ACR Diffuser on a Non ACR Car

[Bryan Savage]

This thread is about the information you will need, should you decide to do this conversion. These are the things I wish I'd known before I started. Some of this will only make sense if you are doing the work.

Before you start vomiting all over this thread, here are a couple of pre-selected answers for you:

1) I'm not an idiot. I am a mechanical engineer. While aerodymanics were not my focus, I understand the principles and the physics behind this.
2) I know that SRT worked very hard on developing the aero for the Viper. That is why I bought the OEM parts.
3) I do not have the talent to push my car anywhere near the limits of its capabilities, so I am aware I likely won't notice any performance benefit from doing this. Only experimentation will determine whether there is a detriment.
4) I did it because I think it looks awesome.

I bought these parts from Safford Dodge of Fredericksburg, Virginia, because I was able to get a little bit of a hookup. With no hookup at all, this kit of parts will cost you around $5,500.

This writeup is not going to be very detailed or photo/video-heavy. I did it myself in a one-car garage in the cold, so taking photos wasn't my priority. I also had the car up on a Quickjack BL-5000SLX. Doing this with a floor jack and jackstands would have been awful.

You will need:

1 x 68289862AB,
1 x 68289863AB,
1 x 68289864AB,
1 x 68289865AB,
1 x 68292409AA for the rear tailpan,
1 x 68252752AB for the set of six strakes,
22 x M6x1.0x25mm bolts (colour of your choice),
6 x M6x1.0 nuts with washers/lock washers,
10mm socket for those bolts,
10mm combo wrench for those nuts,
1 x T30 socket,
1 x T40 socket, and
3/8" socket (yes, 3/8").

I can't remember which was which for the first four numbers, but there's left and right sides of the inner and outer ductwork. These are the expensive pieces and extend way up to in front of the exhaust outlets.

Diffuser Kit.jpg

The ACR tailpan is different than the non-ACR tailpan, so you need that piece. Some of the angles are sharper to accomodate the ducting. I would not recommend trying to save money and use the non-ACR pan.

The ACR tailpan comes with nutzerts pre-installed and is a direct replacement for the non-ACR pan. It also comes with the the back-up light assemblies installed, so you don't need to change those. To change this part, you will need to remove both rear wheels, both rear fender liners, and some of the rear interior parts so you can access the taillight fasteners, which are plastic wingnuts. There are Torx bolts inside the trunk that hold the rear fascia mounting brackets to the car. You don't need to remove these.

The rear fascia and taillight surrround both need to come off to access the tailpan bolts. This is where a second person will be handy, as if you have the carbon fiber taillight surround, it's a super tight fit in place, and since it is stiff and the facsia is urethane and flexible, it is super easy to break the surround trying to handle this large piece on your own. Get a helper. And don't forget to unplug the two multi-pin connectors from the passenger side. They will ruin your party real quick.

2017-03-25 17.24.39.jpg

Under the car, there is an aluminium plate that covers the transmission and driveline tunnel. The ACR ducts use the existing mounting bolts to mount, so you don't have to modify anything for this. HOWEVER, you will need to drill six holes through this plate to bolt the carbon center strips to.

2017-04-04 18.48.13.jpg

I bolted everything up and then used a Sharpie to mark the locations of the holes, then pulled everything back apart to drill them. You could drill them without removing the plate, as you won't hit anything with your drill bit on the top side, but you won't be able to de-burr the holes either. This plate has to come off to change the differential and transmission fluid anyway, so I did that while I was in there (24,000 miles).

With the plate bolted back up, as you begin to tighten everything down... DO NOT install the outer ducts before you have tightened the center strips. You will have blocked all the armholes to access the nuts you're installing on the top side of the plate.

Also, the leading edge of the outer ducts have a piece of 3M double-sided tape on them, and this tape sticks to the body. Be sure to clean this area, and FFS, DO NOT pull the tape backing off until EVERY OTHER FASTENER has been started. Once everything is lined up, there's a little extra bit of tape backing sticking out that you can grab. Pull the backing off and press the leading edge to the body, while tightening all the fasteners a little bit at a time. The tailpan holds up the tailing edge of the aluminium plate, and that plate holds the tailpan up, and the fender liners hold the bodywork together, and the fender liners hold the tailpan in place... short story is that all of these piece hold each other in place, so cranking down on just one of them can make the others a bear to install. Use hand tools and take your time.

The carbon ducts, strips, and tailpan all come with the nutzerts pre-installed. The set of strakes comes with a package of bolts, so don't buy any of those. All you need are the bolts to hold things to the tailpan. The OEM fasteners hold everything else.

