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Over time I had made several mods. to my intake system, but didn't do a baseline evaluation on the stock system so I could accurately assess changes, if any. First I added another intake duct from behind the grill to the airbox, a K and N drop-in filter, insulated airbox, and finally a double walled, triple insulated custom intake tube from the airbox to the throttle body. I plan to test each configuration, and will post results as I complete each phase. I initially returned everything to stock, and have now completed testing for heat soak, under hood temps. gas mileage and timing using 89 octane fuel, and true intake air temp. vs. ambient temp. Some of these tests have been done by others, most notably by members "done" and "Matt Robertson". First I'll state how my RT is setup, and what I used for the testing.

My RT is totally stock with Conti-seal tires running 40 PSI in the fronts and 38 PSI in the rears. It just turned 7000 miles today. I run 5W-20 Mobil One oil and a K and N oil filter. For this evaluation I ran through 3 tanks of 89 octane fuel. In town driving was all in light to moderate traffic at speeds from 25-50 mph. The highway driving was a 260 mile round trip run, and was done at speeds from 60-70 with a couple full throttle runs in each direction. Outbound I drove 65-70 mph, and inbound on the same highway, I drove 60-65 mph. Ambient air temps. ran from about 55-75 degrees. Highway driving was all done in rolling hills at altitudes of 2600-4200 ft. elevation.

For the evaluation I have a Scan Gauge which provides accurate real time (about 2 second intervals) temp. readouts from the IAT sensor, real time readout on timing, and a wealth of other information. Ambient temps. come from the EVIC, as does the gas mileage, which I have found on my RT to be no more than 3 tenths off, and usually less. I also have a remote reading wireless thermometer mounted to the outside of the intake air duct, with the sensor facing the engine to measure under hood temps. I also have an altimeter, and my MDS "on" indicator light, which tells me when the MDS is active. That all said, here are my findings, and opinions on the stock intake system.

---Around town mileage for two tanks of 89, was 15.3 and 16.1 for an average of 15.7 mpg.
---Highway mileage outbound, on-ramp to off-ramp, with no stops, was 26.7 mpg, and inbound, with one stop, it was 28.5 mpg for a two way average of 27.6 mpg. It should be noted that I got in trouble for not stopping for a "pee break" outbound, so I had to stop on the inbound leg. When I stopped the mileage was at 28.6 mpg. After returning to cruise on the interstate after the "pee break" the mileage went down to 27.8 mpg. I feel the inbound mileage would have been even better had I not made that stop.
---Around town, true intake air temp. ran from 1 degree above ambient when cold to about 50 degrees above ambient when stopped at at stop lights. In normal in town driving the intake temp. seemed to center most between 10-30 degrees above ambient, depending on how long a stretch between stops, and the speed driven. Temps. also vary with throttle position....less throttle opening=higher temp. (more heat soak) vs. more throttle opening=lower temp. due to increased airflow through the duct. As the engine warms up and heat soak comes into play the difference between ambient and true intake temp. increases, sometimes dramatically, especially at stops. This is more pronounced as the ambient temp. increases.
---During highway driving, true intake air temp. ran from 3-15 degrees above ambient. Most of the time it was in the 5-10 degree range. Interestingly, on hills (more throttle opening and intake airflow) the intake temp. would decrease to as low as 3 degrees, and the under hood temp. would increase significantly. The reverse was true going down a hill....higher intake temp. and lower under hood temp.
---Timing in town and on the highway using 89 octane ranged from 5-39 degrees. I only saw 5 and 39 once or twice. Around town, the timing is continually changing, and I was unable to pin down a consistent and realistic range. On the highway, the timing seemed to run most between 26-36 degrees, and did not fluctuate as much as in town. It is, however, constantly changing.
---Under hood temps. (the cause of heat soak and increased intake temps.) was also interesting. When cold, out of the garage, it is close to ambient, but quickly rises. In town, with ambient temps. above 65 degrees and after full warm up, the under hood temp. will send the temp. gauge off-scale high which is over 160 degrees. Surprisingly, on the highway, the under hood temp. seemed to run mostly between 40-55 degrees above ambient. As I said earlier, uphill=higher temp. and downhill= lower temp.

Observations: I think I addressed everything?? The stock system is really quite efficient, unless you are seeking more noise and a slight increase in power. Member "maneval69" did a dyno test with the intake tube disconnected from the airbox and picked up 18 HP, so there is obviously a choke point. If you do a lot of highway driving, and not much in town, I'd say drop a high efficiency filter in and go for it. If you want more performance and perhaps a little more gas mileage, you may want to consider a different setup all together, being careful not to use something that draws air from the engine compartment. If you do a lot of in town driving, you may want to take steps to insulate the intake duct and airbox. My next evaluation will be with the K and N high efficiency drop-in filter, and then the additional intake duct from the grill to the airbox. I welcome any questions, comments or criticisms.
 

