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Below is the summary of questions asked at the SRT Engineer Chat Session on the LX forum.

Why did the 392 Challenger receive a different front chin spoiler and what added benefit does this do compared to a 2010 SRT8 Challenger chin spoiler? Will a 2010 SRT8 be able to utilize this new part or will the front fascia also have to be replaced?
The new front fascia integrated spats into the fascia to give a more pronounced front end. The new part chin spoiler matches profile to the old fascia, but it will not work since the attachments are different location and size (however close)

Flow wise, how does the new 392 intake manifold compare to the old 6.1 manifold?
I don't have airflow box numbers but on the dyno on a 392 engine, the two intake manifolds make the same horsepower at the same engine speed. The new manifold excels below 4900 rpm where it makes a lot more torque which is more tuning than absolute airflow.

What are your thoughts on the Eaton TVS supercharger?
Its the most efficient supercharger that I've ever read shows that supercharger technology is certainly not primitive and this particular supercharger is nearly as efficient as a turbocharger. Good Job Eaton!

Can you tell us what changes, if any, were made to the 2011 Challenger rear cradle, cradle bushings or suspension geometry to address wheel hop?
There were 2 changes that reduced occurence
New conical hydromounts on eng allow fore improved damping on driveline torque reaction.
Changed rear cradle (front bushing) to taller snubber - were shorter design for '10

Will the 392 share interchangeable parts with the current 6.1?
PT : 6.1L vs 6.4L is all new - some minor interchangeability misc parts like rocker arms but mostly all new.
Body : Pretty much c/o (except for front fascia attach)
Interior: New seats and seat tracks (can't put '11 seats in '10)
Chassis: New Front/Rear cradles -- Front (new steering / eng mounts, camber), Rear (park brake, susp links)
Electrical : c/o with new alternator and starter (Still CAN based)

Is there a way on a 2009 challenger srt8 to permanently turn the "esp" off?
Sorry, permanently turning off ESP is not a something that can be done in our vehicles.
You will need to press and hold the button each time you want to turn it off.

Will the 07' and up MTCM for SRT's work as well in cars with 3.73 or 3.91 rear gears as it does in 3.06 equipped cars?
And what exactly is the difference from the stock TCM to the MTCM? Thanks!
The TCM calibration contains the gear ratio and it must match the actual gear ratio of the vehicle. If the gear ratio does not match it will go into limp-in mode.

The new Challenger 392/6.4 has a lighted trunk release button. Would I be able to swap my current trunk release button for the new one?
I wouldn't recommend it because of the wiring differences and the connector change that you would need to incorporate.

I have a 2009 Challenger SRT8. Why doesn't it have a factory shift light?

Actually, we do provide an upshift indicator in the EVIC of your instrument cluster.

The 2011 Challenger advertises more camber from the factory for improved cornering. Was this accomplished through adjustable upper arms, revised arm length or mounting changes?
Revised with revised A-arm mounting, revised lower control arm length, revised lower shock attachment (due to new kinematics).
It is much improved for tire patch during cornering and also improves tire wear.

The 2011 Challenger has a revised clutch and transmission input shaft. What benefits does this revised setup provide?
The clutch has a bit higher clamp load to handle the extra torque of the 392. The input shaft changes to a high strength material. Note that the clutch splines change from a 26 tooth to a 10 tooth so they are not interchangable without also changing the trans.

What new capabilities are provided with the new engine management controller in the 2011 Challenger? What capabilities are lost?
More regulatory capability for diagnostics and feature content is typically what drives a new engine management system. Basically new name/new box...
What is lost? Hackability.

What is the purpose of the plastic belly pan on the Challenger? Aerodynamics? What would be the negative effect, if any, off removing it?
The plastic belly pan does indeed help the aerodynamics of the vehicle. If you notice it also holds you brake ducts.

Would there being any hesitation with the new 6.4L Hemi with MDS upon take offs or acceleration?
Nope, your all set. The minimum speed for MDS in the 392 Challenger is 35mph. Transition speed from V4 to V8 depends on how far you press the gas pedal. Faster transitions with more gas the end you should not feel any hesitation.

