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Discussion Starter · #1 · (Edited)
This article covers the following:
- Air Intake (5.7L, 6.1L, 6.4L)
- Throttle Body Selection
- DiabloSport Intune (Tuner)
- 180 Thermostat
- Catch Can
- Heatsoak / Prevention
- Short vs. Long IAT Sensor Usage (pre 2011 - LX/LC and Jeep)
- Black to Grey Converter Cable

First, many thanks to the contributions over the years by many people and the independent research studies performed.

Air Intake Design/Study
- LX Forums Mods Face Off Intake testing - Contributions made by CoolVanilla (LXForum member)
(1) Stock R/Ts and SRTs benefited most from a fender pull CAI like the RDP Intake. This also led to the design of the 4" LegMaker Fender Pull Intake.
(2) Modified SRTs benefited most from a less restrictive intake like AFE's Stage II Intake and actually lost power with more restrictive designs (supported through the gains seen in a less restrictive intake design).

This led to,
- The Frankentake for modified engines - Matt Roberston from the Mods Face off studies, the Frankentake III was redesigned into Frankentake IV.
(1) Frankentake I-III Studies. Showed us a heat shield, with proper modifications was not necessary.

Proper Engine Bay Modifications

Here is a list of things done along with the original test link:

- Inner plastic baffle (air deflector) on drivers side next to radiator has been removed to allow direct air flow to intake area
- Brake Master cylinder cover has been removed. Hand-over-the-hood-opening test says it vents heat

To see pictures of the actual removed part, go to the bottom of page 4 of the AEM intake installation instructions below.

Bottom Page 4, Lower Radiator Baffle Modification

(also supported by Reducing Engine Bay Heat), a 4" tube design (along with Intake material testing and the effects of heat.) and larger filter surface area than stock was essential and producing gains.

(2) The Frankentake IV studies. Taking the AFE Stage II filter design, and what was learned about heat accumulation under the hood, the filter was angled down toward the fender hole.

Aftermarket Intake Consideration Factors

For anyone considering an aftermarket intake:

- (pre 2011 models) switching to the new IAT sensor (better insulated design - the wires are wrapped completely now, the sensor is located in the middle of the intake tube which increases the air barrier all the way around between the sensor and the intake tube)

- getting the IAT sensor away from the engine block and away from the radiator fans blowing directly on it (sensor insulation from heat), IAT relocation down the tube

- using a rubber, plastic or carbon fiber design (best materials with very low thermal conductivity), (note: stainless steel has a low thermal conductivity of 16 vs aluminum that has a very high thermal conductivity of 250 - avoid using aluminum if you choose to use a metal type intake). (purpose is to insulate again)

- using a 4" intake tube (reducing restriction), (stock throttle body is 80mm, 3.5" tube is 88.9mm, 4" tube is 100mm - require a reducer to ensure air flow velocity)

- using a 4" to 3.5" reducer at the throttle body (maintain air flow velocity especially at low speeds)

- getting a filter that has more filter surface area than stock (reducing restriction), Larger filter surface area than the stock filter surface area (Pre 2011 Stock 5.7 & 6.1 - 88 sq/in; 2011+ Stock 5.7 & 6.4 - 130 sq/in); (note: the stock air filter meets the airflow requirements for the 6.4L engine -

- using air located in the fender well (location of the closest to ambient temperature in the engine bay, especially while while idling) Colder air is better than hotter air that enters the engine. {edit} For the 392, the engine was calibrated for an intake temperature of 86 degs; anything better resulted in spark advance.

- The least restrictive design will yield the largest performance gains on modified/heavily modified engines.

make for a good CAI.

The basis from these observations come from my own tests with multiple air intakes, the tests conducted over the years from LXforums, and also how Dodge engineers redesigned the new air box off of the same principles, except they made it easier to maintain the new filter.

Based on user independent testing, here are some of the top performing air intakes: averaged on multiple dyno pulls

In short (no pun intended), short tube and long tube intakes are great at wide open throttle. They do produce gains based upon the consideration factors of good air intakes to the stock setup. The downside of short tube intakes is their stop and go/idle performance and the downside of long tube intakes is their water hazard/filter maintenance accessibility. None the less, based upon the Challenger's weight and the gains listed below, a good after market CAI is roughly good for +0.1-0.2 and +1-2 mph in the 1/4mi on an otherwise stock vehicle.

Short Tube - AFE Stage II, Frankentake IV*, AirHammer Carbon Fiber (gains around 9 rwhp / 8 rwtq - on stock 6.1l and 5.7l) - Filter design was also a key contributor; having a filter design like the AFE or S&B with open reverse cone top to pull air through the lower air hole when aligned properly. These designs also maximize filter surface area.

