hey guys i heard that holes in the back bumper help with less drag i also like the looks of it so i did it to my car. Well im just wondering if it does help or not alot of ppl ask me and i always thot it did.. heres a pic of mine on my car

 

yes they work but you wont see much of a gain unless you are running 140+ trap speeds or something like that

 

how about 100 j/k if anyone else has anything to add put it down a few guys are watching this thread! heres a few more pics

 

old pic

 

This is concrete knowledge from my car and my experiences.

I was in the mid 13s, 13.4xx consistently. I did no power mods, had the same setup I added a front lip, and holes in the rear. This put me at a 13.2xx consistently.

Take it for what it is, these were with the exact same car, the same season, at the same track.

The lip might have helped more, or even been the only thing that helped, but its up to you to decide.

Now I have a stock rear bumper and I put my VX diffuser back in. IMO this is the way to go, I thought the VX diffuser didn't really work, but after putting it back in, I looked real hard, and thought about how it fit, and I think it is going to be better for the air to just not go through the bumper at all, just right under the car.

Next year I'm going to make a real diffuser and sheet the entire bottom of the car, at least from the front to the axles, and from the front of the rear wheelwells back.

 

yeah next season this is what im doing( this is a guys car off this site mad props to him and his car)

 

yeah im not to sure if it works or not but I figure its worth a try, well see this spring.

 

i dont think it helps for a daily driven car unless its producing mad horsepower numbers and going too fast for the streets. BTW your car looks pretty badass

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GreyDel &raquo;</TD></TR><TR><TD CLASS="quote">i dont think it helps for a daily driven car unless its producing mad horsepower numbers and going too fast for the streets. BTW your car looks pretty badass </TD></TR></TABLE>
I bet you would get a little better gas mileage on the highway though

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GreyDel &raquo;</TD></TR><TR><TD CLASS="quote"> BTW your car looks pretty badass </TD></TR></TABLE>Agreed.

-Red

 

I'd be willing to bet just removing the rear bumper cover would be better than cutting holes in your bumper.

 

did you just cut the bumper? and what did you cut it with? im assuming you dont like the look of the rear diffuser

 

i doubt the holes do anything at all, they would only be valuable at like 175mph when air drag becomes a real issue, and then the holes need to be placed specifically where the air would gather the most, not just cutting holes all over.

under chasis diffusers would be more benificial, someone should just create sheet metal to cover the underside of the cars if wind resistance is that much of an issue

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lshatch1.8 &raquo;</TD></TR><TR><TD CLASS="quote">old pic </TD></TR></TABLE>

Minus the fenders, that car looks sick!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by built562 &raquo;</TD></TR><TR><TD CLASS="quote">i doubt the holes do anything at all, they would only be valuable at like 175mph when air drag becomes a real issue, and then the holes need to be placed specifically where the air would gather the most, not just cutting holes all over.

under chasis diffusers would be more benificial, someone should just create sheet metal to cover the underside of the cars if wind resistance is that much of an issue</TD></TR></TABLE>

I'd just like to say again.... it isn't always 120+ 150+ 175+ winds that affect the car... To make it clear again... tornados are 75mph and up... hurricanes are averaging 100mph.... think about that. Before you start placing obsene numbers, think logically. Think with some background in fluid dynamics, ... think with research backing it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CooBlueDAB &raquo;</TD></TR><TR><TD CLASS="quote">

I'd just like to say again.... it isn't always 120+ 150+ 175+ winds that affect the car... To make it clear again... tornados are 75mph and up... hurricanes are averaging 100mph.... think about that. Before you start placing obsene numbers, think logically. Think with some background in fluid dynamics, ... think with research backing it.</TD></TR></TABLE>


First off, what the hell are you talking about?

Second off, how could you possibly "like to say [something] again" if you haven't posted on this thread yet?

Third, before you start making obscene statements, please realize that the windspeed as measured in MPH has absolutely nothing to do with the rate at which a car may travel in this scenerio. If you research windspeed in relation to storms you'll find that when winds reach a certain speed (we'll say 100 mph for arguments sake), that the speed/power of the wind is actually rising at a faster rate than the actual MPH measurement. In essense a 100 mph wind is actually MORE than twice the speed than a 50 mph wind. I'm sure this is mind boggling to you and i'm sure you'll argue this before looking it up but i think if you do some research you'll see what i'm talking about.

Now then. Unfortunately, most people do not have a background in fluid dynamics. Clearly, I would have to guess that you do not either. You said that people should think with research backing statements, yet you offered absolutely nothing in terms of research or evidense to prove your point.

I appreciate those who've posted about specific experiences and experiments and noted some alternatives that may help create a more aerodynamic car. This is useful, even though it might be lacking the empirical research that certain people might be looking for.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lshatch1.8 &raquo;</TD></TR><TR><TD CLASS="quote">how about 100 j/k if anyone else has anything to add put it down a few guys are watching this thread! heres a few more pics

</TD></TR></TABLE>


PS. That car looks hot, much better w/o the Z3 fenders!

