I have a possible customer who needs new stainless steel exhaust for his 1969 Mercedes-Benz 300SEL 6.3 V8. The goal is to retain the same powercurve as stock, I believe the car is for full restauration, so power gain is not a goal. Headers will be left stock.

The situation: exhaust is off the car, I get the exhaust, JIG it, and build from there. Exhaust tunnel under the car is not big, it's pretty much only for stock exhuast, so I need to retain stock exhaust dimensions.

Here are few pictures provided by customer:





Also few dimensions I requested, provided by customer: outer tube diameter 50.8mm (2"), so I think inner is somewhere around 47-48mm (~1.88"). Middle resonator is 340 x 240 x 100mm (13,4" x 9,5" x 4") and rear resonator 610 x 240 x 100mm (24" x 9x5" x 4").

The first idea was to get resonators and pretty much copy the exhaust using 2.1" tubes. The problem is that I can't get MagnaFlow resonators with two inlets/outlets for 2-2.1" tubes. MagnaFlow has that type resonators for 2.25" and up, but there is still a problem with them - the gap between inlets/outlets, as you can see in pictures, there is pretty much no gap at all, and MagnaFlow resonators are just a tad smaller, so I don't have much place to get the tubes line up MagnaFlow...

Second idea was to make a 2-1 exhaust - get two 2.1" tubes join in one bigger, but options are also quite limited - 2.5" / 3". Not sure though.

So, if I try to make something like stock exhaust my only posibility would be going 2.25", that pretty much 3/8" larger then stock inner diameter, I'm pretty sure it's gonna raise power curve to around 1000-1600rpms, which as you may understand is quite a bit for large + old V8. If my math/understanding is correct, the area of two 2.25" ID tubes is 141% of a stock exhaust.

Then there is a sescond chance going 2 tubes into 1 tube. 2.5" ID area is 78% of a stock diameter area. 3" ID area is ~116% of a stock exhaust, which is same as of two 2.02" ID tubes. 2x 2.02" ID tubes would raise powercurve ~ 600-700rpm up, so if my math really is correct, this would be the best bet.

The biggest problem is that I dont know how to make my own resonators... This one calls for me learning how to do it.

So, ok. I really hope that some of the experianced fabricators on here could chime in and help to decide how to go about this. Also maybe there are other adivces or options I haven't thougt of.

P.S. Also... I have to say I dont know the answer... customer asked me - why all the factory v8 come with two tubes not 2-1 system? Maybe someone has an idea? I have few ideas why it is so, but really not sure

P.S.S. Need some ideas ASAP, cause I'll meet customer tomorow, need to get some inputs on all of this.

Thanks, cheers!

 

I can't see pics at work, but if I understand correctly it seems as though you need to expand the diameter of the tubing at the inlet and exit of the resonator. There are tools to do that task. Any good exhaust shop has an exhaust reducer/expander and possibly a bender.

Pic:

 

Thanks for replaying!

That for you in US... we here don't have good exhaust shops and such things yeah, it would be possibly one of the options to somehow reduce diameter at the inlet/outlet of the resonator... but that's quite a bit of reduction needed - from 2.25" to 2.1"

 

those things are useless from my experience. i broke one trying to expand perforated tube.

i wouldn't build the exhaust without the car. building it from a jig based on the oem unit will not guarantee you proper fitment. be adamant about this with him. YOU NEED THE CAR to ensure it will fit properly.

a 2.25" should slip over a 2.1" with about .025" of play if you go that way. if not, just step it up in size. he needs to realize this isn't a car that has easily accessible parts/material to make new parts. that comes with a premium cost too.

 

I was thinking of building it, tacking it strong - something like 6 tacks on a joint, then giving it back to him for a test fitup.

The problem with 2.25" vs 2.1" is that as far as I know, MagnaFlow has ID of a 2.25" and 2.1" is the outer diameter, so, there's quite a difference...

Thanks for input!

P.S. let me know what you think of that tack welded exhaust fit-up test...??

EDIT: I'm not really sure in what condition the car is now, is it movable and so on... if you get what I mean... but if he's not able to give me car, then the only possible way for me is to let him know of a possibility that something may not fit of fit good... and if his ok with that, what the hell if thats not on me...

 

I'd tell him, without the car, not doable.

Car is going to pick up horsepower regardless, you're putting magnaflow mufflers on it lol. If you can get the car, go with what you can go with. If the car was a TRUE resto, he'd buy a brand new exhaust from Merc.

 

I'm relatively new to this forum, but not so new to the "fab" world. I figured another opinion couldn't hurt lol, what I would do for your magnaflow to pipe fitting issue is get yourself a cone, like from vibrant or someone that's 2 inch on one side and atleast 2.5 on the other (doesn't matter as long as its bigger than the magnaflow side) and lay out your 2.25 and your 2.1 and trim the cone to connect your pipes to your mufflers.

P.s. if u can't find a cone that will work I have a local supplier I get my stuff from, just pm me

Joel

 

Why not just make it dual to single back to dual at the tips? Is the resonator and muffler actually a divided enclosure?

 

def. do not do it without the car, the tollerences you are going to have to deal with are far too tight to be delt with by jigging, without the car youre setting yourself up for failure.. just my opinion

 

Thanks, thats one more idea

If you talk about those 2.25" 2 inlet/outlet resonators, I'm not sure are they divided enclosure or not, their MagnaFlow