Wow.I think I've got a headache

 

I was thinking the same thing as I was reading your previous post. Although I will say, when I had no muffler, the sound out of the exhaust (both the straight pipe and the stacks) had some definate V8 type of rumbles to it. But, I still think most of the pulsation "waves" would be smoothed out by the turbine.

 

I've got a Banks straight through muffler, and I hear a definite exhaust note. For example, at 900 RPM you should hear a 60 Hz note, at 1800 RPM a 120 Hz note, and at 2700 RPM a 180 Hz note. Now my ear isn't as good as a spectrum analyzer, but this is about what I hear. When I drive along a row of Jersey barriers, and roll down the passenger side window, my side exit exhaust really gives a nice note, and the inside of the cab acts as a boom box!

Check out this link, this guy hacked his exhaust system apart, and made pressure measurements as he removed each piece to see how much EBP they were causing! If you come to Smokin and want to do this experiment, I'll come prepared with a pressure probe and a hack saw!

http://www.thrashercharged.com/tech_htm/exhaust.shtm

PS... Did the gauge arrive ok?

 

I think I'll have to pass on hacking up my system to take some measurements...lol.

Yes, the gauge arrived ok last night. I was actually leaving the house and saw the UPS truck coming down the street, so I stopped - so did the UPS guy. He asked me my address and gave me the package in the middle of the street. I haven't had a chance to do anything with it yet though, as I left the house at 7:30 this morning for a meeting in St. Louis and just got home about an hour or so ago. Hopefully I'll be able to get someting done with it tomorrow.

 

You'll be hearing from me in the future on that deal.

 

ok, reading all this, i would really like to see a model that converts hp # into the best exhaust size and tipe, say 5 in. single tail exit, to 5 in. single stacks, or dual stacks or dual 4 in. rear exits. if your catching my drift earnest, i think this model has great value for those wanting every lb. of power from their strokers. i myself would change my system in a minute if it wasnt optimal.

 

"The complication with analyzing exhaust gas flow is that it's not a simple mass flow of molecules. Exhaust gas flow consists of a series of high density pulses, and each pulse has a trailing region of lower pressure that helps to pull the pulse following behind it down the pipe. Apparently, a tailpipe diameter that's either too small or too large will not fully exploit this "pulse pulling" effect, and this is basically what leads to the concept of an "optimum" diameter for a given exhaust flow."

This makes sense. However, the low pressure area that is pulling on the following pulse is also pulling back on the pulse in front of it. If the following/2nd pulse somehow had a higher mass than the 1st pulse (maybe due to an acceleration condition) then the 1st pulse would be affected more by the 2nd pulse than the other way around. This makes the system a “Time varying” system. But for the steady state (time invariant) system the system response can be determined by a mathematical process called convolution. Convolving the pipe model with the pulse model will yield a model for the resulting pulse which can then be used to predict the resulting “standing wave” profile (if I remember my System Analysis correctly).

You‘ve latched onto an interesting subject here Gene. I look forward to reading more from you on it.

 

I came across this link below, and when I listen it sounds to me like the exhaust pulses get through the turbine fairly well. Does anyone have the capability to do a sound analysis on these videos?

Powerstroke 7.3L Straight Piped with a Black Tip
http://www.youtube.com/watch?v=K0_IfgF8F2M

 

wheres the model gene.

 

Gene does it make a difference on the brand of exhaust system if I go with straight pipe? I still want a quality exhaust system. Besides the pipe itself, does the muffler make the major difference in an exhaust system?
Who makes the best straight pipe/muffler delete system in the market? or should I be looking for quality and/or workmanship?

 

Nice one Mike.... I'm sleeping from 3pm your time to 9pm. We're 8 hours ahead of you in Central Time, if you're in the west half of TN that is...

Anyway, I'll just sit back and watch this one. I know my stainless mandrel-bent 4" turbo back MBRP is a darned good performer (definitely better'n stock!!), so I won't be making any changes regardless. I like the sound and I like the looks.

 

Im curious to see what Gene comes up with. I have my factory 3 1/2 with a straight through muffler to replace the factory, but I was thinking about joining the cannon club, but if the 4" actualy ends up being a better performer, then ill have to think really hard. I saw I could get a stainless 5" system for 550ish, and thats a catchy price for that size.

 

Izzy do have any sound clips on your exhaust? Is your system a straight pipe? Still trying to decide on a exhaust system. My thoughts were 4" MBRP SS straight pipe dual exits in front of the rear tire. My truck is stock and my first mods would be exhaust and intake. I have 02 F450 flat bed that I weighed a few days ago and weighed in at 9,740 lbs., is that considered a heavy truck? I'm modifying my truck into a mechanic truck and will be adding a significant amount of weight onto it. So what i'm trying to say is that I want an exhaust system that will benifit my future mods. With the exhaust system exiting infront of the rear tires, does that change the sound of the exhaust? Thanks..

 

Thanks for all the interest, as you can see below my book is on the way... Since this is my hobby I first try to figure out on my own how stuff works, then I do Google searches and review online references, but the exhaust system is proving to be sufficiently complicated that I resorted to buying what's supposed to be the "Bible for exhaust system design".

It took me about 6 months to get my PSD engine model to where it is now, so don't anyone be holding their breath while waiting for a definitive answer on the exhaust system. Currently the exhaust system performance is included in my VE function which is discussed in the link below...

What's The Net Volumetric Efficiency, VE (%), For A 7.3L PSD?
https://www.ford-trucks.com/forums/666686-whats-the-net-volumetric-efficiency-ve-for-a-7-3l-psd.html#post5267145

The EBP inhibits the initial filling of the cylinders during the start of the intake stroke, and this reduces VE. The EBP also is a parasitic pumping loss and reduces the TE, or Thermodynamic Efficiency for converting fuel heat energy into HP.

My model employs functions for VE and TE that depend on RPM and BP. I've employed a combination of theory, along with some tweaking, so that the RWHP and RWTQ curve outputs from my model match up with the ones here...

A Quick Way To Estimate Your Dyno Results...
https://www.ford-trucks.com/forums/666835-a-quick-way-to-estimate-your-dyno-results.html#post5265024

which were measured on a 99.5 with an auto tranny, using a water brake load dyno. Ideally, for various types of exhaust configurations, I'd like to come up with a function that gives EBP as a function of RPM and BP.

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I don't have one of my own yet, but mine sounds just like Guzzle's:
http://guzzle.rbmicro.com/mp3/City.mp3

I do plan on getting some clips recorded under different conditions and different perspectives (on the truck, drive-bys, etc), but I haven't had a chance yet. IMHO, I wouldn't dump diesel exhaust in front of the rear wheels -- it'll make your rear rims pretty much permanently soot-black, espeically after some tuning. You can certainly do that if you don't mind black rims, but that would drive me up a wall. Dan (kwikkordead) did his F450 that way with the 5". He has some clips linked from his sig. I have the MBRP muffler in place, and so does Guzzle. If you find Dan's recordings, his has the muffler in place as well.