2011+ Short Tube (392 engine)
- 392 Frankentake IV design, Airaid with their 392 design and Speedlogix 392 Design. Specifically on the 392 engine, comparing all three, an aftermarket short ram, even with hood closed on the dyno, has proven, at the minimum, 9-10 rwhp and 10 rwtq gains from 4,500 - 6,000 rpm (approximately when the active manifold switches from long runner to short runner valves - between 4,400-4,800 rpms) during Wide Open Throttle.

Long Tube - LegMaker 4" Fender Pull (average of 11 rwhp, 8 rwtq - on stock 6.1l; average of 19 rwhp / 16 rwtq - 6.1l with custom tune) (this will require expanding the lower air hole to 4"), Stack Performance Fender Pull, RDP 3.5" Fender Pull (12 rwhp, 5 rwtq - on stock 6.1l), Mopar/AEM Fender Pull (similar to the RDP design), Also, the lower radiator baffle mod to allow more air to flow through the lower air hole (page 4, section I & J). Also works well with short ram intakes.
*It should be noted: when tested on a 390 Stroker that had an AirHammer, the Frankentake IV produced an additional gain of 7 rwhp / 10 rwtq, across the entire power band.

Stop and Go/Idle Scenarios: Short Tube vs. Long Tube. Testing in 45 deg F ambient, the Stack Performance Fender Intake took 4 mins to reach an IAT of 77.2 deg F. The C&L Short Tube took 1 min to reach 77.2 deg F. Here's the data for reference. The long and short of it is that a short open filter element in the engine bay will suffer quicker from stop and go/idle driving vs a long open filter element in the lower fender well. There is some benefit to running a lower t-stat as it will reduce the overall engine bay temperature by 20 degs F.

2011+ 300, Charger, Challenger, Jeep Air Intake Design/Study
The air intake was redesigned in 2011 models. It's a plastic composite design, uses a longer IAT sensor which is also relocated away from the radiator fans and lower engine block, has a larger air filter than the old, seals to the lower fender well hole, has a larger fender well hole, and the manifold has a reducer built in to the design behind the throttle body.

Ralph Gilles makes the comment that the redesign of the air box was to reduce the effects of "spark trim". Here's the video reference (7m:40s)

Throttle Body Size Study

- Throttle Body Size Calculator - the calculated science behind the table below.

Throttle Body Selection Chart
-----------80mm ----------85mm ---------90mm
---------0.8-1.2"/Hg ----0.8-1.2"/Hg ----0.8-1.2"/Hg
N/A hp____360-500_______440-580_______510-660

"Using the chart is simple. If peak power is higher than the rpm in the 1.2"/Hg column, or peak torque is higher than the rpm in the 0.8"�/Hg column, then you should really consider an upgrade. If peak power is higher than the rpm in the 0.8"�/Hg column, or your shift point is is higher than the rpm in the 1.2"/Hg, an upgrade can be of benefit in "max-effort"� application, but isn't absolutely necessary. I even included accompanying power outputs, so you can also make a selection based off of expected N/A power."

5.7l (345 cu/in displacement). Peak horsepower comes at 5,800 rpm and peak torque comes at 4,200 rpm. 4200 < 5190 (torque) and 5800 < 6360 (horsepower) so you should keep the stock 80mm throttle body. Even so, to ensure airflow smoothness, the max you can go with the stock composite manifold is 85mm.

6.1l (370 cu/in displacement). Peak horsepower comes at 6,200 rpm and peak torque comes at 4,800 rpm. 4800 < 4840 (torque) and 6200 > 5930 (horsepower) so you should consider an upgrade to an 85mm. If you decide to go higher, again, 4800 < 5520 and 6200 < 6720, so there really is no need for larger than 85mm. The stock 6.1L manifold port matches the stock throttle body at 80mm. If you decide to get a larger throttle body, what you should also consider is port matching your intake. Since the 6.1l has an aluminum manifold, you can get this done fairly easily. If you don't want to port match, you can go along the route of the Fastman 84mm throttle body or the Ported Modern Muscle throttle bodies.

6.4l (392 cu/in displacement). Peak horsepower comes at 6,000 rpm and peak torque comes at 4,200 rpm. 4200 < 4570 (torque) and 6,000 > 5590 (horsepower) so you should consider an upgrade to an 85mm. As the same with the composite manifold, you should measure to see what the actual interior diameter size is at the point of the throttle body.

Doesn't the stock throttle body meet the maximum inflow requirements of our speed/density air intake system without any problems?
Taking the above research/calculations and going further,

YES, If the 2.5mm throttle plate is factored in as a restriction (80 - 2.5 = 77.5mm), the stock 80mm throttle body is sufficient enough for the entire rpm range of the 392 hemi and doesn't become restrictive until 6700rpm.

NO, If the 9.5mm throttle plate pivot is factored in as a restriction (80 - 9.5 = 70.5mm), the stock 80mm throttle body becomes a restriction between 5600-5700rpm (interesting, when the automatic transmission is in Drive, if you look at datalogs, the transmission shift between 1st gear and 2nd gear is between 5600-5700rpm).

