[jhein]

Originally Posted by PAUL K;6515226[B

]It's interesting your scoop door pulled open when the engine required additional flow[/B]. My 70 with the original engine would only pull it open about half way. I recently noticed my 70 will accept a 3" tall filter. My 74 will not. I haven't had a chance to figure out what the differences are. I'd certainly think additional space you can get between the lid and base would be a win.

No, the opposite. It doesn't open at WOT. Just hangs there like nothing happened.

[PAUL K]

Originally Posted by Formulajones

I've found it to be sufficient enough for over 700hp on cowl induction stuff but again that's at the base of the windshield where a rear facing scoop should be. I've been racing the cowl induction stuff for decades and haven't really found anything that improves it without hacking the car.
I do know just putting an open element filter setup on the car so it's not limited to just the hood and should induce more airflow if the engine is looking for it actually slows the car down.

I remember Bruce Miachles modifying his cowl to pick up air from the front of the car and finding a bunch of power. I agree the trick is to not hack the car.

[jhein]

Originally Posted by unruhjonny

I believe that the "ram air" label for those filters is a misapplied label;
IIRC that "ram air" application is for the Trans Am's.

Right, I'm taking RA to include TAs The "RA" filters are shorter, presumably for better clearance around/under the shaker.

[unruhjonny]

/\ I believe that is precisely why it's shorter.

But if you read some, that shorter element puts the lid a smidge too close to the top of the carb (airflow suffers) - but I would guess that the disrupted airflow from the shorter filter is negated by better all around flow from increased clearance.

[Skip Fix]

Another thing for at least the later TAs (my 78 and 81)the snorkel had a duct that ran up to the front grille between the battery and fender-so it gets cool air from that as well as an open scoop.

[jhein]

Originally Posted by unruhjonny

/\ I believe that is precisely why it's shorter.

But if you read some, that shorter element puts the lid a smidge too close to the top of the carb (airflow suffers) - but I would guess that the disrupted airflow from the shorter filter is negated by better all around flow from increased clearance.

Yeah, I don't know yet what impact it will have on performance, but I'm gonna try it. You're right though, it may have the same effect as drop base air cleaners putting the lid too close to the carb.

I tried the K&N filter lid, but that didn't fit with the taller filter. Maybe it will with the shorter one. But, I've also read that the K&N lid didn't help either, actually made things worse.

[Formulajones]

It depends on what that k&n lid is on top of. Seems to work well with those that have contoured Holley HP carbs, not so much with a q-jet.

[Formulajones]

Originally Posted by PAUL K

I remember Bruce Miachles modifying his cowl to pick up air from the front of the car and finding a bunch of power. I agree the trick is to not hack the car.

Yep, if I can do things that are hidden I'm all for it. Just don't want to do something irreversible of course but I like experimenting

[PAUL K]

Originally Posted by Skip Fix

Another thing for at least the later TAs (my 78 and 81)the snorkel had a duct that ran up to the front grille between the battery and fender-so it gets cool air from that as well as an open scoop.

Hi Skip the 73 on up Firebirds were the same way. I think "Joe's garage" is saying he blocked off the snorkel and drew only air from the scoop and slowed down with his TA. It's fun trying things and looking for something that works. I'm still amazed at your power gain using an adapter to run the 850 on an HO manifold.

[Steve C.]

A tid bit for conversation....

Harwood Areo hood scoop

[https://www.eharwood.com/catalog/scoops/aero-scoops/

John Glegg's Super Stock '73 Firebird had a Harwood hood scoop mounted backward to mimic a Trans Am shaker scoop. Through on-track testing with a computer, he found that the "wrong-facing" scoop worked better than when it was mounted facing forward. Depending on the scoop size and its opening location some front-facing scoop arrangements actually have a negative air pressure. He sealed the carburetor to the scoop and also routed air directly into the air pan from the front grille. The carb was isolated from hot under hood air, a big plus for performance.

Advantage, no big tall scoop to look around and it has sort of a factory hood scoop appearance for him..

This from a article about cold air systems in the 2/'03 Chevy High Performance magazine. It maybe of interest.

"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."

And this...

"Optimum entry will provide a nonturbulent air supply above atmospheric pressure. Front facing hood scoops typically begin supplying air at lower speeds, while rear-facing scoops supply air at higher speeds with less turbulence."


( Information provided in this post does not represent any specific endorsement. And unless specified it is not based on personal experience and is offered for general interest only )

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[Formula403]

That's just the TA vs non-TA filters. Nothing RA specific.

