A year ago I completely insulated the intake on my 03, 5.9 Dakota. Since the daks aren't plumbed into the fender well, I removed the convolute that was attached to the air cleaner housing and plumed right into the fender well (like most trucks!). But I do wonder if it was a waste of time since the components of the intake system probably end up the same temp as the engine compartment because of the radiant heat absorption through the inso. On a side note, interesting thing about the direct line to the fender well is that the air cleaners never seem to get dirty, although I continue to replace every 15,000!
Insulating the air intake? Radiant heat!
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You should get some benefit from the insulation. Radiant heat is only part of the equation - the main contributor is conduction. The heat will soak through the insulation, but the insulation slows down the rate of heat flow. The air flowing in the intake system will be cooler, especially if you are picking it up from outside the engine compartment. After you shut the engine off the heat will soak into the system, but after a short time running the engine, the intake system will cool back down. If you want to block the radiant heat also, you can add a radiant barrier such as thick aluminum foil on top of the insulation. Cooler air is more dense and should give you more power.
When you are making a lot of power, the air is going through your intake at something like 75 to 120 mph. It isn't in the intake long enough to pick up any appreciable amount of heat.
Dry ice is -110F and drag racers are looking for every microscopic edge they can find.quote:
Originally posted by 3000GT VR-4:
That must be why drag racers dry-ice their intake manifolds.
Try running a temperature probe in an intake system someday and observe for yourself what happens to intake temperatures at full power in a normal intake system. Air temp going into the engine at full power is pretty close to the temp of the air going into the air cleaner.
According to my ScanGauge, the intake air temp normally stays at 7 or 8C over ambient on the highway. It rapidly rises in the city, sometimes to 15C over, with the ambient temperature hovering around freezing. I think that's because of lack of engine compartment ventilation in the city. I'll buy the sticking pipe insulation with foam between aluminum layers and will try it on my stock intake, just to figure the impact.
I have a similar question, but from the different perspective. The colder is the air, the more power you get, probably at the cost of fuel consumption, that's clear. How about warmer air preventing ECU to dump as much fuel, thus increasing fuel efficiency at moderate to low power output level?
if your intake plumbing is black or dark colored, it is pretty much an infrared sponge. Just painting it a sliver color will block a significant amount of infrared/radiant heat. The foil OVER the foam insulation would block pretty much everything, radiant and convective, but I still question the need and benefit in 99% of the applications.
You need to measure the air at the intake's inlet, not just external to the engine compartment to be a 100% valid test.
also note many enignes have a warmer inside the throttle body to circulate engine coolant to actually warm the air. These are usually pretty easy to plumb shut or at least add a valve to switch off and on.
My favorite one was the pic a guy posted (elsewhwere) of his foam insulated intake, longer than stock, no wider than stock and with at least 3-4 added bends that ended with his cone filter sitting right behind the radiator.....in front of the exhaust manifold. And he removed the heat shield to make it fit.
The realy sad part? he actually paid someone to custom mandrel bend this abortion. Or more accurately, his mommy did....
[ January 10, 2005, 03:44 PM: Message edited by: kenw ]
You need to measure the air at the intake's inlet, not just external to the engine compartment to be a 100% valid test.
also note many enignes have a warmer inside the throttle body to circulate engine coolant to actually warm the air. These are usually pretty easy to plumb shut or at least add a valve to switch off and on.
My favorite one was the pic a guy posted (elsewhwere) of his foam insulated intake, longer than stock, no wider than stock and with at least 3-4 added bends that ended with his cone filter sitting right behind the radiator.....in front of the exhaust manifold. And he removed the heat shield to make it fit.
The realy sad part? he actually paid someone to custom mandrel bend this abortion. Or more accurately, his mommy did....
[ January 10, 2005, 03:44 PM: Message edited by: kenw ]
All else being equal, a drop of 10° air charge temperature = 1% HP improvement. However, even if the temperature of the air in the inlet pipe is lowered, it is still heated as it passes through the throttle body, manifold, cylinder head, so you won't see the full 10° drop by the time it's in the cylinder, especially with heat soak. Although, every little bit helps in a racing situation. And long term WOT operation should cool the other components mentioned above.
Some real interesting views. I never realized the air was passing at that rate, however, I do admit the intake manifold/plenum temp on a 5.9 is off the charts, so the air charge temp may not really matter. I actually removed the insulation today because the IA motor on the throttle body went (under warranty!) so I wanted to get all that off before the tow truck came up to the house. Depending on some more views, I may/may not insulate come spring. Thanks for the interesting dialog and keep it up!
http://easyperformance.com/ has a good write up on CAI design. It can make a difference, for those looking for every horsepower they can get, or more importantly for those with engines where intake air temps are critical(like forced induction) it is a good idea.
In short, as long as your filter and plumbing isn't unduly restrictive, and the plumbing isn't running next to a high heat source (like an 1/8" from a hot exhaust manifold), I believe you'll get the biggest bang for your buck just by insuring your air intake is taking in cooler air from outside the under-hood area.
Does the warm/hot intake air decrease power and increase fuel economy then?
Generally it will decrease power, about 1% for every 5 degrees F intake air temp increase.
There won't be much if any change in economy as long as you have a computer controlled fuel injection system that keeps your mixture correct.
Fresh air intake theory came in a big way in sports bikes from Yamaha and Honda, Yamaha designed scoops in the front fairings to induce a ram air effect to the carbs on their FZR-750 and 1000 bikes, Honda and others followed, for years, most passenger cars had been fearful of putting fresh air concept as they feared it would also let in water in the intake system during rainy season. Slowly I see the sports cars incorporating this feature, fresh air makes a huge difference in any kind of engine including diesels.
The noise reduction must be worth it. I replaced my busted up foam covered intake with some generic intake hose and now my 1.6 diesel sounds like a pack of bulldozers! The exhaust leak is definately adding to the noise but man, it is ridiculous now!
Cheers, Steve
Cheers, Steve
Gurkha: My 1988 2.0 Cavalier had a tiny front mounted air intake. It was about 1/2" tall and just below the lip of the hood. It worked fine unless you were pushing snow up over the hood.
Steve
Steve
srivett,
I am going back a bit further, the Yamaha FZR-750 was released in 1987, there were few cars then with the ram fresh air intake or with the design of locating the air filter housing away from the heat, most had their sir filters mounted on top of their carbs, TBI or the valve cover thereby getting plenty of heat soak during summer. I thought my T/A's NACA ducts on the hood were for ram fresh air effect but much to my chagrin I discovered they were ornamental and not functional in design.
I am going back a bit further, the Yamaha FZR-750 was released in 1987, there were few cars then with the ram fresh air intake or with the design of locating the air filter housing away from the heat, most had their sir filters mounted on top of their carbs, TBI or the valve cover thereby getting plenty of heat soak during summer. I thought my T/A's NACA ducts on the hood were for ram fresh air effect but much to my chagrin I discovered they were ornamental and not functional in design.
Huh? Cold air induction has been around longer than you think. It wasn't something that ANY bike maker had much to do with advancing except on bikes.
Plenty of mid-late 60s muscle cars had them. Even before that it was VERY common to extend the air intake from the round filter housing on top of the carb to just above the radiator. Or straight up thru the hood. Ever hear of a shaker hood?
I might be wrong, but I believe it was the NASCAR boys in the early sixties that made "outside" ram air advantages popular. Many sixties muscle cars utilized cold air/ram air intakes.
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