2017-04-06 20.58.15.jpg

With all that awesomeness installed, you too can be sure to bash those strakes on every damn bump if you have Pennsylvania-quality backroads. Race Mode suspension activated is mandatory. And don't even THINK about lowering your car around here. Sure, you could take the strakes off, but what's the point of that??

IMG_20170408_221137_531.jpg

Feel free to post or PM if you want other advice or have questions. My Quickjack and I are also mobile if you are thinking of doing this and want some help. Northeast areas only. lol

Cheers!!

[J TNT]

Nice work Bryan ! And nice lift , how do you like it ?

[poptarts]

Got any more pics? Looks awesome good job

[TrackAire]

Wow, best how to project of 2017.

The ACR diffuser complements the rear carbon hatch spoiler perfectly. Nicely done and please post more pictures of the completed project when time allows.

I really think there is a market for this....hint, hint vendors.

[donk_316]

Very well done. I want to do this same mod also.

[sarcasm] Hopefully my car doesn't fly off the road or create so much downforce I collapse my springs! [/sarcasm]

[Murpowa]

Looks awesome Bryan

[V10powerr]

this is amazing work and detailed- changed the entire back end look- thanks so much for sharing your efforts

[swexlin]

Looks great Bryan! And I can second him on our PA roads, they are even worse than ever this spring. Heaves, potholes, drop-offs, and broken pavement.

[ViperTony]

Well done Bryan!

[ViperJon]

You're going to poke your eye out doing things like this.

[Eachey51]

I will attest to how good this looks on a non ACR aero car! But the slightly softer non ACR suspension will allow the strakes to rub quite a bit. Definitely worth doing though, because it looks soo good!

[One Viper Bite]

Amazing write up, and exactly what I talked about a while back on this forum and received significant backlash, lol.

Like you, I studied engineering and am also a pilot. The purpose of a diffuser is to guide and shield low pressure, fast moving air along the ground and out the back of the vehicle without becoming turbulent or changing direction dramatically. This is why many supercars have them integrated without having massive rear wings or front spoilers. It can only help, especially with how aggressive the rear rake is on the Gen V.

Great job! on this! Looks incredible!

[Snakebit10]

Dude. That.........looks........SIIIIIIICK!!!!!!!! MOAR PICS FROM DIFFERENT ANGLES PLEASE.....

[mikesax]

Looks AMAZING Bryan!!

[IndyRon]

Looks good but seems to me there is a market for making new strakes that are either tapered towards the back or 1 inch shorter than the factory ACR for those looking to do what you are doing with it. If your goal is more than 50% aesthetics then those suckers don't need to be touching the ground lol.

[Simms]

Great info!

[SharpMan]

Very cool. I wonder how it balances out. Maybe just the diffuser without adding the front splitter is a good setup as there's no giant wing.

I wonder if Dodge can provide the downforce of the wind, splitter and diffuser separately?

This thread is about the information you will need, should you decide to do this conversion. These are the things I wish I'd known before I started. Some of this will only make sense if you are doing the work.

Before you start vomiting all over this thread, here are a couple of pre-selected answers for you:

1) I'm not an idiot. I am a mechanical engineer. While aerodymanics were not my focus, I understand the principles and the physics behind this.
2) I know that SRT worked very hard on developing the aero for the Viper. That is why I bought the OEM parts.
3) I do not have the talent to push my car anywhere near the limits of its capabilities, so I am aware I likely won't notice any performance benefit from doing this. Only experimentation will determine whether there is a detriment.
4) I did it because I think it looks awesome.

I bought these parts from Safford Dodge of Fredericksburg, Virginia, because I was able to get a little bit of a hookup. With no hookup at all, this kit of parts will cost you around $5,500.

This writeup is not going to be very detailed or photo/video-heavy. I did it myself in a one-car garage in the cold, so taking photos wasn't my priority. I also had the car up on a Quickjack BL-5000SLX. Doing this with a floor jack and jackstands would have been awful.

You will need:

1 x 68289862AB,
1 x 68289863AB,
1 x 68289864AB,
1 x 68289865AB,
1 x 68292409AA for the rear tailpan,
1 x 68252752AB for the set of six strakes,
22 x M6x1.0x25mm bolts (colour of your choice),
6 x M6x1.0 nuts with washers/lock washers,
10mm socket for those bolts,
10mm combo wrench for those nuts,
1 x T30 socket,
1 x T40 socket, and
3/8" socket (yes, 3/8").

I can't remember which was which for the first four numbers, but there's left and right sides of the inner and outer ductwork. These are the expensive pieces and extend way up to in front of the exhaust outlets.

