Cowl induction benefits - Page 7 - Chevelle Tech
Chevelle Tech General Tech Area
Please try and post in specific forums

 93Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #91 of 125 (permalink) Old Jul 4th, 19, 10:38 AM
Tech Team
Harry
 
Join Date: Jan 2011
Location: Los Angeles
Posts: 314
Re: Cowl induction benefits

Quote:
Originally Posted by ranvette View Post
fishhead Any of those systems Ram air Cowl Induction Plymouth had a Air Grabber. All are ways of venting out side temp air to the the engine.Not so much the ramming effect is doing anything really.But if the engine can breath cooler air.Which all the fresh air systems accomplish.I would guess 5 to 10 Hp increase depending on how hot the under hood temps are running on a given day.I know Plymouth did rerate the 383 Magnum from 330HP to 335HP with the Air grabber option.5HP is not a big increase.But in very hot weather with high under hood temps the increase would be more on those days.
My open air cleaner is sealed to my Stock Chevelle Cowl induction hood. I did an unscientific test yesterday. It was 90 deg. outside and we drove the Chevelle to the lake. When we got there, I popped my hood and touched my valve covers and intake manifold. They were hot. I then, took off my air cleaner and touched the inside of my carb. - where the air travels. It was cool to the touch, surprisingly cool. Not very scientific, but, really kind of amazing. Note: if have my internal cowl gate open all the time , so, the cooler air from the cowl is constantly hitting my carb. from the rear of the hood -- even at low speed when the flapper is not open. I think there is a lot of benefit in the summer time keeping the internal cowl gate open (the one with the electrical connection to the gas pedal), it really keeps the carb. cool. It is easy to do, just loosen the clamp on the solenoid, bend the connection tab 90 degrees, then push the solenoid forward to open up the inner gate, then tighten the clamp. Disconnect the electrical at the gas pedal to save wear and tear on your solenoid.

Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
hjdca is offline  
Sponsored Links
Advertisement
 
post #92 of 125 (permalink) Old Jul 4th, 19, 3:45 PM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

I do think you have a good idea.No question that carb and intake is getting a fresh air draft the whole time you are moving.Tempting to do that to mine.But kinda hung up on the idea of it working as designed.Do you notice more intake noise when you roll into the throttle with it like that,I don't mean full throttle but like half throttle.just wondering if there is more intake noise
ranvette is offline  
post #93 of 125 (permalink) Old Jul 4th, 19, 5:33 PM
Tech Team
Harry
 
Join Date: Jan 2011
Location: Los Angeles
Posts: 314
Re: Cowl induction benefits

Quote:
Originally Posted by ranvette View Post
I do think you have a good idea.No question that carb and intake is getting a fresh air draft the whole time you are moving.Tempting to do that to mine.But kinda hung up on the idea of it working as designed.Do you notice more intake noise when you roll into the throttle with it like that,I don't mean full throttle but like half throttle.just wondering if there is more intake noise
No, I did not notice anything, but, my Chevelle is loud and my stereo is loud. From the driver's seat, I can see my air cleaner in the cowl with a strong flashlight. It is really incredible how cool my carb. is to the touch, and my valve covers are seriously hot. This is the ticket for the hot summer here in LA.

I have my Chevelle for a long time, and this is the first time I tried to keep the inner gate open all the time, usually it only opens at 1/2 to 3/4 throttle and more. I remember changing air bleeds after driving the Chevelle and the carb. being super hot... Now when I touch it, it is cool... Big difference.

Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
hjdca is offline  
 
post #94 of 125 (permalink) Old Jul 4th, 19, 6:04 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,677
Garage
Re: Cowl induction benefits

Quote:
Originally Posted by hjdca View Post
No, I did not notice anything, but, my Chevelle is loud and my stereo is loud. From the driver's seat, I can see my air cleaner in the cowl with a strong flashlight. It is really incredible how cool my carb. is to the touch, and my valve covers are seriously hot. This is the ticket for the hot summer here in LA.

I have my Chevelle for a long time, and this is the first time I tried to keep the inner gate open all the time, usually it only opens at 1/2 to 3/4 throttle and more. I remember changing air bleeds after driving the Chevelle and the carb. being super hot... Now when I touch it, it is cool... Big difference.
I unbolted that inner gate and boxed it for later sale or use. Where I live it's hot all the time. The cold air benefits me 100% of the time.
DUTCH MAX HEADWORK is offline  
post #95 of 125 (permalink) Old Jul 4th, 19, 6:08 PM
Lifetime Premium Member
Brian
 
Join Date: Apr 2000
Location: Holland, PA
Posts: 1,612
Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
I unbolted that inner gate and boxed it for later sale or use. Where I live it's hot all the time. The cold air benefits me 100% of the time.
Exactly how I’m running. I never installed the inner door or gas pedal switch when I added cowl induction.
DUTCH MAX HEADWORK likes this.

