pocholin

OK, I had this done today, the shop made pipes as bolt ons, just in cade I didn't like it, Wednesday night I'm going to the track and see if it makes a difference, here are my first reviews on my 1999 E55, which BTW has brand new pre-cats and cats replaced by the dealer under warranty:

Sound
It is just a little bit louder, but that little bit is deeper, it sound nice, but I need more, at idle it is hardly noticeable, i think it is the same at idle, but under some gas or WOT (wide open throttle) it is deeper, but not too loud. With windows closed interior noise is very minimum (compared to stock) with radio on at low volume is hard to tell a difference at any speed, no droning at 40-50-60-70-80 mphfor example if I bring the car to 60 mph, there is no droning inside the cabin.

Performance
As far as I can tell there is some performance gains, we'll have to go by the track results on this, IMO it does feel better (not a little better, but better) on the higher RPM range, aprox after 4500 rpm, I can tell a nice difference. I;ll let you know on wednesday night if in fact there has been an improvement, I've run 13.300 under 80 deg F weather, so it should be better than that, so far the best time under 50 deg F is 13.128, so we'll see.

Here are a couple of pictures of the job, sorry but I forgot my camera when they had it up on the lift :o

pocholin

2nd picture

I'll give this "mod" a try for a couple of weeks and see if people in Dallas can tell the difference, after that I'll put the resonator back and put a Series 60 Flowmaster muffler and test more.

Nektopoli

They could have at least mandrel bent the pipes.

NP

Mach430

Did you weigh the before/after pieces?

nukblazi

Pocholin-

Why flowmaster?
Get those pipes mandrel bent!

thanks dude!

Shine

Good move ! keep us update.

pocholin

In answer to questions, no I didn't get those weighted, no scale available, but I still have the resonator in the trunk, wich still adds weight right now.

I'm not familiar with mandrel bending, what is the difference?

To say "They could have at least mandrel bent the pipes" means that you've done it to yours, right?

Why flowmaster? I've read a lot, if I put a made for Benz muffler I will hardly see any difference, I've read that they are no much different from the AMG I have, it won't make a difference on exhaust flow and very little on sound, so I decided to try what I've always used on other vehicles, Flowmaster.

tommy

Mandrel bending is when the bends are the same exact thickness throughout, so that the exhaust gasses flow through with the least amount of resistance. Especially in your second pic, you can see that the bends are kinked, and not smooth.

Generally, that means that you have to have something inside the pipe when you're bending it, so that you don't get kinked spots.

Not that it'll make for huge differences on the dyno, but your exhaust isn't operating optimally.

speedybenz

Nice R&D work. I look forward to your further comments.

How about running the Flowmaster with the Resonator removed?

What you need is a muffler that flows about 1000cfm of air or two mufflers that flow at least 500cfm of air to decrease backpressure and get the performance.

Jeff

pocholin

OK, Thanks for the mandrel bending explanation, it might affect the exhaust flow a little.

I need to find out on the flowmasters, the exhaust flow.

speedybenz

What is the pipe diameter of the stock system or of the new pipe you just put in?

With your 5500cc engine that makes say 350-375hp at the crank, then you need 375x2.2=825cfm min. airflow for your muffler or 425cfm for a dual muffler system. Two 2.5" diameter mufflers with straight through cores from Dynomax or Magnaflow would due the trick.

Make sure the muffler you use meets these criteria or you will not gain much.


Jeff

nukblazi

Is this HPxD=CFM?
Is D diameter or is 2.2 a constant?

pocholin

I belive the pipe diameter from factory is 2 1/4" (2.25") or 2 1/2", I can't quite remember what the guy said, but we used same diameter pipe as the rest of the exhaust system.

Yes, I'm checking on the muffler specifications to see how much flow it can take.

speedybenz

The 2.2cfm is a constant derived from pipe flow rates vs. diameter. It is the minimum flow rate per Hp needed to provide little to no back pressure (2.2cfm per HP = No Hp Loss)

Pocholin,

Sorry for being so intrusive with regard to your project. It is just my engineering nature coming through. Please don't take offence in my comments.

Jeff

pocholin

Not at all, those kind of comments are more than welcome, in the end this is all trial and error, because we don't know for sure what the exhaust is going to do (as far as performance) until somebody tries it, right?

I'm going to the track tonite and will post timeslips (if it doesn't rain, it is ulgy and cloudy, but rain might just hold up).

speedybenz

Here is a link that talks about making a NO LOSS HP EXHAUST. The article is written by David Vizard and worth reading. Most of my comments come from information contained in this article.

http://www.ntpog.org/articles/index.shtml


The Exhaust Termination Box is really interesting and I really want to try this in the near future.

Jeff

vraa

what happens if you have too much air flow?

Vadim @ evosport

speedybenz: Exhaust Termination Box was am interesting idea that Vizard tested about 5 years ago. It was done at Westech in Riverside, CA. At that time it looked pretty, those boxes were polished stainless and look like an exotic guitar cases, however there were no power gains.

Since then I know he played with this idea for a number of years. My guess it is still in development.

vraa: There is no such thing as too much air flow. Key to an efficient exhaust is velocity in the pipes.

pocholin

OK guys, you tell me, last time I ran it was cold and dry, today it was hot and humid as hell by the beach. I let the engine cool off but after the burn out it was already hot again.
It is hard to tell, I'll have to go back to the stock resonator and make more runs on same ugly weather, depending on how friday looks I might go back to the track (if it is dry)

pocholin

for comparisons here is my best time, 60 deg F, 10-15% humidity, cool winds aprox 20 mph

speedybenz

Vadim,

The article I refer to was written in April, 2002. So Vizard may have come to some better data with regards to the Exhaust Termination box, since the article is less than 1 year old.

It certinly seems like a solid method to provide a muffled exhaust system that still makes full power.

What do you think, Vadim?

Jeff

Vadim @ evosport

Vizard is freelance writer. That article could of very well have been written 4-5 years ago. It is not unusual for freelance guys to sell their articles to different magazines, very often the same article gets published in different magazines at different times.

Do not get me wrong, I like his work and I have read majority of his books on engine building and tuning. In general he is very good, however there some ideas that are a bit of the wall.

speedybenz

Vadim,

I know what you mean about Vizard, sort of like Smokey Yunick.

But I did build a race motor with a 3:1 rod to stroke ratio and that thing made about 10Hp more than similar engines I had to race against and it allowed to me to win a Championship in 450cc Superbike back in 1994. Talk about a free revving engine with a flat torque curve.

Jack Sparks at Carillo made the one off rods and was so interested that I had to fax him all the engine data and dyno runs.

That motor ran with small ports, short durations cams and very little spark advance.

Back to subject, do you think an exhaust termination box placed just behind the second set of cats would work? Then run dual 2.5" piping back into two high flow mufflers. It would provide less backpressure than the stock system, don't you think.

Jeff

pocholin

SO, considering how humid it was, are those times bad? or so so? or just go back to the resonator?

vraa

so why not just build one big exhaust? i'm new at this so your gonna have to tell me why HAH!