02 Flang size, car @ Cust exhaust shop, say no go

[madmader]

I have my car at a exhaust shop in there to get 3 inch turbo back. They now tell me that they want to keep the stock downpipe tell after the flex then add 2.5 back.

The guy says the 2g o2 flange won't hold bigger then 2.25. Is that true? I was going to put an evo o2 on there but I never got it in the mail.

Advise?

 

[vr4play]

When I had a 2.5" downpipe it fit the stock o2 housing.

 

[Enraged78]

I have my car at a exhaust shop in there to get 3 inch turbo back. They now tell me that they want to keep the stock downpipe tell after the flex then add 2.5 back.

The guy says the 2g o2 flange won't hold bigger then 2.25. Is that true? I was going to put an evo o2 on there but I never got it in the mail.

Advise?

Every 3" downpipe I've ever seen necks down to 2.5" for a few inches to mate to the O2 sensor housing. A 3" pipe will not clear, as there is not enough room. The buschur 3" stainless pipe I have necks down to 2.5" for about 4" in length, then grows to 3". A 2.5" pipe will fit without a problem, but you need a 2.5" flange to mate it to the O2 sensor housing. It WILL fit. DSMers have been doing this for years. Check Buschur's picture of their 3" downpipe, and you'll know what it will have to look like. I have had to file down downpipe gaskets to get them to clear the O2 housing, but it does in fact fit.

Matt.

 

[FORMONTOYA]

Every 3" downpipe I've ever seen necks down to 2.5" for a few inches to mate to the O2 sensor housing. A 3" pipe will not clear, as there is not enough room. The buschur 3" stainless pipe I have necks down to 2.5" for about 4" in length, then grows to 3". A 2.5" pipe will fit without a problem, but you need a 2.5" flange to mate it to the O2 sensor housing. It WILL fit. DSMers have been doing this for years. Check Buschur's picture of their 3" downpipe, and you'll know what it will have to look like. I have had to file down downpipe gaskets to get them to clear the O2 housing, but it does in fact fit.

Matt.

Correct. My Hahn Racecraft DP is the same way, about a 4" or so portion that flares out from 2-1/2" to 3".

http://www.hahnracecraft.com/hahn/parts/ejr.htm

 

[Strm Trpr]

I had a Megan Racing DP on my GST.
It is 2.5" til after the flex section, and then 3" all the way back, but then it necked down for mating to the stock cat-back.
Here's a link to a post of mine that shows the pic of the DP.
Print that pic and take it to your shop and ask them to make it work because it does work.
http://www.dsmtuners.com/forums/showpost.php?p=1619763&postcount=62

 

[lasertim]

I am batteling that same problem right now. I have 3" stainless DP that necks down to 2.5 but only for about an inch. The studs on the stock o2 housing ride right on the 3" section of DP so you cant get the nuts on.

Does an EVO III o2 housing have a wider spacing that allows fittment of a 3" DP? I really dont want to fork out the extra $ for a tubular when I will be eventually be upgrading turbos and buying one then.

 

[madmader]

Now the guy is telling me that the o2 housing is an 2 inch, and he can't fit a 2.5 on it. So he is leaving it up to me to get somthing on there whell he puts on 3 inch from after flex back.

What should I do?

 

[Strm Trpr]

I am batteling that same problem right now. I have 3" stainless DP that necks down to 2.5 but only for about an inch. The studs on the stock o2 housing ride right on the 3" section of DP so you cant get the nuts on.

Does an EVO III o2 housing have a wider spacing that allows fittment of a 3" DP? I really dont want to fork out the extra $ for a tubular when I will be eventually be upgrading turbos and buying one then.

I now have a big bad ass 3" thru flex section Megan DP, and it almost ate my stock ported O2 Housing.
It does neck down to 2.75" for the first 1"-1.5", but there's no way the nuts would fit on there.
I opted to buy an Evo III O2 Housing from SBR, and to answer your question, yes the Evo Housing is much larger, and the bolt spacing is larger too.
I have to modify my DP to fit the Evo Housing because of the flange angle, and the clocking of the bolt spacing.
Here's a link to a thread that talks about putting a Megan DP on an Evo O2 Housing with pics to show you the differences. Check out post #8. http://www.dsmtuners.com/forums/showthread.php?t=226596

 

[oldman]

What should I do?

