The lotus diffuser is around $300 new at a dealer. (suprisingly cheap for a Lotus factory part) Used they seem to run from $50 to $200 depending on condition, greed, need to sell. I paid $100 each for the diffuser and the mid/rear undertray. The undertray has several naca ducts to direct air up. Lotus does this as it's rear engined. I like the idea to help with cooling the rear diff/exhaust.

Parts haven't arrived yet. Should be hear in the next day or two. As lazy as I am it' likely to take me 6 months to actually install them.

You want a thread with lots of info? Here's one to add to your favorites...

MX-5 Miata Forum - wings and splitters?

Massive thread at m.net that's been running for a couple years. Lot's of good info from Emilio and others out there running the tracks hard.

 

Can be found here:

Elise SC Rear spoiler (Elise S2) [ESCspl] - €280.00 : Elise Shop, Performance parts for your Lotus Elise


Edit: nvm saw cueball's post, much cheaper at the dealer.

 

They seem to pop up used fairly regulary on the lotus forums. I just missed a $60 one with minor damage. Ended up buying a $100 unit in good shape. The two parts arrived this morning. Here they are...

 

why didnt you just use this as an undertray?

Miata BeatRush Aluminum Under Panel 1990-1997

 

Holy god damn sonofabitch! I have been waiting years for someone to find a relatively affordable rear diffuser of high quality, i.e. an oem part, that translates over to the miata fairly well. IT HAS BEEN FOUND! I would never have thought to check prices on the Elise's unit as I would have assumed it would be $1k.
That is the ****.

Let's get some clear info on how mounting was dealt with, what was fabricated to mount these parts, how that center section covers the rear underside of the miata etc. etc. etc!

-Ryan

 

Who wants pics of my "undercarriage?"

 

The beatrush part is a front undertray. I'm DIYing an ABS splitter/ front undertray. The lotus parts I bought are a rear diffuser and mid body undertray. The undertray pictured goes just ahead of the rear diffuser. In fact the 5 holes at the front of the diffuser mate with teh 5 at the rear of the undertray. Those cutouts on the sides are for the rear wheels. Didn't know if I could make it work on the Miata but thought it was worth a try. About the same price as just buying aluminum sheet and this included 3 naca ducts.

 

fabbing up some little blocker plates on the sides to shroud the front tires. 5.5" or so out from the bumper.

 

Sav - do you have a decent source for ABS?

 

I've always wondered if propping the trunk open a bit would create the same effect as a rear wing, is that what that red miata with the diffuser did? I would be worried the drag created by letting the air in the trunk would negate any gain from the upwards angle.

 

No, that's 12mm birchwood. $36 for a 4x8 sheet at Home Depot. TAP Plastics wanted like $130 for a 4x8 sheet of 1/4" ABS (the thinnest I would consider using).

no.

 

How did you attach it?
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I can't bring myself to use wood on the car...

I think I can get an ABS sheet for $100...

 

Ripped out the front bumper crash structure and attachment points, then took 1" square aluminum and went down to the R-package lip, then a stretch across the front and back at 45 degree angles to the edges of the lip. Two small supports from the edges up to the frame rails as well. It attaches to the stock plastic undertray location in the back (couldn't reach all the way to the crossbar)

Ryan, you'd be stunned at the number of professional racecars using wood splitters.

 

side spats:

 

(4052)BLACK ABS 1/4" THICK 48" X96" SHEET IN THIS SALE! - eBay (item 190289521949 end time Mar-27-09 07:45:47 PDT)

Should be cheaper than that other ABS and more than needed.

 

I know... I kicked the **** around with a guy with a VERY fast civic at the Superstreet Time Attack down at Buttonwillow for a while and his car had a plywood front splitter... I just... it's wood... now I get the cost factor - this guy was sponsoring himself hence the plywood... but then walking over to theTwins Turbo supra that was sitting next to it and chatting with the twins... you got a feel for the difference in quality in the cars, even though the two were almost the same in times. But yes, wood is the poor man's splitter material, and it is plenty effective.
-Ryan

 

Have you shipped a 4x8 sheet of .250" ABS across the country recently? :2 cents:

 

now its a track car.

 

it's real easy to get free composites when you go to an engineering school. just call the big companies and ask for their reject lots. you'll have a 30 yard roll of carbon at your house in a week.