Kennedy Exhaust

[CBernier]

I just bought the Kennedy exh. Does anyone have it? and how does it sound. Did it add any performance?

Craig

[Maverick]

Got one and it sounds awesome. Very easy to install. It sounds the best while juiced and passing a slow motor home on the left and getting the echo feedback off the motorhome. All RV'ers feel like an F16 is going to land on them. Going under overpasses is fun also.

[YZF1R]

Sounds great, easy install. As with any turbo diesel the easier the air gets in and the exhaust gets out the better. I have no engine mods. but it surely didn't hurt anything!

Steve

[mdrag]

CBernier,

I've noticed that I drive with the windows down and the stereo OFF much more often after installing the KD exhaust :D

I completed the 19.5" conversion a few days before the KD exhaust install, so it's difficult for me to say if there were any performance gains from the exhaust.

[hoot]

Question on backpressure. I noticed one manufacturer in my latest Four Wheeler Mag says some backpressure is required to help the turbo spool up faster.

Others are saying the more flow, the faster the spoolup ???????????

[YZF1R]

Perhaps someone with more knowledge can speak here, but I can not see how any back pressure would help a turbo engine. A tuned exhaust on an n.a. engine does help extract gases from the combustion chamber. You know, certain diameter and length for a certain rpm. I would think that the turbo itself would stifle any tuning possible after it other than an open pipe of little or no restriction. I think also that the turbo alone would be a significant restriction as it is pressurizing the intake and would not want anything after it. Obviously a tuned exhaust (headers) pre turbo would be of benefit.

Anybody else able to add anything to what Hoot or I think?

Steve

(Please excuse my stumbling sentences.)

[SoMnDMAX]

Craig,

I've got the first Kennedy Exhaust, and it sounds good!! Not loud at all in the cab or outside when you're cruising, but if you mash the throttle, it'll beller nicely!!

The install is easy, and the fit is excellent.

[imported_]

On a naturally aspirated engine, a 'tuned exhaust'..., one that utilizes the pressure waves of the individual exhaust pulses for a scavenging effect work quite well, provided that one uses equal length headers, BUT... from experiences in racing turbo and supercharged cars, no backpressure results in quicker turbo spool up and therefore quicker acceleration, less 'turbo lag' et al..... then there is the noise issue.

[hoot]

Nov. Four Wheeler on page 32 installing Magnaflow Performance Exhaust in an '02 F250 SD. The article states..

--------------------------------------------------------------------------------
"The 7" diameter stainless steel muffler is designed to provide just enough backpressure to keep the engine happy while not being a hinderunce to exhaust flow"
--------------------------------------------------------------------------------

Also...

--------------------------------------------------------------------------------
"The kit comes with mandrel bent stainless steel pipes, including a 3-1/2" dia turbo downpipe, a 3" collector (Magnaflow says this piece is critical to creating enough backpressure so the turbo can spool up)"
--------------------------------------------------------------------------------

At first I figured the first statement was just a generic one they use for all their exhaust systems but the second one confirms they really do it for the turbo.
I bring this up only because it's contradictory to everything I've learned. Do they mean that holding some of the heat helps the turbo spool?

[Forced Induction]

Does anyone have the Kennedy 4"/5" exhaust?? Where does the system make the transition? I thought I remember reading that the muffler is also 5". What is the difference in sound between the all 4" versus the 4"/5". I really like the look of a 5" system eventhought the performance difference is neglegible. I don't want to attract too much attention either, and are there any resonance issues?
As far as the turbo discussion is concerned, I agree with everone here in saying that a turbo/supercharged vehicle will not benifit from added backpressure or any for that matter. Ultimately, if we could apply a vacuum to the exhaust, that would increase the energy extacted from the exhaust gases and make even more power.

JA

[hoot]

BTW,
I'm impressed with the 4-5" Kennedy exhaust. It looks real good in the pulloff article.

http://www.thedieselpage.com/features/pulloff3.htm

I love the idea of full 5" showing out the back for as far as you can see. Beats a "tip".

[Kennedy]

Forced Induction:

The 4" to 5" transition has been move inside the muffler for a cleaner look!

Mdrag has a pretty detailed pictorial on his site.

[Jelisfc]

How loud is the system when towing? My '03 Dmax/6spd is on order and sooner or later I'll want a louder exhaust. My trailer is around 5K loaded but right now my straight piped gasser really bellers going down the road. It's even too much for me and that takes a lot!!! Don't get me wrong. It sounds great and NO-ONE sleeps in cars next to me as we drive by but after four hours on the road it gets old.

[mdrag]

Jelisfc,

I haven't towed since putting on the new exhaust so I don't know what to say on this issue.

What did Kennedy's 4 passengers have to say about the noise level during the uphill run? That has to be about the hardest that the truck will be pushed...for now...

