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 Firebirds / Formulas/ TAs
 please explain "ram air"
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ponchpowpow
Buffalo

42 Posts

Posted - 06 Jul 2017 :  11:54:37 AM  Show Profile  Reply with Quote
hi,

what exactly is the function of the "Ram Air" system? is air been forced into the intake? what are the benefits?

is it frowned upon by the Pontiac community to add the RA kit to a non-RA car? thanks

Edited by - ponchpowpow on 06 Jul 2017 11:55:35 AM

Steve C.
Crazy Horse

1674 Posts

Posted - 06 Jul 2017 :  12:48:25 PM  Show Profile  Reply with Quote
Are you asking about the induction system for a Trans Am with the rear facing scoop or a Formula with the forward facing scoops ?

The factory engineers knew that drawing denser, relatively cool outside air into the engine, rather than the warmer air from under the hood, was an easy way to improve performance.

Now there have been many discussions on how effective they really were with Pontiac... or more for sales appeal.

On some GTO's and first gen Firebirds it has been stated the forward facing scoops are virtually worthless due to "Boundary layer air".

.

Edited by - Steve C. on 06 Jul 2017 12:59:24 PM
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Steve C.
Crazy Horse

1674 Posts

Posted - 06 Jul 2017 :  12:57:09 PM  Show Profile  Reply with Quote
Repeating old material for interest.....

Without knowing the specific application or type hood/scoop arrangement involved.... here is a tid bit from a article about cold-air packages that might be of interest:

When designing a cold-air package, remember that an optimum entry will provide a nonturbulent air supply above atmospheric pressure. Front-facing hoodscoops typically begin supplying air at lower speeds, while rear-facing scoops supply air at higher speeds with less turbulence. Inside the scoop, all air ducts should be designed so that air entering the carbuertor will do so smoothly- preferably through a air cleaner or other diffusing device. Be sure that the bottom of the air cleaner's lid does not rest too closely to the top of the carbuertor where it will restrict air flow. You should leave at least 2 inches of clearance.
If your building your own scoop, make sure the incoming-air opening is at least 10-15 percent larger than the carburetor venturi size. This typically equates to about a 20- to 25-square-inch opening in the scoop. For optimal performance, the roof of the scoop should be placed about 2 inches above the carburetor. Be careful not to build the scoop too high because additional clearance can sometimes create turbulence. Adding a scoop to the carburetor system can also effect the air/fuel ratio of the existing combination because the incoming air will hold more oxygen molecules. As a general rule, you might want to begin your tuning by jetting up about two jet sizes (from prior optimum jetting) after you've added a cold-air package.

On another note.... and take this one with a grain of salt !

Very sucessful Pontiac Super Stock racer John Clegg stated that a front-facing hood scoop will work as a ram air source only if the car in question is doing 200 mph. He used a small Harwood scoop mounted backwards on the hood of his 8-second former record holding Firebird. It looked like a large size Trans Am scoop.


The Effect of Temperature:
Temperature also has an affect on air density. The formula to determine air density in pounds per cubic foot is: Pressure in inches of mercury times 1.326, divided by absolute temperature in degrees farenheit. (Absolute temperature = temperature + 459.6) If, for instance your induction system draws intake air from under the hood, the intake air temperature on an 80 degree day can easily exceed 130 degrees. Using a barometric pressure of 29 Hg" for our example, the air density under the hood at 130 degrees is .0652 lbs. per cubic foot. Now if you change to a cold air setup which draws 80 degree intake air from outside of the car, the air density is .0713 lbs. per cubic foot This is an improvement of 9.3%! Using a 200 hp engine as an example, this is an improvement of 18.6 horsepower! In practice the horsepower improvement will be less than theoretical because the incoming air will be heated by the intake manifold, and the engine itself. Further improvement can be made by insulating the intake manifold so that it picks up less heat from the exhaust system, and radiator. It is probably not possible to achieve the theoretical density increase, but it should be clear that there is much to be gained by keeping the intake charge cool.

( Information provided in this post does not represent a product indorsement. Unless specified it is not based on personal experiance and is offered for general interest only )

.

Edited by - Steve C. on 06 Jul 2017 12:57:38 PM
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Steve C.
Crazy Horse

1674 Posts

Posted - 06 Jul 2017 :  1:10:21 PM  Show Profile  Reply with Quote
RAISED SCOOP and boundary area effect....


