Re: Exhaust bottleneck?

From: crm (tb.crm@verizon.net)
Date: Wed May 29 2002 - 17:15:42 EDT


Any thoughts on the following catback setup?

2 1/2" pipe from cat to flowmaster 50 series
dual 2 1/4" (or 2 1/2") out the back, exit behind each rear tire (aluminized
steel)
3" chrome tips
$312.50, installed, out the door

is this going to give enough flow and not leave me short in off-the-line
torque?

the above was the recommendation of a "local legend" in mufflers and
exhaust. i was given his name and he seems to come highly recommended from
many different sources.

thanks...

-adam

----- Original Message -----
From: "Stlaurent Mr Steven" <STLAURENTS@MCTSSA.USMC.MIL>
To: <dakota-truck@dakota-truck.net>
Sent: Wednesday, May 29, 2002 3:35 PM
Subject: RE: DML: Exhaust bottleneck?

>
> The gain for the shorty is 11HP not 9HP. I just reread the e-mail from
JBA
> in my archives.
>
> --------------------------------------
> Steven St.Laurent
> C4i System Engineer
> C4i Engineering Branch, PSD, MCTSSA
> MARCORSYSCOM, U.S. Marine Corps
> Office (760) 725-2506 (DSN Prefix: 365)
> "Never be content with somebody else definition
> of you. Instead, define yourself by your own beliefs,
> your own truths, your own understanding of who
> you are. Never be content until you are happy with
> the unique person GOD has created you to be."
>
> -----Original Message-----
> From: crm [mailto:tb.crm@verizon.net]
> Sent: Wednesday, May 29, 2002 1:14 PM
> To: dakota-truck@dakota-truck.net
> Subject: Re: DML: Exhaust bottleneck?
>
>
> alas! i _do_ have the 2 pre-cats...but headers arent in the picture for a
> while...but thats what i said about a cat-back and i might have it by this
> weekend...
>
> -adam
>
>
> ----- Original Message -----
> From: "Stlaurent Mr Steven" <STLAURENTS@MCTSSA.USMC.MIL>
> To: <dakota-truck@dakota-truck.net>
> Sent: Wednesday, May 29, 2002 2:48 PM
> Subject: RE: DML: Exhaust bottleneck?
>
>
> >
> > Before I forget, if you have the PRE-CATS installed on your truck the
gain
> > from JBA shorty headers are only 9HP. If you don't have the Pre-CATS,
> then
> > the long type headers are up to 21HP gain. These were the figures given
> to
> > me from JBA engineers while they prototype the headers units.
> >
> > --------------------------------------
> > Steven St.Laurent
> > C4i System Engineer
> > C4i Engineering Branch, PSD, MCTSSA
> > MARCORSYSCOM, U.S. Marine Corps
> > Office (760) 725-2506 (DSN Prefix: 365)
> > "Never be content with somebody else definition
> > of you. Instead, define yourself by your own beliefs,
> > your own truths, your own understanding of who
> > you are. Never be content until you are happy with
> > the unique person GOD has created you to be."
> >
> > -----Original Message-----
> > From: crm [mailto:tb.crm@verizon.net]
> > Sent: Wednesday, May 29, 2002 11:52 AM
> > To: dakota-truck@dakota-truck.net
> > Subject: Re: DML: Exhaust bottleneck?
> >
> >
> > excellent info Jay! i think after reading this and talking to a buddy up
> > here at work i'll wait till i can get the 3" cat-back. i figure that the
> > larger pipe might not do as much good now but down the road (after a
> couple
> > more mods) it will definitely be called for. no sense putting something
in
> > that i'll have to replace a couple months later...
> >
> > now i just need to decide on the muffler...the quote from the muffler
shop
> > was for a $135 magnaflow, i guess i could knock $50 (or more?) off that
> > price if i took one in there myself.
> >
> > thanks again guys!!
> >
> > -adam
> >
> > ----- Original Message -----
> > From: "Woodruff, Jason P" <jason.p.woodruff@boeing.com>
> > To: "DML (E-mail)" <dakota-truck@dakota-truck.net>
> > Sent: Wednesday, May 29, 2002 12:18 PM
> > Subject: Re: DML: Exhaust bottleneck?
> >
> >
> > >
> > > Main exhaust bottleneck? In my opinion the whole thing.
> > >
> > > First I made a po'boy air intake Z tube, I felt a little more HP,
> probably
> > > mostly do o the colder air. Next I replaced the cat back exhaust
system
> > to
> > > a single 3" and found that to increase throttle response AND torque
> > > substantially. Then I replaced the intake and Throttle Body with a
real
> Z
> > > tube and F&B TB. Throttle response went way up, HP went up on
anything
> > > above 2K RPM, but low (really low) end torque diminished a bit. I
> > wouldn't
> > > recommend that last one if your looking to tow a lot. I have a set of
> JBA
> > > headers in my bed room that I'm not sure if I'll ever get to put on,
but
> I
> > > suspect they'll have the same effect as the TB change.
> > >
> > > I think there's 3 cats on 4.7Ls (except 2000 non-cali daks). one on
the
> > end
> > > of each header then one further downstream after they've merged.
> > >
> > > Jay W
> > > 505/287 Dakota
> > >
> > > >Date: Wed, 29 May 2002 10:02:01 -0500
> > > >From: "crm" <tb.crm@verizon.net>
> > > >Subject: DML: Exhaust bottleneck?
> > > >
> > > >Hello all,
> > > >
> > > >Can someone pinpoint the main exhaust bottleneck for a 2001 Dak QC
with
> a
> > > >4.7? After doing a lot of reading (here and elsewhere), I seem to be
> > > running
> > > >into 2 or 3 differing points. One the one hand, many seem to suggest
a
> > new
> > > >muffler will really free up the exhaust. One the other, I have heard
> that
> > a
> > > >new muffler wont do much because the main bottleneck is at the cat.
And
> > > then
> > > >on the 3rd "hand", I have read that if you dont replace the stock
2.5"
> > > pipes
> > > >with a 3" catback, neither hi-flow muffler nor hi-flow cat will help.
> And
> > I
> > > >guess to round it all out (4th hand), I've heard that the 3" pipes
will
> > rob
> > > >you of low end torque, which is what you need for towing and the like
> > > >correct?
> > > >
> > > >If it makes a difference, I dont use the truck for towing. Mainly for
> > > >driving to work and around town and the occassional day trip. No
> racing,
> > > >other than the normal youthful exuberance on the freeway or at the
> light.
> > > >Basically, I am not looking to build a mean street rod or anything,
> just
> > a
> > > >truck that can sh*t and git if I tell it to.
> > > >
> > > >I dont want to spend money for the same thing 2 times, so I want to
> make
> > > >sure I do it right the first time. I just ordered a Z-tube last night
> and
> > > if
> > > >I can figure out what's best I hope to get some exhaust work done
this
> > > >weekend. I'd like to use stock pipe if possible and avoid getting a
> whole
> > > >new catback system until later on.
> > > >
> > > >Also, is it correct that the 4.7 Dak's have 2 cats? Like a pre-cat
and
> > then
> > > >a main cat?
> > > >
> > > >Thanks in advance!!
> > > >
> > > >- -adam
> > > >
> > >



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