Hey Guys,
I'm new to HHRs but not to performance mods. I've got an 06 2LT 2.4 automatic that I'd like to squeeze more power out of without resorting to forced induction. With an intake, tune, and header back ZZP exhaust, what kind of performance increase might I see? I'd be happy if I could get it up to 200 crank horsepower, if possible.

 

Welcome to the site, most mods result in mediocre HP gain. Even a super charger from a SC Cobalt will only get up to 200 hp. ZZP components to make the sound you might not be happy with.

 

Welcome
How many miles on the engine ? No sense to put added power and stress on a tired motor. If it’s over 100k miles, you should consider a rebuild if you want to add on hp.

 

If you wanted "performance" should have got an SS.
A few people seem happy with a 2.4 tune; I think that basically changes the transmission shift points.

 

It'd high. just north of 200k. That's why I was thinking in terms of only doing things that create more power as a result of lessening restriction. Cams and forced induction would cause wear
I'd probably drop in a lower mileage junkyard engine before I'd rebuild one for this car

 

I just wanted a cheap wagon, but I want to make the most of it I can

 

Best to keep the cold air cold, the under hood kits draw in hot air. Ensure the correct thermostat AC Delco 131-158 and fresh Dexcool 50/50 mix and AC Delco 41-103 iridium spark plugs are installed

 

If you find a mod that creates more power without higher RPMs, then go for it. Not sure that exists, though. Tune that alters the shift points works the engine harder. At over 200,000 miles, it's risky.

New timing and balance chain set, oil & filter, new coolant & 131-158 thermostat, new 41-103 spark plugs, new air filter.

Keep the digital readout (DIC) on the dash set to coolant temperature.

 

I can tell you the engine will go north of 500,000 miles with care and maintenance, most aftermarket exhaust systems were pricey and had a drone sound at highway speeds.

 

Enjoy the car. Great economy, excellent handling with good dampeners. 2LT came with the FE3 “sport” suspension. (Some day I’ll figure out exactly what that means. At minimum, better shocks. Maybe better struts and stiffer springs, IDK.)

Don’t get good tires. Get GREAT tires. The stock 215/50R17 size is excellent on that car.

From your earlier post, those wheels don’t look correct for 2LT. You may have a loaded 1LT. Check the silver RPO sticker in the glove box. Better yet, take a pic and post here. What size tires are those.

Leveling and lowering springs are popular.

Your 2.4 has better rods than those built after a change somewhere during m/y 2007. Someone else here surely know more about it, or peruse the 2.4 Performance Tech section. It’ll tolerate mild forced induction. The trouble is, it’s a lot of expense and hassle for mild gains. Trading up to an HHR SS will give you a MUCH better car at lower cost and a lot less trouble.

An issue with naturally aspirated Ecotecs is that you get ur power near the red line, but timing chain system hates that. Maybe ur car is due for a chain job anyway. You need the ZZP front guide. The stock ones break all the time. Get EOM chain tensioners, the latest ones. GM has a tighter spring in the balance chain tensioner for later models. Be sure to get that. Even tho most sources don’t seem to list it for the HHR, it seems to be listed for later Ecotecs, can’t give you a year, maybe after 2014 ish?

Keep you RPMs down until you do this chain job. You have been warned.

That motor breathes well enough at both ends. Factory 2-1/4” exhaust is fine, but if you have the original muffler, it’s prolly a mess inside. The factory resonator was good, but someone may have replaced it. Factory sized resonator with a nice 2-1/2 muffler or 2-1/4 straight-thru is a good setup.

The headlights are often hideous on these cars due to UV damage. There are some cool ones available at totally reasonable prices. Tails, too.