Really, it is yes and no depending how we determine the flow through the throttle body. ~ 75.67mm meets the minimum flow requirements at 6400rpm for a 392 cu/in engine and ~73.27mm meets the minimum flow requirements at 6000rpm (max HP).

So here's where it gets interesting. The stock 80mm throttle body has a restriction in it; the throttle plate that measures 2.5mm in width along with the 9-10mm (we'll use 9.5mm as a median) pivot point in the center of the plate. This is to say, when you have a 80mm bore, you're actually flowing 77.5mm (80mm - 2.5mm plate) and even 70.5mm (80mm - 9.5mm pivot).

So, here are bores vs. the calculations if we use the stock pivot as a restriction to flow.

85mm - 9.5mm pivot = 75.5mm
84mm - 9.5mm pivot = 74.5mm
83mm - 9.5mm pivot = 73.5mm
82mm - 9.5mm pivot = 72.5mm
81mm - 9.5mm pivot = 71.5mm

Here is the minimum required throttle body bore sizes vs. RPM

80.27mm 7100rpm
79.15mm 7000rpm
78.58mm 6900rpm
78.00mm 6800rpm
77.43mm 6700rpm
76.27mm 6500rpm
75.68mm 6400rpm
75.08mm 6300rpm
74.49mm 6200rpm
73.88mm 6100rpm
73.28mm 6000rpm
72.66mm 5900rpm
72.04mm 5800rpm
71.42mm 5700rpm
70.79mm 5600rpm
70.16mm 5500rpm
66.89mm 5000rpm

So, lets consider/evaluate aftermarket throttle body solutions based on the above data:

Stock 80mm throttle body -
If the 9.5mm throttle plate pivot is factored in as a restriction (80 - 9.5 = 70.5mm), the stock 80mm throttle body becomes a restriction between 5500-5600rpm. For the R/T, this isn't as bad because peak HP is achieved at 5800rpm. However, for a larger engine, the stock 80mm becomes a restriction as you go above 5800rpm.

Ported 80mm to 83-85mm (stock throttle plate) throttle body -
With the stock pivot point (9.5 mm), the bore is roughly between 83mm - 85mm or 73.5mm - 75.5mm in available flow area. Based on this, you are good to roughly 6000 - 6300 rpm. With this throttle body, you should benefit from increased throttle response (approximately 7.5% - 12.0% improvement based on 80mm vs 83mm vs 85mm throttle boost comparison). Some downsides can include that it is not a straight bored interior (moderate dogleg at the throttle plate) and the side that connects to the intake manifold is not port matched (80mm vs the intake manifold 83-84mm).

Fastman Ported 80mm (85mm tapered to 81mm; throttle pivot point 6mm; stock 80mm throttle plate) -
With the reduced pivot point for the throttle plate (9.5-3.5mm=6mm), the 80mm flow area is reduced to 74mm. Based on the chart above, you are good to roughly 6100-6200rpm with this setup. The benefits is that it is a straight cut interior bore and there is no moderate dogleg at the throttle plate. Additionally, you can have the back of the bore tapered to match the 83-84mm intake manifold port (using the 392 plastic manifold as the example).

Modern Muscle 87mm Ported
With the stock pivot point (9.5 mm), the bore is roughly between 87mm or 77.5mm in available flow area. Based on this, you are good to roughly 6700 - 6800 rpm. With this throttle body, you should benefit from increased throttle response (approximately 16.0% improvement based on 80mm vs 83mm vs 85mm throttle boost comparison). Some downsides can include that it is not a straight bored interior (moderate dogleg at the throttle plate) and the side that connects to the intake manifold is not port matched (80mm vs the intake manifold 83-84mm).

Fastman 84mm Overbore with 84mm plate -
With the reduced pivot point (9.5-3.5mm=6mm), the 84mm flow area is reduced to 78.0mm. Based on the chart above, you are good to roughly 6800rpm with this setup. With this throttle body, you'll get benefit of increased throttle response (approximately 9.5% improvement based on 80mm vs 84mm throttle boost comparison). Additionally, you could get the back side bore matched to the intake manifold port (83-84mm).

BBK 85mm True Bore -
With the reduced pivot point (~ 5mm), the 85mm flow area is reduced to ~80mm. Based on the chart above, you are good to roughly 7000-7100rpm with this setup. You would likely need to port match the intake manifold to 85mm.

90mm Arrington -
With a stock pivot point (9.5mm), the 90mm flow area is reduced to 80.5mm. Based on the chart above, you are good to roughly 7100-7200rpm]/b] with this setup. Again, you'll need to port match the intake manifold to 90mm to allow for a smooth bore to intake transition.

I'd be really curious to see what the measurements are for the new 2013 throttle body (part 251). It might help explain why the 2013+ are getting a newer throttle body.

