GS - 2nd Gen (1998-2005) Discussion about the second generation GS300, GS400 and GS430 (1998 - 2005)

CAI question

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Old 08-29-12, 08:10 PM
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818GS
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Default CAI question

There are many intakes for the GS400 but there all under the hood. I was going to make a custon intake to relocate the filter where the bumper is. My question is:
Will the cold air make up for the extended intake pipe?
I am worried that since the air has to travel longer to get to the engine it will decrease performance but on the other hand it has access to much colder air than what is under rhe hood. So CL let me know what you think about this.
Old 08-29-12, 09:50 PM
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clos430
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Just pick this one up and call it a day!


https://www.clublexus.com/forums/2ge...nd-n-fipk.html
Old 08-29-12, 11:49 PM
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818GS
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Originally Posted by clos430
Just pick this one up and call it a day!


https://www.clublexus.com/forums/2ge...nd-n-fipk.html
For that price I rather make one. It is a good intake tho I hope he sells it.
Old 08-31-12, 02:51 PM
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Can anybody give me some insight on this?
Old 08-31-12, 03:13 PM
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RamAirRckt
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Air is warmer the closer to the roadway, I wouldn't be surprised if you lose some power overall.

Where it is stock breathes well and is in a good place. I don't think moving it lower will help anything, and it risks ingesting water in a puddle. I know, I did it once. It was a miracle I didn't lunch the engine. It got that far. Bad sudden storm, night time, didn't see it coming.

Get a thermocouple (they are dirt cheap on some new multimeters) and measure the temps before/after an air intake install. Try to keep ambient temp the same. In most every single case I have messed with air box changes, the intake air temps never changed (meaning got any significance better than stock).

Never ever move the intake air temp sensor. Some think it helps, but reality is the ECM needs to know the ACCURATE intake air temp to do the calculations properly. Best is a MAT sensor, Manifold Absolute Temp. But it isn't used as much now, but is still used on some models.
Old 08-31-12, 03:30 PM
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Originally Posted by RamAirRckt
Air is warmer the closer to the roadway, I wouldn't be surprised if you lose some power overall.

Where it is stock breathes well and is in a good place. I don't think moving it lower will help anything, and it risks ingesting water in a puddle. I know, I did it once. It was a miracle I didn't lunch the engine. It got that far. Bad sudden storm, night time, didn't see it coming.

Get a thermocouple (they are dirt cheap on some new multimeters) and measure the temps before/after an air intake install. Try to keep ambient temp the same. In most every single case I have messed with air box changes, the intake air temps never changed (meaning got any significance better than stock).

Never ever move the intake air temp sensor. Some think it helps, but reality is the ECM needs to know the ACCURATE intake air temp to do the calculations properly. Best is a MAT sensor, Manifold Absolute Temp. But it isn't used as much now, but is still used on some models.
Yah I was scared of hydro lock but we don't get much rain in Cali. Thats why I think this might be good because cold air sinks and thats where the intake will be.
Old 08-31-12, 03:55 PM
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Cold air sinks, but have you ever touched the highway pavement? It is hot, even on a moderate day. You don't see too many race cars ever trying to pick up low under bumper air.

In front is always good, high pressure, any high pressure helps. But temp can really hurt. The ECM/ECU/VCM/PCM (whatever it is called by whatever brand) will pull timing out in pretty big numbers (3-4 degrees is NOT uncommon) to protect against pinging. Even coolant temps when you get in the 90C range most computers are starting to pull timing out. Ever notice the power loss from a hot day to a cold day? Pretty dramatic when you compare side by side.

What I would do is get a thermocouple (2 is best, one in each place) and put it in the place you plan on the intake, and see what the temps are, and then measure in front of the air inlet on the car in the stock location. See which is higher. Always best to test it out first than to put big $ into it and find out it was all a waste. We can't really expect to out think the engineers who designed a lot of this stuff, they are experts in most cases and don't do (what we perceive as stupid) things without good reason.
Old 08-31-12, 06:15 PM
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Originally Posted by 818GS
. My question is:
Will the cold air make up for the extended intake pipe?
I am worried that since the air has to travel longer to get to the engine it will decrease performance but on the other hand it has access to much colder air than what is under rhe hood. So CL let me know what you think about this.
How do you figure that the air has to travel a longer path? The distance, if anything, is actually a bit shorter in this CAI design. I think you are confusing the OEM airbox as the source of the air, when really the extra factory snorkel easily adds an additional ~40cm, along its medium path, to get to the air source.

