Xtreme Rear bumper with diffuser?
Thread Starter
Former Vendor
Joined: Oct 2003
Posts: 8,479
Likes: 417
From: Devil's Island CA
Final production on the one with the diffuser? The rear quarters are done, just waiting to test fit. I was told I should have pix tomorrow of this bumper installed. I will be out all day tomorrow but later tomorrow night I will try to post those pix.
Race Director
Joined: Apr 2010
Posts: 16,253
Likes: 1,657
From: Arizona
I am very partial to the C5-R rear diffuser itself. Regardless what type you make, is there a way you can replicate the C5-R in aluminum and have it bolted to the rear and underbody?
I'll dig up a photo later on. Its almost 5 am, and I got to get to work. Ugh.....TGIF!!!
I'll dig up a photo later on. Its almost 5 am, and I got to get to work. Ugh.....TGIF!!!
Last edited by WICKEDFRC; Nov 4, 2011 at 06:34 PM.
Burning Brakes
Joined: Sep 2009
Posts: 993
Likes: 26
From: La Follette, TN
I am very partial to the C5-R rear diffuser itself. Regardless what type you make, is there a way you can replicate the C5-R in aluminum and have it bolted to the rear and underbody?
I'll dig up a photo later on. Its almost 5 am, and I got to get to work. Ugh.....TGIF!!!
I'll dig up a photo later on. Its almost 5 am, and I got to get to work. Ugh.....TGIF!!!
Race Director
Joined: Apr 2010
Posts: 16,253
Likes: 1,657
From: Arizona
Actually, no. I know that look is not for most, but then again, I am not most. I am me. And I do like that look. The C6 has a similiar (yet lighter version) offered by HighTech. One of the guys on this forum has it on his C6 (which very closely resembles that of a C6-R) and I think it looks awesome. Yes, it is not for most, but if I could work that on with a front splitter and C5-R wing, I'd be set. That is the ultimate look I am striving for with an end-state sometime in the distant future to swap my Forged 402 to a Forged 427 (Possibly Katech, to keep the heritage) So, surely in jest? No. But I hope you got a good laugh out of it. 
Safety Car
Joined: Jun 2009
Posts: 3,888
Likes: 2
From: Frederick, Maryland
Actually, no. I know that look is not for most, but then again, I am not most. I am me. And I do like that look. The C6 has a similiar (yet lighter version) offered by HighTech. One of the guys on this forum has it on his C6 (which very closely resembles that of a C6-R) and I think it looks awesome. Yes, it is not for most, but if I could work that on with a front splitter and C5-R wing, I'd be set. That is the ultimate look I am striving for with an end-state sometime in the distant future to swap my Forged 402 to a Forged 427 (Possibly Katech, to keep the heritage) So, surely in jest? No. But I hope you got a good laugh out of it.
Good luck
Le Mans Master
Joined: Jan 2009
Posts: 6,226
Likes: 33
From: Morton illinois
St. Jude Donor '14-'15
God i wish people would stop calling that a diffuser...its a bumper added on clip. If you want something cool, make it with an entire flat bottom like the c5/6r. Less drag and has performance abilities.
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Le Mans Master
Joined: Jan 2009
Posts: 6,226
Likes: 33
From: Morton illinois
St. Jude Donor '14-'15
Safety Car
Joined: Jun 2009
Posts: 3,888
Likes: 2
From: Frederick, Maryland
Really? Funny you say that, I've seen you in all the diffuser threads, and you of all people should remember that the underneath of the car needs to be plated and have specific "channels" for the air leading from the chin spoiler to the diffuser. So yes, I do. But thanks for the rude comment
To back up my statement, IN YOUR OWN DAMN THREAD....
I mean I can just post the whole damn thread if you want??
Think about what you post before you do
Cmon man..... I use to respect you too
WICKEDFRC- Not trying to deter you but it's really more than just something on the back end to be fully Functional. It'll take a lottt of money to do so. Another point John Shiels made in the thread was that they sit so low,one bump or slope will ruin everything.
I hope this post helps
To back up my statement, IN YOUR OWN DAMN THREAD....
The book is called: "Race Car Aerodymanics: Designing for Speed" by the aforementioned Joseph Katz... I also have read it several times and realized that most rear diffusers are really for looks, not effect. Unless the entire underbody is given the aero treatment, the airflow under the car is too turbulent for a rear diffuser to have a noticeable effect. Most of the "supercars' that have effective rear diffuser aero also have flat bottom panels and mid engines. The mid engine design also makes doing the flat underbottom thing much easier from an engineering standpoint. The picture here is the Brian Glover Design "feeder" panels for the rear diffuser. I'm guessing this is about as good as you could do for a streetable car.
Ahhh... somebody knows about about aero engineering 
The one tip I'd offer is to decide what you want it to do. If you want it for looks, then you'll probably be happy with whatever you decide on. If you are building it as part of the vehicle's aero, I think you'll be very disappointed. As John mentioned, you pretty much require a flat bottom all the way along.
Here's a bit of quick info:
http://www.mulsannescorner.com/diffuser.htm
http://www.nas.nasa.gov/About/Educat...odynamics.html
And you'll be wanting to research and know Bernoullis Principal.
A diffuser is a great piece, but it'll only work if done right.
The one tip I'd offer is to decide what you want it to do. If you want it for looks, then you'll probably be happy with whatever you decide on. If you are building it as part of the vehicle's aero, I think you'll be very disappointed. As John mentioned, you pretty much require a flat bottom all the way along.
Here's a bit of quick info:
http://www.mulsannescorner.com/diffuser.htm
http://www.nas.nasa.gov/About/Educat...odynamics.html
And you'll be wanting to research and know Bernoullis Principal.
A diffuser is a great piece, but it'll only work if done right.
I mean I can just post the whole damn thread if you want??
Think about what you post before you do
Cmon man..... I use to respect you too
WICKEDFRC- Not trying to deter you but it's really more than just something on the back end to be fully Functional. It'll take a lottt of money to do so. Another point John Shiels made in the thread was that they sit so low,one bump or slope will ruin everything.
I hope this post helps
Last edited by TriplBlk; Nov 4, 2011 at 11:40 PM.
Le Mans Master
Joined: Oct 2007
Posts: 6,868
Likes: 770
From: Kelso Washington
St. Jude Donor '09, '13, '15
I LOVE the spoiler.....but not a fan of diffusers as seen here. I'm glad you won't incorporate the reverse lights but even then, it just doesn't seem as elegant/sporty as it should.
But that angle and size of spoiler is excellent
But that angle and size of spoiler is excellent
Le Mans Master
Joined: Jan 2009
Posts: 6,226
Likes: 33
From: Morton illinois
St. Jude Donor '14-'15
Really? Funny you say that, I've seen you in all the diffuser threads, and you of all people should remember that the underneath of the car needs to be plated and have specific "channels" for the air leading from the chin spoiler to the diffuser. So yes, I do. But thanks for the rude comment
To back up my statement, IN YOUR OWN DAMN THREAD....
I mean I can just post the whole damn thread if you want??
Think about what you post before you do
Cmon man..... I use to respect you too
WICKEDFRC- Not trying to deter you but it's really more than just something on the back end to be fully Functional. It'll take a lottt of money to do so. Another point John Shiels made in the thread was that they sit so low,one bump or slope will ruin everything.
I hope this post helps
To back up my statement, IN YOUR OWN DAMN THREAD....
I mean I can just post the whole damn thread if you want??
Think about what you post before you do
Cmon man..... I use to respect you too
WICKEDFRC- Not trying to deter you but it's really more than just something on the back end to be fully Functional. It'll take a lottt of money to do so. Another point John Shiels made in the thread was that they sit so low,one bump or slope will ruin everything.
I hope this post helps
Safety Car
Joined: Jun 2009
Posts: 3,888
Likes: 2
From: Frederick, Maryland
Race Director
Joined: Apr 2010
Posts: 16,253
Likes: 1,657
From: Arizona
This is interesting as I am aware a fully underbody plate to cover all the cracks and crevices would be best. If I am not mistaking, my 944 S2 had an underbody plate that came on the car when I bought it. I thought the C5 had a relatively flat underside, but not compared to my S2. Anyways - I am not looking for an all out race body. Just an all out race look. I won't be doing much track at all. Since I will be looking to retire in the next few years, I just want to complete a specific look I been wanting. That's all. And finding a decent splitter for the C5 is impossible.
Le Mans Master
Joined: Jan 2009
Posts: 6,226
Likes: 33
From: Morton illinois
St. Jude Donor '14-'15
This is interesting as I am aware a fully underbody plate to cover all the cracks and crevices would be best. If I am not mistaking, my 944 S2 had an underbody plate that came on the car when I bought it. I thought the C5 had a relatively flat underside, but not compared to my S2. Anyways - I am not looking for an all out race body. Just an all out race look. I won't be doing much track at all. Since I will be looking to retire in the next few years, I just want to complete a specific look I been wanting. That's all. And finding a decent splitter for the C5 is impossible.
Thread Starter
Former Vendor
Joined: Oct 2003
Posts: 8,479
Likes: 417
From: Devil's Island CA
Yea that would be the idea since we would be using a C5 to build it, it wouldn't be worth it to build it if you had to change your exhaust.
Safety Car
Joined: Jun 2009
Posts: 3,888
Likes: 2
From: Frederick, Maryland
Race Director
Joined: Apr 2010
Posts: 16,253
Likes: 1,657
From: Arizona
Maybe this is what you looking for...
http://breathlessperformance.com/ind...&productId=911
http://breathlessperformance.com/ind...&productId=911
If I knew how to somewhat make one, I would try and draft some plans up for a metal shop and have it perfected and mounted somehow. There has got to be a way.....