DiabloSport Tuner (Intune)
2012 SRT Challenger 392 - 5-speed Automatic
Diablosport Intune DCX Device

Summary - 91 Oct Tune w/ raised shift points vs. 91 Oct Tune vs. stock 91 octane OEM tune
19 rwhp peak gain / 0 rwtq gain (436rwhp @ 6376rpm from 417rwhp @ 6050rpm) - 91 oct with raised shift points
11 rwhp peak gain / 0 rwtq gain (428rwhp @ 6150rpm from 417 rwhp @ 6050rpm) - 91 oct

5.5mph speed increase over stock tune once 2nd shifts to 3rd gear - 91 Oct Tune w Raised Shift points (6400rpm)
2.5mph speed increase over stock tune once 2nd shifts to 3rd gear - 91 Oct Tune
1/4mi improvement of 0.1-0.2sec (autos)
increase the rev limiter to 6,600rpm
turn off MDS fuel saver feature
torque management reduction between shifts

Daily Driveability
A majority of the benefits will come in daily driveability improvements from throttle boost and the tune. The tune will increase throttle boost, reduce torque management and slightly raise your shift point by 100 rpms. The tunes really improve driveability with smoother transitions while accelerating and almost instantaneous power when you need it.

Fuel Quality / 91 / 93 Octane Tunes
The diablo tune (93 octane) is pretty useless unless you have 93 octane available in your area. Unfortunately I only have access to 100% 91 octane with 93 octane (+10% ethanol) . I'm sure there will be a bump in horsepower / torque with 100% 93 octane as the tune adds 1-2 degrees of timing advance. The tunes smooth out the wide open throttle fuel curves between 12.1 - 11.6 a/f ratio.

Throttle Boost
Throttle boost is the 2nd best feature of the device. It definitely improves driveability on autos and gets rid of throttle lag. I would recommend adding 11.5% - 15% if you're modifying the stock tune. The 91 tune has roughly 15% throttle boost built in. I keep toying back and forth between stock and stock with throttle boost added. At 11.5% with the stock 80mm throttle body, it does improve the driveability and gets rid of the throttle lag to get you going (throttle lag is about that 0.5-1.0 second lag where you push the gas but the engine is trying to figure out what gear and how much power to put down; it is also the same lag during deceleration when you let off the throttle and the engine feels like it is engine braking). It also smoothed out transmission shifts as if it were at the right rpm to shift in both auto and manual modes.

Here's some rough calculations between increasing the throttle boost % on the stock settings:

Throttle Boost (increments of 0.5% on the tuner) on a stock 80mm throttle body to simulate similar flow of a larger throttle body at part throttle -
82mm ~ 5.0%
83mm ~ 7.5%
84mm ~ 9.5%
85mm ~ 12.0%
87mm ~ 16.0%
89mm ~ 20.0%

All of that being said, there is a point where the stock 80mm throttle body will reach maximum flow and an aftermarket throttle body will outflow the stock throttle body (83-85mm have 10 more degrees and 87-90mm have 20 more degrees) and as mentioned, you'll be restricted by the 84mm intake manifold opening. For reference

Also, if you use the 91 octane tune with 15% throttle boost built in, anything you add with the throttle boost setting is 15% + your addition.

Torque management
Torque management reduction is built in the tune. One way you can see part of torque management at work is when you datalog stock vs canned tunes.

You'll see a dip in the throttle % in the stock vs the canned tune.

Datalogging is the best feature of the device. It has an analog input if you need to hook a wideband up to the device. Further, you can learn a lot about your car (e.g. crappy fuel results in a certain amount of engine knock).

You can disable MDS fuel saver mode but really, with the 91 tune, it smooths out the transition between 8 and 4 cylinder modes. This might be something to turn off if you change out the exhaust.

A lot of spark/fuel adjustments can be made on your own with datalogging for minor bolt ons (intake, exhaust, throttle body).

I dyno'd both stock and 91 tunes using TT Dyno and an open 1 mile stretch of road. No surprise that the HP/TQ numbers were relatively the same +/- 1-3 HP/TQ. (396 rwhp / 401 rwtq) - go figure as the stock tune is for 91 octane. I'm sure with better fuel, there would be some improvement here as well as running the 93 octane tune. However, the advantage goes to the 91 tune vs stock because of the raised shift points giving the tune an extra 200-300rpm to run through. Final peak numbers (436 rwhp / 401 rwtq).

Stock, (396 rwhp @ 5950rpm / 401 rwtq @ 4500rpm)

Stock (est), (406.5 rwhp @ 6000rpm / 400.5 rwtq @ 4500rpm)

Stock, (417 rwhp @ 6050rpm / 400 rwtq @ 4500rpm)
91 Tune, (428 rwhp @ 6150rpm / 399 rwtq @ 4500rpm)
91 Tune w/ raised shift point (436 rwhp @ 6376rpm / 401 rwtq @4500rpm)

Increased Shift Points
By using the tune and increasing the shift points, you gain a 5.5mph increase from the 2nd to 3rd gear shift.