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magnuman said:
Over time I had made several mods. to my intake system, but didn't do a baseline evaluation on the stock system so I could accurately assess changes, if any. First I added another intake duct from behind the grill to the airbox, a K and N drop-in filter, insulated airbox, and finally a double walled, triple insulated custom intake tube from the airbox to the throttle body. I plan to test each configuration, and will post results as I complete each phase. I initially returned everything to stock, and have now completed testing for heat soak, under hood temps. gas mileage and timing using 89 octane fuel, and true intake air temp. vs. ambient temp. Some of these tests have been done by others, most notably by members "done" and "Matt Robertson". First I'll state how my RT is setup, and what I used for the testing.

My RT is totally stock with Conti-seal tires running 40 PSI in the fronts and 38 PSI in the rears. It just turned 7000 miles today. I run 5W-20 Mobil One oil and a K and N oil filter. For this evaluation I ran through 3 tanks of 89 octane fuel. In town driving was all in light to moderate traffic at speeds from 25-50 mph. The highway driving was a 260 mile round trip run, and was done at speeds from 60-70 with a couple full throttle runs in each direction. Outbound I drove 65-70 mph, and inbound on the same highway, I drove 60-65 mph. Ambient air temps. ran from about 55-75 degrees. Highway driving was all done in rolling hills at altitudes of 2600-4200 ft. elevation.

For the evaluation I have a Scan Gauge which provides accurate real time (about 2 second intervals) temp. readouts from the IAT sensor, real time readout on timing, and a wealth of other information. Ambient temps. come from the EVIC, as does the gas mileage, which I have found on my RT to be no more than 3 tenths off, and usually less. I also have a remote reading wireless thermometer mounted to the outside of the intake air duct, with the sensor facing the engine to measure under hood temps. I also have an altimeter, and my MDS "on" indicator light, which tells me when the MDS is active. That all said, here are my findings, and opinions on the stock intake system.

---Around town mileage for two tanks of 89, was 15.3 and 16.1 for an average of 15.7 mpg.
---Highway mileage outbound, on-ramp to off-ramp, with no stops, was 26.7 mpg, and inbound, with one stop, it was 28.5 mpg for a two way average of 27.6 mpg. It should be noted that I got in trouble for not stopping for a "pee break" outbound, so I had to stop on the inbound leg. When I stopped the mileage was at 28.6 mpg. After returning to cruise on the interstate after the "pee break" the mileage went down to 27.8 mpg. I feel the inbound mileage would have been even better had I not made that stop.
---Around town, true intake air temp. ran from 1 degree above ambient when cold to about 50 degrees above ambient when stopped at at stop lights. In normal in town driving the intake temp. seemed to center most between 10-30 degrees above ambient, depending on how long a stretch between stops, and the speed driven. Temps. also vary with throttle position....less throttle opening=higher temp. (more heat soak) vs. more throttle opening=lower temp. due to increased airflow through the duct. As the engine warms up and heat soak comes into play the difference between ambient and true intake temp. increases, sometimes dramatically, especially at stops. This is more pronounced as the ambient temp. increases.
---During highway driving, true intake air temp. ran from 3-15 degrees above ambient. Most of the time it was in the 5-10 degree range. Interestingly, on hills (more throttle opening and intake airflow) the intake temp. would decrease to as low as 3 degrees, and the under hood temp. would increase significantly. The reverse was true going down a hill....higher intake temp. and lower under hood temp.
---Timing in town and on the highway using 89 octane ranged from 5-39 degrees. I only saw 5 and 39 once or twice. Around town, the timing is continually changing, and I was unable to pin down a consistent and realistic range. On the highway, the timing seemed to run most between 26-36 degrees, and did not fluctuate as much as in town. It is, however, constantly changing.
---Under hood temps. (the cause of heat soak and increased intake temps.) was also interesting. When cold, out of the garage, it is close to ambient, but quickly rises. In town, with ambient temps. above 65 degrees and after full warm up, the under hood temp. will send the temp. gauge off-scale high which is over 160 degrees. Surprisingly, on the highway, the under hood temp. seemed to run mostly between 40-55 degrees above ambient. As I said earlier, uphill=higher temp. and downhill= lower temp.

Observations: I think I addressed everything?? The stock system is really quite efficient, unless you are seeking more noise and a slight increase in power. Member "maneval69" did a dyno test with the intake tube disconnected from the airbox and picked up 18 HP, so there is obviously a choke point. If you do a lot of highway driving, and not much in town, I'd say drop a high efficiency filter in and go for it. If you want more performance and perhaps a little more gas mileage, you may want to consider a different setup all together, being careful not to use something that draws air from the engine compartment. If you do a lot of in town driving, you may want to take steps to insulate the intake duct and airbox. My next evaluation will be with the K and N high efficiency drop-in filter, and then the additional intake duct from the grill to the airbox. I welcome any questions, comments or criticisms.
Very thorough...Nice Job
 

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The only comment I have is:

Thanks and keep experimenting!!! It will help many decide what is best for them (including me).
 

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MM,

Again, another great post!
Thanks for the info.

Admins and Moderators...is there a way to add to the FAQ section? This is a thread that does not need to get lost.
 
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