3" exhaust kit? - Page 2 - PeachParts Mercedes-Benz Forum

TWeatherford · #16 04-26-2007, 01:38 PM

Quote:

Originally Posted by Shorebilly

Just run a 6" stack up thru the hood and be done with it.....er, make that 150mm

SB

Yeah, I've thought of it, and may do it if I can find a spare silver hood to saw a hole in. When I get ahold of my dads 97 F-350 and drop the Cummins diesel in either a 5 or 6 inch is coming out the hood. Loud, but fun.

winmutt · #17 04-26-2007, 01:41 PM

A bigger pipe == less back pressure == longer spool time. The stock exhaust works just fine. If you want something, take off the muffler.

bgkast · #18 04-26-2007, 02:52 PM

Quote:

Originally Posted by winmutt

A bigger pipe == less back pressure == longer spool time. The stock exhaust works just fine. If you want something, take off the muffler.

I think that should be A bigger pipe == less back pressure == shorter spool time

I believe the OD of the stock pipes is right about 2.5"

pawoSD · #19 04-26-2007, 03:29 PM

Yeah, how does less back pressure mean longer spool up time? I have greatly reduced back pressure right now (essentially none) and it spools up quite quickly, faster than it used too, thats for sure. And at WOT I am seeing 12psi, with the exhaust system all hooked up I rarely saw above 9psi.

It feels like it pulls stronger too. I have been watching my boost gauge on take off and it moves to 12psi very quickly....

winmutt · #20 04-26-2007, 04:56 PM

You know not the first time I have been wrong. But.... EGP is what causes the turbo to spool up right. More back pressure == more EGP. So spool time should be longer but run a little cooler?

SirNik84 · #21 04-26-2007, 05:19 PM

the turbo spool is going to be quicker because of the diffrence in pressure. if there is lower pressure (bigger pipe) after the turbo then the pressure before the turbo move more quickly to the low pressure on the other side of the turbine. thats how you get your faster spool.

winmutt · #22 04-26-2007, 05:44 PM

Quote:

Originally Posted by SirNik84

the turbo spool is going to be quicker because of the diffrence in pressure. if there is lower pressure (bigger pipe) after the turbo then the pressure before the turbo move more quickly to the low pressure on the other side of the turbine. thats how you get your faster spool.

This reminds me of may ALDA thread

...

Atleast I admit when I am wrong, you guys need to have a talk with my wife....

pawoSD · #23 04-26-2007, 06:46 PM

I paid closer attention to the boost/acceleration feel of the car today while driving, it has at least a 20% stronger "pull" from 0-50 or so than before. And the turbo spools right up to nearly 12psi by the time I hit 15-16mph, and stays there. Whats weird is when I let off the fuel to shift (I do it manually a lot

) the boost would only briefly fall to about 8psi then would jump right back to 12 very quickly when I went back on the throttle, with the restrictive exhaust hooked up boost would fall almost to 0 between those shifts.

My guess is that so much air is flowing even when off the pedal briefly, that it keeps the turbo spooled longer...only a couple seconds, but it makes a difference because then all that power is available when you apply the throttle in the next gear. So once I have my new header pipe either I, or a shop, am going to put a 3" pipe to the back

It won't cost that much, Lentz will do a custom pipe for $45 + like 20 labor. Either that or I'll patch one together myself.

I also wonder if it will raise my MPG's

Ara T. · #24 04-26-2007, 06:56 PM

It sounds like you have a clogged exhaust or something. I had my exhaust off for about a year and the only thing I noticed was more noise (i loved the turbo whistle). With my exhaust back on it's basically the same except very quiet. The boost falls and spikes back up very quickly between full throttle shifts. And I can drive at 60 mph with no annoying resonation in the cabin.

Why are you letting off the fuel when you're shifting? That's the whole advantage to the automatic (probably the only performance advantage).

#25 04-26-2007, 09:14 PM

Quote:

Originally Posted by Shorebilly

Just run a 6" stack up thru the hood and be done with it.....er, make that 150mm

SB

I am going to try it if I can find a hood with a matching paint color.

PanzerSD · #26 04-27-2007, 01:15 AM

Quote:

Originally Posted by Craig

There are better places to spend your money, the 3" exhaust will make no difference in performance.

Naaah..when I first got my SD it was a dog untill I chunked the 2" for some 3". turbo spools alot faster..and it just sounds awesome

Oh yeah, I had my 3" mandrel bent stuff done for less than a stock system. ALOT less

#27 04-27-2007, 01:21 AM

If it was 2" then a past owner replaced it with the wrong tubing.

pawoSD · #28 04-27-2007, 01:31 AM

Quote:

Originally Posted by Ara T.

It sounds like you have a clogged exhaust or something. I had my exhaust off for about a year and the only thing I noticed was more noise (i loved the turbo whistle). With my exhaust back on it's basically the same except very quiet. The boost falls and spikes back up very quickly between full throttle shifts. And I can drive at 60 mph with no annoying resonation in the cabin.

Why are you letting off the fuel when you're shifting? That's the whole advantage to the automatic (probably the only performance advantage).

The noise with exhaust coming out at the downpipe doesn't really bug me, so a 3" pipe will be no problem at all. I love the turbo sound, its addicting!!

My exhaust is a "truck muffler" with a 2.5 inch pipe from the middle section where the resonators were, to the back, I am betting its fairly restrictive. I can hear air GUSHING out from the broken pipe up front under heavy acceleration, so it certainly would rather leave at that point than go through the rest of the system.

It spools very very quickly, and feels great.

This may be all in my head, but with open exhaust like that, the engine seems to not shake the car anymore when I turn it off, no rough "diesel wobble stop" feeling. I can tell it turns off, but not like before. Is this due to the completely free flowing exhaust?

Idle is also smoother....a lot smoother....

#29 04-27-2007, 08:35 AM

Quote:

Originally Posted by PanzerSD

Naaah..when I first got my SD it was a dog untill I chunked the 2" for some 3". turbo spools alot faster..and it just sounds awesome

Oh yeah, I had my 3" mandrel bent stuff done for less than a stock system. ALOT less

I assume you had some problem/restriction with the "2-inch" system, the stock system (in good condition) should not give you much back-pressure.

I'm sure 3-inch pipes are capable of making more noise. Wouldn't it be cheaper to put some baseball cards in the spokes, or just make voom-voom noises while your driving. Most folks over the age of 12 would like less noise, not more.

Shawn D. · #30 04-27-2007, 08:42 AM

Quote:

Originally Posted by Craig

I'm sure 3-inch pipes are capable of making more noise. Wouldn't it be cheaper to put some baseball cards in the spokes, or just make voom-voom noises while your driving. Most folks over the age of 12 would like less noise, not more.

Most non-car-enthusiast folks over the age of 12 would like less noise, not more.