Diffuser Kit.jpg

The ACR tailpan is different than the non-ACR tailpan, so you need that piece. Some of the angles are sharper to accomodate the ducting. I would not recommend trying to save money and use the non-ACR pan.

The ACR tailpan comes with nutzerts pre-installed and is a direct replacement for the non-ACR pan. It also comes with the the back-up light assemblies installed, so you don't need to change those. To change this part, you will need to remove both rear wheels, both rear fender liners, and some of the rear interior parts so you can access the taillight fasteners, which are plastic wingnuts. There are Torx bolts inside the trunk that hold the rear fascia mounting brackets to the car. You don't need to remove these.

The rear fascia and taillight surrround both need to come off to access the tailpan bolts. This is where a second person will be handy, as if you have the carbon fiber taillight surround, it's a super tight fit in place, and since it is stiff and the facsia is urethane and flexible, it is super easy to break the surround trying to handle this large piece on your own. Get a helper. And don't forget to unplug the two multi-pin connectors from the passenger side. They will ruin your party real quick.

2017-03-25 17.24.39.jpg

Under the car, there is an aluminium plate that covers the transmission and driveline tunnel. The ACR ducts use the existing mounting bolts to mount, so you don't have to modify anything for this. HOWEVER, you will need to drill six holes through this plate to bolt the carbon center strips to.

2017-04-04 18.48.13.jpg

I bolted everything up and then used a Sharpie to mark the locations of the holes, then pulled everything back apart to drill them. You could drill them without removing the plate, as you won't hit anything with your drill bit on the top side, but you won't be able to de-burr the holes either. This plate has to come off to change the differential and transmission fluid anyway, so I did that while I was in there (24,000 miles).

With the plate bolted back up, as you begin to tighten everything down... DO NOT install the outer ducts before you have tightened the center strips. You will have blocked all the armholes to access the nuts you're installing on the top side of the plate.

Also, the leading edge of the outer ducts have a piece of 3M double-sided tape on them, and this tape sticks to the body. Be sure to clean this area, and FFS, DO NOT pull the tape backing off until EVERY OTHER FASTENER has been started. Once everything is lined up, there's a little extra bit of tape backing sticking out that you can grab. Pull the backing off and press the leading edge to the body, while tightening all the fasteners a little bit at a time. The tailpan holds up the tailing edge of the aluminium plate, and that plate holds the tailpan up, and the fender liners hold the bodywork together, and the fender liners hold the tailpan in place... short story is that all of these piece hold each other in place, so cranking down on just one of them can make the others a bear to install. Use hand tools and take your time.

The carbon ducts, strips, and tailpan all come with the nutzerts pre-installed. The set of strakes comes with a package of bolts, so don't buy any of those. All you need are the bolts to hold things to the tailpan. The OEM fasteners hold everything else.

2017-04-06 20.58.15.jpg

With all that awesomeness installed, you too can be sure to bash those strakes on every damn bump if you have Pennsylvania-quality backroads. Race Mode suspension activated is mandatory. And don't even THINK about lowering your car around here. Sure, you could take the strakes off, but what's the point of that??

IMG_20170408_221137_531.jpg

Feel free to post or PM if you want other advice or have questions. My Quickjack and I are also mobile if you are thinking of doing this and want some help. Northeast areas only. lol

Cheers!!

[Voice of Reason]

Looks good but seems to me there is a market for making new strakes that are either tapered towards the back or 1 inch shorter than the factory ACR for those looking to do what you are doing with it. If your goal is more than 50% aesthetics then those suckers don't need to be touching the ground lol.

I completely agree with you here. A vendor who came out with the look of these that function on the street would do well I think. And if carbon fiber is a price barrier they could be made out of aluminum and coated black, most people would never notice the difference and weight shouldn't be a huge factor (but if it is then spend 5x and get the real OEM thing).

DSE I think you'd sell a ton of these, we already know you can make high quality aluminum products from your air box shield!

[Brian GTS]

Man, that does look good. Nice work!

[mjorgensen]

Looks very tough!

[Canadian venom]

Awesome !!!

[Crotalidae]

Very nice indeed!!!

[The_Ruski_Driver]

Amazing work, patiently awaiting for an easier and cheaper solution but you are a def a pioneer to have accomplished this task. Looks superb!

[Bruce H.]

Bryan,

That really looks fantastic! Congrats and thanks for sharing. I can't stop picturing them on my black TA. Great job!

Bruce

[Scott_in_fl]

Seems like you have a decent little kit right there for someone to scan into a CAD file and start popping out some "slightly modified" copies at $2k a pop. Would likely sell plenty of them.