[jace]

Been wanting to upgrade the exhaust on my Mo. Step one was a K&N filter and "venting" the airbox by removing the resonator thinger. Next will be removing the center muffler and replacing it with straight pipe.

Now, I've been considering replacing the muffler with one that will offer some kind of low tone, but nothing too loud. Flowmaster makes a cross-flow muffler for F-bodies, but I think that would be too loud for our trucks (with the CVT, it would probably just drone, instead of rumble). I've kept an eye on ebay for a 350z or G35 OEM muffler/exhaust system that someone is selling because they've upgraded. Has anyone actually switched their muffler for anything else? Sound clips?

Now, I've been under my truck, and I've seen that horrible square tubing pinched exhaust job at the Y-pipe - that sucks. I've seen posts from people mentioning that they've modified a 350z y-pipe to fit, but from what I can find on eBay, the 350z pipe looks nothing like ours?

 

[mgthe3]

I understand some folks wanting to free up their exhaust systems in an effort to gain more power. After all, all internal combustion engines can be looked at as air pumps--the more efficiently you get the air in and out of it, the more power it makes.....under full throttle.

I have had some pretty stout engines in cars that benifitted from intake/exhaust modification.....under full throttle. One of them had a 450+hp V8. I noticed an interesting thing when I had to go back to a more restrictive exhaust because I had to get legal, and, the cops were not very impressed with my loud a$$ car. My low end launches (auto transmission) were decidedly quicker and very obviously had more torque with this restricted exhaust. Yes, I could also feel it lean over up in the 8k rpm range where before it pegged you to the seat.

I love to breeze past ricers as their coffee can exhaust is blaring--while the Mo is inaudible as it walks off and leaves them.
Bye Bye!
Considering that the torque converter unlocks at full throttle, and, I seriously doubt most of us drive their Mos at full throttle--it would be a waste of low end torque (where most of us live) to open up the exhuast more.

But, to each their own!

Just my 2 cents.

 

[Nissmo]

Interesting,
I am curious as to what the Mo would sound/perform like without the center muffler and what purpose it serves. It is unlike manufacturers to put it in the system without a strong motive.

Seems to me I read somewhere that removing it had little effect on sound so?

Backpressure is a science used to tune the powerband so changes need to be approached with caution. Buy the same token this engine is the Nissan do it all up to 300 hp in the Z.

 

[jace]

I'm just used to a little more rumble (check out the sound clip of my blazer from my webiste - you'd never believe it was a v6 )

 

[mgthe3]

Ohhhh yeah, I know that rumble.
There was nothing like feeling a 280 duration .475" lift cam going through a set of wide open header mufflers....and then hearing it scream out 8500 rpm. WAAAAAAAAAAAAA!
I'll never forget the time I stood next to the open headers in Don Gartlet's pit, idling sounded like an assortment of cherry bombs going off....scared the bejesus outta me when they hit the throttle. 1000 to 12000 rpm in a split second, sounded like an explosion.
But noise is noise on the street, I think it is best left on the track where noise= HP.
hehe

Unless of course you have a mad V8 like jaak's.......

 

[MightyMo]

My digital camera is full of pics from the nifty mandrel bent center pipe section I had built yesterday for my Mo. Hopefully I can post some plus sound clips later today...

 

[Nissmo]

My digital camera is full of pics from the nifty mandrel bent center pipe section I had built yesterday for my Mo. Hopefully I can post some plus sound clips later today...

Would love to hear it and your impression of before and after.

Personally I am not looking for loud, just to free it up a bit.
I have very agressive headers, no cats, LOUD system on my Vette and it is not a daily driver or tolerable long term.

 

[MightyMo]

I'm Photoshoping pics right now... Did a G-Tech Dyno test on the Mo earlier today, cut my 0-60 time from 7.1 to 6.9 seconds :4:

 

[MightyMo]

Here we go, everything but the sound clips which will have to wait until tomorrow. Click on the Pic:

 

[njjoe]

MightyMo-

Fantastic job!!!:claphead:

Excellent analysis.

