2G Rear Diffuser Design

[Atuca]

some new photos have come in, showing progress on the diffuser panel!

 

[Archer Fabrications]

Wait, this IS for a 2g riiight?

 

[greengoblin]

What is the Red/Orange stuff? Mold resin?

 

[Atuca]

Yea, the orange stuff is a tooling gel coat. It is dries harder then regular gel coat and is used to make molds. We are also using a mold specific type resin that generates less heat, which warps and deforms less, again very important for making molds. The surface of regular gel is more suseptable to chipping and would not work for a production mold, so the use of this enables us to make dozens of copies. It cost slightly more money but well worth it!

Wait, this IS for a 2g riiight?

In what way would this picture make you think it's not?

 

[Archer Fabrications]

I just wanted to be sure i have never owned a 1g so who knows. I guess it does look mushroomy.

 

[Atuca]

It was hard to find (and trace) the exact bottom of the 2g bumper. There is a flat line in some places, and in others it didn't look right. I actually found a centerline and used a string to create a perfect arc, otherwise it would not be perfect (symetric) on both sides had I done the "try and trace" route.

It will be fit under the 2gb Eclipse bumper just fine, and in fact the excess that is there hopefuly means it will work with other rear dsm bumpers as well.

 

[AngelOfPassion]

Wow. Awesome to see that we have a solid eta on a testable version. I'm trying really hard to get the gsx running well enough to test this out in time. Clutch, flywheel, timing belt and water pump all came in today. Well the flywheel came from Corey a couple days ago but just got it machined today.

Hopefully by next month the gsx will be healthy again.

 

[Atuca]

Yea I think having a final date was good for my friend as well; everyone has a deadline now and dates to prepare for. I just stopped by his house yesterday and everything is going smooth. He actually laid up a second coat on it after we found some thin spots after it dried.

In reality though, this panel is a much easier piece to make. Flat with straight edges, something a big roller can handle with ease.

Post up some updates on your thread Angel, would love to see what you been up to

 

[Archer Fabrications]

Wouldnt you not want it flat so the air curves up and out? Like the evo bumper. The air underneith is trying to lift after all.

 

[Mello]

You are correct with noticing the flat design. Diffuser work best when curved so the fast moving are being channeled under the car quickly expands (without inducing turbulence while expanding) and slows down creating the most low pressure possible.

 

[AngelOfPassion]

Ideally yes, but we wanted to make it an easy bolt on with no cutting of the bumper required.

 

[Mello]

Most likely this design will be more for looks and if any, won't have much functionality. In the end testing will tell though.

 

[Atuca]

This diffuser was designed for nothing but function. As stated, this version is a bolt on affair that will require no cutting of the stock bumper. A few pages back it has been discussed there may be a "Race" version made that will require the removal of the spare tire sheet metal and cutting of the rear bumper, but this version is aimed at those who do not wish to do that.

 

[Archer Fabrications]

Ahhhh well i chopped out my spare well haha.

Another question, since this is only going around the rear bumper won't air get trapped between the defuser and the body? Or do you have some means to seal it? It just sort of seems crude. But i appreciate the effort!

Ideally I'd think you want the whole underbody flat leading to an arc'd defuser sort of the shape of this" ~ "

 

[Atuca]

http://www.dsmtuners.com/forums/roa...75-rear-diffuser-design-14.html#post153354049

http://www.dsmtuners.com/forums/roa...75-rear-diffuser-design-14.html#post153354506




There's over 130 posts in this thread, a lot of this has been discussed already. It is pretty much sealed best you can get. In fact I made a rear subframe panel that seals up more of the air. That will be included as part of this diffuser "product". The sway bar messes up a perfect seal, but its pretty sealed back here.

Yes, an underbody tray leading to this would be awesome, I'd love to do it even on my race car, but that is another large project that is inhibited by a drive train and exhaust, and something that also has to be developed with a front splitter and taken all into consideration.

I'm not saying this diffuser will be the best diffuser in the world, but anything better then this design starts adding more factors then this piece by itself. This is meant as a stand alone installed piece that will provide more benefit then harm.

 

[Mello]

This diffuser was designed for nothing but function.

The limitation you're trying to work within are challenging. You may be disappointed with the results because of this.

 

[Archer Fabrications]

Yeah a stock body dsm, therefore leaving open flaws in aero. This is mostly cosmetic imho

You said yourself in your last sentence "this is meant as a stand alone installed piece that will do more harm then good"

I'm not saying this diffuser will be the best diffuser in the world, but anything better then this design starts adding more factors then this piece by itself. This is meant as a stand alone installed piece that will do more harm then good.

I think it's a great idea.... But i agree with the above post


Also how are you going to test the gains? Do you have a wind tunnnel?

 

[Mello]

You could make a simple nanometer with some hose & water and see if the diffuser is creating lower pressure with/without the diffuser installed. This would be a good start for seeing if you've gained any pressure differentials under the rear end.

 

[greengoblin]

I would like to point out this stuff was all talked about very early in this discussion. Sure every one wants a CDF, wind tunnel tested, full carbon diffuser with a complete under tray. That shit is not going to happen. Actually it is why no one has built something like this for our old ass cars in the first place. This unit is being built and will be tested. If it does not work there will either be a revision or the project will just be done. Either way it is ####ing cool it is happening at all.

 

[Atuca]

fiberglass was laid on the mold. Will do a few more layers like this and it'll be done!

Should mention, this was partially dried already. Those light spots are not air bubbles, which is what I was scared of at first. The way the mold is being made, we may actually do a CNC machined mold. We have access to a CNC machine, but want to see if this design works as intended. As Kevin stated, this will be tested and revisions will be made if the results are not what we are looking for.

 

[greengoblin]

Good to see this moving along. Keep at it.

 

[arrowhead]

Dont know the sequence of your lay up, the last looks very heavy fiber, also you should not wait until is dried to add more layers, since you will then have, what is called lamination separation, make sure you clean with acetone this last layer and give a heavy grit sanding before adding any more layers.

The white spots look like there is not enough saturation on your first layers, dont worry about air bubbles after your first layers there is nothing you can do about them.

Hope it works for you.

 

[Atuca]

From doing the last mold a couple times, we found that the mat was better as a lock layer, as it confirmed to the little dips and around corners better. After that we added the woven for strength. I think it was 6 layers total for the mold. Should hold up to a good number of pulled parts.

Appreciate the feedback sir, you've helped a lot over the course of the project.

 

[Atuca]

Last layer done, time to pull!!

 

[greengoblin]

Let's see the pulled part.