Team Chevelle Member (20 years and counting...
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
)


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

'72 Chevelle Convertible (Mohave Gold) (all SS options, no SS badging)
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


2004 Pontiac GTO (Quicksilver) RIP April 2013
--> Replaced with 2004 Pontiac GTO (Barbados Blue)

2003 Chevrolet Avalanche (Sunset Orange Metallic)
72soft-top is online now  
post #96 of 125 (permalink) Old Jul 4th, 19, 8:05 PM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

Really makes sense the door being functional.Would make more sense in cooler areas.I am in mass so hot now.But can be cool weather to.The car does love shots of 35 to 40 degree air before i put it away for the winter.
ranvette is offline  
post #97 of 125 (permalink) Old Jul 7th, 19, 1:07 PM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

RPO ZL2 Explained. And would apply to Chevelle as well. Best info i have seen

Steve's Camaro Parts - 1969 Camaro Super Scoop
ranvette is offline  
post #98 of 125 (permalink) Old Jul 7th, 19, 3:41 PM
Gold Founding Member
 
Join Date: Aug 1998
Location: 30.1298228, -97.9771166
Posts: 6,799
Garage
Re: Cowl induction benefits

Quote:
Originally Posted by ranvette View Post
RPO ZL2 Explained. And would apply to Chevelle as well. Best info i have seen

Steve's Camaro Parts - 1969 Camaro Super Scoop
It reads like a sales brochure not a technical piece.

The biggest problem facing America today is that lies are so widely accepted as truths.
Alan F is offline  
post #99 of 125 (permalink) Old Jul 7th, 19, 4:36 PM
Lifetime Premium Member
 
Join Date: Jul 2000
Location: Northeast New Jersey
Posts: 8,311
Garage
Re: Cowl induction benefits

To anyone who thinks the Chevy cowl induction hoods didn't work and were just for looks and nothing more than a gimmick to bring new people into the showroom read this that was copied and pasted from the provided link :

...............................THE COLD AIR THEORY .................................................. .

The principle of utilizing cold air induction was nothing new at Chevrolet. It was used in racing as far back as 1963 on the Chevrolet Z11 stock cars running on the NASCAR circuit and again with the "Plenum Air Intake" released as a special service option for the race-oriented 1968 Z/28s. Rather than using a raised hood panel like the 1969 RPO ZL2 option, the first two designs drafted cold air from the base of the windshield under the hood via a special air cleaner and duct, much like the NASCAR racers of today.

Chevy engineer Doug Roe, who worked with Product Promotions chief Vince Piggins, found a dramatic performance gain by taking the cool dense air at the high pressure area near the base of the windshield. Ducting pressurized fresh cold air from this area to the carburetor creates a more dense fuel charge with increased volumetric efficiency resulting in more horsepower An approximate 1% horsepower increase is gained for every 11 degree drop in temperature providing the mixture is adjusted accordingly. That means if your engine has a gross horsepower rating of 350, a drop of 43 degrees would net you an additional horsepower increase of 4%, equal to 14 hp, for a total of 364 hp. These gains are typical, since under hood temperatures in normal conditions are relatively hot, and under racing conditional even hotter. Therefore, given the temperature differential of under hood and outside the hood along with pressurized unrestricted air flow, it is not unreasonable to expect this type of power gain at the upper levels of engine performance.

The reverse drafting method used on the special ZL2 hood was chosen over forward facing scoops which create greater pressures and increased ram effect but have problems associated with air turbulence at the carburetor air horn. Turbulence causes uneven pressures within the metering bodies and upsets correct air/fuel ratio and delivery. Correcting this type of system is involved and not worth the insignificant power increase the additional pressure affords.

.................................................. .................................................. ..............................
end of C & P .........................................
While I agree that the Cowl Induction hoods on both the Camaro and the Chevelle are designed to catch people's eye and draw them into the showroom but the science on them works to add additional HP just by adding the CI hood. The Chevy engineers actually turned down the forward facing scoops as it creates carb mixture problems that must be corrected before any gains can be had.
hydro462 likes this.

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
"I would rather have questions I can't answer than have answers I can't question" :R.Feynman
71350SS is offline  
post #100 of 125 (permalink) Old Jul 7th, 19, 8:26 PM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

Yup ZL2 does add power (From GMs own mouth).It does not look like they rated the camaro as having more power with ZL2 either.That may have been so they did not have to re certify for emissions. And Insurance company's started playing with increaseing rates than to over HP numbers.In 1972 i remember it costs me $450 a year for option 1 coverage 100 deductable on a 1970 SS with a 396. That was a lot of money than
ranvette is offline  
post #101 of 125 (permalink) Old Jul 7th, 19, 8:42 PM
Gold Founding Member
 
Join Date: Aug 1998
Location: 30.1298228, -97.9771166
Posts: 6,799
Garage
Re: Cowl induction benefits

Thanks for posting what I had already read. It gives me an opportunity to dissect it. I will distill the technical merit of this...
Quote:
..............................THE COLD AIR THEORY .................................................. .
Chevy engineer Doug Roe, who worked with Product Promotions chief Vince Piggins, found a dramatic performance gain
Term not defined but clearly marketing inspired.

by taking the cool dense air at the high pressure area near the base of the windshield.
"Cool" is a relative term, not an absolute. Large temperature differentials are required to make full effect of the air.

Ducting pressurized fresh cold air from this area to the carburetor creates a more dense fuel charge with
Misleading that it is pressurizing the plenum.

increased volumetric efficiency resulting in more horsepower
More advertising buzz.

An approximate 1% horsepower increase is gained for every 11 degree drop in temperature
generally accepted knowledge among hotrodders. However nothing indicates that this is the result from this apparatus.

providing the mixture is adjusted accordingly.
If these cars are properly tuned in the first place, it requires more fuel to get that extra horsepower. If it's true then the mixture should lean out. When does the mixture get adjusted? It doesn't.

That means if your engine has a gross horsepower rating of 350, a drop of 43 degrees would net you an additional horsepower increase of 4%, equal to 14 hp, for a total of 364 hp.
There is not any correlation to whether CI can actually deliver a 43 degree drop (in stock form on a hot enough day).
Where is gross horsepower and how often do you use it on a drag strip? On most street cars you see it ONE TIME when you shift. Noone I know runs our cars on a circle track at peak RPM for extended periods to take advantage of the CI.

These gains are typical, since under hood temperatures in normal conditions are relatively hot, and under racing conditional even hotter.
Failed analogy.

Therefore, given the temperature differential of under hood and outside the hood along with pressurized unrestricted air flow, it is not unreasonable to expect this type of power gain at the upper levels of engine performance.

Oh really? With the heat radiating off the glass and hood, especially on dark colors, and the interference of the outer flapper, the inner flapper, lack of significant seal, etc, etc.
Just having fun. I love cowl induction but don't expect anything from it (given my use) other than entertainment.

The biggest problem facing America today is that lies are so widely accepted as truths.
Alan F is offline  
post #102 of 125 (permalink) Old Jul 8th, 19, 6:55 AM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

Cowl induciton Demonstration, air flow, proof of concept


ranvette is offline  
post #103 of 125 (permalink) Old Jul 8th, 19, 9:05 AM
Gold Founding Member
 
Join Date: Aug 1998
Location: 30.1298228, -97.9771166
Posts: 6,799
Garage
Re: Cowl induction benefits

Quote:
Originally Posted by ranvette View Post
Cowl induciton Demonstration, air flow, proof of concept


Cowl induciton Demonstration, air flow, proof of concept - YouTube
All that is being demonstrated is there is air flowing in to the cowl area, which was never in dispute in the first place. The rest is speculation about what’s happening and hyperbole about results. If it was creating any kind of velocity the strips wouldn’t be flapping inside.

It really is a disservice to everyone when someone posts myths about gaining a second and a half in the quarter mile because of cowl induction.

The biggest problem facing America today is that lies are so widely accepted as truths.
Alan F is offline  
post #104 of 125 (permalink) Old Jul 8th, 19, 9:22 AM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

I dont think anyone gains 1.5 secs.I would buy maybe a tenth or 2. I just picture a outside air draft entering the air cleaner.If the electric door is open.Kind of like a fan on low speed.Just enough to get a breeze of outside air if the car is moving.I also see ZL2 was a low build item to only around 10,000 in Camaro and around 30,000 in chevelle.
ranvette is offline  
post #105 of 125 (permalink) Old Jul 9th, 19, 8:11 AM
Tech Team
 
Join Date: May 2005
Posts: 390
Re: Cowl induction benefits

I used 3 pieces of ribbon on my car last night.I taped them center and left and right sides on the hood cowl screen.What i noticed was they were drafted into the cowl.Flapping lightly on the screen.This started around 30 MPH.At about 50MPH i went to full throttle.The car is a auto.All 3 pieces of ribbon were pulled tighter and flat to the screen with electric door open and the engine at full throttle.Vac door was slightly open.So there is a noticeable amount of air entering the open door.It was 85 here last night.So i am sure under hood the air was 0ver 150.Have no idea if i am making more power.But there for sure is outside temp air going in the engine.Under the conditions i tryed it at.
ranvette is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Trying to track down additional 1972 SS 454 Real "W" Convertibles skryla Convertibles 728 Feb 21st, 18 2:22 PM
Cowl induction hood versus non cowl induction appearance mersol Body Shop 11 Jan 17th, 17 11:32 PM
New to Forum w/1972 SS 454 4 Speed Vert elliet1964 New Member Introductions 14 Aug 7th, 16 6:00 PM
70 Chevelle Cowl Induction Hood jjr158 Troubleshooting 24 Sep 24th, 15 8:12 PM
issues with cowl induction on 72 Chevelle 69Chevelle396/375 Troubleshooting 3 Sep 2nd, 13 9:00 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome