So.....
What's the general consensus on after market air cleaners??

Stock (L-82) air cleaner pulls fresh cold/cooler density air from front of the car, but has limited CFM flowage due to ductwork and openings of the air cleaner.

After market has less/no restrictions but is pulling less dense warm/hot air from under hood.

Cool air has more density (available O2) and is ALWAYS better for performance ( overlooking the fact that the stock L-82 doesn't HAVE any performance!!!).

Thoughts???

 

Do a distributor recurve before changing the air cleaner. A recurve effects the whole rpm curve, more air only effects the top end if at all in your case.

 

Back in the late '70s I bought a chrome open air cleaner. It was summertime...didn't really notice a difference.

That Fall when the air turned cold I switched back to stock. The Q-jet felt like it had a fifth barrel..
Best of both worlds...


STA70972

 

The snorkel air cleaner will undoubtedly give better performance, but the open elements look much better (in my opinion.)

Your ‘78 L82 dual snorkel air cleaner is already an upgrade from the single snorkel, but if you want an open element you could always make a cowl induction setup with a different hood.

 

Here's the thing. And first my disclaimer. Although I have run a dyno for over 20 years I know nothing.
OK.
Do aftermarket airfilters flow more air? Generally, yes.
However, How much air can your engine suck?
Do we believe that the designers of our cars looked at the engines air intake needs and decided to limit the air flow for some reason? That seems to be the idea behind aftermarket airfilter sales. Our air filter flows more air than the stock air filter so therefore you will go faster with our airfilter.
And guys line up to buy them!
OK.
Your engine, at FULL NOISE pulls X amount of air.
The engineers look at that and say, as the air filter collects dust and dirt, it's flow will become restricted. So therefore we need a airfilter capable of flowing at least 1 1/2 times the needed air to make certain the engine gets enough air even when the air filter is starting to get used.
they do NOT look at the engines needs and say. Well, the engine can pull X amount of air so let's put a filter on that will limit that! No , they don't!
So, my aftermarket air filter flows 10 bazillion cubic feet of air per minute!
Isn't that nice.
Your engine will never pull anywhere near that.
Most high flow air filters only make a difference at all at the very top end , total full noise. An area street cars very seldom see.

 

Your stock L-82 intake system will provide more air than your stock L-82 can pull. You don't need to worry about that. Eliminating the hot air snorkel to the intake from the exhaust shroud (if it has one) will improve it's performance.
Sucking hot under hood air into the engine will always decrease your performance.

 

OEM L-82 Dual Snorkel Cold air cleaner assembly is better than most of the aftermarket setups since it sources COLD air. Get yourself a free flowing air cleaner that fits in that OEM housing and you are good to go.

 

I don't know what the HP limit is for the dual-snorkel CAI. I have it in both of my C3s, and I'm hoping to adapt it to a 400 hp LS swap.

Colder air is usually "better", but your car needs to be able to use that cold air, meaning you really need EFI to make the most of it.

The real test would be to measure the pressure inside the air cleaner, and see if a vacuum builds at WOT, indicating a flow restriction, then test again with an (ugly) hot air induction air cleaner assembly. I can tell you the temperature difference is significant. Somewhere I have a graph that shows it. I'll post it if I can find the thread.

 

Truth of the matter. In a street car with an average engine, say 300 -350 HP. At RPM levels that said street engine is likely to see.
The difference in HP is so minor it really couldn't be felt. Yes the cold air may make 3 -5 HP more at Max RPM on such a street engine. But that's really about it. Been a lot of testing on dynos to prove this.
at 3,500 RPM on a 325 HP street engine, I think you'd be hard pressed to tell a difference.
Run the airfilter you think looks nice.
It really doesn't make that big of a difference.

 

i cannot find your thread but did find both of our readings. Great contibutors that helped me in this thread. @REELAV8R did some vacuum readings i think?
bottom chart L82 79
https://www.corvetteforum.com/forums/

Bikespace

 

If I am reading the bottom chart correctly, that dual snorkel cold air intake on the L-82 looks pretty darn impressive!^^^^

 

I showed about a 60 degree difference in the top graph, while the car was driving (less at slower speeds, or parked).

 

X2 on that drop/effect when it is colder outside like 40/50's degrees..............

 

Hello again 4-vettes!

I totally agree with you about the air filter world out there. If your engine uses X amount of air when running full throttle (full Noise??) no air filter is going to push more air into the engine. Air filtration has become a "part" that makes people think it can make more power just using this filter. With the new Chevrolet "Mystery Engine" they had racing in the early 1960's they used the first Cowl Induction system on a 396 engine.

Cold air induction works VERY well on the carburetor equipped engine as well as on the EFI systems. It seems that cold air was important back in the early 1960's when Chevrolet introduced their cold air intake hoods on some of their race cars. By 1967 the L88's were using a Cowl Induction system that fills the engine with cool air under pressure at speeds. The Cold air intake is one of the many reasons why the L88's were road worthy on highways. Good high octane gasoline helps but is not the only answer.