75.5 mph @ 6054rpms
79.0 mph @ 4054rpms

91 Tune
78.5 mph @ 6141rpms
81.5 mph @ 4219rpms

91 Tune w/ raised shift points
81.0 mph @ 6376rpms
84.5 mph @ 4270rpms

Final Impressions
Overall, it is a beneficial modification for your vehicle and the stepping stone for all other modifications. Through datalogging, it helped me determine that 91 octane with 10% ethanol was not cutting it and resulted in me finding a 100% 91 octane fuel station. I have reduced the throttle boost feature in the 91 octane tune and customized the car to my driving style/tastes. I have toyed back and forth with returning the device, however, the more I datalog and the more I fine tune the device, the better things get from daily driveability and "lively" driving.

I have yet to get to the track to do a comparison, however, I see the largest improvement coming from the raised shift points. From a pure #'s perspective, you could easily account for a 0.1-0.2sec improvement in the 1/4mi using the 91 Oct Tune with raised shift points.

The typical cost for the device is in the range of $450. For peak HP gains, it is roughly $23 per HP gained. The other cost/performance benefits comes from daily driveability improvements with the most improvement going to automatic transmission vehicles. Manual transmission vehicles can still benefit as well by increasing the rev limiter from 6,400rpms to 6600rpms.

180 Thermostat

Effects on Engine Coolant
With a 180 t-stat and reduced fan settings, the engine coolant flows through the engine sooner and the coolant is prolonged from reaching it's minimum operating temperature of 192-199 deg F. To maintain a coolant temperature below the 192-199 deg F minimum operating temperature, the radiator fan settings need to be adjusted with a tuning device. With the 180 t-stat, tested in 90 degree weather @ 70mph, engine coolant temperature (ECT) was a 188 deg F without any fans on and peaked at a MAX ECT at 194 deg F after a wide open throttle acceleration.

Effects on Engine Oil
A 180 t-stat will prolong the time it takes for your engine oil to warm up. Engine oil will eventually reach the 200+ deg F range regardless of the t-stat utilized. Modern engine oil is designed to operate at 212+ deg F to burn off acid/contaminant build up.

Long term fuel trim adaptives are are not stored until the engine reaches minimum operating temperature (192-199 deg F) and it should be taken in to consideration when operating engine coolant below the minimum operating temperature.

Some benefits of running a colder t-stat are lower engine bay temperatures that can effect short/long intake air ingestion at stop and go/idle driving and running a cooler engine to allow for tuning adjustments for fuel/spark. A downside is shorter engine oil life and the effects of the engine not reaching is designed operating temperature.

180 t-stat fan settings:

The best way to set your fans is to do a test run with the 180 t-stat in. Get up to highway cruising speeds and see what your water temperature is at. Further, you can see what your water temperature is at after cruising and then doing a few Wide Open Throttle runs. Then add 10 to Low Fan (this 10 deg buffer allows the fans to shut off once you get back to cruising speed), 13 to Medium Fan and 23 to High Fan.

For example, if cruising at 70mph the water temperature is at 185 deg without the fans on, then the fan settings would be Low - 195, Medium - 198, High - 208. If at wide open throttle, the water temperature peaks to 188, then set the temperature to Low - 198, Medium - 201, High - 211. These settings ensure that your fans aren't running and the radiator is doing the work it is suppose to be doing while at cruising and high speeds.

Fuse #2 Pull - Short and Long Term Adaptives affecting performance

Long Term and Short Term Adaptive can each change the pulse width by as much as +/-33% for a maximum total correction of +/-66% from base pulse width calculation. Long Term Adaptive values are used during both Open Loop and Closed Loop operation.

Short term adaptives are controlled by the O2 sensors so this is where your air/fuel mix will be tested and adjusted by the PCM once the engine is at operating temperature (192-199 deg F). Short term adaptives will clear once you turn off your engine.

Long term adaptives will begin to store once the engine is at operating temperature (192-199 deg F). After the vehicle has reached full operating temperature, short term correction factors will update Long Term Adaptive Memory cells based on vehicle load (RPM/MAP) to allow the Short Term Adaptive value to be brought back to near zero. Once this correction factor is updated in the memory, it will be used by the PCM under all operating conditions, open loop and closed loop.

This is all more the reason to reset your long term adaptives at the track by pulling fuse #2 (PCM power fuse) for 10-15 seconds so that you can clear the computer's RAM (memory) as they can have either a positive or negative affect on pulse width, even at wide open throttle (open loop).

