The Federal front O2 sensor is located in the front downpipe.

 

Exactly.

 

Why do this? If won't make hardly any difference between the Fed and Calif model. By swapping out the ypipes is where the main increase is. The other increase is the ECU programming which you can not change. By swapping just the manifolds you are doing nothing to gain any HP.

 

Different car, different conditions does not mean they have less HP. Also different Dyno machines. The manifolds have different part #'s but internals are identical basically except a hole for the extra o2's. You will not gain any HP guranteed by doing this. Doing the YPIPE the 2k1 calif ones will gain more than the fed cars because of the extra emissions are located on the ypipe thereselves.

 

You obviously are new to this topic, so I'll hash over it again.

If you upgrade the y-pipe on a '00 CA emissions Max or any '01 Max, you only replace one not both of the pre-cats. The first precat is somewhat build into the front side exhaust manifold. By doing the manifold swap, I'm allowing myself to install a federal spec y-pipe, thereby eliminating both precats instead of just one.

This is the idea behind the O2 sensor relocation and the federal exhaust manifold.

And one comment on the dyno results. It's very funny how they match up at high rpm, but don't at low rpm. I can't see how a different dyno or the fact that they are different cars plays into these results.

 

Doesn't matter if it does match up or it doesn't, still different conditions mean different results on the dyno. Unless we have hard evidence of 3-5 fed and 3-5 calif cars dynoing side by side, that will prove that there is a loss.

Now let me ask this. The ypipe that you order for calif emissions from cattman, etc, it comes with a precat on it already just one instead of 2? If so, I think I understand now what you are trying to say. By getting rid of teh front manifold you basically do not have to order cattmans calif model with the precat still on it correct?

 

Nope. The Cattman CA Y-pipe connects to the front downpipe, not to the front exhaust manifold. It leaves the stock front pre-cat in place.

What I've heard is that the closer you are to the exhaust valves when you remove restrictions, the better. Thus removing the front pre-cat should have a substantially greater impact on performance than, say, installing an HKS rear section. And as we all know, the HKS rear section is good for 10 hp all by itself, right?

And as far as the ECM is concerned, once the main cat fires up, I doubt there's any difference in timing curves between a CA-spec and Fed-spec Maxima.

 

uhhh makes me wonder...if the only reason you are changing manifolds is to get the ypipe to fit then why dont you just get a custom downpipe done?

and i think russ has a point...the ecu has to effect the cali spec cars in some way...

 

Here's a couple of reasons:

1. A custom downpipe to replace the front exhaust manifold would be more costly. I found a Fed spec manifold for $50 delivered.

2. When you buy the Stillen y-pipe, the second piece is basically free. Most people with CA cars, wouldnt' use the second piece and just leave it lying around in their garage.

3. If you did make a custom downpipe to replace the front precat, I don't think it would help very much. Have you seen how the stock front precat bolts up to the front manifold? That outlet on the manifold is HUGE. If I tapered a piece of pipe down to fit the CA y-pipe, I am concerned with the opening being sooooo large. Remember if you are passing air through a larger pipe, you get less velocity and therefore less scavenging effect and you actually start to "dilute" your fuel mixture by leaving burnt air/fuel in the chambers. This is the same logic behind all of the V8 guys saying "bigger isn't necessarily better... you need some backpressure". Many, many people have put humongous exhaust on their cars only to find that they have lost all bottom end on their motor. Just a little side note here... the torque peak on most cars occurs when the exhaust velocity is around 240-260ft/sec. Bigger pipe = more revs to reach this velocity = torque peak at higher rpm. I don't know about you, but my auto is already terrible on the bottom end. I don't want to make it any worse.

Finally regarding the ECU differences between CA cars and Fed cars... I have yet to hear any solid evidence regarding any of these. I am hoping that the CA ecu is only checking for the existance of precats... not making adjustments based on their readings. It is my belief that this is the case and it's only using the initial two O2 sensors for the A/F readings, but I'm no expert on ECU programming.

I am planning on getting dyno results with the entire setup installed and then reinstalling the stock y-pipe and dynoing again. This sounds like the easiest way to do it since the manifold/precat swap will take a lot longer than bolting in a new y-pipe.

 

so just to clarify...

there is no difference in the flow between the CA/NLEV manifold and the FED manifold right?

the only thing thats different is the bolt pattern to the Y?

