MazdaSpeed Front Diffuser
 

http://www.japanparts.com/Pic/pic067/UnderCovers.JPG

Anyone know if you need to have the 99+ undertray in addition to the MazdaSpeed front diffuser (pictured on the yellow car above), or do you just need the diffuser? I'm worried that the diffuser doesn't fit flush against the radiator for proper ducting purposes. If I need both, I'll get them, if not, I won't. :)

I already have the 99+ front end and adjustable rear spoiler with a RE Amemiya diffuser, which should give me roughly .021 front end lift and -.056 rear lift (=downforce at the maximum attack angle) with this front diffuser attached. See http://www.negative-camber.org/crispyrx7/99wing.htm and http://www.rx7.net.nz/newrx7.htm for Mazda's wind tunnel numbers.

One thing I noticed after I started this thread is that the MazdaSpeed front diffuser is made out of fiberglass. The description is as follows: "FRP, Unpainted, Suitable for Normal bumper, *Suitable Units later than chassis No.500001*" Anyway, If I hit anything with my lip spoiler, as I have done before, then I think any fiberglass thing behind it is going to get smashed. Maybe kevlar would hold up, but a flexible material would be better. If your undertray was made of fiberglass... what kind of shape would it be in now? Trashed I'm sure.

Jason at JT was nice enough to answer my questions about it. He further added that this thing replaces the stock undertray so you do not need both.

so whats the cost for the front underspoiler and rear diffuser?

Correct me if I'm wrong, but is FRP really that brittle? The FRP parts I've seen on some racing motorcycles actually seemed pretty sturdy and fairly durable (and even somewhat flexible, although comparing those parts to the MS front diffuser is obviously apples and oranges-- and asking it to absorb a direct hit in the same manner as ABS plastic may be a stretch).

FRP is fiber reinforced plastic. i do believe the '99 bumper and wing are manufactured from this stuff

Most bumpers and lip type things are made from either urethane or ABS plastic. FRP is better than plain ole fiberglass but generally speaking it is not as flexible as something that is made out of regular molded plastic.

It's actually fiberGLASS reinforced plastic, which is kind of a misnomer; it's actually more like plastic compounds used in the resin helping to reinforce the fiberglass mat construction. I was just wondering if it was really that brittle (obviously not as good as ABS or urethane plastic).

I love Google:
http://www.kemlite.com/
"FRP, fiberglass reinforced plastic, is a composite made from fiberglass reinforcement in a plastic (polymer) matrix.

By reinforcing the plastic matrix, a wide variety of physical strengths and properties can be designed into the FRP composite. Additionally, the type and configuration of the reinforcement can be selected, along with the type of plastic and additives within the matrix.

These variations allow an incredible range of strength and physical properties to be obtained. FRP composites can be developed specifically for the performance required versus traditional materials: wood, metal, ceramics, etc."

So bottom line - FRP is as strong as they want to make it, but I still have reservations about its flexibility when my 99+ bumper takes a direct hit. If the 99+ bumper is made of the same material as the 93-95 bumpers (which were thermoplastic urethane), they should bounce back from a light hit, but I'd think that any stiff fiberglass or FRP piece that comes right up to the bumper edge at the front would not fare as well.

I've been debating this myself for a few years. I just wanted to get the rear diffuser.
It looks like I might go with both the front and rear diffuser later down the road.

I don't like the updated rear wing that much. Plus knowing that 2 holes will be exposed at all times doesn't help much either. I'll stick with my stock rear wing. But I would definately get the new 99 front bumper. I already have the lip, but not the actual bumper.

Decisions, decisions... :)

Later,

More benefits would be had with a full body undertray.

r0gu3---Agreed, if you have MAD cash or time, due to the terrain of the underside. You would need special side skirts and rear to make it work perfect and correct.

Diffusers are cool, downforce if you dont like the spoiler. I have both and the front still lights to get light in the front at high speeds, since no I need downforce for the front. I have the RE N1 02 (FS) with and downforce spats, but its not enough to do what the rear does hehe