DIY rear bumper fake vent conversion

[cvmomo1CTR]

I see how you didnt cut out the diamonds from the topside so as to avoid exposing crash beam. Looks good.

Correct Sir, as much I was to have a Diamond match top side I didn’t want to show the crash beam so kept it dark and since I did bumper it works... It actually looks good IMHO. I didn’t know how it would all flow but with rear tips of exhaust being round it works for bumper and diamonds I kept same style as smaller ones. Kind’ve wished I had done that for front ones as well.

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[wintercast]

Do you have actual test data to support that? Opening up those spaces would save weight and material. If it would improve fuel efficiency or performance even by the tiniest imaginable amount, don't you think Honda would have done that from the factory? I can't think of anything better for a manufacturer than saving weight, material, and money while gaining performance and fuel efficiency at the same time!

In a worst-case scenario, allowing air to flow through areas not intended could actually create additional drag and decrease efficiency and performance. It may also alter the airflow characteristics in such a way that causes exhaust fumes to be drawn into the vehicle. We'd need a wind tunnel and several hundred thousand dollars worth of test equipment and fluid modeling software to validate these wild guesses.

Im in this boat. I could possibly see how opening up the fake vents in the back "might" help a little in perhaps allowing air to escape from the bumper - but - is the bumper even acting as a wind catch/sail in this case?

I would imagine opening up the front bumper could just increase drag. A car with no body panels has way more drag.

 

[EtRtcarguy]

This is just a rough hand cut before the cnc version but i did the same thing here. I avoided the crash beam so the screen goes under it.

 

[cvmomo1CTR]

Im in this boat. I could possibly see how opening up the fake vents in the back "might" help a little in perhaps allowing air to escape from the bumper - but - is the bumper even acting as a wind catch/sail in this case?

I would imagine opening up the front bumper could just increase drag. A car with no body panels has way more drag.

Given that Honda for its 2020-2021 model changed the front grille to allow more airflow for cooling goes to tell you that it was an issue they needed to address. Now as for Data I actually am monitoring my cooling thru Hondata and asking others locally who run their Hondata what their temps are.... I am actually running or seem to be running much cooler then mostly everyone else. For example I mean I also have a few other things done to engine like Turboblanket and Downpipe Blanket, but after a long drive I can place me hand on the Inlet pipe and not burn myself, other guys or before couldn’t even touch it and be super hot. ( Again not saying it is because of the cut outs , but I am certainly getting more airflow in the radiator/ engine area.

And as for drag and creating worse drag efficiency. Just look at the rear bumper of most drag cars, you will see cut outs for the reason to not create a parachute effect and have trapped air in the rear bumper, which looking at how our bumpers are setup there is no area for air to escape since we have fake rear vents.

Now onto my next point, given that I have now ran roughly 10 different Civic TypeR’s (some similar mods, some different and some stock) , in Mexico doing some highway pulls up to 140mph( which aerodynamics come into play in higher speeds) I have easily (not close) but easily been faster then all.

In short cannot confirm how effective these are toward performance/gas saving it is, but I can say I’ve seen/felt improvements , and hasn’t seem to hurt anything as of yet.

This is why we mod our cars and learn from one another. I am most certainly not telling anyone to do what I did nor saying it is the best, I made my mods, because I like and dare to be different, and also show the community what I personally did as to give an idea to others who may want to do something to try and improve performance, or at the least the look of the car. Some will love it, others may hate it, which both is fine, I’m content with the outcome, and I’ve seen mostly positive feedback from community which was a plus.

In the end we all just mod to personalize our own vehicles to our liking, we share to give otherd ideas, and perspectives on what works or doesn’t work.

This is just a rough hand cut before the cnc version but i did the same thing here. I avoided the crash beam so the screen goes under it.

Nice ? design, that is looking super clean. Love it .

 

[Brian17Si]

FYI - Great job everyone! I've made an image collage of the conversions and it's now on first post.

 

[imSlow]

Cosmetic improvement, reduce drag, increase downforce.



Thanks Invader and he's 100% correct with his posts. All the super cars and race cars have openings in rear bumpers and diffusers to reduce drag and increase downforce. Air gets trapped in that area of the bumper causing drag to the vehicle's airflow and aerodynamics.



Thanks for your reply. Like Invader said it will improve in a positive way small or larger. Something moving with a wall on it's rear end will trap and restrict air flow. Think if you ran with a parachute open behind you it would definitely add resistance and make it more difficult to accelerate. If you were to cut holes in the parachute you would be able to accelerate and move more freely and quickly.

I feel Honda was really itching to make these vents real but for whatever reason decided to go the more conservative route. Who knows but I got the hint because they started it! One thing I'm sure about is I don't like big fake vents.