The other components that many aren't taking into consideration is the smoother path the air travels in the CAI design referenced. In the factory setup the entering air takes a number of bends and is forced to go through a panel filter where the upper airbox lid cuts off nearly 1/3 of the available filter media before allowing it to enter the MAF. The surface area of the conical filter is easily triple what the factory panel allows. The OEM design, while it is not very restrictive per se, however was created more for quietness beyond other factors.

Road heat is not really an issue here. The oem design has the air coming from behind the grill, over the radiator/condensor support into the oem snorkel and is certainly not cooler than the air entering from another high pressure area in the front lower bumper. I wonder if everyone knows there is a nice ~3" x 4" body colored punch out area just to the right of the left hand fog light just between the 3 horizontal slats. This area even has a nice directional vane that helps push air to the large opening in front of the pass front tire where the new large conical filter sits. This is where I imagine the 2JZ turbo Aristos must have had a factory intercooler?

I know a thermocouple and everything sounds like a great idea, but the expense and time you could have easily built the intake and see how your car reacts/responds. Otherwise good luck on your project!
Old 08-31-12, 08:38 PM
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Originally Posted by ChampGS3
How do you figure that the air has to travel a longer path? The distance, if anything, is actually a bit shorter in this CAI design. I think you are confusing the OEM airbox as the source of the air, when really the extra factory snorkel easily adds an additional ~40cm, along its medium path, to get to the air source.

The other components that many aren't taking into consideration is the smoother path the air travels in the CAI design referenced. In the factory setup the entering air takes a number of bends and is forced to go through a panel filter where the upper airbox lid cuts off nearly 1/3 of the available filter media before allowing it to enter the MAF. The surface area of the conical filter is easily triple what the factory panel allows. The OEM design, while it is not very restrictive per se, however was created more for quietness beyond other factors.

Road heat is not really an issue here. The oem design has the air coming from behind the grill, over the radiator/condensor support into the oem snorkel and is certainly not cooler than the air entering from another high pressure area in the front lower bumper. I wonder if everyone knows there is a nice ~3" x 4" body colored punch out area just to the right of the left hand fog light just between the 3 horizontal slats. This area even has a nice directional vane that helps push air to the large opening in front of the pass front tire where the new large conical filter sits. This is where I imagine the 2JZ turbo Aristos must have had a factory intercooler?

I know a thermocouple and everything sounds like a great idea, but the expense and time you could have easily built the intake and see how your car reacts/responds. Otherwise good luck on your project!
I am not installing a regular CAI. I am extending it to the opening next to the fog light as you mentioned so in fact it does have to travel a longer distance. I like the point you brought up about being less restrictive and flowing smoothly. Both factors will help a lot but with my custom CAI the air has to pass through 2 90 degree bends so it wont be flowing as smoothly as you think.
Old 08-31-12, 08:41 PM
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Originally Posted by RamAirRckt
Cold air sinks, but have you ever touched the highway pavement? It is hot, even on a moderate day. You don't see too many race cars ever trying to pick up low under bumper air.

In front is always good, high pressure, any high pressure helps. But temp can really hurt. The ECM/ECU/VCM/PCM (whatever it is called by whatever brand) will pull timing out in pretty big numbers (3-4 degrees is NOT uncommon) to protect against pinging. Even coolant temps when you get in the 90C range most computers are starting to pull timing out. Ever notice the power loss from a hot day to a cold day? Pretty dramatic when you compare side by side.

What I would do is get a thermocouple (2 is best, one in each place) and put it in the place you plan on the intake, and see what the temps are, and then measure in front of the air inlet on the car in the stock location. See which is higher. Always best to test it out first than to put big $ into it and find out it was all a waste. We can't really expect to out think the engineers who designed a lot of this stuff, they are experts in most cases and don't do (what we perceive as stupid) things without good reason.
This is a good idea. I am going to check the temp in both locations. I don't think the road heat will be a problem because the filter will be high enough that it won't be affected.
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