Dodge Challenger Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
When I bought the car it already had an after market exhaust on it, of which I was clueless about the difference in sound of stock vs aftermarket. The only other Challengers my wife and I had driven were SXTs we had rented and they were very quiet. I knew the SXTs were peppy but I wanted at least a V8, at that time I was ignorant of all the models of Challenger available, but I knew the simple requirements I was looking for a backup camera, a V8, and the price range and searched online until I finally found the car we bought. After driving it for a while and getting more familiar with it, as it had the Super Track Pack on it, I began realizing for the size engine displacement 345 cu in., which is comparable to the 350 cu in. engines I was past familiar with, it just seemed pretty tame for a Challenger!

After discovering they sold me the 2015 car with a complete after market exhaust system on it, and did not even disclose that information to me, which later seemed odd after all the don't do this, or that, without sacrificing warranty as most of us are concerned with. I discovered the exhaust was a cat back American Thunder Flowmaster, which was 2.50" pipe from the stock cats out the rear with Super 40 mufflers, no resonators, using the stock rectangle tips. That exhaust had some pretty noticeable drone that at certain rpm around 2K would produce a vibration in the car that could actually rattle something inside the dash. Plus externally the Super 40 chambered mufflers had a raspy sound, which I honestly did not care for that raspy sound, I like the deep rumble exhaust sound, not raspy.

So I came up on a decision point, as to either trade in the 2015 Challenger on a newer model, or mod the one I had, and since the warranty was close to running out anyway I chose to keep the car and simply go down the bolt on upgrade path, and make this Challenger what I thought it should have been in the first place. After a couple of months researching the internet watching many suggestive videos, of what to either do or not do, the only conclusion was just do it, that's the only way to find out for sure.

I started down mod road with a Spectre CAI, this was the right side dam wall corner isolation type of CAI, with an aluminum tube to connect to the throttle body, which came with an air filter half the size of the one I had installed on my Chevy Silverado, for literally the same engine displacement. This mod started my, (What not to do Shelf in my storage room), because some mods can actually hurt your performance not help it. Reason being the air filter itself was too small, the metal dam isolation wall did not seal to the bottom side of the hood and isolate the corner, which allowed hot engine air over the top of the dam wall directly into the filter, and the aluminum metal pipe held heat from the radiator transferring it to the air going through the tube, increasing the intake air temperature.

First major lesson learned, after market modding of this Challenger is not going to be cheap, if you go the cheap route and there's plenty of that out there, you're better off keeping it stock, and if you are planning on trading your Challenger in, do not start modding in the first place! So I researched further knowing I did not want the corner isolation CAI setup, and absolutely did not want a metal connector tube, and it had to have a large air filter. I went with the AFE Momentum GT with the headlight air duct, it has a tapered polyethylene plastic tube, a sealed air box porting in outside air, and a large air filter, and it improved the 0 ~ 60 time by .2, which is not much at all, but it was better than it was originally which was 5.7seconds so now it was 5.5 seconds, to me any improvement to the 5.7s performance was better than a loss.

I was measuring seat of the pants performance using the cars 0 ~ 60 capability as my measuring stick, which is funny later on, which I'll share later. My next major step was to get it tuned to take full advantage of the after market CAI, and exhaust, which turned into the next money gut punch, once I realized I had bought the year car that Chrysler started locking the PCM (Power Control Module), so to even tune the car required getting an unlocked PCM first. Originally I was going to go the Mopar Scat Pack Stage 1, have my dealer order and install it, to keep what was left of my warranty, I paid for it and the service department ordered my new Scat Pack Stage 1 PCM, after 2 months waiting for it to show up, Chrysler canceled the order because they had revamped the catalogue and changed part #s. So I my CC was reimbursed and I had no PCM, now since I was already running an after market exhaust, I was only getting the Stage 1 tuned PCM itself.

So after much deliberating I decided to go the Hemifever route, bought an unlocked PCM from them, the Diablo tuner, and the custom tunes written by Sean, installed the tunes as I also got the transmission tune as well. Well this literally woke a sleeping dragon out of the 5.7 even with some tire spin I went from a 5.5 second 0 ~ 60 to a 5.0 second time, nice improvement, But, tire spin was increased! So my next upgrade plan was for a set of staggered rims to be able to run wider rear tires, but out of curiosity I decided to just flat decided to do a full burnout, and I did, with blue smoke pouring out the rear of the car so bad I could not see out the rear view mirror. Went down the road and turned around to go back and see my burn marks? What? There was only one mark from the right rear tire. That's when I discovered my automatic transmission 5.7, had a 3.07 Open Differential in the rear, only applying power to the right rear tire.