A 180 t-stat can be beneficial to performance by lowering the engine bay air temperatures (18-20 degs) and reducing the effects of spark trim above 86 deg F for intake air temperatures. All that being said, consistent 80 deg F ambient air temperatures is a good starting point to determine the swap between the stock 203 and 180 t-stat to reduce the effects of spark trim (based on 6 deg above ambient intake air temperatures while cruising at highway speeds of 70mph).

If you are not sure, use the following settings: Low Speed - 200; Medium Speed - 203; High Speed - 213

The Catch Can

Fact - A catch can will keep your intake manifold cleaner

With a catch can, blowby oil vapor condenses and collects in the can instead of in the intake manifold. Typically, 1-2 oz will pool up in your catch can every 3,000 mi. Going by this formula, approximately 3/4ths quart (24 oz) will be caught by the catch can around 36,000mi and not cycled back through your intake.

Heatsoak - Effects on the IAT Sensor

(1) MikeyChallenger - His results: I inserted the probe of the digital thermometer between the fitting that connects the rubber tube to the airbox - only about a 10 inches upstream. I went for a drive and the probe consistently read 15-20 degrees cooler than the IAT. After relocating the IAT to the location of the digital probe, the IAT temps now read within 3 degrees of the digital probe. Mikey's initial theory was "So... the added knock toward the beginning of the run (where temps were reading the highest) might indicate that the IAT was actually cooler than the sensor was reading, allowing for more air entering with not enough fuel to go with it."

(2) Test: Determined that the intake tube material did not affect the actual air passing through the intake tube.

Theory - Move the thermistor to the middle of the airstream and increasing the air barrier surrounding the sensor; it will increase it's reading of thermal convection (air flowing through the tube) and decrease false readings caused by thermal conduction of the intake material.

(3) Test #1: Determined that, in the stock location, the new IAT sensor was reading a different temperature than the old IAT sensor.

Test #2:

Ambient Air Temperature: 94 degs. After WOT (where the red line goes from 100 to 0 %), the temperature line for the old sensor is still laddering down while the new sensor is a flat line. The yellow circle shows the temperature reading during the WOT run and how the old sensor stays around 132 degs F while the new sensor ladders down through the WOT run.

Test Vehicle: 6.1l, Spartan Cam, Ported Heads/Manifold, Bwoody Intake
Difference: only changes made between runs was the IAT sensor swap. test conducted on the same road, under same engine/ambient temperature conditions, applying same driving style.

New Sensor
Start WOT 125.6 deg F
End WOT 116.6 deg F

Old Sensor
Start WOT 132.8 deg F
End WOT 131.0 deg F

Initially it's a 7 deg F difference to the initial entry of the WOT run. At the end it's a 15 deg F difference.

Note the difference in temperature readings prior to the WOT run (7 degs F). During the WOT run, the sensor readings are much different. The new sensor is laddering down during the throttle run while the old sensor is still maintaining it's higher temperature.

Here is the log during normal acceleration between the two sensors.

During acceleration, the old sensor reading results in ST Knock vs the new sensor which reads no knock. It should also be noted that the new sensor is actually reading a higher temperature than the old sensor.

(4) How NTC Thermistors work, pg 11 . The article verifies how the dissipation factor (the ratio of the change in power dissipation and the resultant change in the thermistor's body temperature) can falsify the measured result in a temperature sensor application and the dissipation factor is dependant on size, shape and leads of the device as well as on the medium surrounding the thermistor.

(1) External factors that influenced the old IAT sensor readings resulted in engine knock and a power loss of approximately 20 lbs/ft through the RPM band.
(2) Utilizing the new IAT sensor resulted in less engine knock and power loss when compared to the old IAT sensor in the same conditions: 94 deg ambient.

Further Testing/Afterthoughts

- A dyno test, like MikeyChallengers, should be conducted in heatsoaked conditions, between the old IAT sensor and new IAT sensor to determine if there is a power difference between the two sensors.
- Based on datalog observation, changes to engine pulse width are made every 27-28 centiseconds (0.27 - 0.28). The quickest rate of change for the old and new IAT sensor is 56 centiseconds (0.56). We know, however, that the IAT sensor sampling is taken based on the rate of change of engine pulse width. This is because, in a speed density system like ours, temperature is a variable used to determine the density of air. The MAP sensor is also used in the air density equation.

Air Density and speed (engine RPM) are then used to determine injector pulse width. Long Term and Short Term Adaptive can each change the pulse width by as much as +/-33% for a maximum
total correction of +/-66% from base pulse width calculation once the engine has reached operating temperature (192-199 deg F).

Here is the TT Dyno graph of the WOT datalog above and how IAT and knock impact torque.

