Spark Plugs for the 2.4L
Because there were no posts in the 2.4L Engine category I felt a little left out. I want to try some new plugs just because I need something to do, but Mike @ SoCal told me to hold off since he found no improvement when he put the Bosch Plugs in his 2.4L. So my question is has anyone else been -*test*-('")ing any new plugs. I just wanted to get this in a post so we don't forget about it. I am having a great time on the forum CJ Thanks Again. I also noticed we picked up a few more familiar names. One in particular is Drazic from North Carolina, Welcome, thats two now.

Mike is the Guru on the 2.4's his biggest problem is he just doesnt have a ton of time after i drove both, did extensive reading and talking to guys at car shows that were muscle hounds on both engines all i read is that the 2.2 would be more performance modifiable. all the muscle car guys love the 2.0 and 2.2 Ecotech

I'm still working on the plug shootout...hope to have something posted later today (*note the time of this post!) Hang in there...!

Mike Thank You, I knew you were around and that if you saw the post you would respond. :D

Mike, 2:15am?? When DO you sleep?? lol Of course I am a bit of a niteowl myself and normally force myself to bed around midnight... lol CBL

Kool, some 2.4 info. Its about time (just kidding)! 8)

I think you are probably right John... I didn't think about the time difference... thx for the heads-up! And yes... Mike is great and a wonderful supporter of our HHR's! CBL

Well he only has 3 :lol:

sorta like that hairclub for men only he's into HHR's! lol not just a client, but an owner! CBL

OK guys (and gals!), it's late and I've got to get to bed here, but here's the scoop on the 2.4L plugs: Autolite APP 5263 Double Platinum plugs. Buy a set, gap them to 0.42 (thousandths), and get ready! I had to redo several of my 1/4-0mile runs because I couldn't get good launches using my old style - the tires now spin 3-times longer than stock! Finally got some good starts and checked the times; much quicker with these new plugs. (*BTW: same -*test*-('") track, same start spot on the track for each run, and our "old" plugs were gapped identically). I have to hit the hay now, but will post actual run times & figures tomorrow... Enjoy!

Funny pic Mike!! I like that! Sounds like you finally got the plugs on the 2.4 figured out. I'm putting the Bosch +4's on my 2.2 today and looking forward to it. They have been getting good results for others... CBL

Hi John, - These plugs are same heat range, etc., they are a direct replacement. There is no need to go to a cooler plug unless you do some serious modding (re-tune, turbo, etc.) With the CGS and IMCO 924, the HHR runs a bit rich even at 100+ wide open throttle on the dyno. No danger of knocking or heat detonation yet. Oh, and yes; it was with the black powder-coated valve covers!

BTW: Here is the data we came up with on performance with the two different plugs: AC Delco Plugs (stock) 0-60 = 9.60sec 1/4-mile = 17.22 Autolite APP 5263 Plugs 0-60 = 8.80sec 1/4-mile = 16.69 *(Keep in mind these runs were done with my "heavy" wheels on; they weigh 6lbs per wheel more than the stock alloys. This is why the times are "slow.") Still, a noticeable difference. The car even launches harder; it pulled .44 g's stock, and .46 g's with the Autolites. The 2.4L engine runs noticeably smoother with these plugs too. I use the remote start feature everyday and I can hear the engine sounding much smoother. In addition, it has not "failed" once using the remote start since changing the plugs. My "old" stock plugs had only 9k miles on them, and before someone says "hey, it's just the new plugs" - know that we -*test*-('")ed the Bosch Platinum 4 plugs also and the car ran slower than the stock AC Delco plugs. These Autolite's are definitely a worthwhile upgrade for the HHR owner wanting max performance from their ride. Hope it helps,