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Still no proof of the crushed pipe replacement theory?

6K views 69 replies 29 participants last post by  wild willy 
#1 ·
Anyone with some results of replacing the crushed pipe on the 3.5 alty?
 
#3 ·
I dyno ed my car with just the pipe replaced from the cat to the y with 2 1/5" pipe and a intake with the res taken out. I got 196.4 hp and 222.7 Tq at the wheels. I just put a 50 shot wet kit and got 299 ft lbs of tq and 235.5 hp it was impressive.
 
#5 ·
FAST4DR said:
I am curious about this also. Here is a picture I took of it.

:eek:

OK, now I've seen this "crushed pipe" for myself I absolutely cannot belive that there is not going to be a hp penalty with this. Torque should not be affected but top-end hp most certainly will. The dyno plots I've seen of the 2002 Altima show a dip in hp after 5K rpm. The Maxima doesn't appear to have this so it must be intake, ECU or exhaust related. I would put money on this pipe being the reason.

Cheers,
...Colin
 
#8 ·
I don't have proof, but I replaced the Cat-to-"Y" section and replaced the mufflers. With the JWT intake, the car now pulls VERY hard all the way to redline. Feels like more than 15 HP to me. Before the mods it was very noticeable how bad the power fell off at the top. NO MORE!
 
#9 ·
From what I have read this mod, replacing the 'flat piece', will cost from $75~$100.
I have been kinda confused on the purpose of this section of exhaust due to the fact there appears to be plenty of clearance for a rounded piece in its place.

This weekend I may go to the local muffler shop and have this piece replaced.
 
#11 ·
Altimat -

I'm looking for measurable improvements, such dyno measurements, or 0-60 improvements.

Also, I am tryng to figure out if replacing the pipe section alone will make any improvements. Changing the mufflers alters the equation.

On a related note, I do not believe the exhaust system is warranted, therefore a change in the exhaust system would probably not void the warranty. I would need to read the fine warrany's print, when I get it.
 
#12 ·
marks said:
Altimat -

I'm looking for measurable improvements, such dyno measurements, or 0-60 improvements.

Also, I am tryng to figure out if replacing the pipe section alone will make any improvements. Changing the mufflers alters the equation.

On a related note, I do not believe the exhaust system is warranted, therefore a change in the exhaust system would probably not void the warranty. I would need to read the fine warrany's print, when I get it.
I think you are fairly safe in assuming that replacing the flattened section will net gains. The cost of the mod is less than a dyno run so I wouldn't expect to find any hard data on this.
 
#15 ·
by virtuoso1 There may seem to be room for a round pipe. But why does the "crushed" portion follow the contour of the floor plate above? Clearance maybe?
Uhm, perhaps to prevent heat transfer from the pipe to the floor panel? It's also possible that in early tests with the pipe round, there would occasionally be thumping from the floor when the car hit bump and the suspended pipe banged against it. Thus they flattened the pipe to prevent a noise that certainly all owners would complain about.

Could be. ;-)

OpalBlue
 
#20 ·
i took in my car and they said put it up on the rack and showed me that the pipe gets WIDER and more narrow. He said he thinks it is clearence and not to mess with it.
Take any round pipe and put it in a vise. Squeeze. It will get wider as it gets thinner because the pipe material has to go somewhere. But unless they've added material, there is still going to be LESS FLOW through the flattened section. Why? Because a flattened section of a pipe has less cross-sectional area than the same pipe when fully round. The area decreases as you go flatter. Visualize that same pipe pressed completely flat. No exhaust when flat, period, because the cross sectional area = zero.

That said, I think they flattened it for clearance too, but when they did it constricted the flow.

OpalBlue
 
#21 · (Edited)
akima said:
Get a new joke son, the patato is getting kinds old (See Sponge Bob episode where he rips his pants for laughs-)
Well lets see here.....I turned 43 last wed and you will be 43 in december so who is the son here son......LOL.....BTW its potato not patato...djsassan would be proud of me.....cmon man find a sense of humor..I'm gonna get my potato and 4 foot pipe removed next week...I'll post results
 
#25 ·
Hmmm...

OpalBlue said:
Because a flattened section of a pipe has less cross-sectional area than the same pipe when fully round. The area decreases as you go flatter. Visualize that same pipe pressed completely flat. No exhaust when flat, period, because the cross sectional area = zero.
I'm no mathmetician, but your argument strikes me as a little wiggy. Volume shouldn't decrease simply because you're making a round pipe oval.

Perhaps someone with a math background can help us out. If Nissan simply took the round pipe and crushed it a little, its circumference didn't change assuming the pipe became a little wider in the crushed area. (The metal had to go somewhere, didn't it?) If the pipe was, say, eight inches in circumference to begin with, you'd still be able to take an eight-inch string and wrap it around the pipe without slack, wouldn't you? And from there, wouldn't it follow that the number of square inches in the cross section would also remain? And finally, if so, then the volume of flow would not be restricted at all, only the dynamics of it, probably resulting in exactly zero horsepower loss.

I'm not at all certain of this. I know there are some smart engineers on this forum. Step forward, gentlemen, and set Opal and me straight!

Jarrod K. Wright
'02 3.5SE 5-speed
'98 SE 5-speed
 
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