How cold is the cold air (intake question)?
Thread Starter
Instructor
Joined: Oct 2001
Posts: 196
Likes: 0
From: Cary, NC
How cold is the cold air (intake question)?
I'm trying to decide between the Vortex and the Blackwing intake.
I like that you don't need to cut the shroud with the Blackwing, and that they now have a cover you can add later for cold air if you want.
But both together are more $$ than the Vortex.
So, if I plan to cut the shroud eventually, I might as well do it now with the Vortex.
A couple of questions:
'Why' is the air on one side of the shroud colder than the other, and 'how much' colder is it?
Have any of these companies put thermometers on each side of the shroud and driven around to see what the difference actually is?
How many degrees would be considered significant?
If it's only a few degrees, I'll probably just go with the Blackwing, but if there's a major difference, it might be worth it to cut the shroud.
Thanks.
I like that you don't need to cut the shroud with the Blackwing, and that they now have a cover you can add later for cold air if you want.
But both together are more $$ than the Vortex.
So, if I plan to cut the shroud eventually, I might as well do it now with the Vortex.
A couple of questions:
'Why' is the air on one side of the shroud colder than the other, and 'how much' colder is it?
Have any of these companies put thermometers on each side of the shroud and driven around to see what the difference actually is?
How many degrees would be considered significant?
If it's only a few degrees, I'll probably just go with the Blackwing, but if there's a major difference, it might be worth it to cut the shroud.
Thanks.
Racer
Joined: May 2000
Posts: 405
Likes: 1
From: Dallas
Re: How cold is the cold air (intake question)? (FarmerBob2001)
With the vehicle in motion, the temerature differential if often 15-25F in stock form. With the blackwing cover, it is often 0-3F.
VERY roughly, you get about 1% more HP for every 10 Degrees of temperature reduction. The gain is not huge, but it should not be ignored if you are seeking gains agressively at all.
More exactly, the SAE HP correction calculation is:
CF= 1.18 * (29.22/Bdo) * ((Square Root(To+460)/537)) – 0.18)
To = Intake air temperature in degrees F
Bdo = Dry ambient absolute barometric pressure
CF = Correction Factor
Correction is normalized (relative to) 77F.
VERY roughly, you get about 1% more HP for every 10 Degrees of temperature reduction. The gain is not huge, but it should not be ignored if you are seeking gains agressively at all.
More exactly, the SAE HP correction calculation is:
CF= 1.18 * (29.22/Bdo) * ((Square Root(To+460)/537)) – 0.18)
To = Intake air temperature in degrees F
Bdo = Dry ambient absolute barometric pressure
CF = Correction Factor
Correction is normalized (relative to) 77F.
Thread Starter
Instructor
Joined: Oct 2001
Posts: 196
Likes: 0
From: Cary, NC
Re: How cold is the cold air (C5 Tweaker)
OK. So, a cold air intake will give a few % more HP assuming a 20 degree difference. I assume the more modified your engine, the more HP you gain (the % applies regardless of the baseline?).
So, does anyone know 'why' the air under the shroud would be 20 degrees cooler? I mean, unless the air above the shroud is coming through the radiator or from the exhaust manifolds, what would make it hotter than the air under the shroud? Moving air isn't cooler because it's moving.
So, does anyone know 'why' the air under the shroud would be 20 degrees cooler? I mean, unless the air above the shroud is coming through the radiator or from the exhaust manifolds, what would make it hotter than the air under the shroud? Moving air isn't cooler because it's moving.
Drifting
Joined: Apr 2001
Posts: 1,773
Likes: 0
From: Norman Oklahoma
Re: How cold is the cold air (FarmerBob2001)
The reason outside air would be colder is because the inside air is from inside the engine comparment. The engine obviously creats heat and the air around it is hotter. Another advantage to cold air intakes is the ram air effect you get from them. I decided on the Blackwing for 4 reasons. 1) I didn't want to cut anything 2) I didn't like the risk, even if it is small, of hydrolock 3) I don't like the way the Vortex looks and I didn't want to spend that much for a Haltech 4) the hp differences are small :cheers:
Jerry
Jerry
Thread Starter
Instructor
Joined: Oct 2001
Posts: 196
Likes: 0
From: Cary, NC
Re: How cold is the cold air (99 Corvette)
So, the air under the shroud is coming from outside the car, and the air above the shroud is coming from the engine bay.
