Rear Diffuser Project

vette427sbc

vette427sbc

Well-known member
Joined
Sep 25, 2008
Messages
1,034
Location
Jersey Shore
Ive been planning to make some kind of rear diffuser for a while now. Got most of my plans together and started yesterday...
Heres what Ive got so far:
One of the tunnels out of the mold and roughly shaped. Im going to add a few more layers of glass on it still. The rear valance is cut up about 2"
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Im trying to get the foam piece to match the contour of the bumper... Still in the very rough stage.
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Im not expecting to get any downforce with this, so Ive gone against some of the effective diffuser characteristics in favor of looks :waxer: All I really want is to get rid of the parachute rear body design.
As of now, Im leaving the fins at their current height. I think it might be a little too aggressive for a street car, but Im going to see if it grows on me once the middle and other side is complete.
 
Looking good. Gotta' like the 2 legged, hinged, special mounting tool. Is that from Harbor Freight?
As I recollect - about 16-20 degrees is the desired up slope. Also, it looks like you are higher than the diff and the lower strut rods - so is it the driveway you are concerned about clearance?

Fastening? Bolt-in, or glass?

One last question - how will you keep any flow from getting between the body cavity/fuel tank and the diffuser?

It would be really cool - after install to do a tuft test - yarn and tape and get some pics at speed. Maybe shoot one before install of the rear end too.

Cheers - Jim
 
Thanks Jim!
My up slope is pretty flat... 11.3* if it was a straight shot. The tunnel has a slight arc in it, so the end is probably closer to the 16*

Its not higher than the diff, but it is not lower than the strut rods. It is the same height as the very bottom of the wheel opening. Im going to be hanging it with support rods in the middle, and the edges will be bolted to some tabs Ill have to make on the body.

In regards to keeping air out from between the body and diffuser, I was planning on just making some kind of separate panel to close it off. That piece is still in the planning stage though. Im thinking that since the only open spot for air to get in (before I put in the closeout panel) is pretty small, and right behind the diff. I *assume* that is a low pressure area and might not even have enough wind power to warrant a close out panel. Triple digit speeds may say otherwise... It would be interesting to do a yarn tuft test to see whats going on in that area though.

And that special two legged tool is called a "grab what ever is close that might hold something up while I take a picture" Harbor freight has them on sale Haha
 
Last edited:
lvrpool32 said:
Hows the diffuser coming along??? You still going to Run To The Shore 2?

Nick
Click to expand...

Been busy at work lately, so no major progress on the vette. I may try to get the mold for the passenger side done tonight.
And yeah Im planning on going... Am I missing something or is the registration not up yet? Are you going too?
 
MetalKid - also a member here - has been looking to do a similar project over on DC.

The price on the APR gear is no doubt a detractor. vette427sbc's DIY approach with the foam "buck" and a bit of effort looks very viable.

Cheers - Jim
 
I sorta like the looks of the idea of drilling some holes in the back under the spoiler, and maybe a couple other places, let the air outta the bucket rather than go nutz trying to keep it outta the bucket....older race cars did that, question is....did it work?? if I could find some black trim pieces to fit the holes that I could glue in there without having a cow over it, I wouldn't mind doing that, looks sorta cool, I think....
 
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