Why don't I hear about H-cross pipes or Crossed exhausts on the org? I work with some really hard core drag guys, most mopar type stuff, but anyway one of them was discussing his new exhaust setup with me.
He was telling me about how guys would weld a H into their exhaust so essentially from both headers the "dual" exhaust is connected. The other thing he was talking about is those X type crosses you see in the exhaust for the same reason. He also was showing me dump valves for the exhaust that were electronically controlled.
I said the obvious, what about the noise, he said you jam some of these perforated metal cones in there to pass tech, then just take them out after that.
I thought initally well, I must have never heard of it because max are all fuel injected, but according to him at Atco in NJ most of the serious guys run this exhaust to reduce as much back pressure as possible, fuel injected or no.

Am I missing something, or do people here just not do it?

 

we probly dont have a dual exhaust crossover because we dont have dual exhaust. i know i kinda went out on a limb there, but im pretty sure thats right.

 

Lol how are you going to do an H pipe or X pipe on a car with one exhaust pipe...


About exhaust dumps, there are alot of guys on here with exhaut dumps, either manual, electronic, or boost activated. I can think of 4 guys off the top of my head who have them, me, mikeD, chris'smax, and aaron92se

 

That's kind of what my question was...why not? If some of you guys have spent the money on headers, exhaust tubing is fairly cheap. Having a muffler shop weld you in a true dual exhaust with a cross or H pipe, the cross is less than $200 in whatever catalogue my buddy at has, it would seem to be worth the effort.
My bud is a huge gear head and was explaining the reason for the cross or H is that engines even while running perfect are still capable of building up some back pressure because of the way the timing is, like little pops after each cylinder firing. The pops are not always spaced out from one another every revolution, so this can build up some back pressure.
I am not sure if all of this is worth it, I've just never seen it discussed.

I haven't seen that, but then again I don't come over here very often. So thanks.

 

I dono, a lot of people have thought about doing a true dual exhaust on the Maxima, but I think most people say that its not really worth it considering all the hastle you'd have to go through to get it to you know.. actually fit.. on a car whose underbody was not designed for dual exhaust. You would have to do a pretty extensive amount of work to get it done.. A electronic or otherwise activated dump seems to be a good alternative on our single exhausts

 

I'm looking at putting true dual exhaust on my other car this spring, which never had it an option for it. On older American cars ( 80's and earlier ), it's not as much of a problem since there is more room to work with under the car. However with a newer car, the exhaust route is many times designed into the floorpan, and it's not designed with dual exhuast in mind. Putting 2 pipes under there will usually result in some loss of ground clearance. Also, most exhaust shops aren't set up to do mandrel bends, which if you are going to the trouble you should use. And exhaust tubing is cheap, but it doesn't last unless you get aluminized pipe, which sill rusts out, or stainless steel. I don't want to keep replacing a full custom exaust every few years so I am using stainless steel on mine. I'm looking at close to $800 just for the cats, mufflers and tubing to put mine together. My brother in law and I are cutting , fitting and welding it on, but having a shop do that would cost quite a bit of money.
I looked quick at the underside of my Maxima, and you could probably get away with putting in an X pipe after the cats, ( custom built one, the prebuilts would likely be spread too far ), and run dual pipes along the same route as the stock pipe, then have the pass side go into the muffler at the stock location, and the drivers side opposie that. I saw someone on here the used a crossflow muffler with the second pipe looping around the spare tire well. Not sure how the drivers side muffler would fit up in there. Would be a lot of work and planning to get it to fit and not lose ground clearance. I'd say 2.5" would be plenty for most Maximas.
I'd like to see the difference on a dyno/track compared to a commercially available bolt on aftermarket exhaust. Be intersting to see at what point, if any the gains were significant enough to warrant the added expense.

 

true dual exhaust wont necessarily help. all engines need a certain amount of backpressure to run at the most power. while there are some with turbos and SCs, others will not benefit. by doing true dual exhaust, you will redo the complete exhaust system and end up with most likely the amount of backpressure you need divided by 2.

 

X pipes and H pipes do the same thing our single exhaust does, it combines the exhaust flow from both banks. So for cars with a single exhaust, the principles of dual exhaust and how H and X pipes help them out do not apply because the gains associated with them are already built in to the car. Adding dual exhaust would do nothing but make your car slower because you are just adding weight, it wouldn't add any power, though it would make your wallet lighter..

 

I haven't explained this correctly, look I'm not a drag racer, but the guy I work with is...a diehard. He has at one point owned a Cobra replica, a Hemi Charger, Duster and he currently races a Dart with a full cage and he's down near 11's ( it might be lower but I don't remember exactly).
His explaination is at WOT the X and H pipes allow the engine to breath easier because of the slight inconsistencies of the engine cycle. He is running a V-8 but I figure it would apply to a V-6, it has nothing to do with combining the exhaust only making it easier. He also has dual exhaust dumps for when he can get away with it. He occasionally wins decent money doing this, I assume he knows what he's talking about.
If this explaination isn't clear enough I'll get him to email me and I'll summarize his response.
I don't have any idea if this course of action is a worth while endeavor for the max, I was just wondering.

 

I don't understand the confusion. You asked if it would help, I explained that our exhaust setup (two banks combining into one exhaust stream) has the exact same effect that an aftermarket X or H pipe does on a vehicle equipped with dual exhausts does.

 

Combining the banks isn't the point of the X or H pipe. I will try to get him to email me because obviously I am not explaining it where people can understand what I'm trying to say.

 

actually that is the point. H pipe is "old school" X pipe is newer and provides more gains with smoother exhaust pulses. They are also referred to as balance pipes, because they help balance the exhaust pulses. Basically like Nealoc187 said, a single exhaust combines the two sides and the benefits end up being the same. Beyond the X/H (for dual system) or combination point ( for single ) a dual exhaust system flows better.

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

 

Backpressure is not a good thing, flow velocity is. They are not the same thing, but often confused.

 

++++++++++1 son

 

backpressure is not a good thing, thats correct. but no backpressure...also not a good thing. if you dont have enough pressure on the engine, it doesnt make peak power. ive done this before. i had a chevy 350 with headers and with straight headers, you will not get as much power as with mufflers. just so theres not confusion, it had pretty much the same compression, 10:1.

 

Don't confuse backpressure and exhaust gas flow velocity.

http://www.forums.maxima.org/showpos...1&postcount=33

 

Ok, I don't think I need to get my buddy to do anything now, that seems to make the point.
I guess I expected to see someone actually try using a X pipe on a max, because it does in fact flow better. I thought I saw a max or two with dual exhaust but maybe that was just ricer stuff and not real dual exhaust.
My only issue with the article is that the implied "laminar" flow in an exhaust system is total crap. It can be much less turbulent using the X pipe etc..but it will never approach anything resembling a real laminar flow.
The other thing the guy I work with also swears by is downward pointing exhaust tips, he claims because of their orientation while the car is moving it actually sucks exhaust gas out of the system, which also decreases backpressure.

 

good thing that link works...ive been told all my life that a little backpressure is needed for the engine to run right. isnt that why if you run the engine with no manifolds or headers it will either not run or will run like ***?

 

I've spent years bracket racing my Maxima and I know my car within 3 hundredths of a second. I have an electronic cutout in place of my cat. I run a completely stock exhaust except for a WSP Ypipe and a cutout welded in a 2.5" WSP Testpipe. I have run many back to back runs with the cutout open and closed to compare. Every single time, I am consistantly .15 faster in the 1/4 mile with the cutout open.

On the street with my street tires, I can definitely notice a decrease in low end power and a nice increase in top end power. But with my small track tires, my final drive is increased. So, I am above 4K rpm in 1st gear VERY quickly and I am making a nice deal of power all the way down the track with the cutout open.

But, on street tires, it noticably takes longer to accelerate from 3K to 4K in 1st gear with the cutout open. So of course, I don't have a perfect exhaust setup, but it suits my needs to be quiet as stock on the street and a free flowing exhaust at the track.

 

like i said

 

The way you used the term backpressure was incorrect.

But your termnimology can be switched with flow velocity and it will be true.

 

Yeah sure. I'm not denying anything you said. But my car still has some backpressure even with the cutout open. It does scream on top end pretty well. But suffers SLIGHTLY on low end.