The Curly 1

Does anyone know the Drag Coeffecient of the HHR? Anything that can be done to help it?
I lowered my car (2") and put a front air dam (4") on it and I think it helped the drag coeffecient but do not know for sure.
There is 3 different HHR rear spoilers that I know of, the standard HHR arch type spoiler, the flat SS type and a generic SS looking one sold on EBay.
Does anyone know if there is a aerodynamic difference in them and if so what is better with spoiler or with out and if so which one?
Thanks, Curly

The Curly 1

I come here in search of infintite wisdom. Come on somebody knows something about Aerodynamics?
I am modifying my HHR but I want to be careful not to do anything that will make it worse even if it is just a tiny bit.
I will add a spoiler if I know that it will not hurt it aerodynamically. Thanks, Curly

sp52075

curley there is a thread somewere on this place about the different wind resiance ratings of a few vehicles and it included the HHR but for the life of me I cant find it

The Curly 1

I did some searching and found a few things out. Note These came from several different sourses so may not be exact.
1. The HHR is .354
2. The PT Cruiser is .39
3. The Scion xB is .32

I would have thought the PT would be best as the rear slopes down more and is more pointed in the front. I would have thought the Scion xB is the worst........ By the way one of the compairson sites basically said the HHR was better in every way than the PT. Better performance, mileage and comfort.

Now I would like to know how much it helps the Drag Coeffiecient by lowering the car 2 inches and adding a front air dam.?

Thanks, Curly

JoeR

Contract with a wind tunnel facility, put your car in it and post the results!

Seriously, I admire your tenacity in getting better MPG with the HHR, but you honestly tend to get off on tangents, often inspired by the proliferation of false or misleading advertising out there.

Sorry for being so blunt, but things like intakes and exhaust... The stock intake and exhaust on the HHR is VERY efficient, with very little loss at full power demands, let alone the very low demands at normal cruising levels.

Your best bet in your quest would be to listen to proven science, not advertising hype or the myth and lore out here on the internet.

1. Make sure that your car is properly maintained... Oil changes, filters, etc.

2. Observe proper tire inflation pressures and possibly increase them by a few pounds.

3. Read about "hypermiling"... You don't have to necessarily be a complete "nut" in this regard, but there are some useful ideas, that if followed, will result in considerable mileage increases, especially in stop and go travel.

4. Consider a "good" tune for your car. By "good", I mean from somebody who really understands these cars and can create a tune that will result in better mileage. This can also result in better performance, too. Many think that tuning is an either/or proposition, but that is not true, since the engine is operating in different areas of the tuning tables under cruise and full demand conditions. If you talk to a tuner, just make sure that they have given attention to attaining MBT (Mean Best Torque) timing values under cruise conditions. Not many have, nor have spent the time and effort here, but this is definitely a big gain in MPG if done properly. For example, my 2.4 LE5 with a supercharger and (bad for mileage) 235/40-18 tires can do 37.5 MPG on long trips. It's faster, too!!

Snoopy

Curly......

Remember, the drag coefficient, while calculated the same way is designed and computed for different goals. For example, the 2008 Corvette Coupe has a coefficient of .28. The 2008 Z06 has a coefficient .34 (notice how very close this is to the HHR).

So, the point is.....what YOU may believe is justified, may actually reduce the desired effect. But as Joe suggested, what you do is only as good as a wind tunnel report.

The Curly 1

Anyone know any thing about which spoiler is best or if it is better with out one?

What I am trying to do here is give my car the best aerodynamic advantadges possible with out going to ugly wheel well covers etc. Trying to get the best mileage possible from my car.

jeffs396

Bruce, none of the spoilers will make a difference aerodynamically, it's all in what looks best to you. At the speeds you travel, a rear spoiler won't have any positive effect (downforce) or negative (drag). Proper maintenance & driving habits as others have said will be your best bet.

The Curly 1

I want to modify it and get it to perform the best it can and leave it. Then concentrate on my driving. I agree with much of what you are saying and disagree with some.
Aerodynamics. Sometimes what looks good really is not. That is why I asked the question. For instance the Z06 Corvette looks much more aerodynamic than the HHR. I would have never thought they were so close.

I really do not pay much attention to advertising I try to put what worked on my drag racing car into my HHR. That is help the aerodynamics, save weight, reduce parisitic drag of alternator, air conditioning compressor etc. On my race car I looked at everything and removed it, modified it, lowered it or relocated it.

On the intake and exhaust I believe that opening it up some and tuning for it will improve performance, sound and mileage. I might be wrong as I have been wrong before. I will keep all of the stock junk in case I am wrong.

I do not think any stock vehicle is perfect for all needs and can be modified to work better for your needs. Curly

rommer

Highway speeds vs dragway speeds have little in common.