I completed the installation of my Stillen 2-piece Y-pipe along with the Federal emissions front-side exhaust manifold today. You can see details of this project at:

www.desertpearlmax.homestead.com/Fed_YPipe.html

There is a link at the top of that page that you can click to go straight to the pics if you don't want to read all of my ramblings.

So far, so good... I haven't seen any check engine lights yet. I can't wait to see the dyno numbers to see if this was worthwhile or not. I'll post them here on Monday night.

Take a look at the attached pic. It pretty much sums up this mod!

 

Here's the pic. After I previewed my post, the link disappeared.

 

I think that the ECU reduces the power more than the actual precats.

 

Desert...do you feel a difference?

one more thing i gotta ask is that....is the CA manifold itself more restrictive(precat aside) than the FED....because it doesnt look any more restrictive to me in the pictures...is the inside piping smaller?

it actually looks a little bigger where the precat and the manifold meet

in other words...instead of comparing the manifold with the precat as a part of it...how does the cali would hold up to the fed: without that precat?

cause what im thinking is to just remove the precat(yes its not an easy task but whatever) and to bolt up a custom downpipe with a 5 bolt flange to the manifold...would save time without the lengthening of the o2 sensor wiring too(btw why didnt you just remove the extra sensors all together?)...dont mind me if that sounded stupid:P...just wondering cause I took out the O2 sensor clips just a few days ago and I didnt generate a check engine light

 

Magnificent write-up and fantastic results so far.

Regardless of whether your modification works out in the long run, everyone in this forum who loves their Maxima owes a debt of gratitude to you and people like you who are willing to take risks in the pursuit of improving performance. Obviously it would be wonderful if the dyno results and your long-term driving test prove the value of your modification. But whether they do or not, we've already gained immeasurably from your experience.

Way to go!

 

Look at how ugly that precat is. Congrats!

 

AWESOME!!!!!!!! Great job! Great write-up and pics!

So when can I come to your place for some help on the details/install? I'll buy the beer, lunch, dinner, whatever it takes!

I definitely want to hear that beast roar. How loud is it really? I guess I'll see on the 5th if your able(and I) to make it to the next Maxima meet.

 

Okay, I finally have dyno results! However, I'm not going to post them here... you'll have to check my site:

www.desertpearlmax.homestead.com/Fed_YPipe.html

Don't click on the link for dyno results because I haven't updated that page yet. Just page down and you'll see the dyno plots. Please read the summary just below the plot for my take on this mod!

 

Good job! I wouldn't say that was a loss. Look at your curve... it's raised up from the other ones.

 

I agree, but it's not what I was hoping for. Like I said on my site... I'm not sure if it was worth the $90, 8hrs labor and 11 scabs I have on my hands now.

Pro-Dyno was going to forward my results to Brian Catts. Maybe he can find a way to squeak out a few more HP!

 

so basically are u trying to say that there is no difference between ca/nlev and fed spec cars? how do those dyno #s compare to a fed spec w/ y-pipe auto car? urs is auto right?

is it possible that the ECU makes a difference as well?

well i am extremely grateful for your R&D work and coming up with these results! im sure everyone here feels the same way! it is amazing that we have such dedicated people on here that are willing to help and work to come up with new and better things.

 

Thanks for the kudos. They make my experiment even more worth-while. I don't have any dyno results of other automatics with y-pipes, so I can't answer your 1st set of questions.

I'm not sure of the differences in the ECUs between the Fed and CA spec cars. I do hope there is a difference in their performance, because that would mean that when someone (JWT, etc) finally makes an ECU for the CA cars in particular, I'll get a bigger pop.

 

yea so basically you are going to leave it the way it is... now another question... since the car is CA/NLEV when u go into inspection do they look at different standards or it doesnt matter it has to meet a certain level and thats it no matter Ca/NLEV or Fed spec?

 

Desert: Great job looks like things worked out great! Even though you did not gain a lot of hp by switching out the manifold, your work definitely helped a lot of us out. Thanks a bunch for all your work. Now, if you get your hands on a fed spec ECU

 

Hey Des...so basically one would be better off with just unbolting the precat on the NLEV manifold and using a custom 5 bolt flange?

 

psing23... I don't think anyone here will look for the precats. I don't know what they'd do in an area that actually required CA/NLEV emissions testing... maybe they'd catch it. As long as I take it in warm, it should be doing a good job of cleaning the air and it should pass. P.S. I did dremel off Stillen's "off road only" message so that no one will see that if they look closer.

UMDMaxSE... thanks.

Pmp-n8a... It would be nice if someone would try this and see. My concerns with doing that were cost (I think it'll cost more than $50, ie the cost of my exh manifold, to make the necked-down pipe with 5 bolt flange) and also the possibility of losing exhaust velocity that close to the motor by having the collector/piping being soooo large.

If you could find someone to make this pipe cheap... go for it. My concern #2 is just my personal opinion, which could be easily changed with someone posting actual results. You can checkout my O2 Sensor page for a step by step on how I moved the two downstream O2 sensors. (follow the links on the site in my sig.)

 

Hehehe.... me too.

 

Phil,

Now that you eliminated BOTH precats can't we have CUSTOM headers made? What kind of gains would be reasonable? Maybe Cattman would be interested in making these. I believe he said his shop has the capability of making headers or Belangers probably could.