Is the timing being dropped the main reason why there is almost a 1/2 second difference in 1/4 mile performance between the automatic and 6 speed SRT8?
-- On the 6.1L, there was a non-linearity on the low end torque. The auto did a good job hiding this non-linearity due to torque converter multiplication. All testing done by our group confirms the 6.1L auto is quicker (stock) by 0.2s in 1/4mile.
-- The new 6.4L is a different story. We worked aggressively to ensure the torque curve was very linear. Our drag test numbers confirm that both are within hundreths now.

I need to understand completely, the good and bad features of OHV and OHC
The Hemi stayed with a cam-in-block because of simplicity and low cost and because of the high flow characteristics of the Hemi head.

When will the SRT group fix the issues with the Challengers stalling under braking/turning?
Sorry to hear about the issues that you are having with your vehicle, but it is nigh impossible to properly diagnose a vehicle issue like this on an chat forum. As I said in an earlier post, I would strongly suggest you take your vehicle to your local dealer. It is possible that there is a software upgrade which applies to your vehicle. Additionally, if the problem is persistent and the dealer is unable to solve the issues, there is a process where the dealer network will interact with the design team to diagnose the issue. If you have taken it to a dealer but are not receiving the appropriate level of attention or expertise, I would suggest you try another dealer.

Is any mpg benefit (or possibly an explanation on how an mpg benefit might emerge) when accelerating at around 2700 rpm vs. gradual acceleration at 1800-2200 rpm, as far as achieving good city mpg figures in typical use?
Generally speaking, you'll have better mpg at lower rpm unless your seriously lugging the engine. Best city FE = light pedals, short shifts and get it into 5th or 6th gear as soon as you can.

Is the 2011 6.4 a completely new engine block different from the 6.1 block and capable of a larger bore that the 6.1 block?
The 6.4L block is an all new casting with different machining. The 6.4L bore is larger by .9 mm but the block is not designed for bigger bores than that (even though people can and do increase the bores).

Please bring the Viper Powered Challenger to market!!
.... write to Dodge and demand it. The one we have is getting lonely and needs some siblings !

Is this improvement the result of the new manifold, a cam change, or tuning in the ECM?
All of the above! The 392 has a much better intake manifold that generates a lot more torque below 4000rpm, yet still pulls like crazy >6000rpm. Cam profile, larger stroke, larger bore, and a great calibration team!

Can you provide part # for new motor mount on 2011 srt challenger?

Does the new 392 use the same piston and rod material as the 6.1? (powdered metal)
The pistons and rods are different between the 6.1L and the 392 for geometry. Both rods are powdered metal. All new piston casting casting and all new rod forging.

You guys were out testing at Speedworld in Az.without details were satisfied with the testing of the 392 challys and did you break any axles? This is what I'm finding as the weak link with irs.
Busted.... we were out at speedworld last week. Love that track. We completed hundreds of runs on the 3 cars we brought. Did you happen to catch the massive smokey burnouts and 600 lbs of ballast we placed in the cars, trying to break something.... Not one broken part all day -- as rugged as it gets gents ! We are very pleased with the results on the track..... I'm sure you will agree when you run the 392.
Did I mention I love my job !

On average, how much more gas is consumed from the 6.1L than the 5.7L? Is it much of a difference?
Fuel consumption varies from driver to driver and from drive cycle to drive cycle. The two engine packages are roughly within a few MPG's of each other according to the federal ratings.

What, in the past, has been the reasoning in the past SRT8 models and the current 392 models to not super/turbocharge the engine from the factory?
There was lots of pressure on getting the bigger hemi on the cubic inches - above 5.7L. Speed to market also plays a major part. The 6.4L was the natural bump from the 6.1L as we went to a common FEAD with the. 5.7L.

I've looked all over and found different answers. So, what percentage of drivetrain loss are we looking at?

The parasitic losses of each component can change rather dramatically depending on several variables. Obviously temperature has a big effect and each part responds differently.
rpm and torque also have a big impact. Most industry standards look at this from a fuel economy point of view so the torques are very low compared to what you might see on a track or a dyno run. The big hitters in the drivetrain are trans and axle.
A manual tran is very efficient and will typically be better than 95%. An auto trans is not nearly as efficient but still better than 90% when the torque converter is locked up. A typical dyno run uses 15% losses for a RWD car and that's a pretty good ballpark number.

