Anyone with CRX tail end mods? (or others with ideas/suggestions)

[davelobi]

I'm thinking the back end of the CRX needs something to break up the vacuum of the big flat hatch/bumper area.

One of the big three (thinking Gm but not sure) added a plastic cap to the top of their tailgate on the full sized pick-up. It started as a protector from damage when throwing in lumber etc. They finished it off by letting it hang off the back, past the vertical section, of the tailgate and found it added almost a half of a mile to the gallon.

I'm considering something along those lines. Like a mini spoiler that just goes back, not sticking up. The idea was to allow the air to come together further back behind the car reducing the vacuum. It sort of does, in a small way, what a boat tail would do by reducing drag at the rear of the car. It also actually keeps the back of the car cleaner from sucking dust to the back. This has been used in some of the mini-vans to help keep the back window cleaner.

Has anyone added something like this to their CRX, or any other car, and gotten noticible results?

I'm thinking rubber or plastic that I can stick on the top back edge of the hatch.
Any ideas of what to use? I'm picturing triangle shape and the full width of the hatch. More subtle than a spoiler and not sticking up in the wind.

[davelobi]

Pay no mind to the crudeness of the sketch.
Trying to add to what I meant in case the above verbage was clear as mud.
The black triangle at the back of the car is what I have in mind.
What to use?
Anyone done it?
Results?

[some_other_dave]

There was a spoiler available for the 2nd-gen cars that was pretty much just that, in a rather small form. I think it was available as an option on some JDM or European market CRXes. I always liked the way it looked, but I never looked hard enough to find one for my own Rex.

If it sticks out straight, it will soon wind up "outside the template" and be similar to a spoiler that sticks straight up. If you can get the spoiler to extend out to the template, that should help a little. But you'll have problems created by the sides of the spoiler--vortexes and such, creating turbulence. I'm not sure if there is more of a gain than a loss for that.

Note that the CRX uses a Kamm-back style. It has an abrupt truncation to try to get air flow to separate after flowing over the top (and sides) of the car. You still get a turbulent wake, but hopefully less drag than with a more gradual transition to the back.

The best improvement would be to make a full boat-tail along the "template" lines. Or to make a partial boat-tail and cut it abruptly--sort of like the current design, but further out.

I never did make changes to my CRX. It was far too nice to chop up like that, and I liked it for what it was rather than what it could become.

-soD

[davelobi]

Originally Posted by some_other_dave

Note that the CRX uses a Kamm-back style. It has an abrupt truncation to try to get air flow to separate after flowing over the top (and sides) of the car. You still get a turbulent wake, but hopefully less drag than with a more gradual transition to the back.

The best improvement would be to make a full boat-tail along the "template" lines. Or to make a partial boat-tail and cut it abruptly--sort of like the current design, but further out.

I never did make changes to my CRX. It was far too nice to chop up like that, and I liked it for what it was rather than what it could become.

-soD

I know what you are saying about the kamm-back to get the air to seperate from the car. I read somewhere that GM did just that with the volt as well.

I too, don't want to mess up a nice design. That is why I was looking for something small and subtle if it would have a positive effect without altering the look too much.

thanks.

[davelobi]

soD,
Is this what you were talking about?
Found it on ebay. Ad mentions HF of course but the HF didnt get the rear wiper so that would have to get plugged somehow.
That would look nice maybe for 50bucks but not 200.
I'm still thinking triangle of plastic just straight off the trailing lip.

[Sporty Modder]

I did something similar to my Celica, possible 1 mpg increase. Not sure as I measure my fe by tank to tank.

Made out of coroplast and duct tape, 9" long.

[oil pan 4]

I think if you reese mount a trailer tool box on the back of a smaller car it might make a low attention drawing boat tail.

Ones like this:
trailer box from Northern Tool + Equipment

[davelobi]

Originally Posted by oil pan 4

I think if you reese mount a trailer tool box on the back of a smaller car it might make a low attention drawing boat tail.

Ones like this:
trailer box from Northern Tool + Equipment

You might be on to something. Probably would work.
Give me something else to bang into in the dark when I forget that it's there. Plus, I could fill it with heilium and subtract the weight it added.
Kinda thinking a little more subtle, almost un-noticable.

You meant one of these right?......

[oil pan 4]

Un-noticeable top side aero mods tend to produce un-noticeable improvements.

[some_other_dave]

Originally Posted by davelobi

Is this what you were talking about?

It looks like what I was thinking about. Not sure what, if anything, it would do for you though.

-soD