Have you noticed a DROP in RPMs in TOP gear at a constant speed vs. before the Y-conversion? Just wondering if the increased flow allows the engine to cruise easier at higher speeds. I hate how high the RPMs are at 75-90mph. I know you have an AUTO and I have a 5-speed so exact RPMs aren't relevant, but I'm just trying to justify spending $450 on a Cattman Y-pipe, $100 on a FED exhaust manifold, and $??? on installation for only 15 hp and 8lb./ft. torque.

Is it possible for you to get a sound clip of your exhaust up on your website? I want to decide on how quiet of a muffler to choose.

 

so des....the part where the flanges meet on the NLEV manifold is actually LARGER than the fed spec manifold?

if thats the case wouldnt it be better to use a 3inch pipe with a 5 bolt flange....for those of us looking to boost in the future...this setup would actually be more beneficial than a fed spec 3 inch? (just a guess)

 

Yes, the flange where the precat bolts up to the manifold is much larger on the CA/NLEV than it is on the Fed. I'm sure a 3" pipe would be easier to taper up to this larger flange than a 2" or 2.5" would be. And here's this arguement again:

Peak torque typically occurs at a point where your exhaust velocity is around 240-260 ft/sec. By increasing the diameter of the pipe, you are obviously increasing the cross sectional area, so to reach a given exhaust velocity (like 240ft/sec), you will have to pump more air through the exhaust... meaning more rpms. This essentially means that your torque peak will shift UP in rpms... say from 3700 to 4000 just to pull numbers out of my you-know-what. True, it may give you more top end just because it can flow more, but there is a limit to this as well. Smaller piping also provides more of a scavenging effect... actually helping to pull spent air out of your cylinders. If you don't have enough velocity, you will lose this effect and you will dilute your intake combustion mixture. I am no engine designer, so I don't know too many specifics regarding this, but I do know it to be true. Many V8 people have seen this first-hand. They drop in some humongous exhaust and find that they are making less torque down low than they were before.

Alex, I will try to post some .wav or .mp3 files of my current exhaust setup. This is a little tricky though. As I mentioned before with the audio files I have on my homepage, the "inside" recording sounded like my car before the y-pipe... the "outside" recording doesn't resemble my car AT ALL! I actually overloaded the mic by placing it only two feet away from my muffler. I went ahead and put it on my site anyways because it sounds really mean. Right now it looks like I will be removing the Greddy muffler and welding in my stocker with some new tips. Hopefully that'll get rid of my droning sound between 1500-2000 rpm as well as drop the dB level a bit across the whole rpm range.

P.S. You should be able to get a Fed exhaust manifold for around $50-$75 delivered.

 

hmmmm I wanted to follow your lead on this project but i couldnt find a left manifold....all 4th gens at carpart.com

but I think Im going to see what happens with a NLEV manifold with boost

 

I just searched for a left-hand side non-CA exhaust manifold on car-part.com and found 20 different places with a manifold for $65 or less... one was only asking $30.86 (plus shipping of course). If you are interested in doing the mod the way I did it, I'd search again. Of course feel free to have a custom pipe made to bolt up to the stock CA manifold. I'd like to see how that turns out too.

Alex, I haven't noticed a change in my rpms at a given speed. Looks like the only benefit is the extra HP... and maybe some fuel economy if you can keep your foot out of it.

 

Thanks for the information, experiment, and BATTLE scars!

Is it possible for you to put together a "best way" list for the conversion in the "How To" sticky section?

Basically, what steps to perform in what order, with what parts needed, tools, time to complete, etc.. necessary. I would like to know what gaskets, nuts, bolts, copper tubing length, wire guage, part numbers, etc... you used while it's still fresh in your memory. I plan on repeating your conversion withOUT the extra steps for the experiment once I move and have the extra cash, so I would like a "to do" list while your knowledge is at its peak. Thanks again, because without your conversion I would NEVER have considered doing a Y-pipe because I fear the unbalance of the exhaust with one precat could have caused long term damage. As far as I can tell the only side effect of the CALI-FED conversion with a Y-pipe is the cost and noise factor.

You might try a 50 or even 60 series Flowmaster muffler with DELTA flow to help reduce the resonance and noise level you now get with the Y-pipe.

 

hmmm...I see what you mean on car-part.com...but thats off of a 1996 maxima??

 

You can check with Nissan if you like, but the part number is the same from '95 through '00. The manifold I used on my car was from a '96.

 

I know it's already been said, but great job Desert Pearl! Since I already have a CA Cattman y-pipe, I looked into a custom pipe replacing the pre-cat and got a quote of $250. The guy said it was expensive because of the large flange and the tapering nature of the pipe. If you don't have a y-pipe and are planning to get one, Desert Pearl's set-up is probably the way to go. If you already have a y-pipe, then a fed exhaust manifold and a custom pipe (without the large flange) may be the least expensive. Unless you can get the Stillen pipe to replace the pre-cat for cheap.

 

Since both the Stillen (1st piece) and the Cattman CA spec Y-pipe are built to bolt up to the stock front precat, you might be able to find someone that has bought a newer Stillen (2 piece) Y-pipe but didn't use the 2nd piece because they had a CA car. That might be a way to get a cheap pipe that you know will fit right. Then you'd just need to relocate O2 sensors and buy a Fed manifold. I think I estimated about $90 for this... plus $50 or so for the Stillen 2nd piece. So the whole shibang would cost you about $140, plus labor. If the $250 is including install, that's not too bad a deal... depends on how much you feel your labor is worth!