Is this chart pretty accurate for the finalized 6.4 torque numbers?

Yes, that is accurate even though it is kind of hard to see with the scaling. It should line up to 470lb-ft @ 4200rpm.

With something like this being said, is there going to be any SRT supported methods of swapping engines? As it sits right now, the only way (as far as I know) is to fine someone with 'certain' software.
Mopar offers some awesome crate motor engine packages that we fully support. Mopar - Authentic Chrysler, Dodge, Jeep and Ram Accessories, Service & Parts

My only question is what is the big hold up with getting the sold 392 IE orders to dealerships.
We started building right before holiday, keep in mind new Charger launched at same time so plant has to ramp up slowly to ensure quality . . . etc. we are shipping to our eager customers.

I have a 2008 Charger SRT8, and when backing up with the wheels turned all the way left or right, there's a vibration/shudder in the steering wheel.
The pop is caused by front castor. There is nothing wrong with the vehicle, or the tires. You are feeling stick/slip on tire patch as it differs left/right. The dealer is partially right that the vibration is induced at tire patch. As for competition, all high castor vehicles have this same condition when reversing at full lock on steering.

Are the 2006 6.1L injectors the same as 2009 5.7L Eagle injectors?
The current 5.7L injectors are the same as the 6.1L injectors.

Can you share this information for the 2009 and 2011 Challenger SRT8 6-Speed?
Same motion ratios.
2009: 261 front, and 669 rear
2011: 284 front and 778 rear

Can you define what a leak down check is?
A leak check is a diagnostic test with special equipment to measure the sealing of the rings and the valves. MOPAR sells a cold air intake but the stock parts is pretty good for filtering and low restriction.

Is the "Fuel Saver Technology" on the 392 the same thing as MDS? If so, how come you didnt just call it that? Thanks again!!
Yes they are one in the Marketing Term.

Why do I have a squeal when under light breaking?
For the brake squeal, you should try braking harder to increase the pad temperatures. In the winter, the pads drop below their normal operating range. Drive the car harder. Your dealer is correct. Slight brake squeak is possible if they aren't being used to their full potential.

You ran a 12.44 @ 110mph at Infineon with an automatic 392. Did you guys touch anything on the car at all in terms of tune or fuel type do achieve that time?
We didn't modify the car at Infineon at all. It ran with F1 stock tires and standard premium fuel (91 octane).
The manual and automatic both ran 12.6 flat last week. (temps were a little higher)
The 392 is a beast on the dragstrip -- blast to drive !

Is there a reason SRT doesn't go to a tire that's wider than a 255 in the rear from the factory for L-series cars?
It's always a struggle for design office to use a smaller, fuel efficient tire on the base car, and nice big, wide performance tires on the SRTs while using a common wheel house and make both look awesome.

Now that Ralph Gilles is the head honcho over there in Design Office, and in charge of the Dodge Brand, maybe he can put his magic touch on some new patentable solution! Go Ralph!!!!

Can the new 6.4 heads be used on a 6.1 block?
The heads will screw on but there's differences for chamber volume and valve heights so they are not an easy switch. The new heads flow more but I don't have the numbers.

What does the new 6.4 fuel pump flow?

200 L/hr

Did you guys get a chance to throw some drag radials on a 392 and run it by any chance?
Yes we tried the new Nitto 275/40s. The F1s (stock) were quicker than the Nittos - no lie. We were launching the manual at 4500rpm with medium clutch release. It may have something to do with overall driveline changing with change in tire RPM.

What do you think of installing a 5.7 police package oil cooler on the 6.1?
During the development of the 6.1L Engine we did evalaute the need for an engine oil cooler. Our testing resulted that we did not need the oil cooler. We did find that going to the 392 that it was required.

Premium Member
23 Posts
thanks, really really interesting reading, I have a IE coming in about a week.

all the best...

301 Posts

"What new capabilities are provided with the new engine management controller in the 2011 Challenger? What capabilities are lost?
More regulatory capability for diagnostics and feature content is typically what drives a new engine management system. Basically new name/new box...
What is lost? Hackability.

Game on Diablo!
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