Any object moving through the air is soon surrounded by a layer of slower-moving air known as the boundary layer. The boundary layer clings to the surface of the object, interfering with the flow of faster-moving air around or into the object. This can defeat the purpose of a scoop, particularly a ram scoop, by blocking air from entering the scoop inlet (except perhaps a small amount of the boundary layer air itself). To avoid that impediment, many scoops are raised or extended outside the body to place them above the boundary layer. This can increase the scoop?s effectiveness, although the scoop will then increase the vehicle?s aerodynamic drag.

Rear facing Trans Am hood scoop ? Now how close does the rear opening need to be to the base of the windshield to be taking advantage of positive air pressure ?

.


Edited by - Steve C. on 06 Jul 2017 1:13:18 PM
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ponchpowpow
Buffalo

42 Posts

Posted - 06 Jul 2017 :  2:39:12 PM  Show Profile  Reply with Quote
Steve C.

thanks for the reply. i should have mentioned that the question about RA was for the first gen firebirds and GTO's. regarding the boundary layer, cooler air will still be available for the carb via the scoops vs under the hood hot air wont it? thus slightly improving performance?
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Bill Boyle
Horse Feathers (Charter Member)

USA
4794 Posts

Posted - 06 Jul 2017 :  2:40:10 PM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Open scoop or closed? Makes me laugh. Hot air/cold air, forced air?

At a Corvette sponsored autocross many years ago, there was no one in my class, so they bumped me into a class with Corvette's. My hood scoop was closed from the factory but, your's truly, opened it up to let "cool" hot Florida air into the carb. I sealed off everything that let air into the hood from underneath. Well, to everyone's surprise, the TA came in second and I was immediately challenged by the Corvette owner that was bumped to third and no trophy. He complained that I was illegal because of the hood scoop being open. Forget the fact that he had well over 100 hp more than my ride, and was missing the rear pan under the rear chrome bumper where the exhaust is located and clearly visible. HA--said the techs and the challenge was dismissed. I made so much more HP and Torque with that open hood scoop where 60 mph was probably the fasted anyone could go down a straight on that course...yeah right, gimme a break. Talk about a sore loser. If I had been driving his Vette, I would have won!

Whatever increase in power the engine may have developed because of the open hood scoop was probably negated by the 90 degree weather and 120 degree hot air it was sucking down the carb.

Cool air makes more hp--no doubt about it. Quicker ETs in cooler air for most cars, maybe a faster mph too.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Steve C.
Crazy Horse

1674 Posts

Posted - 06 Jul 2017 :  3:01:33 PM  Show Profile  Reply with Quote
"Regarding the boundary layer, cooler air will still be available for the carb via the scoops vs under the hood hot air wont it? thus slightly improving performance?"

Answer.... YES

Recently we installed fuel injection on my Trans Am. During initial programming I was taken back by the actual under hood air Temperature from the sensor we temporally located by the intake manifold. It is now located under my hood scoop next to the air filter for input into the ECU.

.


Edited by - Steve C. on 06 Jul 2017 8:44:39 PM
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ponchpowpow
Buffalo

42 Posts

Posted - 06 Jul 2017 :  4:24:36 PM  Show Profile  Reply with Quote
thanks for the replies. it all makes sense now. when i was a young kid, i noticed how much better and faster my firebird ran when the sun went down and the air temp dropped about 20 degrees. couldnt really figure it out but it was a great feeling.

so whats the purpose of the single and duel snorkel air cleaner set-ups? its under the hood and letting the hot engine heated air in the carb. i cant see how that would be good for performance. thanks
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Steve C.
Crazy Horse

1674 Posts

Posted - 06 Jul 2017 :  8:51:21 PM  Show Profile  Reply with Quote
Presumbing underhood air inlets. I will go out on a limb here and suggest years ago it was a cost reason why the factory did not route cooler air to the air cleaner. Today on many cars the factory intake draws cooler outside air off the side fender or front rather than engine bay hot air.

.

Edited by - Steve C. on 06 Jul 2017 8:55:36 PM
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Steve C.
Crazy Horse

1674 Posts

Posted - 06 Jul 2017 :  9:39:13 PM  Show Profile  Reply with Quote
One online formula suggests a 455 cubic engine at 5000 rpm requires 109 square inches of filter area. The usable portion of the filter or effective filtering area.

A rhetorical question. Which will supply the needs here 'better', a dual snorkel or single snorkel air cleaner. Another situation to consider, for which I have no answer, will the opening size of the single snorkel be adequate to supply the volume of air for a round filter that has 109 square inches.

This is not the engine's intake volume requirements. Another formula for that. But a similar situation applies.

A potential for a complex situation......

