Underpanel Mods -- Any serious impact on mpg?
 

Hi folks,

Does anyone have any substantial evidence that the underpanel mods can significantly improve mpg?

I've read here that people had seen some better mpgs (or MsPG, I guess) from the Beatrush front underpanel, and several fit freaks suggested or attempted mods to the rear underside of their cars after imagining that the car's rear bumper on the underside acts like a pair of giant air scoops. Does anyone have long-term data suggesting that 1) the front Beatrush panel does improve MPG significantly (like more than 1 mpg?) and 2) do rear underpanel mods do anything at all? I wonder if perhaps on the rear undercarriage air flows mostly straight out between the wheels and does not get "tangled up" in the rear bumper as we suspect. I agree that the bumper looks aerodynamically "dirty" underneath, but then wind tunnel results are often quite different than what "looks" to be the case.

The biggest improvement that as been reported is a more stable ride, and a slight increase in mpg's... it also keeps the engine bay cooler, so you can expect a little more pull on hot days... as for the back, i think apexanimal did some tests and it came out that the air flowed very well in the back... i fear that putting something there might make things worst...

Thanks cr4zy, that is pretty much what I suspected. This might be apexanimal's thread you are referring to:
https://www.fitfreak.net/forums/fit-...long-post.html
Unfortunately it looks like some of the thread's posters got a bit cheeky.

btw, this winter i will start to think about a homemade underpanel... if i see that it's something profitable i will definitly make a DIY... the biggest challenge so far are the slits, but i might try to find something like hood vents and fit them on the panel... so stay tuned!

Do you mean the cooling vents like those seen on the Beatrush panel? Those might be doable with a Dremel & cut-off wheel -- pencil in a three-sided, rounded shape, cut, then carefully bend down the flap by hand and smooth the sharp edge with sandpaper or a rasp (for safety). An auto jigsaw with a thin blade might perhaps be faster and more accurate.

i tought about that, but beatrush uses 2mm aluminium, so i don't know how well that would go... i've seen someone on turbomiata putting corvette hood vents on his hood... that's waht gave me the idea... anyways, i will probably be doing a lot of testing this winter to see what's best...

This is an interesting thread about the underpanels especially about the rear one. I have the Beat rush and I love it!

I'll be keeping an eye on this for the rear under panel.

Now just a question, what have you thought about using for the panel? Aluminum? Coroplast?

I was thinking about aluminium, but honestly i still have'nt checked for availabiltity or pricing... i will probably make protoypes out of cheap materials to start with... and if aluminium does'nt do, i know a great local plastic company, and i've done buisinness with them quite a few times :)

Keep us updated with your progress!!

lol... i will! but it might take some time... things still have'nt settled yet at university :p

Just checking in to see if anything new has popped up with the rear diffuser.

Still have'nt made anything for the front yet, i crawled under the car while doing a few things, and checked quickly... but for the rear i don't think i'll put something, a friend of mine made a full underpanel, and the bumper was acting like a parachute in the back... i tought about coating the inside of the panel with bumper undercoater, it might make a little less noise and help with heat transfer...

Well, i've looked at prices on Mcmaster and so far, it seems that a sheet of aluminium would start at around 70$ (48" x 48") a bit pricey for homemade, but i think it might cover more surface than beatrush... As for the vents, i've seen some air duct grills that would be a good option... only thing is they're pretty thin. I'm not too familiar with material compability, I know that steel and aluminium can't be welded together, but do they corrode together? would there be an issue with these two in direct contact???

Stay tuned, for perhaps a cheap beatrush underpanel :popc:

Great
 

Awesome, I was thinking of hitting up a local scrap yard/ recyclers to get some large sheets of aluminum. Let me know if you get some measurements from the rear.

If you want some measurements of my front Beatrush panel, let me know and when I do my oil change, I'll get some measurements for you.

corrugated plastic

Generally steel and AL don't corrode together. THat is my experience with bicycles, anyhow.

Actually this might be a prototype... but i'm looking for something more durable :cool:

its already been done with corrugated plastic.