--- New Sensor ___ Old Sensor

@ 4500 RPM
New Sensor_____Old Sensor
295 lbs/ft_______278 lbs/ft____ - 17 lbs/ft delta
118.9 deg F_____134.6 deg F__ - 15.7 deg F delta

@ 3000 RPM
New Sensor_____Old Sensor
240 lbs/ft_______229 lbs/ft____ - 11 lbs/ft delta
124 deg F_______132.8 def F___ - 8.8 deg F delta

The above is just one of many continued tests that should be conducted to verify the validity of the old vs new IAT sensor but the initial facts and results are showing that the new IAT sensor, at less than $6, is a cost effective modification. It helps to prolong a loss in torque as the engine reaches thermal equilibrium (heatsoak) and it also reduces the effects of external heat sources that cause the sensor to read higher than actual air flowing through the intake tube.

The new 2011+ IAT Sensor

The expectation from this mod is to improve the IAT sensor reading by convection (heat in the air moving through the intake tube) and to reduce the amount external factors that influence the IAT sensor reading through conduction (heat transferred through the engine materials caused by thermal equilibrium).

-2011+ Long IAT Sensor Mopar PN 05149279AB - $6.13 (dealership)

Old Grey 2009-2010 R/T IAT on top, New 2011 Grey IAT on bottom

Utilizing the new Sensor - Senarios

(1) If you already have a grey IAT connector (typically found on some 2009 Challenger R/T models), all you have to do is purchase the 2011 Long IAT Sensor for a plug and play direct swap. In 2011+, all the IAT sensors are long sensors for 300, Charger, Challenger and Jeep.

(2) If you have a black IAT connector (2008-2010 Challengers, and pre 2010 model Charger, 300 and Jeep), you can make your own converter cable or PM me (rayzazoo) for a plug and play black to grey converter cable.

- Black connector in the middle with red tab (found on most 2008-2010 Challengers, Chargers, 300s and Jeeps) vs Grey connector on the right with yellow tab (found on some 5.7l Challengers and all 2011+ models)

- Black to Grey IAT Converter Cable - Used for 2008-2010 Challenger, and pre 2010 Charger, 300 and Jeep models with the black IAT plug connector.


Figure 1 - Old - LEFT: 2008-2010 Black IAT SRT and some R/Ts; RIGHT: 2009-2010 Grey IAT some R/Ts (sorry for the broken plastic tip)

Figure 2 - New - 2011+ IAT Long Sensor

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Would you mind posting a few pictures on here when you make your extension? I just installed a JLT CAI on my 5.7 yesterday and although the wires makes the connection its a touch more taught that I am comfortable with. I was contemplating an extension but I dont want to mess it up.

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5,013 Posts
Discussion Starter · #4 · (Edited)
is the 392 IAT somehow better?
The only difference I've seen is that the sensor is placed in the center of the air stream rather than near the side wall. I look at it as another heatsoak reducing measure seeing that Dodge decided to change the design. It also gives me a new project to tinker with as well as research on the dreaded "grey" plug that everyone has been trying to replicate.



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Interested in the part number as well. I also wonder if replacing the old style with the new will cause any thrown codes?

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'16 A8 Scat Pack
12,373 Posts
I just installed the "clean air tube" Mopar p/n 4861940AC on my '10 R/TC automatic.

This tube includes the '11 style sensor (long), and I just took it on a 1800 mile trip. No codes thrown, and it seems that throttle response is improved too, along with a little more "intake growl" compared to the stock tube with the "goiter".

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'16 A8 Scat Pack
12,373 Posts
Just unplugged the the connector from the old sensor/air tube assy, and plugged it right back on the new sensor/air tube assy.

I didn't realize that there were "different" connectors on some cars. I just did a quick check on mine, and the factory connector is grey. The car was delivered in March '10, so it's an early '10 build.

The automatics for '10 have the "goiter" or tuning chamber sticking out the side of the fresh air tube, and the new tube is the p/n for an '11 Charger 5.7l (there was a thread or two about this) that doesn't have this chamber.

Maybe I lucked out, but the grey connector snapped right onto the new long version sensor. After 1800 + miles, I would think that if the connector wasn't making proper contact, that the car would have thrown a code early on. It saw from mid 90's to mid 30's temp range already, and no problems what so ever.

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5,013 Posts
Discussion Starter · #10 · (Edited)
For the people that have the black version of the IAT connectors, I'm working on making a converter cable between the black and the grey. Also, I'll work on a 5.7L / 392 Grey connector extension cable when the parts are available mid September so stay tuned. The female connector parts should get in by next Wednesday so I'll keep you posted on the swap.

Now, if all goes well, to alleviate the troubles of parts ordering, soldering and to save some people money of a $25 order from for less than $3 worth of parts, I placed my order for 10 connectors with components. All said and done, a Grey IAT extension cable or Black to Grey IAT converter cable would cost approx $12.76 + $4.95 (USPS shipping) = $17.76. I'm still searching for the individual black male/female connectors but for now, the IAT extension is it which is why the cost is higher.

