I've been thinking about trying to improve the rather anemic performance of my 2008 HHR Panel with 2.4...was thinking about headers, low restriction cat, in fact totally new exhaust from the engine all the way back. Looks like about a grand will take care of the parts, but I'm wondering about how much increase I can expect. I've certainly never been a fan of 4-Bangers, even less a fan of spending money on trying to get them to make any power but when the neighbors riding lawnmower will almost out run you, something's got to be done.
I'd guess a complete system with headers should realistically give an extra 25 or 30 H.P. to the 172 H.P. the engine already puts out, but was wondering if anyone has done something similar with dyno runs before and after....also curious about MPG improvements. I'm not so concerned with upper RPM performance, more with mid-range improvements.

Also, there doesn't seem to be a lot of choice for headers, and no manufacturer I recognize the name off...anyone have recommendations?

 

Maybe a cat back system will help in the sound department but not much gain with headers and things, now you might want to split to a dual muffler or straight pipes like Lunchbox did, but I think your best gains would be with a proper tune!

 

It is properly, and freshly tuned.

The sound don't matter much to me since I hear very little, and what I do hear is distorted but I sure would like some more power. I love the vehicle, but hate how slow it is...Wish I could afford to swap in a V8, or even a V6.

It used to be easy to pick up 40 to 50 HP with headers and the right exhaust system on most of the V8's I've had, so thought it might be worth while to pursue with this 2.4....heck, an extra 25 HP would seem like a LOT I bet...

 

Which tune do you have?

 

It's just set/cleaned to factory specs...didn't mean to imply at had been "tuned"...I suppose a few extra HP could be had by reprogramming, but since I can't do that myself, it will have to wait until/if I make enough changes to warrant it...

 

I've got to agree with ol blue on this one. The exhaust upgrade would make sense if you had mods to warrant it, especially if ya don't care about the sound. A proper tune is the cheapest/easiest way to wake up your trucklet. If you are thinking of forced induction for the future than a complete exhaust system would make sense.

-my 2 cents

 

CorvetteMongo has "Pilot's Hearing" like me, his career flying single and multi-engine piston aircraft has done his ears in like mine.

My personal recommendation would be a GMPP/Borla CatBack system, they do have a sweet sound, and you'll feel in improvement in low end torque and throttle respose on your "Butt Dyno" there Mongo.

The last time I looked, Borla was closing the systems out for $315, which is better than half off of their original pricing.

 

The factory 2.4 catback is actually pretty free flowing for the amount of power you can make N/A. The Manifold isn't half bad either, as the later manifolds were the same as the 2.0 LSJ from the Cobalts(Same as the Catback). About the only thing you can really improve on is the downpipe. I would recommend an aftermarket downpipe, an intake, and follow it up with a tune, that should give a nice bump in power.

Now, Mongo, you're confusing a "Tune", with a "tune up". A tune is an actual change to the Engine computer's programming. There are a few different options for this. You have Trifecta, which I've seen mixed reviews on. There is also HPTuners. The only problem with HP, is that there aren't "dealers" like there are with Trifecta. When I was trying to get my 2.2 tuned, I couldn't find asingle person that would do it, locally or remotely. Those are the main 2, there might be others that I'm not aware of though.

 

Thanks for the info...Back when I was building and driving drag cars, you had to be more a mechanic and needed to know nothing about computers...it seems all that is reversed now...
Personally, I think the HHR just screams for a V6 or better yet V8 conversion...that 4 probably never will make enough power to make driving it really fun...

 

Well, if you really want to make it scream(or whine, rather), you could always bolt up the Eaton M62 from the Cobalts. ZZP made around 220whp with just a catback and the stock 3.4" pulley on a 2.4l.

And you don't really need power to be fun. My old LT was a 2.2 5spd with little power mods, Just a 2.5" downpipe and 2.4l cat back(sounded good though). It was however on Fe5 struts with Pedders springs and fat sticky summer tires. I would keep up with and sometimes beat the SS guys in Autocross. Power isn't everything.