Mr.E.G.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GarageAlchemist &raquo;</TD></TR><TR><TD CLASS="quote">LMAO !!!!! you guys are like 13 year olds playing D&D

I get plus 20 Downforce ! your roll.. ohh snap aeropodic backpresure !!! + 15 with a +4 stamina buff </TD></TR></TABLE>


hahahaha, you're momma plays D&D

2point2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tek_civic &raquo;</TD></TR><TR><TD CLASS="quote">here is another idea i just thought up. EDIT: duhh forgot to add the pic


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

LOL.. lovin' the ms-paint engineering.

Mr.E.G.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point2 &raquo;</TD></TR><TR><TD CLASS="quote">LOL.. lovin' the ms-paint engineering. </TD></TR></TABLE>

i swear man, thats how they design f1 cars.

Bense

P1_Variable

Here are some auctions in japan that are selling the parts you guys could use for this.

http://page9.auctions.yahoo.co...12631
http://page10.auctions.yahoo.c...91152

Enjoy

Jose-aka-Pedro

Here ya guys go.

http://images.google.com/imgre...lr%3D


NOTICE the three trails of smoke












Modified by Jose-aka-Pedro at 3:31 AM 6/25/2006

Mr.E.G.

what happened to the post made by tekstyle? did it get deleted?

tekstyle

i know what. i might start making a rear diffuser for my car too since i got some left over material from my front splitter. should i make it like the NSX rear diffuser ( with the big hole that sandwiches the exhuast in the rear side) or close the space created by the bumper)?

like this

got this photo off of team-integra.net, username "vitamin_d"

here are other examples:

Mr.E.G.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tekstyle &raquo;</TD></TR><TR><TD CLASS="quote">i know what. i might start making a rear diffuser for my car too since i got some left over material from my front splitter. should i make it like the NSX rear diffuser ( with the big hole that sandwiches the exhuast in the rear side) or close the space created by the bumper)?

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

i wouldgo with the second option. but before we go any further lets make sure that we all understand what the rear diffuser is there for.

the ideal situation is that your completley flat underbody will mate with the diffuser. a lot of these after market diffusers dont sit flush against the underbody since the factory underbody is not smooth. the end result is that the diffuser is basically just another big protrusion into the underbody airflow.

when i first got into aerodynamics i was totally confused by the function of a diffusor because after observing aftermarket diffusers i assumed that they were basically like an underbody wing or something.

here is an example of a factory underbody on the rear of a car:



as you can see there are many obstacles underthe car to slow down the flow of the air (which we know to be a bad thing)


here is an example with your typical off the shelf aftermarket diffusor. if it doesnt mate flush against the bottom of the car, all if is doing is trapping the air on top of the diffusor.



as i mentioned, when i first started getting into aerodynamics i though that the air was supposed to flow across thee diffusor since so mant of the aftermarket designs guide so much air across the top of themselves. THIS IS NOT WHAT IS SUPPOSED TO HAPPEN. which means one of two things: most of the aftermarket stuff is either for looks or these guys dont know what they are doing. either way, its no bueno.

here is an example of a diffusor that mates smoothly to the underbody like its supposed to :



now before someone gets all bent out of shape there are examples where the air is supposed to flow acorss the top of the rear diffusor... sort of.

a perfect example is this whit subaru that you posted up:



the pieces of the diffusor that stick out behind the wheels are actually designed to catch the air off of the rear tires at an angle to create some high pressure on the top of these little fins. but technically they are just pieces that are attached to the diffusor, and not actually the diffusor its self.

personally i like the diffusor on that green integra. but it all depends on whether or not it sits flush on the under body.

tekstyle

apparently, it does!


the only problem i have is that air still can get into the space through the holes in the wheel well. on the 98+ bumpers, i cut out the grill area for that purpose.