Parts List
-Black IAT Extension Cable - $18.80 x 1 (dealership)
-2011 Long IAT Sensor Mopar PN 05149279AB - $6.13 (dealership)

In order to make the grey female or male connectors, here's the following parts needed. These parts are purchased through, however, require a $15 minimum order, shipping is $10. $25 for less than $2 for a single complete grey component.
-Grey Female Connector PN 184002-1 - $0.80 x 1
-Receiver Wire Contact PN 184030-1 - $0.34 x 2
-Sealed Sensor Connector Rubber Plug 184140-1 - $0.015 x 2

-Grey Male Connector PN 184164-1 - $0.62 x 1 (not available)
-Wire Tab PN 55931-1 - $0.36 (only ordered in QTYs of 10,000+) so plan is to reuse the black IAT extension harness tabs.

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Just unplugged the the connector from the old sensor/air tube assy, and plugged it right back on the new sensor/air tube assy.

I didn't realize that there were "different" connectors on some cars. I just did a quick check on mine, and the factory connector is grey. The car was delivered in March '10, so it's an early '10 build.

The automatics for '10 have the "goiter" or tuning chamber sticking out the side of the fresh air tube, and the new tube is the p/n for an '11 Charger 5.7l (there was a thread or two about this) that doesn't have this chamber.

Maybe I lucked out, but the grey connector snapped right onto the new long version sensor. After 1800 + miles, I would think that if the connector wasn't making proper contact, that the car would have thrown a code early on. It saw from mid 90's to mid 30's temp range already, and no problems what so ever.

I have the grey connector too! mine was also delivered in mach 2010.

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2,047 Posts
Thanks for the part# rayzazoo!

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5,013 Posts
Discussion Starter · #13 ·

I got the parts in today and here is the result. It still needs to undergo testing so I'll keep y'all posted.

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2,047 Posts
Picked mine up this morning and after install I am pleased with the results. After building some good heat soak doing some low speed cruising engine sag normally pronounced when clutching at a stop was minimal. Acceleration remained crisp even when pulling away on grades. Haven't tested full throttle acceleration after heat soaked yet. Just washed her and don't have the heart to get her all slimed with bug guts today. I suspect the results will be favorable though. Thanks again for the heads up rayzazoo!


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5,013 Posts
Discussion Starter · #16 · (Edited)
A $4 solution to reduce false IAT readings

So initial test is complete and the converter (black to grey) works along with the new IAT.

The driving characteristics did change in feel, however, I won't let that be the sole judge of why this project should be considered. Just to note, transitions of accelerating and decelerating were much smoother but more driving will be necessary to make a full determination.

I think the key takeaway is the new sensor design reduces the effects of radiant heat on the sensor all for a measly $4 (those with factory grey connectors) and $21 (those with factory black connectors).

As you can see, the new design (left) vs the old design (right); the old design has exposed wires and the new design insulates them. Also, the new design moves the sensor further away from the intake pipe sidewall. This is not to say that the sensor won't heatsoak, but it will be less prone for exposed wires to absorb radiant heat from the intake side wall and provide a more accurate intake air temperature reading.

The next step is taking the black connectors and converting them to the grey connectors (for those that have a factory installed grey, this is not necessary). This has worked out successfully without codes or issues.

So, in the end, what did we accomplish by doing this? Well, we've effectively reduced the potential for the sensor to read false temperatures due to radiant heat from the intake tube sidewall effecting the exposed wires of the old sensor.

As a note, putting this all together, I think the 392 stock air intake has been very well designed and, we 2008-2010 owners, should mimic some of the design aspects, especially if it only costs us $4 to do. Also, the materials surrounding the IAT sensor should be ones that do not absorb heat as quickly and keep the overall temperature of the intake tube down.

Now I need to clean up my engine bay wiring as my next project.

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951 Posts
i'll pick up the 2011 sensor pn 05149279AB this afternoon and try it out

I'm dying to know what your results are as well. I have a Feb 09 R/T with mega-heat soak issues in South Florida.

I noted the p/n of the 392 sensor p/n and since I have the gray connector, its a plug and play for me, correct? Will relocating the sensor to the box help even more? I've got the Robo-Fab CAI.

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5,013 Posts
Discussion Starter · #19 ·
Driver Update with the new sensor:

In heatsoaked conditions, here are some more driving characteristics I noticed with the change.

- Transmission shifts on acceleration and deceleration are smoother.
- It feels like the car is in ESP Partial off mode
- The car cruising has a more freer feeling to it. For example, if you let off the accelerator, you don't get as much of an abrupt slow down, but more of a casual cruise down.

The best way I can describe the feeling is driving with ESP off vs ESP on.

Now, taking note that the intake I have relocates the sensor away from the stock location as well but I think the idea here is to create more of an air buffer between the air tube sidewall and the sensor.

In all, things are looking good with this modification. Also, no issues with codes etc.
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