Header difference?

OK, looking at two different headers for the SoopeKia. Both are bolt in affairs, same length etc. The difference between them is:

1.65" primaries and a 2.1" collector

1.5" primaries and a 2.24" collector.

What would the differences create on the dyno? I mean, ideally I guess I'd want the larger primaries and larger collector.... but they don't make it that way. Thoughts?

What is the collector SHAPED like?

The answer is try them both on the dyno. Big tubes/small collector may end up working better because the velocity stays up from tube to exhaust pipe. But the other way may be what you need depending on your exhaust system...

they're bothe shaped the same, equal length 4-2-1 setup to the stock location. Stock cat is the biggest restriction in the exhaust, the second restriction is hte stock muffler (which is already gone, complete 2.25" cat-back)

Money isn't there to spend $1200 on a pair of headers to see which works better. This is an either/or situation. Ben (SF1) suggests the smaller primaries, bigger collector.

The 2.4L Theta engine uses cam timing/valve overlap in place of EGR to meet EPA regulations. If that matters.....

Eeeny meeeny miney mo!

Generally smaller primaries will produce better low to mid range, and larger will produce more high rpm power. Are the collectors the same length? A longer collector will usually help broaden the power curve some. But I really don't know about your situation because one has larger primaries with a smaller collector and visa versa.
I really think that unless you have this engine really built to the max, that you aren't going to notice a difference in the two. So in that case refer to the post above mine.

With a 2.4L engine I would go with the larger of the two primary pipes if peak power is desired. The slightly smaller collector should not be a major issue since the pipe size down stream is bigger at 2.25 and the length of the collector is short compared to the upstream pipe length.

Ideally the bigger collector should be on the header with the bigger primaries.

Here are the two:

Second picture no workie

There it is. Top one is the larger primary, smaller collector. Second is smaller primary, larger collector.

I think the top one looks cooler.

well, A.) it's behind the engine against the firewall and 2.) I'll be wrapping it in header wrap anyway. But I'm leaning to it because it's HALF the price. $400 vs $800 is a big difference. That's literally the price of getting it tuned.

In reply to Bobzilla:

That should be the prime decision factor IMO, performance differences between the two will probably be negligible.

That's what I was going to say

That's what I'm leaning towards. Put that extra money towards a better cat and tune and actually get good gains that way. As far as I can tell, no one has done intake, header, cat, exhaust and tune on the 2.4 yet. This should get interesting. I'd love to be in the 175-180whp range with it and similar torque numbers but with an additional 700rpms up top.

Half price trumps any difference in performance, IMO.

Related question: The Hyundai/Mitsu/Chrysler 2.4 "World Engines" - are they the same motors, or just the same technology and each company produces its own engine? I.E. do all performance goodies swap?

Short blocks share parts, heads are all built by each company. Meaning: Mitsu built its head, Chrysler its and Hyundai it's own. Intake and exhaust parts between them I don't believe swap from one to the other.

You operate under peak power (even when racing) more often than not, and depending on the type of racing, at lower speeds.

I therefore say more torques. Whether it will truly make a difference? That really depends. I'd rather get the best custom dyno tune I could (in reference to the $400 vs $800).

What you really need is the large primary with the large collector.

Have you found any reviews of either product?

I gambled with a half priced header and ended up with one that wouldn't fit. It hit the firewall, the subframe, and the steering shaft.

Luckily the more expensive one that I eventually bought only hit the steering shaft

Those actually look quite a bit different. The top one is a 4-2-1 and the bottom one looks like equal length was the intent. Assuming that the top one was built with the correct cylinders paired up it will probably be your best all around performer.

Well they both pair the correct pairs of cylinders, so you got that going for ya. The 1.65" primarys are probably too large, and the 2.25" collector exit is probably too small, and whatever the minimum diameter either collector comes to is probably too large. Get whichever is cheaper. If there's one that only costs $150 thats probably the one you want.

Cone_Junkie wrote: Have you found any reviews of either product? I gambled with a half priced header and ended up with one that wouldn't fit. It hit the firewall, the subframe, and the steering shaft. Luckily the more expensive one that I eventually bought only hit the steering shaft

The OBX fits.... someone has already used it. That's the top (and cheaper) one. the nice thing is there is plenty of room back there to fit them. The Jun has been used in Korea on the 2.0L (which is externally the same).

+1 for taking the cheaper one. There won't be anywhere close to $400 worth of performance difference between the two.