OK, I've been bouncing back and forth about installing a Y-pipe for quite awhile. I'd love the extra power but I'm concerned about three issues:

1) Legal issues
2) Warranty issues
3) Mechanical issues

I don't want to get into the legal and warranty issues here. What I really want to discuss is a mechanical issue that sprung posted in a previous thread, an issue that I've heard before and that NOBODY seems to be willing to address. I've copied sprung's post here for reference:

I've thought long and hard about the y-pipe, still do. The reason I haven't done it yet may be unjustified but I can't help thinking about it. Because I have a Cali emissions Max the Y-pipe for my car only eliminates 1 of the pre-cats. This somewhat concerns me to have each side of the motor breathing differently. This thought became more of a concern when I read someone's post about how a dented y-pipe can cause one side of the motor to run leaner than the other b/c of the difference of flow.

I'm not really sure if it's even a problem but it just doesn't sit right with me . . .

Frankly, it doesn't sit right with me either. My question is, would the Y-pipe create long-term engine damage on 5th Gen Maximas by causing each side of the motor to breathe differently?

[Edited by y2kse on 01-01-2001 at 03:34 PM]

 

why you gotta say this when i'm about to buy my Y-pipe!!!! hehe....

 

Yeah. I know. I hate to be a party pooper. But I intend to keep my Maxima for a long time and it just doesn't make sense to risk shortening my engine life for the sake of a few more horsepower.

I'm hoping that someone like Daniel B. Martin will show up and give us their view. We really need someone who knows their **** to comment on this.

[Edited by y2kse on 01-01-2001 at 03:09 PM]

 

well, i'm planning on keeping my car for a long-time too.
but that's not going to keep me from modding my car to my taste.
if my engine blows up, or seizes, then i'll just get a new engine put in!!(even better).
but, i can say these things with confidence cuz i know it'll be a long~~~~*** time before my engine will come to that sorta conclusion.
i guess my point here is, enjoy the drive!

 

That works for me. Let me know how your install goes.

 

Very interesting. 52 views and no-one has attempted to answer my question. Guess I'll keep posting by myself for awhile just to keep the thread alive.


[Edited by y2kse on 01-01-2001 at 08:59 PM]

 

I was starting to think I was the only one concerned about this! I haven't taken much of an active role in getting an answer but I would still like to know. Since no one here really knows (or hasn't said so if they do) I've been taking the wait and see approach. Quite a few people have them now so I'm going to wait and see if anything develops...
Hopefully this thread gets more attention than my original post.

 

most of the gains in the 5th Gen Y-pipe have to do with the improved exhaust flow inherent in the design of the Y-pipe rather than with removal of the rear pre-cat. If that's the case, I can't help but wonder if it would be possible to create a Y-pipe for 5th Gens that continues to incorporate a rear pre-cat. Not only would such a Y-pipe be legal for street use, it would also remove any flow imbalances between cylinder banks.

Whatcha think of that idea?


[Edited by y2kse on 01-02-2001 at 12:33 AM]

 

I don't know the answer to the lean problem, but if you keep the rear pre-cat, it'll defeat the purpose of the aftermarket y pipe. Removing the precat = taking out the restrictive part.

 

I guess that's the crux of the issue, Kev. Over time, does it hurt the engine to remove the restriction from only one bank of cylinders?

 

I think Kev is right, removing the pre-cats is where the benefit of a y-pipe comes from.

 

I don't know enough to give you an answer... the 4th gens aren't like this right? I think 2 cats are removed...

 

Yes. Both pre-cats are removed in the 4th gen.

 

I asked a friend of mine this question(who builds import and domestic engines for a living) and he said you shouldn't worry about a problem at the moment but since one side of the engine has to breath harder it will over time throw off the natural balance in the engine. Also could damage piston rings(again over a long time)...so he also suggested that anyone who is concerned about this should try to cutout the other pre-cat. I don't know if that can be done...but hope this helps.

 

I think the reason Stillen and Cattman don't make a Y-pipe that removes the front pre-cat is b/c that pre-cat assembly is actually part of the exhaust manifold on the that side of the motor. So what we really need is a for a company to make us a set of headers...wouldn't that be nice.

If they can make headers fit in those Accord V6's, CL's and TL's I'm sure they can come up with something for us! We need to put the pressure on.

 

Thanks for the info, blackmax2000. That confirms my suspicions. I'm certain others will find your friend's revelation interesting as well.

The front pre-cat is actually a part of the exhaust manifold. I don't think it can be cut out. I heard that some people tried to gut the front pre-cat, but apparently that drove the O2 sensor wild and it threw a check engine light.

[Edited by y2kse on 01-03-2001 at 01:56 PM]

 

I think the 4th gens have aftermarket headers available, but they cost over $1000. It'll be very nice to have headers... maybe someone can do a custom header and have the shop produce more of them?

 

Sounds good. But what about the O2 sensors on each side of the front pre-cat? Wouldn't they still freak out if they didn't see a reduction in emissions when the engine was cold?

I just don't see any way around this. The only logical way to balance the flow for each side is to install a pre-cat on the section of the Y-pipe connected to the rear cylinder bank. I doubt any Y-pipe manufacturers would be willing to do that.