Cuda340

I extracted the SRT engineers’ comments from last night’s Challenger Chat Session. Here they are:


I've asked this question before about a "nanny program" that restrains the performance during the first few thousand miles and was told no it does not exist by your team. However many members of this forum consider it gospel that the car achieves a better level of performance after a few thousand miles, care to speculate?
I don't know, I'm still at 2000 kilometers!

That's true, no "nanny program" in any of our SRT products. However, it is normal to feel your car's performance improve (sometimes significantly) with a proper break-in. It will also get slightly better fuel economy after a proper break-in.

I read the Visor warning label about no full throttle for the first 500 miles. My question is how much damage do think could be done if that is not adhered to? I know my car had been driven alot before I got it with 327 miles on the clock. I suspect it was not grannied either, can you enlighten us on how critical the break in is? I also want to comment on the "Nanny", my car ran 17.6 mpg for the first tank, we refilled at 519 miles and upon returning to the freeway my mpg went up to 22.8 with cruse on set at 80(in Texas on I10) driving was the same only difference was over 500 miles on the clock. It changed again at 1500 miles, care to comment on the break in program, no nanny just break in specs?
Trust me again, no Nanny. The 6.1L is built "tight" and take some level of miles (~500) to properly seal the rings and reduce the friction in the rotating components. MPG will go up...5mpg seems a bit high, but not totally out of the norm...especially when you consider the differences in wind during your trip.


Question 1: Is there a throttle response and/or transmission up shift update in the works to help eliminate the time lag of throttle transitions that lead to a more linear and consistent driving experience throughout the RPM range? In typical light to medium city driving, my car (and some of the other posters here) experience a lackadaisical throttle response which leads to flat spots (in addition to a delay in downshifts) that make the car feel like a lumbering giant slowly awaking from a nap...unless you mash the throttle and/or use the autostick.

I'd keep mashing the throttle But to be honest, the 6.1L is cammed to make the big power it makes up to and therefore yes, the torque is a bit low light city driving. The throttle cal would feel worse if it was changed (trust me)....we felt this was the best balance for city driving at part throttle and track driving at WOT.

Question 2: I believe the car up shifts too quickly in light to medium driving. Any possible programming changes for this?

The transmission in your car is adaptive and will adjust to the way your driving each time you drive your car (it resets each time you start your car). So, if you drive more aggressive, the car will shift the way you like it. Try it out and get back to us next time.

What is the deal with the 180 deg tstat that everybody talks about. They guys at the SRT track experience were saying that it was nothing but snake oil. Is there anything to by gained with the lower tstat. It regularly gets over 100 deg in my town during the summer.

A 180 degree thermostat is nothing but a waste of money. Your car will run at ~212F and run very good at that temp. There is also part of the calibration that accommodates the engines warm-up and running <200F....there is less spark advance in those areas, which equals less performance.

Wish I could mash the throttle all the time, but then everyone would have to get out of my way! Would changing the rear end gears help or would that contribute to the problem?

It could help, but that's quite a tear-up...does it really bother you that much.

Will do regarding the tranny shifts. Aggressive driving good - passive driving bad.
Any other tips to keep the car tuned for the optimum everyday driving experience? Thanks for being here and answer our questions - cool deal.

Make sure your car is breathing cool air. These cars are prone to sucking some warmer air expecially in city traffic. There is a nice big hole at the bottom of the airbox, make sure that is lined up with the hole in the sheet metal below that.

Read your reply about 180 t-stats. Wondering if I should take both off and go back to stock. I was not expecting to gain much, but I certainly don't won't to lose power!
Is there any condition that this would be beneficial?
What about the Mopar CAI?

I don't think you'll lose power from the testing and development I've done, but your welcome to prove me wrong. Try both combinations out at the track next time you go. The best way to go is a warm engine and cold air. So, my suggestion would be stock t-stat and CAI.

I am sure you guys play with these engines.
How much power is the 6.1 good for without bolting on a supercharger?
What are some of the biggest bang for you buck bolt-ons for the 6.1?

See you've got a CAI, that's the easiest. Catback would be next. Beyond that you have to be extremely careful not to impact calibration.

If the new reorganized company said you could raid the parts bin and create a “Super Challenger” what would your dream Challenger have?

We already did it when we stuffed the Viper V10 motor in the SEMA Challenger. Those Italian motors make power, but not much torque until you twist them hard. We'll see what they let us play with. If times were different, we're sure we would have that V10 Challenger in production for you.

