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View Full Version : GI: Underbody Diffuser to help gain MPG

Fluid Motorsports
05-26-2009, 02:33 PM
Hello Everyone. First off I want to say that this seems like a very helpful community from what I have browsed so far. Hopefully I can aid in being helpful as well.

I am the owner of Fluid Motorsports.com (.net is someone else) and I mostly cater to the MR2/VW/RX8/Subaru community. I am using my partners SN since its easier this way. I am currently in the process of making front underbody diffuser panels for the MR2 Spyder. However in order for me to buy enough plastic sheets to get the cost at a highly desirable pricepoint, I need to make at least 20 panels. I figured I would try out this forum as well since the Fits are already known for good mpg.

To give you an idea of what I am reffering to please see this this link and pic: http://autospeed.com/cms/A_2456/article.html

http://us1.webpublications.com.au/static/images/articles/i24/2456_32lo.jpg
The rear diffuser smooths out the air from underneath and provides a smoother exit. As a bonus it also help to add downforce since the air underneath the car is moving at a much more rapid rate than the air on top. A lower car will get better mpg as its having to fight less air.

I myself have a metal skidplate (which doubles as a diffuser as well) in my 250hp AWD Golf R32 and I can now see 30+mpg on the highway on a daily basis. Keep in mind this car is heavy and shaped like a brick. 33mpg was attained in below 32 degree weather! (cold weather is not good for seeing high mpg figures)

http://farm4.static.flickr.com/3399/3311999562_4b3523c8ca.jpg
http://photos-h.ak.fbcdn.net/photos-ak-snc1/v2129/107/16/57200486/n57200486_32857087_9671.jpg
So as you can see an underbody diffuser would help greatly. We already have a 2 door Yaris to work on so I can start making measurments. Due to shipping, the panels would come in two halves with a bent joint on each end to make attachment a cake job.

Before possibly becoming a vendor on this forum, I would like to know if there is interest for this. I dont necessarily need 20 people here but on both forums I need a total of 20 people. Price is not set but would be somewhere between 120-140 shipped. All neccesary hardware would be included. I havent decided if 3m tape will do or if screws will be necessary.

If I can get enough interest I will order a batch of sheets and begin making panels to provide pictures. Please let me know what you guys think.
mrbond
05-26-2009, 04:14 PM
Honestly, I'd be interested in this, but only if the end product looks similar in fit/finish to the unit in the link you provided.
schleppy
05-26-2009, 05:18 PM
I'd be interested if the plate had an access door for the oil drain plug and filter. I don't want to have to pull the panel everytime I do an oil change.

Thanks!
kustom play
05-26-2009, 05:22 PM
how long have you been in business?

ive had an MR2 since 03, and a V-dub for a year and never heard of fluid motorsports

edit:

just checked the site, you dont really have anything listed for the MR2 or VW, looks like you have stuff just for the MR-S
07WYarisRS
05-26-2009, 06:58 PM
i understand the smoother air flow but how does more downforce = better mileage?
the way I understood it the more downforce the slower the car. the slower the car the more HP is needed to maintain the same speed.
WolfWings
05-27-2009, 08:12 AM
This actually reduced the front-end downforce to an extent, because there's less for the air to 'catch' on the front-end underside of the car. It just slips past much more smoothly, the improvement is dramatically less turbulence.
scape
05-27-2009, 08:44 AM
I figured I would try out this forum as well since the Fits are already known for good mpg.

perhaps i'm being sensitive here, but how ignorant...
scape
05-27-2009, 08:45 AM
with that said, the panels sound like an interesting idea ;D
BailOut
05-27-2009, 11:12 AM
While I appreciate the focus on fuel efficiency this is like just about every other FE mod in that the MPG gains are so small as to be unquantifiable, especially since it only covers a small part of the under body and the Yaris (at least the LB) already has belly pans in the nose.
Fluid Motorsports
05-28-2009, 10:29 PM
perhaps i'm being sensitive here, but how ignorant...

woops. I had made this post on the Honda Fit forums originally since I plan on making one for them as well. Just change the word Fit to Yaris :P
WolfWings
05-28-2009, 10:52 PM
While I appreciate the focus on fuel efficiency this is like just about every other FE mod in that the MPG gains are so small as to be unquantifiable, especially since it only covers a small part of the under body and the Yaris (at least the LB) already has belly pans in the nose.

Difference is this is one solid, smoothly-curved plastic sheet instead of a half-dozen dozen little blocks that all have gaps between them. And a lot of the Yaris sheets are there more for protecting against road-debris and splashes than trying to keep the airflow as smooth as possible.
voodoo22
05-29-2009, 08:18 AM
It's always interesting to see what people will do to save fuel when all they really have to do is plan their trips, drive speed limit or below and keep their car maintained.

I've driven non stop hwy trips and got 39 mpg on a full tank.

I've driven entire tanks for my mainly hwy commute but with some mixed driving and easily attained over 50 mpg per tank.

Our AT Yaris sedan has zero mods. I use standard oil, filters and regular gas. The only difference between the two types of tanks I described above was the speed I drove at.
tk-421
05-29-2009, 01:44 PM
I'm interested. How is it different from this underpanel? http://www.yarisworld.com/forums/showthread.php?t=17894
intake
05-29-2009, 02:06 PM
this increase engine temp, because of hot air flow reduction.

i do not like it.