rear diffuser - Fuel Economy, Hypermiling, EcoModding News and Forum

fabrio. · 04-13-2008, 11:07 AM

Hi boys

I am going to make the rear diffuser on my car, but serching in all my documentations, I do not understand what is the ideal rear diffuser angle in order to drag reduction.
I suppose, that this angle, he is conseguence of same car measure like the lengh of total body and the lengh of rear diffuser, but also the ground clearance.

Do you have some indications to tell to me?

thanks

tasdrouille · 04-13-2008, 04:14 PM

Don't go with more than 10 degrees and you'll be fine.

fabrio. · 04-13-2008, 04:38 PM

thankyou tasdrouolle, tonigth I have installed the rear diffuser.
Small spaces do no permit me to change the actual inclination that is aboud 2°, but afterday, I will go to measure him.
Do you think that this small 2° inclination is bond or bad ?

tasdrouille · 04-13-2008, 06:51 PM

2 degrees is ok. A couple degrees more would be better, but that would mean cutting your bumper so it's a no go. You just don't want your diffuser to be too steep else the flow will not stay attached to it.

By looking at the brackets you made to support the diffuser I'd say it's more than 2 degrees for sure, but you measure and tell us.

fabrio. · 04-13-2008, 07:14 PM

yes, afterday, I measure him correctly, and tell you.
For increase the actual angle, I must change the actual rear diffuser with other material more slim of actual.
The limit from spare wheel compartment!
With slim element, I can retrive few centimeters for gain angle.
I think that you have look my last work about the rear diffuser.

Ok, for now, I thank you

Compaq888 · 04-15-2008, 03:40 PM

I used common sense..make sure the air flows and doesn't get stuck anywhere...

diffuser taken off

diffuser on car

tjts1 · 04-15-2008, 04:46 PM

Quote:

Originally Posted by Compaq888

diffuser taken off

It looks very smooth. What kind of material is that?

Compaq888 · 04-15-2008, 06:56 PM

honestly I have no idea...I just went to the home depot roofing section and they had a lot of these sheets...

tjts1 · 04-16-2008, 03:21 AM

Quote:

Originally Posted by Compaq888

honestly I have no idea...I just went to the home depot roofing section and they had a lot of these sheets...

Cool thanks, I'll check it out.

fabrio. · 04-16-2008, 01:12 PM

good clear work Compass, thankyou for your prensence

I think (but), that in your rear diffuser, the sepaation point of flow, isnt' fixed because, the rear end of pannel is too up curved
This one, cause not predictable turbolence (i think)