Full 3 inch exhaust: to load on a 87 300SDL? - Page 2 - PeachParts Mercedes-Benz Forum

Junkman · #16 08-12-2010, 09:59 AM

I'd pull the old exhaust off and buy 3" mandrel bend pipe to replace the curves. Mandrel bends can be bought all the way to 180* bends & cut to match most factory bends. Buy enough 3" straight pipe to connect the pieces. A local shop can do the install using the stock flange. Perhaps have a machine shop modify the flange if appropriate. Around here, cash gets a better deal.

babymog · #17 08-12-2010, 10:05 AM

I've done this with 6" for one of my coaches, had the pipes butt-welded instead of clamped, made a really nice 304 Stainless Steel system for much less than the OE aluminized steel system.

latitude500 · #18 08-13-2010, 05:34 PM

Anybody purchase any products from these guys, they seem really inexpensive when it comes to stainless steel pipe, 45 degree bends and flex pipe.

Almost to good to be true.

http://performance-curve.com/3x6flexpipe-3ply.aspx
And for 409 stainless steel 45 bend that is mandrel bend it's only $18.00.

http://performance-curve.com/245degreemandrelbend409ss-1-1-1.aspx

Way cheap, Yes, I'm thinking of building my own system.

Lowflyingbird · #19 08-13-2010, 10:26 PM

KLG Stainless
They sell 304 in a dull looking I believe annealed grade , and in a sanitary/food grade shiney (not polished)304. I have not found any place that beat their prices for mandrel elbows, reducers, V bands, or fittings.

I bought from them many times.
I plan on starting my 3" stainless exhaust tomorrow.

Lowflyingbird

babymog · #20 08-15-2010, 10:25 PM

Quote:

Originally Posted by latitude500

Anybody purchase any products from these guys, they seem really inexpensive when it comes to stainless steel pipe, 45 degree bends and flex pipe.

Almost to good to be true.

http://performance-curve.com/3x6flexpipe-3ply.aspx
And for 409 stainless steel 45 bend that is mandrel bend it's only $18.00.

http://performance-curve.com/245degreemandrelbend409ss-1-1-1.aspx

Way cheap, Yes, I'm thinking of building my own system.

409 stainless is NOT what you want, it is what GM used for some of their "stainless steel" exhaust systems, and they aluminize the surface to give it a bright finish. It is not a non-magnetic stainless, does not polish well, and does rust.

You are probaly looking for a 304 stainless system (or 308, 316, whatever you find in a 300-series, 304 is standard non-magnetic stainless).

It will stay nice much longer.

Lowflyingbird · #21 08-29-2010, 11:00 PM

Here is what I welded up from 3" mandrel bends and straight pipe all 304. I kept the turbo flange, tab to transmission mount, & rear muffler hanger. I only have to hear it before installing the turn down tip. If it sounds good as is, then I just weld the tip. If it needs a little more smoothening, then I have a Vortec header insert to shove it the turn down.

jonbobshinigin · #22 08-29-2010, 11:17 PM

Can you get a list of parts that you used? Also, a video would be GREAT!

vstech · #23 08-29-2010, 11:33 PM

did you mig it? I have a decent mig setup, and a spool of SS wire, but my shield is co2/argon mix, I gotta either get an argon tank, or I wonder if I could use Nitrogen... I got plenty of nitrogen... can it be used with SS?

edit:
wow, long info on welding SS... short answer, no.
long answer...
Stainless and Nitrogen Purge Gas Question.

Ed as you are aware Nitrogen is a lot cheaper than argon when utilized as a purge gas for stainless. My question, When MIG welding stainless tanks edge or corner welds, tube or pipe open root welds, can nitrogen react with the stainless and have a negative impact?

Answer: Nitrogen has a diatomic, "two atoms" per molecule. Nitrogen in the diatomic form is usually insoluble in molten stainless. However if the nitrogen gets into the weld arc, the plasma arc energy can seperate the diatomic molecules and create monatomic molecules.

The monatomic molecules are soluble in the weld. The nitrogen, monatomic (seperated molecules) become an alloying element and can reduce the ferrite in a stainless weld. A reduction in ferrite in some alloys can cause the weld to be more austenitic and sensitive to hot cracking. If nitrogen enters a weld or the welding arc, it can have a negative and sometimes a positive influence. Thats the reason one of my gas mixes for duplex has the addition of nitrogen, and the other gas mix does not.

There are stainless alloys which do not need ferrite like 320 / 310. With these alloys nitrogen has no negative impact on these alloys. Also if the stainless alloys have high ferrite levels they typically can afford to loose a little of the ferrite to the nitrogen.

With closed root, austenitic stainless welds, as found in tanks, corner, edge welds, or thin gage, partial penetration tube welds, nitrogen is the logical, economical, purge gas choice for all austenitic, duplex, martensitic and precipitation hardening stainless steel applications. The only concern would be a few specific, ferritic alloys in which nitrogen could cause severe weld mechanical issues.

Lowflyingbird · #24 08-30-2010, 05:32 PM

All said and done, I used three 3" 90 deg. elbows from KLG stainless. I do not remember who I bought the tube from, probably off ebay. The Magnaflow muffler from Performancepeddler on Ebay $54. The pair of 1/2" thick 3 bolt stainless header flanges off Ebay too $? Thin stainless solid rod for hangar $4. I use 75/25 argon/Co2 mix gas with my stainless wire in my MIG, it works fine for rough work. I heard now they offer a tri gas mix which is about $5 more and is perfect on many metals, have not used it yet. I spent about $120-140 in materials.

Gillig · #25 08-31-2010, 08:13 AM

Cut out the mufflers and replace them with hardware store exhaust pipe. Will cost about $20 in parts and about an hour labor.

pawoSD · #26 08-31-2010, 05:44 PM

Quote:

Originally Posted by Lowflyingbird

Here is what I welded up from 3" mandrel bends and straight pipe all 304. I kept the turbo flange, tab to transmission mount, & rear muffler hanger. I only have to hear it before installing the turn down tip. If it sounds good as is, then I just weld the tip. If it needs a little more smoothening, then I have a Vortec header insert to shove it the turn down.

I see a complete lack of a flex pipe to compensate for engine movement. That is going to vibrate a lot, and put a lot of strain on the turbo, exhaust pipe, and exhaust mounts. Was this taken into consideration?

Lowflyingbird · #27 08-31-2010, 08:11 PM

Hi,
There is no flex pipe on these generation cars, turbo or non-turbo.

scottmcphee · #28 08-31-2010, 09:16 PM

Cutting out the cat converter is a simple $30 fix that can unrestrict your exhaust probably more than an extra 1/2 inch on the tube.. I'm just saying.

pawoSD · #29 08-31-2010, 11:22 PM

Quote:

Originally Posted by Lowflyingbird

Hi,
There is no flex pipe on these generation cars, turbo or non-turbo.

I think you are massively mistaken....you'll learn when the turbo or other mounts are damaged....The diesels like the move around quite a bit on their mounts.

In fact, just about every car's exhaust I have ever seen has some form of flex pipe on it near the engine.

nickofoxford · #30 09-01-2010, 12:26 AM

my personal preference is a 4" straight pipe. sounds awesome and almost as deep as a straight pipe cummins while retaining the high pitched cry of the turbo.