2.5" to the flex, it won't be a perfect fit but as long as you keep it centered, it will fit and hold.

 

[lasertim]

I now have a big bad ass 3" thru flex section Megan DP, and it almost ate my stock ported O2 Housing.
It does neck down to 2.75" for the first 1"-1.5", but there's no way the nuts would fit on there.
I opted to buy an Evo III O2 Housing from SBR, and to answer your question, yes the Evo Housing is much larger, and the bolt spacing is larger too.
I have to modify my DP to fit the Evo Housing because of the flange angle, and the clocking of the bolt spacing.
Here's a link to a thread that talks about putting a Megan DP on an Evo O2 Housing with pics to show you the differences. Check out post #8. http://www.dsmtuners.com/forums/showthread.php?t=226596

Thanks, I gotta weigh my options now. I am not going to dick around with cutting and re-welding my DP. I will just have to keep an eye out for a used tubular.

/whoring. You can have your thread back

 

[madmader]

2.5" to the flex, it won't be a perfect fit but as long as you keep it centered, it will fit and hold.

I was told by him a 2.5 won't fit at the 02 housing because the flang mounting bolts are not spread far enough apart.

 

[lasertim]

I have seen on more than one DP where they dent the DP tube right where the nuts go. Just a little bit though, not much.

 

[oldman]

I was told by him a 2.5 won't fit at the 02 housing because the flang mounting bolts are not spread far enough apart.

I don't get it, there are tons of people running stock O2 housing with a 2.5" flanged DPs, myself included on my old setup, a 1G o2 no less. Without seeing the type of flange he's using, I can't comment further on why he can't make it work. He can also either enlarge the stud holes on the dp flange or remove the studs on the o2 housing, drill and enlarge the O2 flange and use nuts and bolts instead.

 

[vr4play]

I didn't have a problem bolting my standard 2.5" flange to my stock o2 housing, but if this guy is having problems, why doesn't he use a slotted flange? I know from experience that some shops are too lazy to build the down pipe and will suggest cutting the existing after the flex section and adding on from there. The shop that built my 3" exhaust cut my 2.5" downpipe after the flex and added on. They came up with all kinds of excuses why they couldn't give me 3" all the way.

 

[madmader]

Well i get the filling from them that the guy who is talking to me is not wanting to do it, or don't have the supplies to do it with. But all and all he won't stright forword tell me that.

 

[GVR4592]

Find somebody that is qualified and willing to do the work, the guy sounds like a lazy ass.

 

[trebornash]

Really, find a real custom exhaust specialists
With a mig,some tubing,a bender,a chop-saw,and a torch you can do anything.
I took some 3.5" mandrel bends off a F350 diesel tailpipe and used'em for my downpipe and rear under axle bend to muff.I welded in a new threaded O/2 bung/nut for sensor to screw back into where stock O/2 hole was on the intermediate pipe"new stick of 3"alluminized tubing".I cut the factory flange off the old downpipe and ported to 2.5".got 2.5" gasket from Mits.and butted up my 3.5"F350 mandrel to it.Added a 3"x10"flex tube.Tacked all the factory ground wires back in place.
I'm sure a 1G wouldn't be that much harder.
So when it comes to fabricating exhaust there's no limit,it can be done.

 

[Nanan]

Unless you get a tubular O2 housing you are going to have a 2.5" neck on the DP where it connects to the O2 housing. I have an Evo3 O3 housing and it still needs that neck, as said above the 3" diameter is right where the bolts are.

 

[madmader]

Well, I got a message saying it is done. Will see tomorrow what ,"is done" really means.

 

[madmader]

Well i got it back. It is like they said, 3 inc back after the flew at the down pipe. There is a resignator i had them put in about where the cat was. Has a magniflow muffler.

Even with the stock down pipe I can fell the diffrance. It sounds deep, and only gets depper when hammered on. At ideal it sound stock, only when i boost it starts sounding really deep.

A++

 

[trebornash]

Which Magnaflow muffler did they use?Got any pics? MAGNAFLOW

 

[tstkl]

dejon tool's told me a ported evoIII o2 housing can use a 2.75 inch downpipe.

 

[madmader]

5" x 11" Oval Offset/Offset Satin Stainless Steel Universal Muffler 3"
I'll make sure after work, i'll also shoot a part number up here later.