Radiator air flow experiment
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
you called it...
Originally Posted by Star79
I'm just thinking back to Rich's "tuft" tests. At speed, his car (okay all our cars) is taking air IN from:
the cowl
the side vents
the grills/front/below the spoiler (obviously)
So where is all the air GETTING OUT? Other than a couple hundred CFM that's getting inhaled/combusted, I'd guess that most of it is leaving through the bottom of the engine compartment, then below the car and out the sides??
I dunno, is all this getting-more-air in just increasing the high-pressure area under the car? That can't be good for high-speed stability/aero.
the cowl
the side vents
the grills/front/below the spoiler (obviously)
So where is all the air GETTING OUT? Other than a couple hundred CFM that's getting inhaled/combusted, I'd guess that most of it is leaving through the bottom of the engine compartment, then below the car and out the sides??
I dunno, is all this getting-more-air in just increasing the high-pressure area under the car? That can't be good for high-speed stability/aero.
On your scoop, you've limited yourself to a given opening area, that can only increase preassure in that small area at speed. I would recommend losing the bottom and moving the side "fences" outboard. You'r trying to keep the high pressure air from "spilling" out the sides, and your deep spoiler will force air up and in, increasing pressure a bunch if the 'fences' are correct for your car.
At low speeds (under 15-25 MPH) none of this matters, it's all fan and radiator. With A/C, it's especially important that you vent effectively, but either way, get ready for a hot floor!
Hans
Thread Starter
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by ESU
Maybe I should take those 2 10 inch electric fans I was using for the radiator and move them to the two openings behind the front wheels to help remove hot air from the engine compartment?????
ESU
ESU
Thread Starter
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by Star79
I'm just thinking back to Rich's "tuft" tests. At speed, his car (okay all our cars) is taking air IN from:
the cowl
the side vents
the grills/front/below the spoiler (obviously)
So where is all the air GETTING OUT? Other than a couple hundred CFM that's getting inhaled/combusted, I'd guess that most of it is leaving through the bottom of the engine compartment, then below the car and out the sides??
I dunno, is all this getting-more-air in just increasing the high-pressure area under the car? That can't be good for high-speed stability/aero.
the cowl
the side vents
the grills/front/below the spoiler (obviously)
So where is all the air GETTING OUT? Other than a couple hundred CFM that's getting inhaled/combusted, I'd guess that most of it is leaving through the bottom of the engine compartment, then below the car and out the sides??
I dunno, is all this getting-more-air in just increasing the high-pressure area under the car? That can't be good for high-speed stability/aero.
I think this continued at speed...
Thread Starter
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by fauxrs2
Alas on the 78 and all the rubber nose cars I imagine... there is a big fat steel plate that is hidden behind the eurathane that is our legal 5 mph bumper...it is bracketed and welded to the frame.. so no opening that up 
Melting Slicks
Joined: Apr 2004
Posts: 2,083
Likes: 2
From: Montreal Qc.
Originally Posted by rihwoods
The front spoiler restricts air going under vette and creates downforce..when I did the yarn tuft test,I was not able to get photos of air at side vents except at idle,and air was coming out....
I think this continued at speed...
I think this continued at speed...
(at least that's what I remember reading, I could be mistaken).
On the other topic, I bet Norval doesn't have that big heavy metal plate behind his license plate anymore. I also thought about taking that out/off somehow and adding a pre-72 style center grill/intake. Nothing the ol' plasma-cutter couldn't remedy.
Thread Starter
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by Wrencher
This is correct. Most of the air exits under the car. The early Gran Sport C-3's solved the preasure problem by using tons of louvers. The most effective vents fot C-3's are the big '68-69 side gills, but only if you remove all the "obstructions" (vac tank, coolant tank, heater hoses, etc) like the LeMans cars.
On your scoop, you've limited yourself to a given opening area, that can only increase preassure in that small area at speed. I would recommend losing the bottom and moving the side "fences" outboard. You'r trying to keep the high pressure air from "spilling" out the sides, and your deep spoiler will force air up and in, increasing pressure a bunch if the 'fences' are correct for your car.
At low speeds (under 15-25 MPH) none of this matters, it's all fan and radiator. With A/C, it's especially important that you vent effectively, but either way, get ready for a hot floor!
Hans
On your scoop, you've limited yourself to a given opening area, that can only increase preassure in that small area at speed. I would recommend losing the bottom and moving the side "fences" outboard. You'r trying to keep the high pressure air from "spilling" out the sides, and your deep spoiler will force air up and in, increasing pressure a bunch if the 'fences' are correct for your car.
At low speeds (under 15-25 MPH) none of this matters, it's all fan and radiator. With A/C, it's especially important that you vent effectively, but either way, get ready for a hot floor!
Hans
Good point also about the "hot floor"....I did not think to take Raytek readings today....but I will tomorrow..also, I'm ordering shields for the exterior footwells like on my 69.which has much lower temps than the 78 at interior footwells..
Thread Starter
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by Star79
Didn't you say that after you stopped, all the yarn had been sucked in?
(at least that's what I remember reading, I could be mistaken).
On the other topic, I bet Norval doesn't have that big heavy metal plate behind his license plate anymore. I also thought about taking that out/off somehow and adding a pre-72 style center grill/intake. Nothing the ol' plasma-cutter couldn't remedy.
(at least that's what I remember reading, I could be mistaken).
On the other topic, I bet Norval doesn't have that big heavy metal plate behind his license plate anymore. I also thought about taking that out/off somehow and adding a pre-72 style center grill/intake. Nothing the ol' plasma-cutter couldn't remedy.
You may be thinking of the yarn I had just behind the rear window.. ???
They were being "sucked in" towards window at 40 mph...
Rich
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Thread Starter
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Here is the yarn thread....
http://forums.corvetteforum.com/show...highlight=aero
Here is one pic from JPhil's yarn test at 65 mph....note yarn blowing out of side vent..interesting is turbulent air in front of vent..at least it appears that way....the 78 vettes have a flair just at front of side vent....maybe that causes the turbulance..???
And one stopped to illustrate his placement of yarn..
We dubbed his vette "Stringray"......
Rich
http://forums.corvetteforum.com/show...highlight=aero
Here is one pic from JPhil's yarn test at 65 mph....note yarn blowing out of side vent..interesting is turbulent air in front of vent..at least it appears that way....the 78 vettes have a flair just at front of side vent....maybe that causes the turbulance..???
And one stopped to illustrate his placement of yarn..
We dubbed his vette "Stringray"......
Rich
Last edited by rihwoods; Aug 16, 2006 at 01:02 AM.
