Thoughts on gain from boat tail on 94 eclipse

[aerohead]

Originally Posted by Rango318

I've been wanting to build a full tail on my 94 eclipse basically right after i bought it. I really like the way Redneck made his recently and was going to base my build off his.

My only issue is, will it really help that much?
I mean, it seems like i see a lot of these done to cars that are not very aerodynamic in the rear, such as a metro, but the eclipse is a bit more angular off the rear window. I would love to see a 10% or so increase, but is it really possible with this car?

Any opinions or thoughts are much appreciated.

Also, what would most people recommend to use to build the frame of the tail? I do not access to many larger tools, so i will be doing this whole build with small hand tools and brute force.

A full tail would provide for a 28.3% mpg improvement at 55-mph,and 34% improvement at 70 mph.

[Xist]

Originally Posted by aerohead

A full tail would provide for a 28.3% mpg improvement at 55-mph,and 34% improvement at 70 mph.

That much? What is the most that anyone has achieved so far?

What could I expect for my Forester?

[Rango318]

Originally Posted by Cd

Rango318, your car has a hatch that swings up.

It would be a simple thing to prop the hatch at the correct angle for good aero and run some tuft testing to see the results.

I know only the center section swings up, so you would have to fill the gap that is formed on the sides when you open the hatch glass.

( This would also keep you from getting carbon monoxide in the car during testing ! )

I'd love the see the before and after results of a tuft test of the car ( hatch closed and propped open at the correct aero angle.

That is a great idea just to test the idea. I had thought about using it as part of the tail, but not to use it to see if it would help. Thank. I think I will try it today.

Originally Posted by aerohead

A full tail would provide for a 28.3% mpg improvement at 55-mph,and 34% improvement at 70 mph.

Can i ask how you got those numbers? I love to do math and such and would really like to know how to calculate such a thing. I can only hope i get these numbers.

[Rango318]

So, i did some testing today. Did a tuft test, which i will upload pics of tonight. I did one test with the hatch closed, then one with the hatch open, and all gaps sealed. I made it as close to the correct angle as possible. I then ran one tuft test. I decided to fill up, and drive to where i work and back to get a real life style test.

My tank last week, monday thru friday was a new high of 43.84.

To run my test, i did everything i would usually do when going to work. Stopped at the store, stopped in the parking lot at work.

The only things that i did not test for : usually the return trip is at night, so it is colder, engine is cold, and the headlights are on. All of which i did not include in this test.

All I can say about the results is WOW. I drove 58 miles on 1.091 gallons (53mpg). I am going to leave it like this for this week of work and see if i see this big of a change again. One can only hope.

[Rango318]

So here are some of my pics from todays testing. I will try to have them in order, but if they are not, I hope you can figure it out. hatch down was first, then enclosed hatch up.

[Xist]

Originally Posted by Rango318

So here are some of my pics from todays testing. I will try to have them in order, but if they are not, I hope you can figure it out. hatch down was first, then enclosed hatch up.

What am I doing wrong? I cannot see them!

[Rango318]

Originally Posted by Xist

What am I doing wrong? I cannot see them!

Sorry. I tried to upload them last night but I believe the files may have been too large. I'm going to try to resize them and get them on again today

So I am having an issue uploading them and having them large enough that you can actually see them. How did you get the ones posted on the first page?

[Rango318]

Ok. I think i got it.


yep

Ok. first 3 are before the hatch is up. Also the last one is as well. the rest are hatch up

[Xist]

I always wondered if window glass curved more than the template.

[Rango318]

Thanks for the help Xist.