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08-05-2010, 12:34 PM
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Blinded by the light
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Join Date: Sep 2009
Posts: 7,674
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READ ME: All about Intake Air Temperature / CAI / MAF
Here is an air intake lesson for everybody because it really seems like a lot of people don't actually understand how this concept works. This is mostly due to the way gimick products are advertised.
First the science, then the why it matters.
Intake air temperature effects fuel mixture. Air density increases as air temperature decreases. Cooler air has more air molecules than warmer air. The computer will always try to maintain a given air/fuel ratio. So by monitoring the intake air temperature, it knows how to adjust the fuel injectors to apply the right amount of fuel.
As intake air temperature decreases, the air density increases, more air = more fuel needed to maintain the ratio. A side result of more air and more fuel is more power! So, the lower the intake air temperature, the better. However, no matter what you do, you will never get the intake air to be cooler than outside ambient air temperature.
As intake air temperature increases, air density decreases, less air = less fuel needed ot maintain the ratio. A side result of less air and less fuel is less power! This is why when it's 100 degrees in the summer going up hill, it feels like you're dragging a grand piano behind the truck. This is also why an intake that sucks air from under the hood is bad because it can be a crisp 150 degrees under there!
Since your stock intake is plumbed to the outside (in the grill by the right headlight, you are already drawing in outside air, which is as cool/cold/fresh as it is going to get. Adding a new shiney piece of pipe will not change that or make the air be colder. This is why aftermarket CAI kits are a useless waste of money on our trucks. This is PROVEN. If you monitor the intake air temperature sensor, you will see that it matches the outside air temperature exactly. Net gain, nothing.
Now that you know air temperature, you have to know air flow as well. In addition to know the air temperature to regulate fuel flow, it also needs to know how much of that air is flowing. The MAF detects air flow (hence the name...). This combined with the temperature let the computer regulate the fuel flow with precision. If the MAF is dirty, broken, or disconnected, the engine will shit. If due to engine mods that require more air flow, you have to make the intake larger, you will need to buy an aftermarket larger diameter MAF.
The stock intake is more than enough for the stock heads, cylinders, and exhaust. Adding a larger diameter intake will not gain you anything since it is already at peak efficiancy. This is dyno proven. Further reasoning why aftermarket CAI's for our trucks are useless waste of money.
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08-05-2010, 12:49 PM
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Sept. 2011 TOTM
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Join Date: Jan 2010
Posts: 1,772
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Hells yeah... I regret getting mine, back before I knew better.
Last edited by TurdFX4; 08-05-2010 at 12:53 PM.
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08-05-2010, 01:14 PM
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Chrome Dont Get You Home
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Join Date: Dec 2009
Posts: 1,169
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
great guide should be put under the welcome threads or something
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1990 Ranger Extended Cab
2.9L V6 5 Speed Transmission
Planning to put a 347 and a T-5 in it eventually
Quote:
Originally Posted by FireRanger
It looks like someone attacked the front of the truck with a bedazzler.
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08-05-2010, 01:24 PM
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OIF Veteran
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Join Date: Feb 2010
Posts: 6,044
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
As per the request of the OP and since this topic comes up frequently I stickied this thread. Please no bickering about CAI's here.
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2001 Ranger 4x4 Stepside
-RCD Suspension lift
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-Auburn gear LS
-James Duff traction bars
-Headers
-Flowmaster duals
-SCT X-Cal2 and some small exterior mods
http://www.cardomain.com/ride/2321189
2005 F-150 Lariat 4x4
- LED third brake light
-Weathertech floor liners
-Edge tuner
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08-05-2010, 05:57 PM
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Learning to use the forums
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Join Date: Jul 2010
Posts: 11
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Two questions
1. If you can FLOW that air more aerodynamicly wil you see increase because of the added air pressures beign forced through the tunnel?
2. if you could some how plumb a cooler of some type be it a freon charge or soemthing would that produce a useful result?
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08-05-2010, 06:19 PM
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Blinded by the light
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Join Date: Sep 2009
Posts: 7,674
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Quote:
Originally Posted by supercomet32
Two questions
1. If you can FLOW that air more aerodynamicly wil you see increase because of the added air pressures beign forced through the tunnel?
2. if you could some how plumb a cooler of some type be it a freon charge or soemthing would that produce a useful result?
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1: No, the intake is not restricting anything on a stock motor. Dyno testing shows a stock intake vs a pretty looking aftermarket ones yield no improvement, and often reduce performance if anything.
2: Yes. However the resistance of the cooling coils would restrict the air flow so much, it would probably make it worse. An air box and cooling coil large enough to achieve this would be roughly the size of your windshield. Not practical.