 

There has to be a difference. The presence of the extra precat itself makes for a more restrictive manifold. Plus, the fed manifold provides equal exhaust paths, which the cali spec does not.

 

I'm still not sure about one thing...
The fed setup has two small and easily removable precats, and the Cali has one small precat and on big precat which is hard to remove, right?

 

The Fed-spec Maxima has NO . . . that is . . . ZERO pre-cats. The CA-spec Maxima has TWO pre-cats. Both the Fed-spec Maxima and the CA-spec Maxima have ONE main catalytic converter. And there is no such thing as an easily removable pre-cat.

 

that blows...so essentialy the precat is part of the manifold?

that means you wouldnt be able to see it and would have to remove part of the undercarriage to access it right?

 

OK

 

On a CA emissions Max, the front exhaust manifold connects to a pipe (called a three-way catalyst manifold) containing one of the pre-cats. The rear exhaust manifold connects to the y-pipe which contains the second pre-cat in one arm of the "y". The three-way catalyst manifold connects to the other arm of the "y". The y-pipe then joins the main catalytic converter. Both the three-way catalyst manifold and the y-pipe can be accessed from under the car.

 

I couldn't have said it better. The only thing I have to add is that the flange bolting the front-side exhaust manifold to the "three-way catalyst manifold" (ie precat) is a goofy 6-bolt flange (or maybe it's 5 or 7... you get my point). It is much bigger around than the "collector" on the Federal exhaust manifold. I will have pics on my site in the VERY near future... like Saturday or Sunday. You can check out the differences then if you'd like. Also, I will be posting dyno numbers on my site tomorrow night (with the main part of the Stillen y-pipe) and also on Monday night (with the Federal exhaust manifold conversion). I will also post info regarding any problems with this mod (ie check engine lights, etc).

 

I'm going to be gone this weekend and next week and am looking foreward to your results. I know I'm being lazy, but are you going to post on this thread, start a new thread or post only on your site? I just hate scrolling through a weeks worth of posts.

 

I will post another thread, but the info will be on my site also. I just finished removing my y-pipe. I'm all ready for the UPS guy tomorrow!

BTW, the front precat has a 5-bolt flange.

 

alright man good luck!! i hope everything works well!!! cause if this does it will ROCK!!!

 

hey there desert pearl. I have the same car as you..I wanted to ask you if your maxima's check engine light had come on...and what did you do.
I actually took mine to nissan and they said 3 of my 02 sensors were out..I was planning to replace them..but, they're so dang expensive. Would it be cheaper if i bought the sensors and replaced them myself..well, my boyfriend anyways. haha. Since then..my car has been stalling alot, and I don't know if it affects the gas mileage thing..but, i haven't been gettn' good gas. you seem to know alot about this..and seeing that you have the same car..pleas give me some advice!! thanks.

 

WHAT THE FCK !!!!

Hollyoldthreadthisisbatman...

Dude lol wait im a little tipsy ahahahah lol omg ahahah lol ahahah yo first off dont trust nissan for sht second go to autozone have them check your coded then come back on the org read the stickies for your code and find you solution man

 

Buy em from Dave Burnette at South Point Nissan, whose number is in the FAQs, and replace em yourself (or have your boyfriend replace em). If your primary O2 sensors are faulty, they will affect your mileage.

 

holy mother of all ressurections! None of the original posters are even around anymore...

 

I'm still around... just not into the Maxima scene anymore.

Well, I tried to PM you, but your account isn't set up to do that. Your symptoms do sound like O2 sensor problems, so I believe the dealership, however we still don't have enough information. Here's what I'd recommend. Go to AutoZone as recommended above. Have them pull your codes and tell you exactly which sensors are faulty. They should have replacements, probably made by Bosch. If they are complete replacements with wiring harnesses, then the installation would be easy. Try not to buy ones that require splicing or soldering to install, as this is difficult to do with the type of wiring used on these sensors. You can always price out Nissan replacements from dealerships that are friendly to our board such as Courtesy Nissan. They usually give discounts if you mention this too. The only problem is that you have to wait for shipping. Feel free to email me... that way you won't get slammed for resurrecting 5 year old threads. My email is on my Maxima site which is linked below in my sig.