Welcome to the Corvette Forums at the Corvette Action Center!

I Installed Ram Air In My '71 Big Block

Antz81

Well-known member
Joined
Dec 21, 2013
Messages
936
Location
Auckland, New Zealand
Corvette
1981 4 speed
It'll shed 150,000 BTU's per hour which is about twice as much as your home furnace cranks out.

150000 btu but is about 44kWhrs. Our induction furnace at work can melt a decent amount of metal at that power. If the radiator was to dissipate the same amount of energy I suspect it would melt.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
Ram Air

I would estimate it took me 100 hours to construct my Ram Air but the outcome was worth the effort and minimal expense because of the significant fuel mileage increase alone.
 

kpic

Well-known member
Joined
Mar 29, 2014
Messages
2,292
Location
Columbus, NC/NE Georgia
Corvette
1997 boosted silver coupe
Toobroke...
You're oblivious to what Antz and Mikey said and yes, I understand why.

You figured the BTUs incorrectly. As it is the usual, it's no big surprise.

Mikey was being a nice guy and gave you a hint about how much HP is really being used. Hint: you're not driving a top fuel engine blasting 1320' with the pedal to the floor. So the amount of power being used is not as much as you assumed; Get it?

Anyhow, you're a self-acclaimed engineer so here is a whole bunch of formulae; go figure it out:
Part 6: Speed and Horsepower

That is go figure if you can.
 

stevolwevol

Well-known member
Joined
May 28, 2015
Messages
250
Location
Michigan
Corvette
1977 light blue
I think if you measure that actual underhood temps withe car in motion, you'll find it's nowhere near 200 degrees. Probably pretty close to ambient actually.

In an effort to evaluate the effectiveness of the '73-'75 Corvette factory cold air intake and calibrate it against the seemingly optimistic claims of the GM marketeers, I instrumented my own car. While the air temp near the filter did rise dramatically with the car sitting idling, it dropped to a reading of only 2 degrees F warmer with the car in motion.

The car in motion may get much better (cooler) closer to ambient air temps than when it's on a dyno. This could be the variable that gets little attention. There has been so much contradiction and argument about hp improvement, or decline due to air temps under the hood w/open element. Just my thoughts.. What say you?
 

kpic

Well-known member
Joined
Mar 29, 2014
Messages
2,292
Location
Columbus, NC/NE Georgia
Corvette
1997 boosted silver coupe
The car in motion may get much better (cooler) closer to ambient air temps than when it's on a dyno. This could be the variable that gets little attention. There has been so much contradiction and argument about hp improvement, or decline due to air temps under the hood w/open element. Just my thoughts.. What say you?

A dyno uses correction factors to compensate for ambient temperature and air density. In short, using correction factors standardize the results from dynos all over the nation or the world. No matter if it is hot or cold, the dyno will read close to the same power. "Close" means less than you'd notice.

SAE J1349, SAE J1995 and J2723 are the controlling standards. SAEJ1349 is the heart of it.
Here's a cute brochure on the subject.
http://www.sae.org/certifiedpower/brochure.pdf

It the temperature of the "charge" air that effects power.

Turbos and blowers are good examples. When air is compressed, its temperature increases. This is why the output air from her turbo or my blower go through an intercooler before going into the engine.
Although it is called an intercooler, in reality it is an aftercooler which cools the charge air after the compressor stage compresses it.
 

Antz81

Well-known member
Joined
Dec 21, 2013
Messages
936
Location
Auckland, New Zealand
Corvette
1981 4 speed
A dyno uses correction factors to compensate for ambient temperature and air density. In short, using correction factors standardize the results from dynos all over the nation or the world. No matter if it is hot or cold, the dyno will read close to the same power. "Close" means less than you'd notice.

SAE J1349, SAE J1995 and J2723 are the controlling standards. SAEJ1349 is the heart of it.
Here's a cute brochure on the subject.
http://www.sae.org/certifiedpower/brochure.pdf


This us why i like reading toobrokes threads. I normally learn something interesting.
 

kpic

Well-known member
Joined
Mar 29, 2014
Messages
2,292
Location
Columbus, NC/NE Georgia
Corvette
1997 boosted silver coupe
This us why i like reading toobrokes threads. I normally learn something interesting.

