[Tom Welch]

Cowl induction systems work well if put together properly, drive a non a/c car that has cowl venting an open a vent in the footwell. The air flow is amazing. The base of the windshield, where the cowl vents are located is a high pressure area on all cars. If you do cut the firewall be sure to seal the cowl induction to the cowl and the cowl vent. If you dont do this all sorts of heat and motor smell comes in for the ride. I believe that 67 Z/28's had a cowl induction that was not part of the hood but went from the air cleaner to the cowl just below the hoodline.

[David Pozzi]

David Viszard did a temperature test on a "Fresh Air" hood, and the air cleaner housing with rubber seal didn't make a measureable difference in air temps at the carb. The hood alone blows cold air down on the carb and intake. He found the hood did a lot but a cool air snorkel connected to the cowl would probably yield the same results. Ram air pressure isn't supposed to be a significant factor. The cool air IS a big deal.

The cowl air inlet was done on a Chevelle by Smokey Yunic before GM did the Camaro.

[toofun]

Unless I am reading this wrong I think he is asking what the difference between the z28 smokey yunick design air induction is compared to the cowl hood induction system. I can tell you that the reason they went to a cowl induction system is because they had to retain the STOCK HOOD. IMHO The cowl induction system with the cowl hood is much more efficient than the firewall induction system. With the design of the cowl hood and windsheild, the air flowed alot better with this design rather than at the vent through the firewall approach. I believe Jody made a home made cowl induction pan that was totally sealed to the hood without the extra snorkle. It looked awesome and he said that when you kicked it, you could literally hear the air being sucked into the induction system. Anyway you slice it, you can definately feel a difference on those cold crisp new england days!! Ram air is good for colder air but the RAM AIR EFFECT doesnt really play a part until you reach speeds of over 120 mph so Ive been told.

LOVE THIS TAG!!!!

[chicane67]

The 'hood' system starts to become effective around 35+ MPH by providing good clean but more importantly, cooler air.

Most aero dynamic device's attached to a first gen Camaro (spoliers and such) dont really have a measureable effect until about 75 MPH. The hood however is fed by the positive pressure created at the base of the windshield. I remember from years back, that at around 90 to 100 MPH, the pressure is around 0.87 or 0.89 as measured around the base of the windshield...... from the base of the windshield to 9 inches up and around 13 to 16 inches wide is where the highest recorded pressure is from. Mind you that this would be effected by the rake of the chassis.....