Stock Cold air intake performance upgrades

[Ricko1966]

Cold air is better than hot air for performance due to air density but not the dramatic claim that some aftermarket companies claim. And yes freeing up restrictions on the air cleaner will make a difference,that's why gm used dual snorkel on some but not all. Here's some dyno testing on a mostly stock 350 2bbl, also the 305 engine will never keep up with an equally built 350,but they can make a lot more than they do stock for not a lot of money or work.

https://www.motortrend.com/how-to/sucp-0610-small-block-bolt-ons

 

[SquareRoot]

Cold air intakes are a joke to begin with. Way too many variables to quantify a 10-15 horse "gain" on a chassis dyno. Folks hear more intake noise and think they gained 40 horse.

They do serve a purpose on EFI engines I have found out firsthand. My PF4 had hot re-start issues in the summer when it was 110 degrees outside. It took me and the Edelbrock tech line some time to figure it out. After shutdown, the under hood temps would spike. If I tried to restart it, it would crank a long time before firing. After I added the cold air intake, it mostly went away. What happens is the IAT sensor reads that super hot air and retards the timing making it hard to start. The cool rush of outside air prevented the issue. On an old school carb , I suppose it wouldn't matter.

 

[77Dmax]

I know cold dense air increases power. I'm saying he won't do better than the factory setup.

Cold air isn't that simple with a factory carb either. The thermal vacuum switch is designed to keep the air cleaner temp at 115 degrees. Keeping the air temp consistent keeps the mixture proper. Ditching the thermvac system and piping in cold air will actually create a lean condition on an engine that is already tuned extremely lean. He'll need to tune the carb for colder air. Lots of folks disable/break the thermo switch but don't realize how important it is for driveability. Even the hottest cars to leave Detroit have the same system in place.

 

[TDoc]

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What is the purpose of this ^. It’s just siliconed to the air cleaner. I removed it and no drive ability issues. Cold starts just fine. Pretty sure this thing was gone when TBI came out in ‘87 on trucks.

The heat tube that comes off the manifold is gone and the vacuum operated door disconnected when I bought this in December. It’s done just fine 0 degree cold starts.

 

[77Dmax]

What are you pointing at?

I'm not surprised the thermal system is disabled. 95% of people have no idea why it's there or how it works. It won't have any effect on cold starts.

 

[Ricko1966]

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What is the purpose of this ^. It’s just siliconed to the air cleaner. I removed it and no drive ability issues. Cold starts just fine. Pretty sure this thing was gone when TBI came out in ‘87 on trucks.

The heat tube that comes off the manifold is gone and the vacuum operated door disconnected when I bought this in December. It’s done just fine 0 degree cold starts.

In case of a backfire the paper air cleaner doesn't catch fire and burn the fuel in the carb,and so on and so on. Didn't use to be uncommon for a car to burn to the ground from an air cleaner fire. Yes it's a 1 in a million thing,but 100s of millions of cars used to run around with carbureators and paper filters.

 

[AuroraGirl]

What are you pointing at?

I'm not surprised the thermal system is disabled. 95% of people have no idea why it's there or how it works. It won't have any effect on cold starts.

thermac is for driveability not starts
So when its cold , the flap closes, and it pulls intake air from the exhaust manifold stove which means once your engine has run for like 30 seconds the air coming in would be incredibly warmer compared to ambient cold

 

[77Dmax]

thermac is for driveability not starts
So when its cold , the flap closes, and it pulls intake air from the exhaust manifold stove which means once your engine has run for like 30 seconds the air coming in would be incredibly warmer compared to ambient cold

See my other post. The system is in constant operation and tries to maintain a consistent air cleaner temp, even after the engine has reached operating temp

 

[AuroraGirl]

See my other post. The system is in constant operation and tries to maintain a consistent air cleaner temp, even after the engine has reached operating temp

i wasnt disagreeing ,i was expanding on the "It wont have any effect on cold starts" my bad
I never heard of the constant regulation, but it makes sense based on how its vacuum and temperature controlled actuator is

 

[AuroraGirl]

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What is the purpose of this ^. It’s just siliconed to the air cleaner. I removed it and no drive ability issues. Cold starts just fine. Pretty sure this thing was gone when TBI came out in ‘87 on trucks.

The heat tube that comes off the manifold is gone and the vacuum operated door disconnected when I bought this in December. It’s done just fine 0 degree cold starts.

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this is from the 1980 manual, i notice the thermac section is not as detailed in the 1980, and doesnt contain a delay valve. i bet the consistent 100 degrees was an evolved principal over the original use, because they realized they could get it to consistently deliver 100 degree air, so added that component as is noted in the 1987 manual below:

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[77Dmax]

I gotcha now. The intake pad was also heated with the exhaust crossover which helped with cold running.

It's mind boggling how GM came up with all this and made it work.

 

[Ricko1966]

I gotcha now. The intake pad was also heated with the exhaust crossover which helped with cold running.

It's mind boggling how GM came up with all this and made it work.

You should see how complex it was on a late 60s Olds turnpike cruiser model. Earlier though when he said what is this. I thought he was referring to the flame arrestor,not the thermal system.