What are your thoughts on a larger (85mm) Throttle Body?

My guess....potentially 1-2hp. Let me re-answer your question...I've tested an 84mm throttle on the 6.1L and it was 1-2hp. The cork is on the exhaust side...specifically in the cats.


In a previous Chat Session, you stated that the biggest tire for the front of a Challenger is a P245/35/20. What is the biggest tire that will fit on the rear with the stock 9" wheels? A 275/40/20?

245/45/20 front
255/45/20 rear

Lots of people put 255/45 on front and 275/40 rear and get away with it but under extreme suspension compression and steer angle conditions they will rub.


1. Several forum members are reporting problems with cracked rocker panels (in front of rear wheel opening) and leaking rear differentials on their Challengers. Are you aware of these problems and any corrective measures?


2. How accurate are the tire sensors? I compared my tire pressure on the EVIC with my digital tire pressure guage and the EVIC registered 2 psi more.
1) The only time we experienced cracked rocker panels was when we misplaced the car on the hoist or improperly placed the floor jack. We have "zero" warranty for differential leaks. We need more info on this one... where are the leaks coming from? Are these all SRT's? All we can recommend right now without more details is to take your car to an authorized dealer and have it checked.

2) TPM's are accurate to +/- 1.5 psi and about as accurate as most tire pressure gauges.


So I would need free(er) flowing cats and possibly larger diameter exhaust to get maximum output from a larger TB. How do the cats or total exhaust system factor in when adding a supercharger, and you start pushing more air through the engine?

Your on the right track HotRod....take the systematic approach to this. Just remember: Air In = Air Out. Uncork the exhaust with some Mopar Headers (which will eliminate the cats) and you should be open to a fair amount of mods. Just don't blow it up with a ton of boost...Or if you do, build it bigger!

The EPA approved headers and Cat's are what came on your car stock. Any Off-Road part offered by Mopar, or the Aftermarket is not approved by the EPA (hence the "Off-Road designation).



Was a true high performance CAI shot down as a stock item for this car? It's certainly a consideration to replace the stock air box.

A CAI open element intake won't happen on the Challenger due to water ingestion and pass by noise requirements. We'd love to if we could.

I didn't buy my Challenger SRT8 because it was easy on gas, but I can't help but wonder why don't get better fuel economy out of the SRT8? Highway should be mid to upper 20's running at 75mph. GM is doing it with the Corvette without compromising performance. I know some of this is due to drag, but GM is claiming the Camaro can do the same.

We are constantly improving our vehicles, check the fuel economy numbers between the 08 and 09 Challenger SRT8.

I would like to know why the Drivers seat does not have a quick release for entry to back seat? Is Mopar working on EPA approved Headers/ Cats?

Blame the beancounters for the seat situation. We win a lot, but not all the time...

Are the ALCOA wheels supposed to have more than one set of weights on them? My experience tells me with stick on weights there should only be one set. My car has two sets of weights on one of the wheels, some vibration is present, can you verify the correct balancing of the wheels?

There should only be two groups of stick on weights. One for the inboard side of the rim, and one for the outboard side of the rim.

I don’t have my Challenger SRT8 yet, but it’s being delivered next week. However, I would like to ask a question concerning the clutch. Is there an easy way to verify the throw-out bearing is not putting un-due pressure on the release fingers when the pedal is in its full-up position? There seems to be quite a few members in this forum that have had to replace their clutch already, and perhaps one of the symptoms is that the pressure plate is being pulled away from the clutch disc or they are not fully releasing the pedal.

The hydraulic clutch release system is self adjusting. We have seen a few clutches come back and the vast majority have been burst due to a missed shift.

I have read about the "Bump Steer" on the Challenger, did you guys do anything to address it on the SRT cars? I am also concerned about the alignment being "AT" specs with no room to adjust, was this addressed on the SRT line of Challenger?

For 2009 the base Challenger has roll understeer in the front suspension (toe- out in jounce). The 2009 SRTs maintained roll oversteer in the front suspension (toe-in in jounce) that SRTs have had since 2005. Roll oversteer really helps the responsiveness. Neither is enough to qualify as high amounts of bump steer.

Now that you have the opportunity to try both the LSD and BLD on the SRT8, which do any of you all prefer and why?

The mechanical diff offers big advantages in traction by hooking up faster, before slip occurs, and being able to transfer more torque to the higher traction wheel. The trade off is a slight reduction in initial turn-in response.

RRUNNER

Thanks Cuda, good stuff.