Cool. That answers my question. Thanks.
I haven't had time to crawl around the engine bay/under the car to try and figure that out.
Now I just need to make up my mind on which intake to get..
Cool. That answers my question. Thanks.
I haven't had time to crawl around the engine bay/under the car to try and figure that out.
Now I just need to make up my mind on which intake to get..
Le Mans Master
Joined: Oct 2001
Posts: 6,710
Likes: 2
From: Southern California
Re: How cold is the cold air (FarmerBob2001)
So, does anyone know 'why' the air under the shroud would be 20 degrees cooler? I mean, unless the air above the shroud is coming through the radiator or from the exhaust manifolds, what would make it hotter than the air under the shroud? Moving air isn't cooler because it's moving.
Safety Car
Joined: Oct 2000
Posts: 4,949
Likes: 10
From: Monticello MN
Re: How cold is the cold air (intake question)? (FarmerBob2001)
[QUOT
Have any of these companies put thermometers on each side of the shroud and driven around to see what the difference actually is?
How many degrees would be considered significant?Thanks.[/QUOTE]
A while ago, I saw a test report by an individual, on this forum, who actually measured the temperatures under a C5 hood relative to outside air temps. His test showed a difference at rest, but hardly any difference once the car was moving. I'll try to find the link and post it. It was interesting.
Also, I don't believe there is any real "ram air" affect by any of the aftermarket intake systems. Don't forget, that engine is sucking pretty hard when it's accelerating. Kewlbrz compares this to racing down a hallway with a vacuum cleaner hose trying for a "ram air" effect while the vacuum is running. It's not going to happen.
I'm a standard Blackwing fan, personally. No shroud cutting, no exposing the filter to crap coming up off the road, including water, and a very real performance increase from the best flowing filter on the market...IMHO.
Ed
Have any of these companies put thermometers on each side of the shroud and driven around to see what the difference actually is?
How many degrees would be considered significant?Thanks.[/QUOTE]
A while ago, I saw a test report by an individual, on this forum, who actually measured the temperatures under a C5 hood relative to outside air temps. His test showed a difference at rest, but hardly any difference once the car was moving. I'll try to find the link and post it. It was interesting.
Also, I don't believe there is any real "ram air" affect by any of the aftermarket intake systems. Don't forget, that engine is sucking pretty hard when it's accelerating. Kewlbrz compares this to racing down a hallway with a vacuum cleaner hose trying for a "ram air" effect while the vacuum is running. It's not going to happen.
I'm a standard Blackwing fan, personally. No shroud cutting, no exposing the filter to crap coming up off the road, including water, and a very real performance increase from the best flowing filter on the market...IMHO.
Ed
Melting Slicks
Joined: Mar 1999
Posts: 2,499
Likes: 0
Re: How cold is the cold air (intake question)? (FarmerBob2001)
I use an autotap to check the air temperature that the engine sees. I have a cold air intake and for what it's worth I have seen a difference between 10-15 degrees between standing still and driving, particularly during hot days. I haven't measured the engine compartment air temp where the stock air cleaner is however.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
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
Intermediate
Joined: Dec 2001
Posts: 33
Likes: 0
From: Elgin IL
Re: How cold is the cold air (C5XTASY)
I believe you are correct that "Ram Air" is a fallacy. I’ve done calculations of density changes in air at different velocities of automobile travel, and there is no noticeable increase in density until you start to get over 200 mph.
I think ram air is a marketing tool.
Similar to the throttle body bypass mod.
Common sense makes you think it will do something.
Calculations can show that you are wasting your time, and may even be taking a risk in the north of freezing the throttle open on a cold day.
As for the cold air question. Everyone knows more air = more horsepower.
I know nothing about the SAE hp calculations, but Charles Law tells us based on temperature alone that a 10°F temperature decrease will provide a 2% increase in mass air flow, or air density.
I think ram air is a marketing tool.
Similar to the throttle body bypass mod.
Common sense makes you think it will do something.
Calculations can show that you are wasting your time, and may even be taking a risk in the north of freezing the throttle open on a cold day.
As for the cold air question. Everyone knows more air = more horsepower.
I know nothing about the SAE hp calculations, but Charles Law tells us based on temperature alone that a 10°F temperature decrease will provide a 2% increase in mass air flow, or air density.