why don't you try one and see for yourself. everyone that doesn't have one says that. keyword: R&D
but it does take some work and testing, if your not a motivated swimmer, you'll never see positive results.

I'm not saying that you won't see ANY improvements... But if you have a fully sorted aero package the effects of the diffuser will be significantly increased.

yes, that statement would be true regardless of what we were talkin' about.

anyone know anything about the time this will be able?? i already have my bumper put out for this. i have a few road signs at the house and have been really thinking about fabbing up something just like this. im just not really sure about the angle and all that other stuff. thats kinda why i would rather buy one. then replicate it.

Speaking of road signs... Wasn't there someone who made one of out road signs before? I know FM did a photo of a sign being used under the car a long time back, but I thought there was a diffuser one too.

road signs? aren't those steel? sounds waaayyy too heavy to me. i'd use aluminum.

Not saying that I would make mine out of them, but if you are on a budget and want to be creative it WOULD work.

well my road signs are deff aluminum. i have a huge one that i got from the old wilson dodge place that i was going to cut and make a flat bottom tray out of for my car. i had a splitter on my ae86 that was made out of a hyw 49 sign. i use what i can get my hands on. i didn't steal any of them i wait till i see them putting up new signs and pay off the road crew for the big ones.

Yes road signs are defiantly aluminum. I have stacks of them at work that are not useful anymore that I plan on using for my aero project.

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I would be interested in said projects... Haven't decided what I want to use as my flat bottom yet and additional ideas are always great.

I have some .040" thick 7475 Aluminum Im using for this stuff,under shrouds and the like.I got it cheap,you really cant weld it well and I doesnt like to be bent either.But it is light and stiff.I have no Idea what it would cost to buy on the open market..Edit:$147.50 for a 4'x8' sheet from aircraft spruce
(G)

yea its not very pure. it has other metals mixed in with it to keep is more rigid i think. thats kinda why i been putting off not welding up this stuff i have here. there is a sign store not far from my house. i need to go talk to them about where to get some good good clean aluminum.

This is about as good as it gets. The drag from the OEM bumper is almost if not totaly eliminated.

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Matt does have an aerodynamicist working with him on the aero develop of the car. They have definitely made leaps and bounds in the Miata world for sure...

I'm not a mechanical engineer or anything but all the different oem diffusers that I've seen on performance variants aren't obnoxiously huge like some of those pictured here.

Thats because most of them dont do anything

Not extremely relevant to this discussion, but if your diffuser is made of aluminum you can dump your exhaust in at a nice angle and it willspeed up the flow. I can scan some pages of the Milliken book that cover diffuser design when I get back from the track

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I would like to see how this theory works and how subtle the blend in would need to be to prevent turbulence from being formed. Post those scans when you get the opportunity.

very true but wouldn't that mean when you lift off the throttle it would interupt the "flow"?? or the more exhaust there is the more thats being forced out the diffuser and at some point it would creat some unwanted turbulence. might not be the best idea for the high hp, high exhaust flowing turbo guys. if im wrong let me know. these are just my :2cents: