clermont

Which dual exhaust setup is best, X or H pipe?

Stillen uses X design, HKS and Borla use an H pipe, Injen from what I can tell uses neither.

Is one really better than the other?

I have read that X pipes are best for reducing back-pressure though I'm not sure why.

It would seem logical to me that a design like Ingen's where the pipes are separate from the cats all the way to the tips would be the ideal setup but apparently that is not the case. Why is that?

Also, does any one know of a Titanium exhaust with an X pipe design? I think I want to go with Stillen but the added weight is discouraging.

StarcraftBW

iTrader: (10)

get the one is the most Expensive hehehe......stillen is the best IMO

booger

iTrader: (6)

Actually...I think Stillen uses 2 y pipes and welds them together . I have the Stllen too . Heavy . Thinking of taking out the so called X and making it a H . Need to find out more my self .

Samstag

The X pipe promotes more "scavenging", which in a nutshell means that as a piston on one side is in exhaust stroke, it's forcing air down the cats and through the X. The venturi effect would cause a drop in pressure on the other side of the engine, effectively pulling residual exhaust gas from the piston that previously went through the exhaust stroke. In a normally aspirated engine this will allow better performance. An H pipe does basically the same thing, but not quite as efficiently. That's my understanding.

I don't know how the Stillen G35c/350z version compares to stock weight, but the G35s version is 13 pounds lighter than stock. My aching muscles say they're both pretty damn heavy. I just installed the Stillen in my sedan last night.

EDIT: Corrected wording because I forgot this isn't a G forum

ragtopz

i dont remember the details, but yeah, the x is better than the h.

dwnshift

iTrader: (1)

Run a true dual.......the diameter of the piping should be determined by what modifications you have.....cams, FI, etc.

clermont

That didn't help so much... what kind of true dual do you think is best and why? (X, H or strait dual)

As far a diameter, all I really care about is that my headers, cat and exhaust are all of equal diameter. I'm still unsure about FI though. I hate turbo's, SC's are ok but my preference will always be NA.

dwnshift

iTrader: (1)

Straight dual....no X or H. Wont help on this type of engine set up. What matters most is tube diameter, primary lentghts and how the headers flows.
Exhaust diameter going over 2 1/4 will hurt unless you have a pretty modded engine. For heavily modded NA motor ru a 2 1/2 straight dual.

DaveO

My two cents...

An efficient "street" exhaust system not only reduces backpressure but also maintains reasonably high exhaust gas velocities.

X-pipes significantly increase exhaust gas scavenging from the cylinder that is on the exhaust stroke and also help to pull the "charge" into the next (opposite bank's) cylinder. This

Here's a write up on X-pipes and H-pipes that you may find interesting.

http://www.carcraft.com/techarticles/69238/

As for the differences in weight, 2 gallons of gas is approximately 12lbs.


DaveO

ares

iTrader: (2)

if you look at things as "only 12lbs" and thats just 2 gallons of gas, youll never lighten your car. but the fact of the matter is, if you look borla/injen vs stillen, its more like 25-30lbs, which is "just 5-6gallons" but Ill take it, cause Im only gonna have 5-6 gallons of gas in my car when I race, so I dont think youll be shaving the weight off there.

10 here and 20 there adds up.

I also heard the X/H pipes help the sound, the last gen viper had an H pipe because it was side outlet so the sound didnt mix behind the car either and it sounded like a 5cyl tractor rather than a 10cyl beast.

dwnshift

iTrader: (1)

Cannot compare what works on a V8 with what works on a V6.....for that matter you cannot even compare a straightline 6 with a V6. Its the nature of the engine and the H and X just wont do what it does for an 8 cyl or more motor.

ares

iTrader: (2)

well the vipers a V10, I wasnt reffering to its HP or whatever. I think the new viper has rear exhaust and does straight dual. the H was only to help with sound due to side exhaust.

booger

iTrader: (6)

Downshift...I sent you a PM

kzshin

Single pipe with correct diameter size, and single outlet exhaust will be the best. Like Greddy Ti racing.

clermont

Thanks for the feedback, very informative. Any way you can elaborate on why a straight dual is best for our engine?

kzshin

straight dual is not the best.

Jung918

I'm all confused? So go with a single exhaust with a 3 inch piping or go true dual with 2 1/4? Anyone make exhaust that small?

dwnshift

iTrader: (1)

What modifications do you currently have and what are you going to do?

PoWeRtRiP

most all the true duals are 2 1/4 ish

clermont

Supercharging often tempts me but most likely I will only be doing equal diameter headers, cats and exhaust, maybe coupled with slightly larger injectors or increased fuel pressure if I start running lean. In addition I'll be adding a lighter flywheel and sways but that should have nothing to do with the exhaust.
I'm also debating weather an intake is worth it or not... the stock one seams more than adequate... any thoughts on this?