[Formulajones]

Originally Posted by PAUL K

I think what you guys do is quite impressive. A lot of Brand X guys have to be scratching their heads to see a couple of stock looking Pontiacs drive in, click off impressive times and drive home. Mid tens out of a street driven car isn't easy.... Along with the 16 mpg

Thanks Paul, I'm sure you already know it's not as easy as it sounds. Making HP isn't that difficult but putting the whole package together in a street car while still trying to keep drivability and nice manors, cool temps, and decent mpg all while looking stock is more work and effort than many realize. Then to try and back it up in a car that's over 2 tons with a decent number and not using a power adder is a real challenge. The gas mileage was just a happy bonus after the 4L80E went in.

Here's one clip. This was an easy leave. Funny part is the RobbMC starter decided to spit the gear off right after we got done with tech, so once I got it started we just left it idling in the pits for what had to be 30 minutes then made this pass and still went 10.80-something at 127 and was over 100 degrees outside Then got parked for no roll bar, probably a good thing with the starter issue anyway.

https://youtu.be/L3O5SQlEwTY

[Formulajones]

At any rate, to keep this thread on track, those 2 tiny little hood scoops you see in the video is the only air that big engine gets to ingest. The air cleaner is an L88 style, I made the box with the filter in the hood and did all the fiberglass work so it's completely sealed to the hood when shut. Basically just like an L88 Vette.
Those GTO scoops aren't known for being the best setup either since they are in the middle of the hood that many say is a dead zone. But it seems to work well enough for what we do.

[Steve C.]

If the scoop isn't actually breaking into the "boundary layer" of airflow across the hood, the forward facing scoop will be of little help and see very little of the "ram air" effect to help achieve any HP benefit.

"These first Mopar-designed scoops relied on the “boundary layer” principle. With this arrangement, the opening of the scoop wasn’t flush with the top of the hood. Instead, the inlet was raised slightly to account for the air flow passing over the nose and hood of the car. A scoop with an opening flush with the hood surface was essentially mounted in dead air. Placing the scoop in direct line with moving air improved the “ram” factor."

https://www.onallcylinders.com/2015/...op-technology/


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[PAUL K]

Originally Posted by Formulajones

Thanks Paul, I'm sure you already know it's not as easy as it sounds. Making HP isn't that difficult but putting the whole package together in a street car while still trying to keep drivability and nice manors, cool temps, and decent mpg all while looking stock is more work and effort than many realize. Then to try and back it up in a car that's over 2 tons with a decent number and not using a power adder is a real challenge. The gas mileage was just a happy bonus after the 4L80E went in.

Here's one clip. This was an easy leave. Funny part is the RobbMC starter decided to spit the gear off right after we got done with tech, so once I got it started we just left it idling in the pits for what had to be 30 minutes then made this pass and still went 10.80-something at 127 and was over 100 degrees outside Then got parked for no roll bar, probably a good thing with the starter issue anyway.

https://youtu.be/L3O5SQlEwTY

That's a good video. It really give the sensation of speed. Was that with the 3.42 and overdrive transmission?

[Skip Fix]

I've always had the snorkel and scoop open. It does run a lot better without air cleaner element. I made a "cage' like the l-88 one to ho;d the base on the carb to run the Shaker with no filter. But even the Camaro/IA with a 14x 4" filter ran WAY better no filter. I just need to rig the base on the carb to see if it likes contoured air into the carb. I know a lot of stocker guys that run just the carb base

[Formulajones]

Originally Posted by PAUL K

That's a good video. It really give the sensation of speed. Was that with the 3.42 and overdrive transmission?

Yes

[Formulajones]

Skip brought something up I tried that I forgot about. Trying to run no filter.
While he states the ta scoop worked best with no filter, I tried that in my ra formula and it was a horrible mistake.
The car slowed more than a half second and was down a huge amount of mph. As I mentioned it had a habit of blowing the crank case filter element to the back of the air cleaner. All this told me how turbulent the air must be inside the air cleaner and it must have screwed up the carbs ability to meter fuel properly, the filter slows down the air as well as straightens it. Filter back in place and it went back to running normal et/mph.
Shows how effective those forward facing formula scoops can be

[Formulajones]

Skip also mentioned the base of the air cleaner and how stocker guys run just that.
I mentioned this in another thread I think but I've found more power on the dyno running those factory style bases that have nice contour vs the aftermarket base that tends to be notchy with sharp edges so there is something to it with a nice base

[PAUL K]

Most engines will make more productive power and the fuel curve can can be tuned better if a free flowing air filter is used. It's often very difficult to fit an air filter of adequate size.... There is a "reason" Super Stock cars don't use an air filter or any type of factory cold air packages. They simple won't supply enough volume for a high horsepower engine.