Will rear defuser help keep bumper clean?

[Bird325]

My '01 GTS gets dust and sand on top of the bumper and in the license plate area with only a short trip (1 mile) from home to the highway. I even get bug splatters on the REAR bumper when running the highway at high speeds.

Will adding a defuser under the car at the rear change the air flow enough to avoid this?

 

[Zentenk]

I heard it will but I have not seen very many good looking diffusers.

 

[KNG SNKE]

Yes it will help but only the functional, gaudy one that stick out past the rear bumper.

 

[dave6666]

It's a diffuser, and yes my one of one design greatly reduces debris.

Oh boy green light to post pics of my car. Again

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[Matt M PA]

While I have no idea whether or not it would help....I can only imagine how many holes that would have to be drilled in the car to install.

 

[dave6666]

While I have no idea whether or not it would help....I can only imagine how many holes that would have to be drilled in the car to install.

Zero holes were added on mine. Used all existing mounts.

 

[Bird325]

Would Dave's one-of-one defuser be considered gaudy or functional or both?

His actually looks less obtrusive in person. Note to Dave: Take an eye level picture from the back to add to your library for future reference. Did you keep the templates?

 

[georgethedog]

I think it looks good. Only Dave can speak to its functionality. Nice work.

 

[dave6666]

No, no templates, just a CAD drawing

And the reason it looks less obtrusive in person is that it's not obtrustive

 

[dave6666]

Mike... You just live down the street. Mosey your ass over here and look at it. I'll even stop posting in my underwear and get dressed for ya

Alternatively, we could go cruising because that's the view you'll have of my car

 

[Bird325]

Time to wake up again, Dave! Horsepower and bling does not a driver make.

If you go to the NTVCA meeting today, I'll get another look at it.

 

[RobZilla]

I have just four individual blades. Only required adding two holes/bolts in addition to the factory existing hardware.

It greatly reduces the sand/debris build up on the rear but it does not provide near the funcitonality of a diffuser designed for performance.

 

[dave6666]

Speeding down the highway is not a skill sensitive manuever. HP and bling DO prevail!

 

[Bird325]

I think the little tail spoiler on the GTS may cause more of a collection of debris than on your RT/10. Thanks for the input though.

 

[Bird325]

Speeding down the highway is not a skill sensitive manuever. HP and bling DO prevail!

My point EXACTLY!

 

[KNG SNKE]

No Daves is the best looking one I have seen thus far. The gaudy one extends past the rear bumper by at least 4 inches. The only thing I heard about the individual fins was they did not do anything to disrupt the air in the back of the car therefore still tons of dust. I don't have experience with them though.

I second that notion, Dave, make me one .

 

[dave6666]

Rob the plate on mine was exclusively to cover the unused rear exhaust hole. It may or may not add functionallity over just the blades like you have. Also, mine is more poser sized in contrast to the farm implement sized AF version.

Mike I will not be attending the meeting even though David promised beer. I'm OK, no reason to sound the alarm. I do have beer on site

 

[RobZilla]

I think the little tail spoiler on the GTS may cause more of a collection of debris than on your RT/10. Thanks for the input though.

The RT/10's collect more debris than the GTS's. And it's diffuser as opposed to defuser.

 

[Matt M PA]

Thanks for the clarification.....nice design!

 

[Russ M]

I have just four individual blades. Only required adding two holes/bolts in addition to the factory existing hardware.

It greatly reduces the sand/debris build up on the rear but it does not provide near the funcitonality of a diffuser designed for performance.

Rob,

Do you have any side angle shots? It looks very nice from the rear.

You would be surprised at the function, I bet you are within 15% optimum the way they are. Im assuming they are SRT diffusers right?

 

[markk]

I'm glad someone brought this up. I thought it was oil spots getting up there from a underside leak and then the dirt was sticking to it. I'm glad to see it is a common issue simply based on airflow.

 

[RobZilla]

Single blades (4) from XVipers. Ive got no idea what optimum is but my goal was less sand and debris on the back of my car all the way to the rear window. Id bet the blades knocked it down nearly half. If I angled them out a lil more I bet it would have even more success.

A quick one I found. Test shot from a shoot but you get the idea.

Larger: test1 - ViperClub Photo Gallery

 

[Voodoo Rob]

There was someone on here that bought the eBay diffuser for 4 or$500 a few weeks ago and that one didn't look like a diving platform off the back of the car.

 

[RobZilla]

If you do a search or any fact finding you will learn that the "diving board" extension is necessary for a full functioning diffuser. Of course that is in combination with front and side splitters. This was debated and discussed several times in the past. Dave knows what Im talking bout.

BTW Dave - I forgot you changed to the side exhaust.

 

[justingeer82]

hey dave what are your angles of the blades? it kinda looks like 20,70,90

 

[Fatboy 18]

I have the 4 blade Auto form diffuser on my car, to be honest it helps keep dirt off but you do still get a fair bit of dirt there after a good day out. I had much more dirt without it. The good thing about the auto form diffuser is it bolts up to the car using all the factory bolt holes so there is no fabrication work involved. I think if you want a totally dirt free rear end the diffuser should stick out of the rear of the bumper line by at least 2/3 inches.

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[dave6666]

Several design things being said here and since I did research it I'll capture them as facts.

The plane that the blades mount to must be the most rearward projection on the car for the highest level of function. I wanted a combo of function and looks so mine does not project as the most rearward feature.

I am not aware that the angle of the blades, more specifically the blades that simply attach to underside of the rear bumper cover without the mounting plane extending out, that having them angle out versus straight in line with the car would make any difference. That design is such a simple offering of the diffuser concept that tweaking it is more likely for looks than additional function. Mine adds a slight amount up the function food chain as the mounting plane does extend 1" past the bottom edge of the bumper cover, but even so is far from the full function possible.

The purpose of the rear diffuser is to make the air less turbulent at the rear of the car thus creating less aero drag at the rear. Less turbulence = less swirling debris. I still get dust back there but no more leaves and grass clippings.

The blades on mine are all identical and are all straight in line with the car front to rear. My cost if I remember was about $100 DIY. And yes, I do have the side splitters and front splitter for the package someone mentioned.

 

[Detlef]

Attached are a couple of shots of how the SRT blades look on mine. I like the look but can't say they reduce the dirt build up any.

 

[dave6666]

Mike... If the turnout yesterday at your meet was down that's because they were all here in Burleson. I saw a blue/white GTS trolling my car as it was parked at Home Depot yesterday and then later a black SRT coupe in the neighborhood over here where us poor folk live. That's a lot of Vipers in one day for a town of 25K.

 

[plumcrazy]

they look much better on a dark car. they kinda disappear. daves looks to be the best built (no surprise)