Too steep?

[sbdeadelf]

Hi,
I'm somewhat new here. Read lots, but not posted much. I've been cruising around in an early Chevy Sprint and have been happy with the 50ish MPG I've been getting.... but...

On the highways, speed is a real issue. Cd is around .38 and the car isn't super adaptable for improvement I think. So if I want to get that 50mpg, I've got to keep it pretty slow. And that brings me to the next problem- going even 65mph on the freeways here in CA in a 1650 lb car is feeling more and more like attempted suicide. Now that gas is cheap again, every yayhoo in their lifted 4x4 needs to go at least 80, regardless of what other cars might be using the lanes around them.
So I'm pondering what larger cars might be fairly easy to get a really good Cd from. So, are these too steep? I just extended the existing rear window angle ( of a Dodge Intrepid) and then messed around with the tail underside. I'm guessing the sawing and welding wouldn't be THAT bad, and it only extends the overall length of the car around 2 ft.


As near as I can measure, the back window is around 17 degrees which sounds like it might be marginal? I've read a lot of happy boat tail stories, and a few sad ones so I thought I'd pick your more experienced brains for some opinions.
Thanks in advance,
Dan

[NeilBlanchard]

Hi & welcome to EM,

You might get some decent boosts from an upper grill block, and rear wheel skirts, and by smoothing the wheel covers a bit more. A gasket sealing off the front hood gap can help a lot, too.

What tire pressure are you running? And what are those two brackets on the front under the bumper?

[Frank Lee]

I wouldn't let other drivers dictate what I drive

Make sure the headrests are in the right place, paint it blaze orange, just don't buy a tank cuz of them!

[Sorrow Six Star]

one of those dodge cars that looks similar to that has a really great CD it might be that one...
like it.

[sbdeadelf]

Hi Neil,
I've been tempted to try a lot of those mods (once I stop the oil leaks and get EFI put on), and I was also tempted to try raising the center section of the hood a bit to ramp the air over the windshield more. But during a 5 hour drive, I find myself fearing for my life often enough that I'm starting to consider other options. The tires are 155/60/15s and are at 44psi. They're a bit hard, but the thing handles GREAT compared to the 155R12 rubber it came with. Now if I could only find a nice legal aero mount for a .50 caliber rear deck gun....
Those brackets are my infinite MPG brackets! I can go 300 miles and not have used any gas in the Sprint at all! .... and it only uses a tiny bit more diesel in my pickup truck as it tows it. XD Sorry, I couldn't help it. They're for one of those nifty folding tow bars. Some trips I need my truck for something heavy, but if I have to stay out for too long, I bring the Sprint and use it for the light-weight jobs until I HAVE to use the truck again. I admit a bicycle is even easier to bring along and I use one of those pretty often too.
Once gas goes back around $5/gal again, the Sprint will be a lot more fun to drive.

[sbdeadelf]

Originally Posted by Sorrow Six Star

one of those dodge cars that looks similar to that has a really great CD it might be that one...
like it.

That was the Dodge Intrepid ESX (same name as the one above, other than the ESX, but it was very different in a lot of ways).

The base Intrepid looked fairly aero, and improvable, and they're selling pretty cheap once the engine blows.

[Frank Lee]

They could have called that the SEX... I do like that look... But they are so big and heavy.

[winkosmosis]

The Intrepid already has a good cD I believe. I remember reading back then about how various styling elements were created for the sake of aero, like the high trunk.

I wouldn't buy a vehicle with a plan to build a big boattail. I don't think it's ever really worth it. Ask yourself if you are really going to make something that looks anything like the photoshops, much less a professional rebody.

90s cars were aero enough.

How about an Oldsmobile Aurora

Edit: Site with pics hassling about hotlinking

[aerohead]

I would recommend you take the time to work through the seminars posted in the sticky near the top of the forum page.
Nearly any question you have can be answered there.That's what they're there for.
Then check out the Aerodynamic Streamlining Template.That's also for you,if and when you decide to do mods.You can design a 70-mpg car body for your Sprint with it.
You have one of the sweetest powertrains ever created.

[sbdeadelf]

Thanks for pointing out the link to the Aerodynamic Streamlining Template! I had read all the seminars already, but missed the 'pretty pictures'... they always work better for me. And actually... comparing my second sketcy to this template:

it looks surprisingly good I thought! Of course 'Microsoft Paint' and real life are totally different stories.
Point well taken winkoz- I probably have too many projects already, and they seldom do turn out as well as they do on photoshop (or lowly 'paint'). And they sometimes even take longer too. XD
That Olds is quite pleasing to the eye, both aesthetically and aerodynamically. I'll have to ponder all that. I'm more comfy with the GM cars anyway... but was awfully tempted by the idea of a TDI swap.
And Frank, I completely agree with your take on 'not letting others dictate'... COMPLETELY... but... for my own sanity... I have to consider tanking up a little. (Not that I'm actually likely to get around to it any time soon) I think in coastal CA there's more of the 'life is just TV!' attitude... or maybe we're spoiled, or maybe it's just like this everywhere and I've gotten jumpy in my old age.
The Intrepids are pretty heavy, but even in stock form, they're the same 3300 lbs as a VW Passat. Stripped of some of the creature comforts, and swapped to a TDI... it might not be that bad?
I do still love them Sprints though!