 

its your car, thats the main thing here. i hear lots of people talking ****. no, i wouldnt do that to my car, but to each his own. just make sure the work is done right so it looks right. any real tuner will look "how" stuff is done. they look at what is done too, but it doesnt matter whats done if it aint done right. and yes is will help, its like having a parachute on the back of the car with no holes. with holes, its like having a parachute with holes in it, it'll flow better, but still not perfect. there were photos of a guy that just put the sheet metal to cover it up, so the air doesnt even go in there, that is a good idea. if it was me, I would cover it like that one dude, but, i would put a diffuser on it also(its like an undercar wing) just so i wouldnt get any lift in the rear. i roadrace, and if you know anything about "eg's" its that, if you dont have really good suspension, the rear comes around fast. the weight in eg hatches front/rear is 72%/28%. thats no weight on the rear wheels at all. if you make a diffuser, it will keep weight on the rears at high speed. yes your holes work. and if you like the way they look, cool. sorry i rambled.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrjdm2u &raquo;</TD></TR><TR><TD CLASS="quote">its your car, thats the main thing here. i hear lots of people talking ****. no, i wouldnt do that to my car, but to each his own. just make sure the work is done right so it looks right. any real tuner will look "how" stuff is done. they look at what is done too, but it doesnt matter whats done if it aint done right. and yes is will help, its like having a parachute on the back of the car with no holes. with holes, its like having a parachute with holes in it, it'll flow better, but still not perfect. there were photos of a guy that just put the sheet metal to cover it up, so the air doesnt even go in there, that is a good idea. if it was me, I would cover it like that one dude, but, i would put a diffuser on it also(its like an undercar wing) just so i wouldnt get any lift in the rear. i roadrace, and if you know anything about "eg's" its that, if you dont have really good suspension, the rear comes around fast. the weight in eg hatches front/rear is 72%/28%. thats no weight on the rear wheels at all. if you make a diffuser, it will keep weight on the rears at high speed. yes your holes work. and if you like the way they look, cool. sorry i rambled.</TD></TR></TABLE> I have got to give you props for being a n00b and being able to post like this. There is a God.

-Red

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlsmi2 &raquo;</TD></TR><TR><TD CLASS="quote">First off, what the hell are you talking about?

Second off, how could you possibly "like to say [something] again" if you haven't posted on this thread yet?

Third, before you start making obscene statements, please realize that the windspeed as measured in MPH has absolutely nothing to do with the rate at which a car may travel in this scenerio. If you research windspeed in relation to storms you'll find that when winds reach a certain speed (we'll say 100 mph for arguments sake), that the speed/power of the wind is actually rising at a faster rate than the actual MPH measurement. In essense a 100 mph wind is actually MORE than twice the speed than a 50 mph wind. I'm sure this is mind boggling to you and i'm sure you'll argue this before looking it up but i think if you do some research you'll see what i'm talking about.

Now then. Unfortunately, most people do not have a background in fluid dynamics. Clearly, I would have to guess that you do not either. You said that people should think with research backing statements, yet you offered absolutely nothing in terms of research or evidense to prove your point.

I appreciate those who've posted about specific experiences and experiments and noted some alternatives that may help create a more aerodynamic car. This is useful, even though it might be lacking the empirical research that certain people might be looking for. </TD></TR></TABLE>


I was never creating a clear fact nor claiming it or anything obscene or outlandish, just giving ideas because I am sick of people in every thread claiming super wind speeds are the only ones that matter. (yes there was research, the wind speeds for a visual), as for how the wind accelerates, what do I care child... the point is it is fast and has lots of resistance... take some valium and chill child. It helps and wind sucks... Our cars are limited in top speed because of the wind resistance remember? drag... etc..

 

it helps

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CooBlueDAB &raquo;</TD></TR><TR><TD CLASS="quote">


I was never creating a clear fact nor claiming it or anything obscene or outlandish, just giving ideas because I am sick of people in every thread claiming super wind speeds are the only ones that matter. (yes there was research, the wind speeds for a visual), as for how the wind accelerates, what do I care child... the point is it is fast and has lots of resistance... take some valium and chill child. It helps and wind sucks... Our cars are limited in top speed because of the wind resistance remember? drag... etc.. </TD></TR></TABLE>

well i may have thrown an obscene number out there and i have studied air flow, drag and fluid dynamics for that matter. the thing is our cars are not limited to top speeds only due to drag, thats insane, then why do people keep going faster in the quater mile, we have yet to reach 'terminal velocity' of a civic.

i believe air does get trapped there (in the bumper) but the amount of force created there at low speeds is not enough force to create any real change in quater mile times, now when you increase the mph to about 175 mph the force would be much much greater causing significantly more drag.

then to say that tornados have 75mph winds and look at the force they have, but also look at the amount of air being moved at that speed. simple physics F=MA . i sneeze at 100mph but you dont see me knocking any buildings down

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by built562 &raquo;</TD></TR><TR><TD CLASS="quote">simple physics F=MA . i sneeze at 100mph but you dont see me knocking any buildings down</TD></TR></TABLE>

I don't know, i heard your breath be kickin' sometimes. j/k Well we have one guy here who actually went to the track and it produced a .2 reduction in time which is about 3-5 whp increase. I'd say that is good for a free improvement.

Nothing short of a massive buildup or F.I. will net significant gains in my book, but not only would diffusers add about 1-3 MPG, it's gonna make you a little quicker. Personally, I'd just put sheet metal over the area instead of cutting mad holes in my bumper

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FuNkDrSpOt &raquo;</TD></TR><TR><TD CLASS="quote">

I don't know, i heard your breath be kickin' sometimes. j/k Well we have one guy here who actually went to the track and it produced a .2 reduction in time which is about 3-5 whp increase. I'd say that is good for a free improvement.

Nothing short of a massive buildup or F.I. will net significant gains in my book, but not only would diffusers add about 1-3 MPG, it's gonna make you a little quicker. Personally, I'd just put sheet metal over the area instead of cutting mad holes in my bumper</TD></TR></TABLE>

you cant compare whp with ******* holes in a bumper, there is no correlation. Just take carbon fiber panels and run them done under your entire car and have fun

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Soccerking3000 &raquo;</TD></TR><TR><TD CLASS="quote">

you cant compare whp with ******* holes in a bumper, there is no correlation. Just take carbon fiber panels and run them done under your entire car and have fun</TD></TR></TABLE>

true that, someone just make some diffusers and be done with the holes in the bumper thing