Exhaust questions

[Voodoo Chick]

Hey......No one has ever really explained any of this to make sense to me, so I'll ask you guys out there.......what does each different type of exhaust do specifically, like H-pipe, X-pipe, straight pipes, etc..... what provides the best performance? Which one sounds the best? I would love to hear all your opinions/knowledge on this. What type is the loudest possible? What type is quietest? I know I could look it all up via google, but I'd rather hear all your first-hand experience. :)

[TheRX7Project]

Straight pipes are the loudest, and also the most performance for high RPM motors. I.E. if you are going for peak power at 7k RPM or more, straight pipes are your best bet. They're just super loud. Of course the sound level will also depend on what kind (and how many) mufflers you stick on, and also depends on if you are running headers or stock manifolds.

H-pipes are stock-style dual exhausts. They have a single crossover pipe between the two cylinder banks (on V-engines only, obviously) and keep low-to-mid range torque better than any other style.

X-pipes are like a cross between the two, more for mid-range. They still have the "crossover" section but also flow better because instead of being an "H" crossover (with a 90-degree "turn" into the crossover pipe, and exhausts pushing against each other from side to side) they have an X-shaped crossover, allowing the exhaust to keep flowing in the direction it wants to go, but still keeping some of mid-range allotted by having a crossover.

Noise is all going to depend on mufflers. Remember that with noise restriction also comes flow restriction- i.e. the more "free-flowing" the muffler is, the less sound it muffles.

Size also makes a big difference with exhausts. A large diameter exhaust will flow well, but go too big and the gasses won't be able to properly scavenge each other, resulting in a loss of low end and midrange. Too small of a pipe will be restrictive and have the opposite effect (no top-end).

[Prince Valiant]

The basic thing about straight pipes vs H and X is that the purpose of the X and H is to bleed off a little excess pressure, reducing the friction of the exhaust charge as it travels down the exhaust pipe.

Exhaust gases encounters resistance as it travels down a pipe...resulting in large part from friction--other things as well, but for your question, friction is the only important thing. The friction is the result in part of exhaust charge exerts against the fixed diameter of the system. A large charge in a small pipe equals high pressure. A small charge in a large pipe equals low pressure.

The force, or resistance that friction exerts is predicated in part by the pressure exerted by the exhaust charge. Just like if you slide a book along a desk w/ no wt, and then slide the same book with a 5lb wt, you'll find the heavier of the two harder to slide...the coefficient of friction is the same, but the heavier requires more force. Pressure is like that weight...though the coefficient of friction for the gas remains the same, the the pressure can change, thus changing the amount of HP it takes to push the exhaust out the system.

So with a straight pipe, there is no pressure bleed off...so typically in most applications, it will yield the least HP.

An H-pipe allows a bleed-off as the charge passes the H...excess pressure gets bled off into the neighboring pipe, yielding less resistance than the straight pipe.

An X pipe likely allows greater pressure bleed off, so in some applications it might gain you more power...some might also argue that there is more of a "scavenging" effect for X-pipes, similar to how the collector of an exhaust works, or how tri-y's work.

As far as sound, each has it's proponents...personally I've always like the X pipe sound best, but I've heard people who hate it.

I can only speak to a test of exhaust systems car craft conducted on a ford mustang once...all else was the same-mufflers/headers/rest of the exhaust...and they tried each.
HP differences weren't terribly great...10-15hp (3-4% in this example), but the power curves differed greatly. Straight pipe came in last, then H with a few above it, and then X...but iirc, they said the big difference came in mid-range power, with the X-pipe and one point in the rpm range producing as much as 25ft-lbs of torque more than the straight pipes...suggesting that a scavenging effect actually does occur.

[Voodoo Chick]

Thanks for the answers! You both helped very much, it makes alot more sense now. :)

[PureSound15]

H pipes typically sound better with a chambered muffler, too.


Sound all depends on the motor though.

[pjturkey]

Hey......No one has ever really explained any of this to make sense to me, so I'll ask you guys out there.......what does each different type of exhaust do specifically, like H-pipe, X-pipe, straight pipes, etc..... what provides the best performance? Which one sounds the best? I would love to hear all your opinions/knowledge on this. What type is the loudest possible? What type is quietest? I know I could look it all up via google, but I'd rather hear all your first-hand experience. :)

I have an X-pipe and it definitely changes the sound quite a bit.....I actually liked the sound better before my car had 3" w/X-Pipe. The X-Pipe gives it a higher pitch. I had a full PYPES system but I got rid of the mufflers because they made my 455 Olds sound like a 5 Litre mustang.

Best Sounding: Duals w/some form of performance muffler

Performance: Straight X- or H- Pipe. I put cutouts on my car after the X-Pipe and before the mufflers and quite honestly the X-Pipe seems to SHHHH it down. It's not nearly as loud as open headers.

Performance and quietness: X-Pipe w/pypes Violator or race pro muffler. They sound really gay IMO (like a Ferarri/something with more than 8 cylinders) but they perform well.

[Voodoo Chick]

My car has an X-pipe, with cut-outs, and that's the weirdest sounding exhaust I think I ever heard........not a bad sound, actually really cool, just WEIRD. Almost like a cackling sound, with these really odd bass pulses. With the cut outs capped off, way too quiet, but open, VERY loud. After 2 years, I'm still not 100% certain I should keep this system, although it performs quite well, it just sounds so damn strange.

[pjturkey]

My car has an X-pipe, with cut-outs, and that's the weirdest sounding exhaust I think I ever heard........not a bad sound, actually really cool, just WEIRD. Almost like a cackling sound, with these really odd bass pulses. With the cut outs capped off, way too quiet, but open, VERY loud. After 2 years, I'm still not 100% certain I should keep this system, although it performs quite well, it just sounds so damn strange.

I always viewed it as you have to find the right sound for the persona of the car. For example, I went quieter because on the outside with the hood closed, my car looks 100% bone stock. Nobody would ever guess by looking at the outside of the car that I get kicked off the track for not having a cage.

On the other hand, if you're running air shocks, a chrome diff cover, and red tinted windows with a red-eyed skull hanging from the rear view, how the car is supposed to sound changes quite a bit ;-)

....everyone will hate me for saying it, but cherry bombs sound cool..........

[Voodoo Chick]

I always viewed it as you have to find the right sound for the persona of the car. For example, I went quieter because on the outside with the hood closed, my car looks 100% bone stock. Nobody would ever guess by looking at the outside of the car that I get kicked off the track for not having a cage.

On the other hand, if you're running air shocks, a chrome diff cover, and red tinted windows with a red-eyed skull hanging from the rear view, how the car is supposed to sound changes quite a bit ;-)

....everyone will hate me for saying it, but cherry bombs sound cool..........


I love Cherry Bombs, too, to be honest......I actually think the exhaust system on my car suits her, with the cut-outs open, it sounds as demonic as she looks.......which I really love, but I don't know......exhaust systems come and go over the years, so I suppose it's no big deal in the long run. I'd really love to see your car in person sometime, it seems to me like it must be awesome.

[Waver]

H pipes typically sound better with a chambered muffler, too.


Sound all depends on the motor though.


I have heard mixed opinions on this one, just with the way my car sounds three months after I put the x pipe on with the chambered flowmasters. Some say it sounds really good, others say it is too raspy. To me it sounds all right, but I might switch to a different catback depending on how things go