I my own terminology Sport Mode on the 5.7 automatic is simply a poor mans positive traction, because computer wise, Sport mode actually works with the ABS brake system, by applying brakes to the slipping wheel to stop it's slipping and let it grab traction, the only problem is if you dial up the 5.7s output power with a tune, you override the Sport Modes ABS programmed handling capability, and the brakes cannot stop the right rear from spinning. So the curtain is pulled back and the Wizard of Oz is exposed!

So now my plans for staggered rims went to the back burner, and I even thought possibly I may not even need wider rear tires if both rear tires where supplying traction to the road, so I ordered a Mopar 3.09 LSD (Limited Slip Differential), and using ramps and jack stands installed it myself. Still running the 245 rear tires I went from the 5.0 second 0 ~ 60 to 4.6, now I'm getting somewhere. So now it seemed that the next logical step was wider rear tires so I put on a staggered set of rims 9" x 20" in the front, 10" x 20" rear, ran the Pirelli P Zero 245/45/20s I had on the car in the front, and the MT Street/Comp 275/40/20s on the rear, had serious drift when I hammered it, and had the alignment checked and they corrected the rear trust angle and now she launches straight.

Now to my dissatisfaction with the Flowmaster raspy exhaust sound, no offense intended to the Flowmaster loyal owners! I did some experimentation, cut out the Super 40s and replaced them with Cherry Bomb open tube glass packs and since my cars resonators were eliminated a short set of Cherry Bomb glass packs for resonators. I learned that adding the resonators at the tail pipe actually hurt performance, so I removed those and the performance returned, and the Cherry Bombs sounded awesome. The Cherry Bombs as resonators helped cut the drone to almost nothing but affected the overall engine power, the drone without the resonators with the Cherry Bombs was less than it was with the Flowmaster Super 40s though, and was acceptable, but keep in mind I an after power, I am not really concerned with the drone, it just was worth mentioning.

Now I have discovered through my experimentation the glass pack type sound is what I wanted, but I have no intentions of having a butchered up setup under there, so I ordered a set of Cat Back MagnaFlow Competition Series exhaust and did the 5.7 ever love that setup, and tire spin is much worse now! I had previously bought a set of BBK shorty headers but had them on the back burner because the installation instructions said you had to remove the motor mounts and jack up the engine to install them. I was not too crazy about doing that and saw where some others had actually done it without removing the motor mounts, so since I was going to undertake installing the BBK headers, I ordered the MagnaFlow high flow cats to complete the setup. OK it is possible to install shorty headers without removing the motor mounts, that is 100% true, it is not easy, but you can do it.

Understanding that your 5.7 HEMI is a large air pump, because your fuel is cylinder injected, if you modify the air intake flow and the exhaust output flow, and the motor is tuned, to take full advantage of those modifications, the engines power is significantly increased and when that power is transferred to the rear wheels the tire spin is seriously increased. When I said earlier, "I was measuring seat of the pants performance using the cars 0 ~ 60 capability as my measuring stick, which is funny later on, which I'll share later." I no longer measure performance through 0 ~ 60 time at this point it is really irrelevant, the true power being thrown to the rear now is unbelievable compared the the car we drove home that night in September of 2017.

I am presently researching tire composition for the best lauch possible as the adventure continues, I'm also waiting on TheFastman to finish my 82mm Throttle Body as that is probably my last bolt on to the car. I named my Challenger Black Beauty and she is just that, I know this was long, I hope you enjoyed reading. Ry
 

·
Registered
Joined
·
5,161 Posts
Nice write up.
I like my Nitto Motivos, I run 315s on the rear and 245s up front, I have 10.5" rear wheels. I have the Scat Pack Stage 1. My next mod is the 3.09 LSD, then hopefully a Tune, long tube headers and catted mids. Eventually a nice cam is planned for.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #3
Nice write up.
I like my Nitto Motivos, I run 315s on the rear and 245s up front, I have 10.5" rear wheels. I have the Scat Pack Stage 1. My next mod is the 3.09 LSD, then hopefully a Tune, long tube headers and catted mids. Eventually a nice cam is planned for.
I've been looking at the Nitto NT05 the Tire Wear composition # is 200, the Mickey Thompsons Street/Comps I am presently running are 300, the rubber is harder and they spin easily, my previous Pirellis were 240 and they actually hooked better than the M/T.
 

·
Registered
Joined
·
438 Posts
Awesome write up man. You spent some money on that badboy...
 
1 - 4 of 4 Posts
Top