On a related note, the intercooler on a turbo does a similar job. The intake air goes through a radiator looking device in the grill that allows ambient ram air to cool the intake air as it passes through the intercooler. Some high performance racing trucks have liquid spray nozzles on the front of the intercooler to increase the effectiveness of the heat exchange. It will still only cool the intake air down to ambient temperature, but it can do it faster. Also impractical for us and only applies to intercooled turbos.
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08-07-2010, 01:46 PM
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diMwit
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Join Date: May 2009
Posts: 341
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Story time! Saw a guy that raced a slant 6 with a 4 barrel. He had copper fuel lines wrapped around a coffee can. He'd fill it up with dry ice on race day and drop a second off his quarter mile time!
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'88 STX Super Cab 4x4
2.9 5spd 180,000 miles
Crappy Paint, Worn Parts,
Fix'em as they Break
when Nowhere is Now Here
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08-07-2010, 02:03 PM
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Blinded by the light
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Join Date: Sep 2009
Posts: 7,674
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Quote:
Originally Posted by Yrac
Story time! Saw a guy that raced a slant 6 with a 4 barrel. He had copper fuel lines wrapped around a coffee can. He'd fill it up with dry ice on race day and drop a second off his quarter mile time!
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Highly unlikely that this is true. Fuel density change with temperature is nothing like air. And cooling gasoline is not going improve combustion.
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08-07-2010, 02:14 PM
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DISABLE ADBLOCK: LOLZ
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Join Date: Dec 2009
Posts: 1,471
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Quote:
Originally Posted by FireRanger
.... If due to engine mods that require more air flow, you have to make the intake larger, you will need to buy an aftermarket larger diameter MAF......
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I scale MAF tables with a single scalar value on Mitsubishi or Subaru. If you have the ford software you can do this also.
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Looking for a professional retrofitter to add HIDs or LEDs to your Ranger? PM me if your looking to have work done, and have cash to spend.
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08-07-2010, 02:43 PM
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Blinded by the light
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Join Date: Sep 2009
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
I mean larger in diameter to accomodate the need for more air flow.
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08-08-2010, 08:00 AM
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Tank Diver
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Join Date: Mar 2010
Posts: 3,129
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
One could wrap the intake tube with insualation to prevent the air from heating up while traveling from the head light area to the intake manifold but I imagine the benefit would be marginal.
One could also wrap the exhaust manifold with insulation to bring down engine compartment temperatures though in a moving vehicle, I would think that the resulting benefit would again be marginal on a stock engine.
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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap
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08-08-2010, 09:37 AM
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DISABLE ADBLOCK: LOLZ
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Join Date: Dec 2009
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
Quote:
Originally Posted by sgtsandman
One could also wrap the exhaust manifold with insulation to bring down engine compartment temperatures though in a moving vehicle, I would think that the resulting benefit would again be marginal on a stock engine.
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You are right for the wrong reasons. Keeping the exhaust hot helps it move faster through the "hot end" of the exhaust.
I do this on Turbo-cars all the time because you want to keep the gasses really hot through the runners on the way to the turbine. That's why I have ceramic coated runners.
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Looking for a professional retrofitter to add HIDs or LEDs to your Ranger? PM me if your looking to have work done, and have cash to spend.
Quote:
Originally Posted by FireRanger
I'm dying to see this at night. Someone go tell the sun to give up already.
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Quote:
Originally Posted by beef08
Your the man, you bring our dreams to a reality within the lighting spectrum
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Quote:
Originally Posted by BCobe
Jp7 you always do AMAZING work! Hats off to you sir
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Quote:
Originally Posted by FireRanger
People so often confuse "hating" with "knowing better".
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08-08-2010, 09:48 AM
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Tank Diver
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Join Date: Mar 2010
Posts: 3,129
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
I was thinking about a normally aspirated engine and the direct correlation to air intake temperatures.
From what I understand, keeping the exhaust temp hotter for better performance also applies to normally aspirated engines as well.
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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap
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08-08-2010, 09:51 AM
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Blinded by the light
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Join Date: Sep 2009
Posts: 7,674
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
I'm not sure what benefit keeping the exhaust hotter has in a normally aspirated engine. You want the combustion to be peak but once it leaves the engine, it is just waste.
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08-08-2010, 10:20 AM
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Tank Diver
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Join Date: Mar 2010
Posts: 3,129
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Re: READ ME: All about Intake Air Temperature / CAI / MAF
The thinking is that the longer you can keep the exhaust hot, the faster it will leave the exhaust creating a vacuum of sorts and thus allowing the cylinder to clear better for the next air/fuel charge but this is a digression from your original subject matter...
Edited for word omission
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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap
Last edited by sgtsandman; 08-08-2010 at 11:23 AM.
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