It's the same reason I enjoy reading his threads.

Same as others, I know he is wrong; however, I didn't know how to prove it. So, I looked up the SAE Standard for dynos. It levels the playing field.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
Mileage Check

Next Tuesday I'll have the chance to do another fuel mileage check when I make my 500 mile round trip to Santa Barbara and back. In the past something has always screwed up my fuel mileage checks but hopefully nothing will go wrong this time. The last time I went to the coast and back my #2 wire was flashing to ground so I ran the distance with a dead cylinder. I'm hoping to get 16 mpg.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
About two years ago when I was thinking about converting my L-88 style hood to ram air I read about some tests conducted with one of the latest "super bikes". At 150 mph it gained 10% torque which is pretty impressive and I would think it would gain 5% at half that speed (75 mph). Since I converted my hood to ram air I haven't done any full throttle testing but I'm certain it would run a 70 to 110 mph a bit quicker with the forced air. As I'm inducting the air from in front of the radiator where the pressure is the highest it should get a boost in performance. But the best thing of all for everyday driving is the cooler air.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
The Benefit Of Ram Air

I am still trying to understand why my fuel mileage increased so much. I was expecting a little gain so I was shocked when it gave a 33% increase. When I am traveling 70 mph the force of the wind against my hand is substantial and it's that same force that is feeding my #3310 Holley's primaries. It could be the force is simply turning the fuel droplets into a super-fine mist and that's why the mileage increased so much.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
With my air cleaner completely enclosed by the Ram Air hood it's a lot quieter under a full throttle but that isn't a problem for me. I made the modification for the cool air and as it happened to give me Ram Air I consider that a bonus. I got the idea when I was looking at my '82's hood that also has the opening just in front of the radiator. And as the air intake is up high rain isn't an issue.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
Free Supercharging When Ram Air Is Done Correctly

Ram Air is actually free supercharging that is using the air resistance itself to add power. At 80 mph my water manometer is showing 1-1/2" Wc which is a heck of a lot better than 0" Wc. And the fact the air is about 100 degrees cooler than the under hood air even more power is made. It's a WIN WIN situation as far as power goes but it may be very dirty emission wise. At 75 mph there is about a 5% gain in power because of the pressurized intake air so on a 400 hp engine I'm talking about 20 FREE horsepower. On my recent trip to Santa Barbara and back I noticed it was REALLY beginning to make power once I exceeded 75 mph because of the camshaft and Ram Air.

Remember this................the base of the windshield is a great place to induct air IF the hood doesn't have a L-88 style dome on it in front of the air intake. Add a L-88 style dome and there isn't any pressure until about half way up the windshield because the dome acts like the leading edge of an airplane wing. The middle 60's muscle cars that had "Ram Air" weren't really ram air at all because the air inlets were placed in the wrong spot of the hood. To get Ram Air the air inlets needed to be placed at the front of the hood where air pressure is the greatest.

Do you remember the middle 60's Thunderbolt Fords that used the inner headlight openings to induct their pressurized air? When it comes to Ram Air that is as good as it can get because the pressure there is the highest pressure. That's why I chose to induct my air from in front of my radiator because frontal air pressure is the highest pressure.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
I am amazed over how much sand I find in my air filter when the air intake is in front of my radiator. And as the air intake is so high rain water isn't a problem at all.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
Now days many vehicles have Ram Air that is inducted from the front of the radiator like mine is. Do you remember the Ford "Thunderbolts" that had Ram Air piped to the inner headlights?

I was looking at my '82 one day and got to wondering if I could modify my L-88 style hood to make it function like my '82's hood. Yep, it took at least 100 hours of my time but in the end it came out great. But the biggest advantage of the Ram Air is the "cold" air as cold air contains a lot more oxygen. And as the air pressure also puts pressure on the gasoline in the float bowls the air/fuel mixture remains the same (or at least I think it does).
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
I never expected my Ram Air would cause choke problems when I drove it at 45-50 mph. The incoming air was actually buffeting the choke butterfly and causing it to partially close and set the fast idle cam to it's first notch. Even after driving it 100 miles it would STILL be fast idling when I pulled up to a stop sign. It took some basic engineering skills to figure out how to solve the problem.
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom