C5 Rear diffuser making progress
Le Mans Master
Joined: Feb 2007
Posts: 9,296
Likes: 1,531
From: Oviedo Florida
2024 C5 of the Year Finalist - Modified
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2016 C5 of Year Finalist
It looks great to the untrained eye. The problem so far--NO down
force. That's why I have one, that's why track folks turn up their
nose at form not following function.
Granted the Op has not finished this project and I believe he will
be attempting to have downforce.
PS OP----The empty space between the exhaust needs to be filled
in. You loose all your downforce with a gapeing hole in the middle.
The air instead of flowing under your car is blowing out the back.
deflate ing the preasure under your car. You could possibly offer
a bolt on plate to those that need function. Just a idea.
force. That's why I have one, that's why track folks turn up their
nose at form not following function.
Granted the Op has not finished this project and I believe he will
be attempting to have downforce.
PS OP----The empty space between the exhaust needs to be filled
in. You loose all your downforce with a gapeing hole in the middle.
The air instead of flowing under your car is blowing out the back.
deflate ing the preasure under your car. You could possibly offer
a bolt on plate to those that need function. Just a idea.
Burning Brakes
Joined: Oct 2008
Posts: 800
Likes: 12
From: Wichita Kansas
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
It looks great to the untrained eye. The problem so far--NO down
force. That's why I have one, that's why track folks turn up their
nose at form not following function.
Granted the Op has not finished this project and I believe he will
be attempting to have downforce.
PS OP----The empty space between the exhaust needs to be filled
in. You loose all your downforce with a gapeing hole in the middle.
The air instead of flowing under your car is blowing out the back.
deflate ing the preasure under your car. You could possibly offer
a bolt on plate to those that need function. Just a idea.
force. That's why I have one, that's why track folks turn up their
nose at form not following function.
Granted the Op has not finished this project and I believe he will
be attempting to have downforce.
PS OP----The empty space between the exhaust needs to be filled
in. You loose all your downforce with a gapeing hole in the middle.
The air instead of flowing under your car is blowing out the back.
deflate ing the preasure under your car. You could possibly offer
a bolt on plate to those that need function. Just a idea.
Drifting
Joined: Mar 2011
Posts: 1,807
Likes: 331
From: Ocala FL
Yes I am addressing the under pan for the ones that are concerned with function. I feel also that there is enough interest for one not so elaborate for the common street car. Probably more so. There are way more C5's that are for enjoyment than acrual ones that see the track. So you have to look at where you greatest market is as well. But I will be making one with the under pan to accomodate both sides. Road pilot I would still like to see pics of your setup. Here is a pic of what I am looking at to incorporate into my panned diffuser. Again thanks for the feedback.
VERY PROMISING so far. I'm curious if it would be possible for you to do the version with the under trans piece as a removable piece that you can add to the "street" version? That way you could have a modular design that should help in costs to produce and sell. Just a thought.
Le Mans Master
Joined: Feb 2007
Posts: 9,296
Likes: 1,531
From: Oviedo Florida
2024 C5 of the Year Finalist - Modified
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Modified
2021 C2 of the Year Finalist - Modified
2016 C5 of Year Finalist
Yes I am addressing the under pan for the ones that are concerned with function. I feel also that there is enough interest for one not so elaborate for the common street car. Probably more so. There are way more C5's that are for enjoyment than acrual ones that see the track. So you have to look at where you greatest market is as well. But I will be making one with the under pan to accomodate both sides. Road pilot I would still like to see pics of your setup. Here is a pic of what I am looking at to incorporate into my panned diffuser. Again thanks for the feedback.
no mufflers or catback. I installed a small Magnaflow muffler
much closer to the collector (I have headers). I wonder if a stock
setup will be to much heat for the glass/carbon pan. At least that's
what I did.
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Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I have discussed this issue with a few people. There is enough under draft that flows over the exhaust for sufficient cooling. If this was an issue the C6 would have been designed differently.
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
VERY PROMISING so far. I'm curious if it would be possible for you to do the version with the under trans piece as a removable piece that you can add to the "street" version? That way you could have a modular design that should help in costs to produce and sell. Just a thought.
Drifting
Joined: Mar 2011
Posts: 1,807
Likes: 331
From: Ocala FL
Drifting
Joined: Oct 2008
Posts: 1,595
Likes: 191
From: Wilmington DE
Seriously let him finish the original design first. Every time someone starts to make a rear diffuser the racecar guys come in and want a track diffuser. If it can be made with an add on undertray later on that's great but let him finish his original design first.
Melting Slicks
Joined: Jul 2005
Posts: 2,990
Likes: 346
From: Mt. Pleasant S.C.
But it is designed differently! On the c5 the mufflers are horizontal and on the C6 they are aligned longitudinally. On the C6 the air flows straight over them and out as they are centered in the chassis and aligned longitudinally. The c5 has those two slots in each side of the rear bumper to vent the muffler heat because the mufflers are horizontal and the bumper cover hangs down over them. You have closed the slots.
Le Mans Master
Joined: Jun 2002
Posts: 8,352
Likes: 103
From: In the pit, trying to love someone.
But it is designed differently! On the c5 the mufflers are horizontal and on the C6 they are aligned longitudinally. On the C6 the air flows straight over them and out as they are centered in the chassis and aligned longitudinally. The c5 has those two slots in each side of the rear bumper to vent the muffler heat because the mufflers are horizontal and the bumper cover hangs down over them. You have closed the slots.
So what are you going to do about heat from the mufflers? GM put those slits there to let heat out and people still have problems with their rear bumpers warping, which is why companies like ACI sell braces for them. The C6 doesn't have vents there because the mufflers are not placed right against the bumper.
I said the same thing earlier. GM added those slits on purpose to allow heat to escape, because bumpers were warping from heat. What if you were to add some sort of vent in that area to allow some heat to pass through?
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I'm not sure how much heat if any is actually vented through these vents. Wish I could do some wind tunnel test to have an actual visual of the venting and wind drag. I put over 1000 miles on this diffuser with no issues of heat stress on the diffuser or the rear bumper fascia. I will look more into the heat retention as testing goes on. Thanks for the feed back.
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
Update. I met with the vendor this past week. Have a mold maker coming up in a couple months and will hand it over to him to start the process of reproducing. During this time I will be working on an add on under pan. Also we discussed the various exshaust designs and how to accomodate most all with the same diffuser. This is a challenge but I have a few solutions. I fit and built my diffuser using a B&B quad bullet set up. Excellent for this because there is no oval can behind the vents. If you run a Corsa tigershark which probably has the largest can out there this causes a interference with the diffuser.The Corsa actually sets about 3/4" below the bottom of the rear fascia. I will mold the diffuser as designed and supply templates for trimming per type of exhaust used. Also thinking of an add on piece to cover the the muffler where diffuser was trimmed.
Racer
Joined: Mar 2012
Posts: 272
Likes: 388
From: SWFL
2026 Corvette of the Year Finalist - Modified
2025 C5 of the Year Winner - Modified
2024 C5 of the Year Finalist - Modified
Update. I met with the vendor this past week. Have a mold maker coming up in a couple months and will hand it over to him to start the process of reproducing. During this time I will be working on an add on under pan. Also we discussed the various exshaust designs and how to accomodate most all with the same diffuser. This is a challenge but I have a few solutions. I fit and built my diffuser using a B&B quad bullet set up. Excellent for this because there is no oval can behind the vents. If you run a Corsa tigershark which probably has the largest can out there this causes a interference with the diffuser.The Corsa actually sets about 3/4" below the bottom of the rear fascia. I will mold the diffuser as designed and supply templates for trimming per type of exhaust used. Also thinking of an add on piece to cover the the muffler where diffuser was trimmed.
