987 Cayman Diffuser

Finally managed to get far enough along on the master pattern to take some pictures. I have another two days of massaging this thing to make it look pretty, then three days to layup the mold. First part should be on the car in a week. The way it sits right now with the car at factory ride height there is 5" ground clearance. The fins at the deepest point are 2-1/2". Please excuse the tongue depressors holding the diffuser up as I didn't want to drill holes in the pattern. Any thoughts or suggestions before this thing becomes a mold would be appreciated. I will be offering a discount on the first ten diffusers to Planet9 members and an even larger discount for the combination splitter/diffuser.

I like it. Any pics from underneath to see how far forward it goes? Sent from my iPhone using Tapatalk

It is in line with the back of the rear wheel wells and sldes under the aluminum belly pan under the transmission.

West Vancouver? Hey I'm from North Vancouver! Maybe I can check it out sometime...

That's where the car is from. I'm in Surrey but you're more than welcome to come. Give ma a call [phone removed].

The fins look a bit too thick. Does anyone else think so?

Yes but I still think it looks neat. Nice job.

I don't mean it in a bad way but just some feedback.

Is that a 987.1 w/ led lights or a 987.2 ? Anyway looks great! Good job

Joe, is there any way to make the fins thinner? Looks good nonetheless.

Will this work for both 987.1 and 987.2 ? Sent from my iPhone using Tapatalk

I'm also in for the fins being to thick

I am in agreement on the thickness of the fins. They don't share enough of the gracefulness of the 987's. I think they make the car appear heavy but we are looking at them from a road kill angle. Of course you have to add into the appearance of the flat grey that also adds to the blunt agricultural look. Someone should photoshop the cars blue color onto them for fun to see if it lightens them up a bit. Nice work Mr. Toth I like your overall design and how far in extends under the car. I think it might actually clean up so areo in back of the car. They would be fun to play with in a wind tunnel or a Go-pro on the back bumper and some yarn pieces.

Ok guys I hear you. Yes the fins are thick, I was being lazy looking ahead at production. The thinner fins create issues with gel coat and laying in material. They are at present 1-1/4", I can take them closer to 3/4". This will be made for .1 and .2 cars. I will post pictures once the fins have lost some weight. Thanks for the feedback.

How about painting the diffuser Racing Yellow and the fins Guards Red?

Looks great. Definitely interested in getting in on that discount.

OK getting picky here... After closer inspection of your pics it appears to be on a plane parallel to the road surface. I would like to see it with more of an airfoil shape curving up and terminating up to the stock bumper. This would not be possible at the center because of the exhaust exit but it would on either side. The mufflers may interfere with this ... but not that much? Now getting more picky...I would like to see the strakes end with a full arc or a shallow angle up to the bumper. They look to end presently with a 90 with about a 2" inch radius. How about a box section for the exhaust with the airfoil and strakes on either side? How about replaceable strakes that bolt to the base? I can understand the mold is getting more complex...just charge more. The beauty is in its function.

I think it looks pretty good as is and agree that thinner fins would look better. As for generating down force, well just be happy it looks good, it would need to be much deeper and longer to have any measurable effect.

skrace, the bottom is flat and on a 2 degree upward angle from the attachment point at the front. This gives me 3/4" clearance under the mufflers. Yes I could change the angle and slope from behind the mufflers. I didn't want to box around the mufflers as this would create a low point and restrict air flow. I like the full arc idea for the strakes. Replaceable .....that's possible. Charge more.....mmmm....how many sales do I lose going from 650 to 1000?

Another vote for thinner fins.

skrace...took another look at it on the car. The diffuser is 17' deep at the widest point, if I were to give it more angle behind the mufflers that's a max 3-1/2" of the back end. What does that do for us?

You are right Joe...its a tough call. Market wise there is the group that just likes to look good and others like myself that function drives much of the appeal. To be able to do both is a cost factor that needs to be looked at if possible. The 987.1 's and .2's are out of production and will end up at DE's more frequently in the future so you will be limited with the numbers. You can have a market with the guys who will want to drag GT4 wings on their 987's around if they think it will help even just a little. Who knows how long the 981 's will be around but I think they will outnumber the 987's in the end. I think your diffuser is long enough to be aero positive and it wouldn't be that hard to add further flooring in front of it if engine temps allow it. The biggest hang up in the Caymans /Boxsters obviously is the exhaust location. Think about this for the discerning Cayman owner...A package deal of a redesigned and located up into the car exhaust with a carbon fiber under tray diffuser bumper combination...probably could be done for...$10,000.00. You do realize if it sells to good guys like APR and Stephen will steal it.

Here a quick photoshop . Painted body color and flat black. left is 987.1 rear bumper and right is 987.2 Rear Diffuser by C987S , on Flickr

Yea.. thats the ticket! much better

Well you got me. I'm changing the angle behind the mufflers. Yes I like function as well, when I racing cost was not a consideration. I do like to provide parts with a performance benefit as well as looks and thus far with my other stuff that has been the case. I also aim at trying to that at an affordable price and there is the big compromise. Wouldn't be the first time my designs have been stolen and copied, I'm flattered and feel sorry for the folks that need to copy someone else's work for lack of their own creativity.

WOW, thank you for that ep3hatch03

No problem. Thanks for the great work. I did a photoshop on my car also. Rear Diffuser by C987S , on Flickr

Why worry about function? A tiny little diffuser like this has almost no aero benefit. Just make it look bitch'n.

Anyone remember the little rear diffuser/underwing on the 951s? Porsche add that little thing to help plant the rear of the car and reduced Cd by .02

The diffuser will be functional. The performance is based on the volume for air expansion. This unit is approx 48" x 17" x 2 1/2" for air expansion to create low pressure under the car. The longer the diffuser under the car, and the deeper the channels , the more performance. Thinner vanes will reduce drag. You want to keep the vanes level to the ground so that your channels stay as deep as possible. In theory, the diffuser could be as long as about 24" if it went under the aluminum plate upto the sway bars. I think there is a 10 degree angle to the underbody. A diffuser has a larger surface area than a traditional wing and will see less disturbed airflow than a wing. A diffuser will work best when the car has a front splitter and smooth underbody. The max low pressure point will be created at the front of the diffuser.