The transition from 4->5 on my KD exhaust occurs about 1 foot before the 5" muffler. Kennedy pointed out that the transition is now in the muffler.

I'm very pleased with the sound - loudness and quality - from this exhaust. It will definetly roar when you get on it hard, but with every day driving, I do not find it objectional. There is a resonance with SLOW accleration from about 30-50 mph, but give it slightly more throttle - it goes away - that's it for criticism. The sound mellows a bit after the truck is warmed up.

No problems at highway speeds (75 MPH in OK), you can carry on a normal conversation and listen to the stereo without problems. No complaints from the wife or kids... :D

Here is a link to a previous post on the 4->5 Kennedy exhaust:

http://forum.62-65-dieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=003754&p=

QUOTE:
================================================== ========

"I picked up the family at OKC's airport yesterday evening - about 3 hrs. round trip, with the legal speed limit most of the way 75 mph
I tested out Kennedy's exhaust by cruising/accelerating at various speeds from 0 to 85 mph, with/without the stereo on. Most of the trip was at 75 mph. The outside temp was right around 100 degrees, so not much cruising with the windows down.

First off, my wife DID NOT notice/comment on the exhaust difference until we stopped for a bite to eat - about 25 minutes after I picked her up. I will admit that I avoided full throttle application up to that point. She had to get something from one of her bags in the bed, and was standing to the side of the PS tailgate. Since we had just pulled off the highway, I left the truck idling to cool down the turbo and went to help her out. That's when she first noticed that the truck was a little louder, and commented on the big exhaust These observations were more likely a result of the link I emailed her for the pics I posted on KD's exhaust and the 19.5" wheels...

I did not feel the sound level was too loud while maintaining steady highway speeds - you can tell this is not a stock exhaust, but no trouble listening to the stereo or carrying on a normal conversation. I like the growl with full throttle acceleration, and would keep the window down when leaving a toll booth for the full effect. As far as performance gains, the seat of pants dyno says the truck accelerates quicker (see below), with the turbo spooling up quicker and slightly more turbo whine (or I'm listening more carefully). The max EGT recorded by my SPA DG-111 is about 60 degrees lower, and the max boost is the same at 23 psi.

I only made one highway trip of about 2 hrs with the 19.5" wheels/tires before upgrading to the KD exhaust. I felt there was a small, but noticeable DECREASE in performance with the larger wheels/tires/OEM exhaust. After the exhaust upgrade AND bigger wheels, I feel that the performance is improved compared to stock exhaust/wheels - so I gained back what I lost from the 19.5" conversion, plus some.

The only negative I've noticed is exhaust resonance with slow acceleration from about 30 - 50 mph, and it goes away if you step on the throttle a little harder...

Very pleased overall with this exhaust!"

================================================== ====

I'm still feeling the same about Kennedy's exhaust- more windows down driving lately though :D

mdrag

[Jelisfc]

Thanx, My wife's only comment about the new truck is "I hope it won't be as loud as this one." to which I said nothing!!! She still gives me grief over her getting pulled over by the cops in my striaght piped big block years ago. Funny how I never have been pulled over for loud pipes but both my wife and Dad have.

[SledZep]

Jelisfc, maybe they (Wife & Dad) use more throttle than you???
Nah, couldn't be. Could it?

[big dipper]

Well, I received the Kenedy 4/5 exhaust and installed it Friday. The full 5" tail really "fits the bill" When looking at the back of the truck. It is tucked up nice in the center and even in the rear so you can get a slight tilt downwards incase any little rascals try to make it their home. The incab noise is (as the wife put it) 2 stages over stock. It has a nice rumble or drone at idle, but I didn't notice any while driving or cruising. With the windows down you can tell that it is attracting some attention, but it doesn't seem that it would cause any trouble. With the windows up, It is noticable, but not annoying. You can have the radio turned down pretty far and still be able to hear it fine. For that matter, with the radio on, you can still have a normal level conversation while still noticing you have an authoritative truck. Overall I am very pleased with the turn out, and I have received quite a few compliments already for just installing it 2 days ago.

To compare, I have heard a Dynomax exhaust and it seems comparable outside but the Dynomax has a cracking sound which makes it seem louder. It also is definetly much louder inside than mine. Along with an added drone - pretty constantly.

BTW-I have a cc/sb. I was also on the phone with JK while his wife was driving to the pull off. JK informed me he had the phone clipped on the overhead console and was looking at papers in the passenger seat and talking to me HANDS FREE and I could hear him just fine with the 4/5". Actually I didn't really "notice" the truck until it downshifted and even then it was not bad at all. THAT was my deciding factor!

[ 09-29-2002: Message edited by: big dipper ]

[ 09-29-2002: Message edited by: big dipper ]</p>