[dmfrazee]

I'm replacing my factory exhaust with headers and was told to put in a X pipe or H pipe. Can you tell which one is better or do they both do the job? It's a 1979 Camaro Z28 with a 350 motor.

[327NUT]

I really don't think it matters that much. I would just install the exhaust and fit the cross over pipe where it fits the best. You'll never notice any perf. gains or losses with a normal car in a street invironment.

[Irelands child]

Straight from Flowmaster (and similar to what I've seen elsewhere when I researched for my '31). The bolding is mine.

"Is an "X" pipe better than and "H" pipe?

Not necessarily. Flowmaster has performed extensive dyno testing of traditional “H” pipes and various “X” pipe designs and has found that in most typical street applications, there are no clear benefits of one over the other. “X” pipes have become a buzz word in the world of performance exhaust, and are now produced in a wide variety of styles and designs. Some types perform well, and some others can be quite bad due to the excessive turbulence generated in the merge area. Unlike anything else available, Flowmasters Scavenger X-Pipe design features patented D-port technology to maximize the communication surface area between the two banks of cylinders, and maintain the exhaust pulse velocity for peak scavenging. In terms of sound, an X-pipe will generally provide a smoother, higher pitched tone than that of a traditional “H” crossover pipe. In some specialized race applications such as small cubic inch engines and /or restricted (small bore) carburetors, we have found that an “X” pipe can respond well over an “H” pipe. As with all race applications, there is no substitute for time on the dyno, developing the engine package as a system."

[matts37chev]

if you are building new, from scratch, I would go for the X

[Irelands child]

Originally Posted by matts37chev

if you are building new, from scratch, I would go for the X

Not if you need the room for other components - the 'H' pipe is a LOT easier to build around vs the piping that has to be routed to the center then either run parallel down one side or back to each side - all at an angle.





Pretty simple and it works. As far as room, the second photo is the finished car as it sits as I write this, waiting for a transmission oil pan change !!!!

[matts37chev]

I didnt say it would be easier

[mikey44]

I have the same dilemma with my 81 Z28. What is the benefit of putting either in at all?

[Bonneville462]

I woundn't use either.. They will ruin that great Chevy V-8 sound.. It will sound like a V-6....

I run a nice pair of Porter Steel packs as far back as possible..

[65 Imp SS]

Here are a couple of articles to check out:
http://www.pontiacstreetperformance....p/exhaust.html
http://www.carcraft.com/techarticles...ion/index.html
I ended up running an x-pipe with a "warmed" over bbc (pic in avatar) and it is different from the norm dual exhaust but it does not even come close sounding like a v-6...

[oldbogie]

Originally Posted by dmfrazee

I'm replacing my factory exhaust with headers and was told to put in a X pipe or H pipe. Can you tell which one is better or do they both do the job? It's a 1979 Camaro Z28 with a 350 motor.

The idea of both is to share muffler capacity of one side with both sides. Mufflers and cats, which you're probably not using, are the biggest flow limiting devices on the engine. So the crossover lets either bank of cylinders to see the total flow of a dual exhaust. It's not quite that straight forward in actual practice, but better than a single exhaust isolated on each cylinder bank. Each has it's own tone qualities, the H pipe emphasizes the lower rumbling notes, the X pipe favors the higher sharper notes, too a large extent the mufflers will affect either crossover's sound preference. Too the end of using both muffler the crossover needs to be ahead of the muffler or cat.

Clearance to the roadway may dictate which, generally I find that X pipes need to mount lower to clear the transmission or drive-shaft where H pipe can often be tucked up between the bell-housing inspection cover and the transmission, but in either case your specific lay out will determine where there's any space/clearance advantage. Headers compared to cast manifolds, or more specifically their collector, will push the H pipe toward the rear and often down to clear the transmission which will then be as low as an X pipe.

Tuners using the H pipe can search for the optimum location on the collector but this is a pain to do and for a street engine not worth the effort for the very small torque gain. The x pipe does not seem to be sensitive to location in terms of offering small gains in one place over another.

Bogie

[southshore30]

I have seen the first link before and find it funny to see how popular Flowmasters are and to see them as the one of the worst performers in those test results as well as the loudest. I used to have them on the Mustangs I drove back in high school but am a Magnaflow guy now

[Irelands child]

Originally Posted by southshore30

I have seen the first link before and find it funny to see how popular Flowmasters are and to see them as the one of the worst performers in those test results as well as the loudest. I used to have them on the Mustangs I drove back in high school but am a Magnaflow guy now

Soooo your point? You like Magnaflow better. Great! That's called a personal choice and is part of business models and competition.

Now, those alluded to test results - please post any unbiased test results across a spectrum of engines and vehicles along with different exhaust systems.

[Figbash]

I built an X pipe for my Chevelle and ended up sawing it out and replacing it with an H pipe. I doubt there was much difference in power or torque from the 540 with 3" exhausts, but the difference in sound was significant. The X pipe took out most of the low frequency rumble of the typical big block and made it sound raspy. Once the H pipe was in, the traditional mellow chest thumping sound of the big block returned.

Tom

[Will Burton]

Just happened to see an interview with the founder of Heart Throbs mufflers on Stacey David's Gears. He described tests of H vs X and reported that they got consistently higher HP with H pipes.

[76_TA]

H pipe system installed on a 76 Ttans Am