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#1
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300 SD straight pipe option?
Greetings,
This past weekend I was told that a straight pipe would make the 85 SD faster. I have read that these pipes make the car louder, but also return more power. Has anybody here done this mod to a 617 and what were your results? I am very happy with the SD and would like to avoid any headaches. Viva Cuba Libre, CubanDiesel |
#2
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Your SD isn't going to get any faster, or gain any more HP with a straight pipe. It'll just get louder.
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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate Sooner or later every car falls apart, ours does it later! -German Narrator in a MB Promotion Film about the then brand new W123. |
#3
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Itll help the turbo spin up faster but thats about it.
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1985 CA 300D Turbo , 213K mi |
#4
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Diesels aren't as sensitive to backpressure as gas engines. You might get up on boost slightly quicker but your gains will be minimal as the stock exhaust flows quite freely. Others have tried it here and the general concensus is the only real gain is noise. So if you are dying for attention go for it, otherwise save your money.
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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons ) white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank) desert storm primer 63 T-bird "The Undead" (long term hibernation) http://ecomodder.com/forum/fe-graphs/sig692a.png |
#5
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Louder, slightly faster boost, meaner sound, and 1-2mpg.
You won't get any more HP than you already have, you will just feel it sooner. I've run with a straight pipe for the last two years. I've even been thinking of adding a muffler. *shock*gasp*horror* straight pipe |
#6
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Forget the straight pipe.
But, I can tell you that removing the resonators is a perfectly viable option. I'm highly sensitive to noise and I was reluctant to do it. But, the pipes leading into and out of the resonators were shot and I figure that I'd roll the dice. Cannot tell the difference from the operation with resonators to the current operation without resonators. Whether the lack of resonators provide any increased performance due to lowered backpressure is unknown.......but, I'm doubtful. |
#7
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Straight pipe on my OM616 turbo for the last 3 years,no noise gain at idle and cruise,slightly aggressive note at higher RPM while accelerating,EGT went down,operating temps went down,even under hard driving,temps stay under control,MPG went up,so did throttle response and acceleration,I also modded the air intake for inducing fresh air.I would definitely recommend this mod.
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99 Gurkha with OM616 IDI turbo 2015 Gurkha with OM616 DI turbo 2014 Rexton W with OM612 VGT |
#8
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Yeah so far im saving up for a good muffler but want to add a better flowing down pipe.
Anyone know where i can find a mandrel bent down pipe for the SD?
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Current: 05 E320 CDI 07 GL320 CDI 08 Sprinter 05 Dodge Cummins 01 Dodge Cummins Previous 2004 E55 AMG 2002 C32 AMG (#2) 1995 E300 1978 300D 1987 300D 2002 C32 AMG(blown motor :[ 1981 300SD 1983 300SD 1987 300SDL 2002 Jetta TDI 1996 S420 1995 S500 1993 190E 2.6 1992 190E 2.3 1985 190E 2.3 5-Speed |
#9
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Quote:
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#10
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My SDL had no exhaust on it when I picked it up last July, just sounded like a tractor around town. Not any faster, just noise.
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I'm not a doctor, but I'll have a look. '85 300SD 245k '87 300SDL 251k '90 300SEL 326k Six others from BMW, GM, and Ford. Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG] |
#11
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I noticed on that other thread people are comparing backpressure on a gas engine to a diesel. We all know that on a gas engine a certain amount of backpressure is desired for optimal performance. My knowledge so far is on a diesel the less back pressure the better, in every aspect minus noise but even then I dont think it would be that bad since I drive a 5.9L Cummins with 5" stacks straight piped behind my head. On the turbodieselregister.com which I am a member of, people who want a lil more performance to their trucks put on a civil lil system and it helps a lil and the sound isnt bad but for anyone who wants lower egts, better mileage, (sound), and a system not getting filled with soot from literally pouring fuel down the engines throat from the performance diesel tuning today straight pipe is the way to go for most.
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1976 300D 115 Blue Grey exterior 95K miles 2004 Dodge Ram 2500 Cummins Silver exterior 5"stacks etc... |
#12
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Quote:
Incorrect. Backpressure is always bad. Too low of exhaust velocity hurts power on an N/A gasser at lower RPM.
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I'm not a doctor, but I'll have a look. '85 300SD 245k '87 300SDL 251k '90 300SEL 326k Six others from BMW, GM, and Ford. Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG] |
#13
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Quote:
Turbos Another object that might be sitting in your exhaust flow is a turbine from a turbocharger. If that is the case, we envy you. Not only that, but turbos introduce a bit of backpressure to your exhaust system, thus making it a bit quieter. All of the typical scavenging rules still apply, but with a twist. Mufflers work really well now! Remember, one of the silencing methods is restriction, and a turbine is just that, a restriction. This is actually where the term "turbo muffler" is coined. Since a turbine does a pretty good job of silencing, OEM turbo mufflers can do a lot less restricting to quiet things down. Of course, aftermarket manufacturers took advantage of this performance image and branded a lot of their products with the "turbo" name in order to drum up more business from the high performance crowd. We're sad to say that the term "turbo" has been bastardized in this respect, and would like that to serve as a warning. A "turbo" muffler is not necessarily a high-performance muffler. Pipe Sizing We've seen quiet a few "experienced" racers tell people that a bigger exhaust is a better exhaust. Hahaha… NOT. As discussed earlier, exhaust gas is hot. And we'd like to keep it hot throughout the exhaust system. Why? The answer is simple. Cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large exhaust pipe will cause a slow exhaust flow, which will in turn give the gas plenty of time to cool off en route. Overlarge piping will also allow our exhaust pulses to achieve a higher level of entropy, which will take all of our header tuning and throw it out the window, as pulses will not have the same tendency to line up as they would in a smaller pipe. Coating the entire exhaust system with an insulative material, such as header wrap or a ceramic thermal barrier coating reduces this effect somewhat, but unless you have lots of cash burning a hole in your pocket, is probably not worth the expense on a street driven car. Unfortunately, we know of no accurate way to calculate optimal exhaust pipe diameter. This is mainly due to the random nature of an exhaust system -- things like bends or kinks in the piping, temperature fluctuations, differences in muffler design, and the lot, make selecting a pipe diameter little more than a guessing game. For engines making 250 to 350 horsepower, the generally accepted pipe diameter is 3 to 3 ˝ inches. Over that amount, you'd be best off going to 4 inches. If you have an engine making over 400 to 500 horsepower, you'd better be happy capping off the fun with a 4 inch exhaust. Ah, the drawbacks of horsepower. The best alternative here would probably be to just run open exhaust! |
#14
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i have
a straight pipe in place of the back muff on my 350sdl. it sounds like a baby cummins. not too bad though. i cant feel any difference in performance and i imagine that i might get a half mile to the gallon better economy, cant tell for sure though.
i like it, but when i get read y to sell i will put the muff back on. i did the same with my 500sec. there the sound is much better. love the growl. also feel half to one mpg better. tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#15
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To see how backpressure effects a diesel you can dig through this research paper.
http://naca.larc.nasa.gov/reports/1937/naca-tn-619/ To summarize the findings with respect to back pressure for you A diesel is less sensitive to back pressure than a gas engine. Turbochargers and diesels are a great match. Basically when it comes to back pressure on a diesel, a drop in back pressure gets you a little more power. As back pressure increases the power from a diesel engine drops off at an increasing rate. In other words its an exponetial function.
__________________
green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons ) white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank) desert storm primer 63 T-bird "The Undead" (long term hibernation) http://ecomodder.com/forum/fe-graphs/sig692a.png |
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