The gasoline being drawn into the engine with a carburetor actually "cools" the intake plenum down. This cooling effect is well documented in shows like the Engine Masters TV show. They show the EFI systems making marginally less power than a properly set-up carburetor can because of the gasoline and the warm surfaces it cools down before getting burned. Carburetors are not a "bad thing" as a good EFI system is just a little better at controlling the fueling of the engine. But for power alone it appears that the carburetor will be around for a while as they have the potential for making power while cooling down the intake manifold.

The cold air intake on my 1988 C4 is simply a hose that pulls air into the MAF sensor from in front of the radiator and it is "fairly" effective. I am curious about documenting the temperatures under the hood and the IAT while sitting, running and parked after a run. If I need to I can insulate the bottom of my air box (in the hood) to prevent any heat from affecting my IAT.

Try cooling your fuel and see what happens, denser gasoline gets into the combustion chamber and makes more power. All you have to do is get the gasoline away from the front of the engine's heat and the excess heat from the radiator. The fuel for my engine comes from the fuel pump (in the tank) up and over the bell housing and feeding the throttle body from the rear versus the front like most applications. This allows the fuel to be considerably cooler than going through the mechanical fuel pump that lives in Hot air flowing from the radiator and then up in metal lines from the FP to the carburetor allowing even more heating time above the intake manifold. I have not measured the temperature of the gasoline but that is coming through my system over the bell housing versus the standard way.

Keep the engine happier with Cool air and Cool fuel and it will reward you with more power and performance. Just don't expect your new Air Filter to make 10% more power by flowing X+ air... Smart advertising K&N!!

 

I did do some temp readings years ago. Here is the thread:
https://www.corvetteforum.com/forums...g-results.html

To do vacuum readings inside the air box I used a piece of clear vinyl hose taped to the side window as a water monometer. Acceptable vacuum inside the air box at full throttle and max RPM, indicating little to no restriction to the incoming air, is 1.5" of water column.
You cannot use a vacuum gauge as it is in inches of mercury. Mercury is 13.6 times denser than water. This means that the water monometer will be 13.6 times more sensitive to vacuum vs using a vacuum gauge.

Some paper filter are VERY restrictive to incoming air. To see the difference I did a run with the paper filter in place got the water monometer reading. Then did a run without the paper filter. The difference in readings was so significant that all the water in the monometer was sucked into the engine vs with the paper filter in place I only had 1" of water vacuum indicated.
Due to the height restriction of the side window it could indicate as much as 12" of water vacuum.
That means that the paper air filter was creating a restriction to the engine that exceeded 11" of water vacuum.

 

I kinda figured the stock L-82 dual intake was pretty good. I have to also agree that at anything but WOT (and even then) it probably flowed pretty decent.

Cold air is ALWAYS better than warm/hot air.

The open element air cleaners look great, but I drive with my hood on and a stock L-82 is kinda boring to look at!!! Gonna keep the stock system (blocked the heat riser already and EGR block off is next). Will save my pennies for the Tremec 5 speed!!!

Thanks for all the replies, it's a great discussion!!

 

A few years ago, I did a bit of dyno testing on air cleaners. What we found to have the greatest effect on engine power and performance is the distance from the top of the carb's airhorn to the bottom of the air cleaner lid. Once this distance gets tight, as it does when people use the drop-base air cleaners with a low-profile air filter to gain hood clearance, power is dramatically affected. I found that the minimum distance from the carb's air cleaner gasket on the airhorn to the bottom of the air cleaner lid, to avoid serious upper-rpm performance problems, is 3 inches. Most air cleaners have a 1" "dome", which means that the minimum distance from the air cleaner gasket on the carb to the top surface of the air filter is 2 inches. Anything less than that and you will have issues. So, for instance, you cannot run a 2" tall air cleaner on a drop base - it puts you way below the 2" minimum height required above the carb. Check your heights and clearances - this can affect you more than the style of air cleaner you're using... Run the tallest filter you can, and get the air cleaner lid as far above the airhorn as you can without hitting the hood.

Lars

 

Sounds like really good advice, thank you Lars.
It does seem so very many on this forum are always trying to squeeze things under the stock hood.
Perhaps a lower intake manifold is a better compromise than a drop base air filter.

 

Lars's comments made sense to me since a drop base air cleaner with a 2 inch or less air filter width from the airhorn base to the bottom of the air cleaner lid would create an air restriction requiring the incoming air to "climb" up over the air horn to enter the intake, affecting volume and velocity of the air charge.

Interestingly, the OEM L-82 dual snorkel cold air cleaner allows for not only a 3.5 inch high filter element from the airhorn base to the lid (I just went to the garage to measure mine) PLUS, as demonstrated previously by Interpon's charts, significantly colder incoming intake air. It appears that the OEM L-82 dual snorkel cold air cleaner apparatus is a win win, more than 3 inches (3.5 inches) AND, at least as significant, providing colder air to the engine which everyone knows colder air will produce more power. Colder intake air charge is the reason for intercoolers on Turbo engines.....as a more extreme example.........

 

Exactly, the place the OEM filter assembly loses points is in complexity and appearance. Some remove the hot air flappers and associated vacuum lines and switches to curb the complexity. And some of us just go with the open air filter for looks. (Loss of power is actually very minimal).
But at the end of the day. The original factory setup really does work best.