Author Topic: Open Shaker (Read 1971 times)

N PRGRES · « **on:** July 31, 2024, 07:26:49 AM »

I am curious why the open shaker is "preferred" over the scoop in the fender? I would think the fender would still draw in nice cool air as opposed to cutting open the shaker. I get that the fender scoops can be hard to find and such, but I guess my thought is that driving in the rain would be less risky with a closed off shaker.

rkellerjr · « **Reply #1 on:** July 31, 2024, 08:12:49 AM »

My shaker is not open but duct work runs from the breather to the front of the car for fresh air for the motor. I'd think the fender slots are for helping to cool the engine bay, allows hot air to escape.

N PRGRES · « **Reply #2 on:** July 31, 2024, 08:48:09 AM »

Quote from: rkellerjr on July 31, 2024, 08:12:49 AM

My shaker is not open but duct work runs from the breather to the front of the car for fresh air for the motor. I'd think the fender slots are for helping to cool the engine bay, allows hot air to escape.

No, mine has a snokle that goes from inside the front of the fender to the ground to pick up cool air thats piped into the air cleaner

roadking77 · « **Reply #3 on:** July 31, 2024, 01:17:31 PM »

On my 77 the shaker is cut open. I dont know how much of a difference there is in getting fresh air directly to the carb over the snorkle of the air cleaner. The snorkle has a hose that connects to the front side of the dr. fender and does pull in air, but I dont think the fender vents make that much difference with that. I agree with Rich that they will most likely do more to cool the engine bay than provide fresh air to the carb. As far as rain, I have been caught in some pretty good downpours driving my car and never noticed a problem.
On my 79 I found a really nice uncut shaker. It will be interesting to see if it makes any difference. I suspect it will not.

5th T/A · « **Reply #4 on:** July 31, 2024, 04:27:01 PM »

The air extractors in the front fenders and the open shaker serve two different purposes. According to Pontiac documentation the air extractor reduces under hood air pressure and front-end lift.

The attached photos are from "The Fabulous Firebird", Michael Lamn.

IMG_3898 by Lawrence Alexander, on Flickr

IMG_3900 by Lawrence Alexander, on Flickr

All Trans Am's 1970 - 1972 had an operational door in the shaker that would open under full throttle. A switch connected to the throttle linkage would energize two solenoids in the shaker housing. 1973 - 1976 TA's had a nonfunctioning shaker, a metal plate was held in by three rivets that could easily be drilled out. The window sticker on my 1973 TA had a $27.00 credit for deleting functional Ram Air, I believe all 1973's had the option deleted. I recall reading in a period publication that removing the plate would cut a tenth or two off the quarter mile times. I removed the plate on both my 1973 and 1975 TA. I could not really tell a difference seat of the pants, but loved hearing the sound of the secondaries opening on the Quadrajet carburetor. For 1977 - 1981 the shaker was non functional unless you used a Dremel tool to open it up.

Somewhere I recall reading some tests that said there wasn't enough air pressure at the rear of the shaker to improve engine performance. You have to keep in mind the other inlets to the air cleaners remain open and would essentially dump any additional air pressure. All TA's and probably all Firebirds starting in 1973 had a fresh air duct from the left front fender. Cooler denser air provided by the ducting should give better engine performance. I know Pontiac used this cold air setup set up on Grand Prix's from 1974 - 1977.

For those who are interested a functional flapper for their shaker scoop there are aftermarket kits available. Some us vacuum to pull the spring-loaded door open and others use solenoids. I am pretty sure they make functional kits for all years of Gen II Trans Ams.

« **Reply #4 on:** July 31, 2024, 04:27:01 PM »

b_hill_86 · « **Reply #5 on:** July 31, 2024, 04:41:30 PM »

Here’s a current discussion of the same over on PY

https://forums.maxperformanceinc.com/forums/showthread.php?t=874950

FormTA · « **Reply #6 on:** August 01, 2024, 03:58:10 AM »

I can see it being a real benefit to the 79 up cars as they don't have much in the way of air inlet. Any help getting air out of the engine bay will help cool air in. I'm surprised they say it's noticeable at low speeds. When my formula was still on the road I didn't notice any difference driving it over my TA other than cornering. Both cars had the same engine setup too. (Before the LS swap).

