if im not mistaken, the h pipe is the crossover pipe that links both exhausts together...adds a few extra horsepower and evens out the exhaust flow, making it sound better(i think)..no, not mandatory........
I havbe read that an x-pipe balances pressure better than an h, believe in car craft. There was an ariticle where a shop in new york worked on a cutlass and the x pipe yielded performance gain equal to if not greater than open headers and greater than an h:, although very marginal and did not seem worth the effort.
Suppose if your hard core and trying to squeeze hp from everywhere you can, you would benefit, but for a mild street/strip I dont see the need, other than to say "hey, look what I got"
Somebody please correct me if I am wrong (like I really have to write that
), as I would like to know more myself
'70 SS 396 4spd
"You're just jealous because the little voices are talking to me"
I have an H-pipe and think it isn't worth the trouble. No track improvement that racing between night and day wouldn't net. The exhaust not on the top end is a little less raspy, so I guess at high flow is does good to equalize pressures, but how much power that nets I didn't see.
I see it this way. Exhaust is flowing in a given direction and instead of it making a 90 deg turn and going into the H-pipe it's gonna take the path of least resistance, straight to the muffler... The H-pipe is like a venturi of sorts and the exhaust blowing by it will actually creat a vacuum in the H piece of pipe. We know each cyl doesn't fire at the same time so there are pulses. Each side of the exhaust may infact help pull the exhaust from the other side. This effect is greatest at idle. As the speed of an engine increases the pulses blur together and the effect is nulified.
Other than an effect on the idle sound I don't think it is worth the effort of adding it!! My .02
I have now read the article. It surely says that an x pipe is better. It may look like back peddaling om my part but I generally am skeptical about track times to prove something. Different drivers, different track conditions, different launch technique etc all are too may variables to show an improvement to me that is very small. Sure if you put a blower on a car its gonna show a big decrease in ET. But with 1 or 2 tenths I am always skeptical.
I like to se dyno tests to prove something.
Again, I'm not saying that an X pipe is better or worse.. I dunno and I would tend to agree that the exhaust flow has a more direct flow on an X than a hard turning right hand corner that it has to make on an H pipe.
So I remain, interested but unswayed one way or another.
Dyno tests would certainly convince me.
I guess thats why I like Muscle Mustangs and Fast Ford Magazine over Car Craft and Super Chevy. They usually try to usse a dyno to prove something over a seat of the pants type story. To be sure however, they all use track time analysis...
I know it looks like I'm back peddalling...
X, H, or the new O pipe, it ain't that much actual gain, or could be in certain applications. The X SOUNDS better to me, on certain applications... And in my logic, if you're gonna spend money on one of these, you might as well spend the money on the latest version. The H has been around for a while, The X is the newest to be tested and raved about, but the O is the whip, but yet to be tested. Seems they can't keep the car running long enough to get a accurate comparison
Do your reasearch, make a decision, and defend it to the death...Unless you're prone to changing your mind of course.
------------------ 71-72 Malibu
"I'm high all right, but on the real stuff
High octane gasoline
A clean windshield
And a shoe shine"
The car actually averaged .134 seconds improvement in the quarter mile. This version of the test is an edited version, not containing the entire text of the original article in the October '96 issue of Pontiac Power. It was actually a very well controlled test. Same day, same driver, same lane, parts re-installed to check repeatibility, constant fuel level and weight of the car, the car was driven back down the strip to avoid the dust of the return road, and weather conditions were monitored throughout the test. The temperature varied by 1 degree, humidity by .03% and the barometric pressure by .08inhg. .13 seconds at 160 feet per second, about 110 mph, equates to 21 feet margin of difference, a full car length at the finish line. Lets say you're running 13.0's in your Chevelle, and you figure out a simple way to knock .13 seconds off your e.t. Now that 13-second ordinary ride becomes a 12-second powerhouse.
67 Nova 3475# daily driver
10:1 406, 700R4, 224° Comp cam, RPM and a Q-jet - 11.76 @ 116
64 Chevelle Road Racer in the works
67 Nova Wagon under construction
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