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+--- Thread: downpipe and the rest of the exhaust for 617 turbo (/showthread.php?tid=6244)
downpipe and the rest of the exhaust for 617 turbo - MTUPower - 02-16-2015
I still have a AirResearch stock turbo for my 617-95X. I believe the next modification which will produce the most effective increase in power is a larger exhaust. Since I have a small hole already in my downpipe I want to change it out to what it will eventually be. I believe I may end up with a HX30 turbo. I don't have alot of money so give me your thrifty suggestions. I want to increase to a 3" exhaust overall and keep the a (or the) center muffler. I don't want to be loud- but it's already louder than stock as I removed the rear muffler and put a straight pipe in for under $20.
Help me out with ideas and suggestions....
RE: downpipe and the rest of the exhaust for 617 turbo - barrote - 02-17-2015
if u have a waste gated turbo , wich i think it is, u can build your exaust as direct as u can (big radius turns , change path) and install a exaust mufler at the end. noise wont be that bad. the thing with the 3" is that u may not need that big. that will depend on your turbo exit.
remember bernoulli´s law "any increase in section diameter will result in increase in pressure and decrese in motion. oposite will happen for decrease in section, with the bad thing will be the gain in velocity, and for more velocity more power is needed.
so calculate your best diameter and go for a direct exaust.
good luck
RE: downpipe and the rest of the exhaust for 617 turbo - raysorenson - 02-17-2015
I recently built a 2.5" exhaust for a 617 engine swap and re-used the mercedes muffler, but not the middle resonator. The muffler was actually built for 2.5" tubing but the actual size of the mercedes exhaust is about 4mm less than 2.5". Going to 2.5" is about a 15% increase in area on an exhaust that's already more than adequate. Another thing I noticed is that the bends in the Mercedes exhaust were compression bends. The tubing diameter reduced in the bends. Going to a 2.5" with cut and welded mandrel bends, which is what I did, eliminates area reduction in any bends.
If you have a band saw and a tig welder, this is cheap. If you go to an exhaust shop and ask them to build a 2.5" exhaust system, it will probably be the worst comprression bent shit you can buy unless you pay them 4 figures to cut and weld mandrel bends.
RE: downpipe and the rest of the exhaust for 617 turbo - barrote - 02-17-2015
hy there,
i have a complete 70mm till the end , small mufller at the end, maybe not more than 30cm long in the inside. works great. really great makes less noise than some old MB with compete exaust. of course the turbine kills a lot of noise.
mine is a 124 , 605 ed.
tig and bends do the trick.
RE: downpipe and the rest of the exhaust for 617 turbo - Druk - 02-17-2015
If you can track down a seller of brewery or food manufactury stainless pipe it comes in 45 or 90 pre-formed bends and straight lengths and is 1mm wall and grade 316 or better. The bends are all true diam. Because it's for industrial use it was a whole lot cheaper than over-priced 'auto' stuff and better quality.
Mine is made from 2 1/2" mostly 45's tacked together then taken to a proper welder and TIG'ed. The rear silencer is Range Rover 3" and that was too noisy on acceleration so a cherry bomb got welded into the straight center section.
![[Image: alda015_zpsf41dfa93.jpg]](http://s62.photobucket.com/user/a10ruk/media/300TD/alda015_zpsf41dfa93.jpg.html)
![[Image: silencer2_zps3147337e.jpg]](http://s62.photobucket.com/user/a10ruk/media/300TD/silencer2_zps3147337e.jpg.html)
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RE: downpipe and the rest of the exhaust for 617 turbo - MTUPower - 02-17-2015
I don't have a TIG welder and after looking at the CL ad here they are too expensive to buy. Thanks for the other ideas; still interested in the downpipe info. I thought stock size for the exhaust was 2 1/2 inches already....?
RE: downpipe and the rest of the exhaust for 617 turbo - raysorenson - 02-18-2015
It's a metric tubing size. 60mm as I recall. It slips inside the 2.5" stubs on the stock muffler. If you look closely at the welds on the muffler inlet and outlet you can see.
Tigs are pretty expensive and you'll want 220v once you get one. I'm using an Eastwood tig200, it's $750 and uses 110 and 220v. It will do aluminum but it's not the best aluminum welding unit.
Another option is to cut the bends and tack them together with a MIG, then have someone else TIG them. You might be able to MIG the whole thing but I wouldn't try it. MIG is a PITA for butt welding thinner metal. Then there's the issue of accurately cutting the tubing. I've only tried it with a bandsaw, which is the ideal tool for the job.
RE: downpipe and the rest of the exhaust for 617 turbo - TKMad - 02-18-2015
Hey Ray, how does it sound with just the resonator missing?
RE: downpipe and the rest of the exhaust for 617 turbo - raysorenson - 02-18-2015
It hasn't been started yet. I'm waiting on it to warm up before I start on it again.
RE: downpipe and the rest of the exhaust for 617 turbo - MTUPower - 02-21-2015
Is the downpipe connection the same for the stock turbo and the HX30? If I make the downpipe 3" until the center muffler than back to stock size is that pointless?
RE: downpipe and the rest of the exhaust for 617 turbo - raysorenson - 02-21-2015
I wouldn't bother going larger than the outlet diameter of the exhaust housing.
To answer your question, exhaust loses heat and volume as it travels through all that plumbing.
RE: downpipe and the rest of the exhaust for 617 turbo - Captain America - 02-26-2015
Put it out the hood Brother!
RE: downpipe and the rest of the exhaust for 617 turbo - MTUPower - 03-02-2015
(02-21-2015, 07:00 AM)MTUPower Is the downpipe connection the same for the stock turbo and the HX30? If I make the downpipe 3" until the center muffler than back to stock size is that pointless?
I started the thread because I want a larger exhaust- and with my other mods a larger exhaust will free up some HP. However I'm not buying and installing a new turbo yet- so I want to install the exhaust yet still be able to use it with a new turbo. That's why I asked about the downpipe question... help please!