Mr.E.G.

i would personally want something that is more flush to the underbody. that isnt terrible but its not ideal either.

but before it sounds like im being too negative let me say that that integra is probably more realistic for a street car than what i have in mind.

but to help it i would seal the opening off with something. when you are playing with a small margin of downforce as you would be in this case, it is important to not let little things screw it up.

overall i think that integra piece is impressive and it probably represents a good compromise of several needs

thehatchninja

There are some pretty great ideas here. I'd love to implement these on a road race car.

Bense

interesting read

hondamark35

i agree, very interesting. what would be equaly interesting is for me to get some rough numbers together and see what kind of effects i get before and after adding some stuff to the underside of my EK coupe. i'll try to do it real scientific like... looking foreward to posting my results...

Mr.E.G.

i have thought long and hard on various home made testing equipment for measuring downforce and drag. if you want any suggestions im here.

thehatchninja

do it mark!

StormBringer

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

ahhhhh, i had it backwards. i thought the big one in the center was the radiator, and that the smaller ones were trans or oil coolers.

thanks for the info


Modified by Mr.E.G. at 1:58 AM 6/8/2006</TD></TR></TABLE>

Depends on what Porsche you are talking about, the GT3 I believe has both the side radiators as well as the one in the center, the standard 911 has two on the sides of the car, but what you see is actually the air conditioning system condenser in front of the actuall radiators.

Its a major pain the in the butt for 911 owners becuase stuff gets sucked into the vents in the front bumpers and then the cars start to run a hot, and you have to pull the front bumper off to really clean up in there. Some owners have pulled out dead birds, leaves, nests, all sorts of crazy stuff, I found a canvas sand bag, minus the sand sucked up on the left side of mine once.

MidShipCivic

Besides posting all this fricken pics whos acutally done it. Who knows how to find these points to add aero.

I'd like to filter out some **** here.

Mr.E.G.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MidShipCivic &raquo;</TD></TR><TR><TD CLASS="quote">Besides posting all this fricken pics whos acutally done it. Who knows how to find these points to add aero.

I'd like to filter out some **** here.</TD></TR></TABLE>

i have made homemae aerodyamic parts and i can say ive had good luck with them none of them were ever for my car but for friends cars and i would build them and help them dial them in with pretty good success.

i have never done an entire underbody but making the parts isnt the hard part. im not sure what **** you wish to filter exactly.

nfn15037

How do you quantify the success of your designs? Lap times? Wind tunnel testing?

MidShipCivic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nfn15037 &raquo;</TD></TR><TR><TD CLASS="quote">How do you quantify the success of your designs? Lap times? Wind tunnel testing?</TD></TR></TABLE>

Which is part of what my question is I have a definite way of findingif it works.

nfn15037

Other than lap times (which isn't all that accurate-you need good datalogging with GPS and acclerometers) or a wind tunnel, there is no way to get any sort of empirical data. Sure, you can cover the car with telltales and go video tape it in motion, but that merely gives you a sense of what is happening, making something else happen is a whole other story that requires knowledge and a good bit of testing. This is why back yard aerodynamics is a bit of a guessing game. Something 'feeling better' or 'looking like it should work' usually isn't better or doesn't work.

MidShipCivic

Still dont see the awnser, for a simple tool.

No you dont need a road course or a bunch of sensors with datalogging.

A Magnelhelic Gauge can tell you if something you made is working simple and easy.

nfn15037

Right, you can see a pressure differential but most people don't know what to do with that information. That is a very limited testing method. I think that even simple aero testing procedures are beyond the scope of this thread.

But what do I know, I'm just a simpleton EE

kb58

Two good books are Race Car Aerodynamics by Katz, and Competition Car Downforce by McBeath.

I used some of the ideas from these books on my mid-engine Mini. A completely flat undertray, rear diffuser and top exiting radiator. My only testing was doing 120mph and was shocked how stable it was. Any other street car I've been in starts buffeting, with one end or the other wandering around due to lift.

Real testing will be to monitor shock absorber travel over speed to get an idea of lift/downforce.

Here's the undertray, rear diffuser, top radiator exit, and rear diffuser detail.







Modified by kb58 at 6:12 PM 8/18/2006