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Discussion Starter #1
I have been wanting to learn to tig weld for a long time. So, as an early Christmas present, I ordered the bundled Tig 200 and Plasma 60 from Eastwood. The Tig 200 is an entry level AC/DC inverter unit allowing to weld steel and aluminum. After it arrived, I spent the next few days practicing on thin .063 aluminum; basically the most difficult stuff to weld. After running through an entire 125 cf tank of argon, and finding just the right settings, etc.... I decided to embark on my first welding fabrication project.... A new diffuser.

I had the stock diffuser in place with a few minor mods to help improve performance: http://www.lotustalk.com/forums/f163/more-diy-aero-mods-221297/... but wanted to create a single piece unit, of an optimized design.

The stock and aftermarket diffusers all use a basic flat ramped cross section, which limits the amount of expansion possible (diffuser angle), before the flow separates from the diffuser. I wanted to see if I used a curved gradually increasing cross section, how much air expansion I could get, before I got flow separation. I started by conducting some basic CFD analyses and it turns out, you can get quite aggressive with the ramping. But this type of design certainly creates fabrication challenges. So with my basic design layed out, I got some large sheets of .063 aluminum and went to work. The plasma cutter made cutting the curved pieces a breeze. But again, welding such thin aluminum takes practice, patience, and a good heat sink behind the material you are welding.

I also fab'd up a new low profile exhaust tip. Welding stainless steel is a breeze compared to that aluminum...

This is what I ended up with. I still have to install some black aluminum mesh to cover the exhaust/license plate bracket to give it a finished look...

Fortunately, being a complete novice at tig welding, much can be hidden with a grinder and flat black paint.... but overall I am very pleased with the result.

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I think the next project will be a new front splitter, incorporating a front diffuser...

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I'm learning to weld. TIG is the most difficult.

You did a really good job and have terrific fabrication skills.

I am v impressed.


"The Argony and the Ecstasy" (sorry....)
 

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Impressive work. Should be easy to make the front splitter. Maybe do air foils for the rocker panels to match.
 

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Wow! That looks great, nice work.

Besides increasing the ramp angle, you can also widen at the back, creating more area or volume for expansion. Hard to do inside the limits of the bodywork but possible once outside of the back end of the car.

For the front splitter and diffuser, do you have an idea for where to exhaust the diffuser? The ones I have seen that appear to work exhaust behind the front wheels and vent behind the front tires as well as louvers on the tops of the fenders.
 

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Very nice design and fabrication! Kudos.
 

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Discussion Starter #12 (Edited)
Thank you all for the kind comments...

For the front splitter and diffuser, do you have an idea for where to exhaust the diffuser?
Not sure just yet. But space-wise it looks like the only location is into the wheel well, and then venting.... suggestions are welcome...
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That is horrible, terrible, sooo unacceptable...

Just so you don't have to be reminded of this everday, I can only suggest that you immediately ship it to me (Please include any/all mounting brackets and if you could cut a hole for the stock exhaust exit:D)

I also like that you covered the thee vents on the engine pan. I never understood why Lotus is trying to do ground effects, and then added holes where you want low pressure


(Just to make sure my silly sense of humor is not misunderstood, I love your design)
 

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Well Done mate!
 

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Aesthetically, I think your rear diffuser is a huge improvement over stock! :clap: Functionally, it is likely to be only a slight improvement -- primarily from better separation of the disturbed air off the rear tires from the central part of the diffuser.

As to the central part of the diffuser, wind tunnel studies have shown the appropriate discharge angle is proportional to the length of the "undisturbed" airflow area ahead of the diffuser deflection point. In other words, the central diffuser exit should be steeper than the sides on our cars. But, package constraints often dictate otherwise so we get what we can.

Because our Eliges have so little front overhang, front diffusers similar to the rear type may not be feasible. Better to raise the center section of the splitter to pump more air to the rear diffuser then decrease the rear wing (drag) to end up with a faster car. At the front, fair in the splitter to body area and you can create a small diffuser effect if you have a deflection point where this fairing meets the flat underbody.

If you want to get really wild, there always are guide vanes and vortex generators (often the same thing) to minimize the high pressure zone ahead of the tires. A DTM Elige, anyone?
 
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