-njjoe

 

[mgthe3]

Kewel, great job doing the analysis.

I don't mean to nay say ya MightyMo, it looks great, a vast improvement over the stupid hanging center section.

I'm a little skeptical of time charts due to the variation of driver input---it could never be the same twice, especially when it is only a 10th off. I would expect the dyno charts to look very close to what yours show though.

I think just changing the center section benifits the look and ground clearance most of all---which is a good thing.

I would love for the MO to have a stock intercooled/turbo'd VQ so it could rival a normaly asperated V8 in power. But, I do enjoy the quietness and sublime power that makes the MO what it is.


If it were a 69 DZ Z28 or even Nissmo's Vette....that would be a different story.

 

[jace]

good deal - that's what i'm after for the center muffler delete.
now, wanna mock up another section of pipe and sell it to me?

 

[.:DSï]

Why are the hp readings too low? is that normal?

BTW thats a clean work

 

[zebelkhan]

good deal - that's what i'm after for the center muffler delete.
now, wanna mock up another section of pipe and sell it to me?

I just installed nerf bars. Now you cannot see the center muffler unless you crawl under my MO...

 

[MightyMo]

mgthe3:
What is this thing you speak of, "driver input"?

With a CVT, running on the same stretch of road at the same time of day 1 day later, you really can't get more consistant than that.

Look at the 60' times, only .029s ahead, so the launch was virtually identical. That means almost all of the .239s improvement was made simply with my foot on the floor.

As for beating V8s, we're already at least on par with the X5 4.4i and the Cyanne S or Tuareg V8, so who needs a big heavy gas guzzling V8? :4:

jace:
Well, it took us about 7 hours to do. Second time around should be faster, but you also need to factor in steel, so I would SWAG at around $600-700 for a mid-pipe of the same design would be a fair number.

If you aren't anal about using mandrel bent tubing for absolutely maximum flow, just go to your best local exhaust shop. Tell them you want their top tube bending monkey on the job, and they can probably whip something up for far less, and without all those endless welds.

.Sï:
First off, any dyno will read %20 to %25 lower at the wheels than at the crank, because of paracitic drive line losses, and even more so for AWD vehicles.

Then add that the G-Tech is an 'on-road' dyno using accelerometers, so you have wind drag working against you as well.

Lastly every dyno reads differently, you always have to take the numbers with a big grain of salt and try to use it only for pre-mod/post-mod comparisons using the same test method.

 

[Nissmo]

Great write-up and encouraging results.
I think I am going to do it by splicing a straight pipe into my 2000 mile old mid pipe. Should be a cheapo trial and provide like results.
Thanks

 

[MightyMo]

BTW, anybody in the SF Bay Area, if you want to give the system a try, especially if you have a bone stock car and can provide that perspective with a review, just let me know. It would only take us 30 minutes tops to zip it on.

 

[MightyMo]

Sound clips are now online, click the pic:

 

[See5]

Today I had the muffler shop cut out the muffler and replace with straight pipe.
I hope I get >10 miles more per gallon because the sound difference is nil.
It is hard to belive Nissan spent the Yen on the muffler for all it does not do???
The Mo has 2,200 miles.

 

[njjoe]

It is hard to believe Nissan spent the Yen on the muffler for all it does not do???

Although only a relatively small number of MO owners have removed the center muffler, there is enough evidence to suggest the muffler is not needed. Nissan could have saved a few yen by installing a smaller muffler, or saved even more by eliminating it all together.

Unless of course they wanted the most quiet exhaust note possible to enhance the image of the MO as a refined, luxurious, and quiet automobile.

Were the marketing guys at Nissan aiming for sporty or refined??

A good alternative would have been to delete the center muffler from the SE models only.

-njjoe