Wallington · « **Reply #7 on:** August 02, 2024, 12:48:00 AM »

You'd probably need to be driving otherwise identical cars, both with front spoilers, hood seals even better, and one with TA fenders and the other with Firebird fenders. Then you just may feel one is a little more floaty with air build-up. But moreso with underhood heat with the bigger engines, or Turbo. The shaker on these is too far forward to benefit much of the low pressure air at the windscreen. 70-75 Formula scoops were better when open but still a touch short. 76-81 Formula scoops even if open, would do nothing. Too far back, too slim. I think all 'big engines' should have had a fender extractor just for heat. The TA had theirs, the non-TA should have kept the 71 Firebird type.

N PRGRES · « **Reply #8 on:** August 02, 2024, 06:13:42 AM »

Not sure how this topic went to the fender air extractors as thats not what I was referring to, I don't have the two confused. The topic was the open shaker vs the air intake scoop that routes throught the front of the left fender.

kherz80ta · « **Reply #9 on:** August 13, 2024, 08:20:06 PM »

I know there was a discussion years ago, and I think the conclusion ended up being that the open shaker was superior. Mainly as this was how the early cars were designed by the factory. If I remember correctly, the under hood air cleaner duct was a change by Pontiac as a result of federal noise standards. Which sounds kinda silly, except that a quadrajet carb with the back barrels open does make a nice loud throaty sound. Typical big brother trying to destroy the muscle car era.

N PRGRES · « **Reply #10 on:** August 14, 2024, 05:51:46 AM »

Quote from: kherz80ta on August 13, 2024, 08:20:06 PM

I know there was a discussion years ago, and I think the conclusion ended up being that the open shaker was superior. Mainly as this was how the early cars were designed by the factory. If I remember correctly, the under hood air cleaner duct was a change by Pontiac as a result of federal noise standards. Which sounds kinda silly, except that a quadrajet carb with the back barrels open does make a nice loud throaty sound. Typical big brother trying to destroy the muscle car era.

Hmmmm its more direct but the car doesn't car where it's pulling cold air from. Look at how air is routed in todays cars, its about the same set up. The main point would be to not be pulling in warm air from the engine compartment. I am sure there are many ideas and thoughts but without true dyno testing, the answer will probably never be known. I am sure the open shaker pulls in more air.

TA301 · « **Reply #11 on:** August 16, 2024, 06:48:39 PM »

Since the engine is an air pump, it makes more power with more air. Therefore, opening the scoop will allow in more air but this happens more at 20 MPH and up. In conjunction with the factory air intake/tube bringing in more air, it is obvious the car will make more power. For my 301NA, I installed the 301T cold air scoop that brings in even more cold air right from under the front bumper cover.

Wallington · « **Reply #12 on:** August 16, 2024, 09:39:34 PM »

I have that on mine, the big mouth duct. Given the amount of turbo cars they are still a rarely seen part and a simple clip on for any models of the type.

TA301 · « **Reply #13 on:** August 17, 2024, 04:16:02 PM »

Here is my TA with the said cold air scoop installed.

roadking77 · « **Reply #14 on:** August 17, 2024, 07:03:55 PM »

Looks like the bumper is going to bolt up in front of that, unless Im missing something

« **Reply #14 on:** August 17, 2024, 07:03:55 PM »

Wallington · « **Reply #15 on:** August 18, 2024, 06:19:22 AM »

I had to check something on the car so took a few quick pics of the big-mouth turbo ducting. This is on a 78 Formula, no front skirt. I don't have an existing pic showing where it pokes in relation to 80-81 Turbo TA with enclosed front spoiler.

20240818_160418 by Ben, on Flickr

20240818_160440 by Ben, on Flickr

20240818_160510 by Ben, on Flickr