"The overall size and shape of the system has a profound effect on air flow. In some extreme cases, the air box and/or the air delivery system is the greatest source of restriction. The inlet to the air box is a good example. In many instances this opening is one half the cross sectional area of the throttle body or carburetor opening. It would be like trying to run a marathon while breathing through a soda straw. An original-equipment cylindrical air cleaner box covering a throttle body or carburetor is another example. Most often, these round air cleaner housings are sealed to the outside air. The engine must then breathe through a snorkel attached to the perimeter of the housing. At times the snorkel is fed through a network of hoses and scoops."

Damn, isn't Google fun :)

.

Edited by - Steve C. on 06 Jul 2017 9:53:34 PM
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ponchpowpow
Buffalo

42 Posts

Posted - 07 Jul 2017 :  09:55:14 AM  Show Profile  Reply with Quote
so would it work if i were to open the airlets on the hood scoops to allow cool air into the engine compartment? under the hood temp wouldnt be as hot. i could use a regular air cleaner (non-snorkel, non-RA) and have similar performance that a RA set-up would offer? thanks
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Steve C.
Crazy Horse

1674 Posts

Posted - 07 Jul 2017 :  10:22:25 AM  Show Profile  Reply with Quote
That topic has been touched upon here....

http://www.psp.aquacomp.net/topic.asp?TOPIC_ID=5873

Again it depends on what model car and scoops involved. And again there will be the controversy over if the scoops are affected by a boundary layer effect or not.

I'm just taking wild stabs here for some sort of conversation. I will suggest there are others on this forum that are lurking and have ideas and thoughts regarding the subject !

.

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Blued and Painted
Chief PONTIAC

USA
3405 Posts

Posted - 07 Jul 2017 :  11:58:41 AM  Show Profile  Reply with Quote
The forward facing scoops on the 2 gen Formula has a rain trap built in. A jog in air flow just behind the scoop opening. Rain and air pressure run/bleed off right and left and dumps out on the core support. It would be hard to build boost with this configuration.
With some fiberglass and shaping tools, air flow could be improved/tuned to be more effective.
The bellows connecting the hood to the dual snorkel air cleaner could also be improved.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 07 Jul 2017 12:04:32 PM
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DanM
Buffalo

80 Posts

Posted - 25 Aug 2017 :  09:41:42 AM  Show Profile  Reply with Quote
Jim Hand described a cowl induction system he built and installed. He claims to have measured addl 1 mph and about 0.1 of a second on the quarter mile. I've thought at length about this and plan to build one myself. In general here's how he made it.

At the base of the windshield is a high pressure zone. There are two sets of grates to allow air into the cab via the vents we all know and love. (note: those vents are perfect examples of how much air you would get at cruise. Pull those vents wide open and there's quite a bit of air. right? what if you directed some of that to the engine?) From the engine compartment you must cut a hole through the firewall.

Get a dual snorkel air cleaner to provide as large of openings you can get for minimal restriction.

Online you can find plastic or steel 4" round to oval adapters. Get four of those. Get some 4" dryer hose. Cut two 4" oval holes in the firewall to match the adaptors.

Assemble.

Now you will have a cold air induction system. The bigest expense will be the air cleaner. But you won't need a bona fide GTO air cleaner so you can get whatever is cheapest on the web for a quadrajet. (about $200)

Or save yourself some work and get the Spectre 733 air intake system.

https://www.spectreperformance.com/search/product.aspx?prod=733&gclid=EAIaIQobChMI3-6B-cDy1QIVDRxpCh0q-AyFEAQY&mkwid=saFaj5tvp&crid=178292231167&pdv=c

I think I'll get one of these next week.
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DanM
Buffalo

80 Posts

Posted - 25 Aug 2017 :  09:55:38 AM  Show Profile  Reply with Quote
Regarding adding RA to a non RA car: I'm a purist (except when I'm not) and get greatly annoyed when I find cars claiming to be a GTO but have a chrome bumper. For goodness' sakes, enjoy your chrome and call it a Lemans like it is. Then there are 'restorers' who remove the bumper and add lots of badging to call it a GTO. Or they change the wheels to something non-stock. Or who knows what else.

But if you add RA because it gains you 20 HP - then more power to you (literally). But if you add RA just to make it look cool and in reality it doesn't gain you 1 single HP but costs you $500 then shame on you.

I have a 400 now but I kept the 350 logo on the rocker panel because that's what came with the car. I have an in dash tach because my car is not a GTO and the hood tach wouldn't be correct. But then I have posi, boxed rear control arms with anti-sway bar, 60 profile tires, 4 bbl, dual exhaust, etc. I'm keeping the bumper and keeping the badging but improving everything else.

I'm not going to re-paint it the original puke green and you can't make me.

I'm keeping the AM/FM converter where the ash tray used to be but installing CD player with Bluetooth elsewhere...
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