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So I read the many many threads on y pipes for the DE. The two that were the obvious consideration for me were the HR pipe and the 370z pipe. It was a little unclear as to the measurements of the pipes because some people measure dinner diameter and some people measured outer diameter. The commonality was that the design of both pipes were much different and more efficient than the DE pipe.
first the easy part of the comparison. I weighed both pipes and they both weigh 14.6 lbs.
the outlet of both pipes are virtually identical although the 370Z is slightly smaller at 59.43 mm compared to 61.30mm for the DE pipe. In inches that is 2.4 in compared to 2.5 inch.
The difference in the inlet ID is 8.5mm or .3 inches. The DE pipe inlet id 2 inches compared to 1.7 inches for the 370 pipe.
from what I understand, the HR pipe is the same dimensions inner diameter as the DE pipe. This of course begs the popular question is bigger better?
I have to wonder why the Nissan Engineers would put smaller Inlet pipes on the y-pipe of a car with a larger motor with more horsepower. I assumed that a newer y-pipe would have improvements. One Improvement is that there are these rubber dampers on each Inlet pipe which presumably reduces NVH. One concern about using this pipe is that the larger output from my engine is going into a smaller Inlet pipe. The difference is not insignificant. Perhaps some engineer Minds on this form can weigh in on this. Anyhow I will install the pipe and see if there are any improvements or not.
So I read the many many threads on y pipes for the DE. The two that were the obvious consideration for me were the HR pipe and the 370z pipe. It was a little unclear as to the measurements of the pipes because some people measure dinner diameter and some people measured outer diameter. The commonality was that the design of both pipes were much different and more efficient than the DE pipe.
first the easy part of the comparison. I weighed both pipes and they both weigh 14.6 lbs.
the outlet of both pipes are virtually identical although the 370Z is slightly smaller at 59.43 mm compared to 61.30mm for the DE pipe. In inches that is 2.4 in compared to 2.5 inch.
The difference in the inlet ID is 8.5mm or .3 inches. The DE pipe inlet id 2 inches compared to 1.7 inches for the 370 pipe.
from what I understand, the HR pipe is the same dimensions inner diameter as the DE pipe. This of course begs the popular question is bigger better?
I have to wonder why the Nissan Engineers would put smaller Inlet pipes on the y-pipe of a car with a larger motor with more horsepower. I assumed that a newer y-pipe would have improvements. One Improvement is that there are these rubber dampers on each Inlet pipe which presumably reduces NVH. One concern about using this pipe is that the larger output from my engine is going into a smaller Inlet pipe. The difference is not insignificant. Perhaps some engineer Minds on this form can weigh in on this. Anyhow I will install the pipe and see if there are any improvements or not.
Piping is always quoted in INSIDE diameter, where it counts. No point in measuring O.D. because that has virtually no effect on flow. (Of course, some metallurgist in our midst will say I'm wrong for some reason but for all intents, it's splitting hairs.)
The HR/VHR Y-pipes flow better merely due to how the pipes are bent. They do not have extreme (~90 deg) bends in them and have a more gentle overall curve, promoting scavenging. If you look at aftermarket Y-pipes, say, the vaunted MD XYZ...
...it's fairy easy to see that it too has a smoother bend in it. Even the famous Nissan S-Tune Y-pipe, while looking close to stock DE pipe, has a slight bit less restrictive pathway (and enlarged exit pipe of course).
The MD y pipe looks great, but has a heavy price tag. Certainly it is a case of you get what you pay for because it is a work of art.
it was kind of bothering me that the inlet of the 370Z pipe was so much smaller than my original pipe. I drove it around and it seemed to be smoother but I'm sure it takes time for the ECU to adjust to it. While I was having lunch I was nosing around online and low and behold I find an HR pipe in my same town and the seller said shoot me an offer. So I shot him an offer and he accepted and within 30 minutes I was picking up and HR y-pipe. I took my calipers and measure the inlet and the inlets were virtually identical to my original y-pipe. The bottom line is that this is the pipe to get for our car. Even though the 370Z pipe physically fit, the inlets really are too small and it should not be considered.
since I already did A Y pipe swap, the bolts did not have to be cracked a loose and it was a pretty easy swap although the threads on the outlet of the y-pipe were rather stripped and it took me a significant amount of time to work them over with some penetrating fluid and some anti-seize compound. I finally got the HR pipe installed and fired it up briefly and it sounded awfully nice. I'll drive it around for a few days and let the ECU get used to the new y-pipe.
Left inlet is HR pipe...right inlet is 370z pipe
anyone want a gently-used 370 y-pipe?
Last edited by DeusExMaxima; 10-05-2018 at 06:02 PM.
That 370 y pipe looks like a solid downgrade, maybe it has more to do with the dual exhaust systems on the 370 vs the single to dual exit muffler on the 350...
That 370 y pipe looks like a solid downgrade, maybe it has more to do with the dual exhaust systems on the 370 vs the single to dual exit muffler on the 350...
Deff looks like a choke point in the system.
Good point Mike. The Z34 exhaust is a dual pipe/dual resonator affair but both pipes also dump into a single, but dual-inlet, dual outlet rear muff. The S-Tune on my 34 definitely had a bigger, different sound than the S-Tune on my 33 because of the dual pipes.
I am sooooo glad I found an HR pipe. When I measured the 370Z pipe, and realized that the twin pipes were a smaller diameter, I just sat there and had that sunken feeling that I screwed up. I installed it anyway and the car ran about the same. I think the design made it flow better, but the smaller ID offset and possible performance gain.
On the other hand, the HR pipe is another story. I have had about 10 days to drive it around. It CLEARLY has more power. How much power is hard to define. I noticed it immediately when I pulled out of the driveway and just eased it up the street. Even though I was babying it, the car seemed to jump with a small input from my right foot. When I drove it hard, the engine really started to sing without being too loud. Its slightly louder and a lower rumble than before.
Without a doubt, this is a great way to improve power and retain a stock appearance.
One thing I curious about....in order to fit the HR pipe, you have to remove some plastic aerodynamic pieces. This leaves a large space under the car thats uncovered. Did anyone make a plastic piece to fill in the space?
I had an hr y pipe and when I went to install it I realized that entire piece would need to be removed. I ended up just going with an aftermarket exhaust.
Luckily I sold the hr y pipe relatively easily for $100
I had an hr y pipe and when I went to install it I realized that entire piece would need to be removed. I ended up just going with an aftermarket exhaust.
Luckily I sold the hr y pipe relatively easily for $100
For me it was two pieces on each side, not terribly large pieces. Next time I have the car up on jack stands, I may see if I can fabricate something from sheet plastic.
Another thing to consider with the smaller 370 pipe is emissions. Just an ASSUMPTION ON MY END, but maybe they needed to slow down the exhaust some so the cat could effectively burn the unused gas in the exhaust to meet new CAFE standards????
Another thing to consider with the smaller 370 pipe is emissions. Just an ASSUMPTION ON MY END, but maybe they needed to slow down the exhaust some so the cat could effectively burn the unused gas in the exhaust to meet new CAFE standards????
Like I said, just a random thought.
I thought the same thing, although the 370 exhaust system may be freer flowing because its almost a dual exhaust.
10-05-2018, 09:49 AM
370z and 350z DE y pipe
