So I am looking at the dealer brochure, and it states the 2.4 for 07 has 175 hp. I know that is measured at the crank. So I am thinking. "Hey! That is just 25 away from 200 hp!" So I am on a hunt to achieve that goal without a blower, turbo, juice, going internal, or high octane tune.
I am thinking header, free flowing cat, and cat back exhaust, CIA, tuning, and Performance coil packs, fresh tune up, Royal Purple fluids should get me there.
Without doing a search to find recommendations for each thing, I figure I would ask What the pros think. Free flowing exhaust and intake should free up 10-15 combined. I don't think it is possible to squeeze 10-15 hp out of a low octane tune, and hotter coils, but there has got to be a way to wring it out of the motor.
So what parts do you guys recommend?
That 25 hp is just hanging out, and needs to be discovered.

Thanks

 

cam and headwork

 

Hotter or performance coils aren't going to do much. The stockers are fine for what you're talking about.

 

is the header from a cobalt the same? and would a 2.4 fit on a 2.2?

 

Oddly enough, 2007 is the only year that the HHR 2.4L is listed as having 175 HP (165 lb-ft TQ). All other years are listed as 172 HP/167 lb-ft (except for 2006 which is listed as 172 HP/162 lb-ft). I wonder if those are differences due to real changes or did GM just remeasure and get a different number that year (or is it possibly an error/typo)?

Anyway, 25 HP my not sound like a lot, but that's 14.3% improvement over stock. Now if it were a 400 HP V8, 25-30 HP could probably be added with simple bolt-ons + tune. As it is, I think you'd be lucky to get to 185.

 

Don't forget you can get 4-7 hp from a high flow air filter.

Lots of people here have done cold air intakes, but rarely see an increase because the stock flow is pretty much optimized.

And from what I've read, even the GMPP exhaust doesn't add very much bang for the buck.

But you could easily beat 200 with a cam and a tune. Your '07 has probably lost some power since it was new, anyway.

 

Well, you should decide what type of driving you mostly do..
High HP is great for bragging, & Dragging.

But Torque is what snaps ya back in the seat when ya mash the go-pedal..
& for a street machine, that is what I would aim to increase..
That's everyday usable power.

If you cam up with pretty hairy cams (lot of duration) you can actually make it slower at low speeds (torque dip), but get over 3500- 4K rpm & then they kick in.. That's not my idea of practical for an everyday ride ...

Just sayin.

 

my guess is that it would cost at least 50 dollars a hp after stock numbers on a 2.2 or 2.4

 

Without going internal and with premium pump gas(assuming by high octane you meant ~100+).

It is very possible. You should get some help with an intake, header, downpipe, premium, tune. The LSJ throttle body may help too. You won't need a cat back.

Those variances in model year hp could be subtle changes in the intake manifold or in the tune. Leaning more towards tune since the they were flex fuel capable later on.
Yes the 2.4l manifold would work on a 2.2l. I know with the 2.4l Cobalts the early manifolds are not an interchange for the later models. It is common mod to get more power out of the 2.2, but look it up and make sure of exact fitment.

 

I've been running my K&N intake for a few months now...took it off this weekend because I thought I was taking a trip to the dealership and I can actually tell a difference in power reverting back to my stock intake. The K&N is great in the upper ranges and the sound is incredible, but off the line the K&N takes a major dip compared to the stock unit. I think you'd be better off to keep the stock setup and just add a nice drop in filter.