Here are a few good links related to this topic...



Porsche forum - https://rennlist.com/forums/964-forum/820881-rear-bumper-venting-2.html



Hey, this is real no Photoshop and here are some images of the work in progress. I'm going to be cutting the bumper and struggling if I'm going to cut the entire section or just the slanted thinner section in middle and spray additional section flat black behind vents.

I hope I can put an end to this myth. I participated in the design of the FK8 & NSX GT3. All “fake” vents that came with your car were meant to be “real.”However with regulations not just in the US, the entire world, to comply it had to be closed. However for whatever reason our marketing division didn’t pass this to our customers. Just like the new Supra, it also has vents that were closed but they openly notified their customers they are meant to be open to increase performance. Hope this makes sense to all owners.

 

[Brian17Si]

I hope I can put an end to this myth. I participated in the design of the FK8 & NSX GT3. All “fake” vents that came with your car were meant to be “real.”However with regulations not just in the US, the entire world, to comply it had to be closed. However for whatever reason our marketing division didn’t pass this to our customers. Just like the new Supra, it also has vents that were closed but they openly notified their customers they are meant to be open to increase performance. Hope this makes sense to all owners.

Wow, to start thank you and honored to have you write on post. Beautiful designs and absolutely hits the mark for enthusiast... related to the vents this does help in the facts we the customers were looking for. In my soul I knew this was EXACTLY what happened. It was clear as day once I took the bumper off (great affordance) and amazed to see the clean metal cuts with intent for opening. I basically followed the guidance there and finished off the design on my ride. Thank you for writing and something of value to hear after many years of assumption.

 

[zroger73]

I participated in the design of the FK8 & NSX GT3.

Does filling out an online survey for a chance to win a $100 Amazon gift card qualify one as a "design participant"? I'm asking for a friend.

However with regulations not just in the US, the entire world, to comply it had to be closed.

Please point me to the specific requirement in the Federal Motor Vehicle Safety Standards that applies here.

If the vents were intended to be open, why aren't they open in countries where there are allowed in order to reduce cost and improve performance?

If vents are required to be closed in the US, why are they open on many vehicles such as the C8 Corvette and even the 2021 Honda Ridgeline, and, oh, the 2017-2021 Civic Type R?

 

[rflkptr]

If vents are required to be closed in the US, why are they open on many vehicles such as the C8 Corvette and even the 2021 Honda Ridgeline, and, oh, the 2017-2021 Civic Type R?

I like this question. Though for whatever it is worth, my 2021 Ridgeline has similar vent styling to the most recent generation of Accord, where the vent from the front pipes air across the front of the tires. So unlike our cars, it's not an opportunity really for air to enter the engine bay (from my amateur perspective!).

I will say that the C8 and even several models of Benz I've noted have vents that are opened like mine now are, with no visible routing of air towards the bottom or sides of the vehicle.

Break

As an update to those who are taking on this project - I opened the front and rear vents and left the OEM material largely in place. I did paint black spraypaint along the bumper supports to make it look OEM. I have a filter sock over the air filter to prevent excessive water seepage, and have driven through 1 torrential downpour and several thunderstorms over the ~1 year I've had the vents opened.

 

[Brian17Si]

Does filling out an online survey for a chance to win a $100 Amazon gift card qualify one as a "design participant"? I'm asking for a friend.



Please point me to the specific requirement in the Federal Motor Vehicle Safety Standards that applies here.

If the vents were intended to be open, why aren't they open in countries where there are allowed in order to reduce cost and improve performance?

If vents are required to be closed in the US, why are they open on many vehicles such as the C8 Corvette and even the 2021 Honda Ridgeline, and, oh, the 2017-2021 Civic Type R?

Haha! Was going to ask for image credentials but felt it was too excessive. With you calling it out though anyone can say anything. I was concerned it could be $100 gift card scenario. If Imslow shows some proof would you consider it valid info?

 

[Brian17Si]

Does filling out an online survey for a chance to win a $100 Amazon gift card qualify one as a "design participant"? I'm asking for a friend.



Please point me to the specific requirement in the Federal Motor Vehicle Safety Standards that applies here.

If the vents were intended to be open, why aren't they open in countries where there are allowed in order to reduce cost and improve performance?

If vents are required to be closed in the US, why are they open on many vehicles such as the C8 Corvette and even the 2021 Honda Ridgeline, and, oh, the 2017-2021 Civic Type R?

My thought was more around reduced hassle and not spending a single penny more on mass reproduction car. If Honda is going through regulations in some countries is different or pain just close them all from factory. This doesn’t mean they are not functional or intended to be with certain models etc. But again I’m just guessing and the saga might still continue.

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