Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,323
Garage
cat after muffler

Was lightly reading “cartech” about exhaust systems.
Reason is I have parts to build yet another system. My car won’t fit the muffler I bought after the small cat I have so I’m looking at the cat after muffler. Read some threads that said it simply won’t work. Hmm well ok but why? temperature. Obviously the cat needs higher temps to light off the bad emissions and to do its job. Ok but how hot? My exhaust gets hot, I use a turbo that makes it hotter I believe. Generally my egt is 700f after running and idling. Driving is hotter.
Well the cartech says the egt needs to be 350-500f. This means that most likely my system including a muffler directly after the turbo would have serious heat after the muffler at least enough to light off the noxious emissions and help in the ways the cat helps. This muffler would be a straight through type. I could see how maybe some temperature could bleed off because of the larger chamber/outer surface cooling could effect the overall temperature of the egt after the muffler. But I could wrap that muffler or thermocoat it. This could help keep more temp in.
This system isn’t built yet. I’m just thinking. I’d love some input from those who are capable of giving intelligent thought. I’d rather not get someone who says
“ya no” but has no other input.
Thanks.

__________________
Turbo powa!
1977 911s. it's cool
Old 07-13-2020, 11:11 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered
 
Join Date: Nov 2017
Posts: 538
Many older cars have their catalytic converter pretty far from the engine. They have been moved much closer so the reaction starts as soon as possible after startup. Your cat will work fine after the muffler, but it will take a little longer to get hot than if it was before the muffler.

One additional thought- a fiber packed muffler may clog up a downstream cat and create problems. The channels inside a cat are pretty small.

Sent from my Nokia 7.1 using Tapatalk

Last edited by Mixed76; 07-13-2020 at 01:04 PM..
Old 07-13-2020, 11:21 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 14,391
Garage
If adding a cat you may not need a muffler, the cat quiets things down by itself. I've tried a large race cat in place of the muffler body with decent results. Turbos hate cats however, there's no getting around that. Cats create back pressure and sound horrible, all the cool whistles and burbles are gone. Using the larger race cat helped reduce the loss in power when compared to the OE unit with no muffler.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 07-13-2020, 12:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,323
Garage
True Brian but this is a system made for times where I need some emission related tidiness. I have decided to use an old obx muffler which is small in diameter (2.5") so not really performance oriented but would work. Also I'm thinking of de-tuning the car.....I know how that sounds but honestly I'm moving this car in a more show related direction. I'm using higher CR pistons and efi with a gt35r and 930 trans. I haven't dynoed it but it's kinda scary, at least to 130.
Also I have two other mufflers which are bigger (3" straight through) and more flowy And a zork.
__________________
Turbo powa!
1977 911s. it's cool
Old 07-13-2020, 01:41 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered
 
Join Date: Aug 2004
Location: Charleston, SC
Posts: 815
Garage
Would installing a V Band clamp coming out of the turbo, then a section with a cat and another V Band, then your muffler - work? Like a sideways U with the exit back on the driver side? If it would work, you could have a section of straight pipe you could simply swap out your cat for when not needed.

I have one or Rarlyl8's straight through mufflers that uses a straight section out of the turbo, then a U bend and the muffler is on the bottom...I have been thinking of doing the above so I could easily swap in and out a race cat if I need to use a cat for some reason.

Just a thought for you
__________________
Emery

1988 930 coupe - Silver Metallic
TurboKraft 3.3L 8:1 CR, SuperSC Cams, GT35R, B&B Headers, TK intercooler, Tial WG, ARP, tecGT based phased sequential EFI & ignition, Wevo shifter/coupler, ...
Old 07-17-2020, 04:12 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered
 
TurboKraft's Avatar
 
Join Date: Mar 2005
Location: Phoenix, AZ
Posts: 2,774


An older custom catalytic-equipped 3.0" stainless high-flow exhaust we built to get a customer through emissions testing. V-bands would allow for interchanging the catalytic for a straight pipe on track-days, while still running a muffler and helping him pass db requirements.
__________________
Chris Carroll
TurboKraft, Inc.
Tel. 480.969.0911
email: info@turbokraft.com
http://www.facebook.com/TurboKraft - http://www.instagram.com/TurboKraft
Old 07-21-2020, 09:35 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,323
Garage
That look really packaged well Chris.
__________________
Turbo powa!
1977 911s. it's cool
Old 07-21-2020, 10:54 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered
 
Join Date: Aug 2004
Location: Charleston, SC
Posts: 815
Garage
Chris, LOL exactly what I was thinking!
__________________
Emery

1988 930 coupe - Silver Metallic
TurboKraft 3.3L 8:1 CR, SuperSC Cams, GT35R, B&B Headers, TK intercooler, Tial WG, ARP, tecGT based phased sequential EFI & ignition, Wevo shifter/coupler, ...
Old 07-21-2020, 05:58 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Turbofrog
 
smurfbus's Avatar
 
Join Date: Aug 2009
Location: Europe
Posts: 1,615
My solution was the cat being the muffler for my MOT. I also have the flap to lessen the noize when getting out of my garage and when needed (kids/animals/older people/cops). I have the backdate hand throttle/heater lever/handbrake unit and I use the heater lever for that flapper

__________________
************************************************** *******************************
79 930: HX40Super, MS3pro+ID1000+044+E85, Ignition: 123/TUNE/MSD6A, BB+2*turbosmart38, WMI. Weight 1110kg
Old 07-22-2020, 12:54 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered
 
kevinbodman930's Avatar
 
Join Date: Feb 2016
Posts: 334
Gotcha,How does she sound?

Sent from my SM-N976U using Tapatalk
Old 07-22-2020, 01:05 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Turbofrog
 
smurfbus's Avatar
 
Join Date: Aug 2009
Location: Europe
Posts: 1,615
If your asking me, IMO its better with that 100CELL metal CAT for longer rides without noice cancelling headphones. It does lower the noice level a bit. For mondays trackday I used my sony MDR1000 headphones to not get headache with zork only and long hauls over 80mph. No trailer for me ever. Uumph, that is when its running right. I do have some time on tow truck, once when injector seal let go and other time when I run out of E85 (yup they took my car to gas station and I filled it while on the tow truck to make sure it was out of gas: I have sort of a AAA service)
__________________
************************************************** *******************************
79 930: HX40Super, MS3pro+ID1000+044+E85, Ignition: 123/TUNE/MSD6A, BB+2*turbosmart38, WMI. Weight 1110kg

Last edited by smurfbus; 07-22-2020 at 01:29 AM..
Old 07-22-2020, 01:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,323
Garage
ok ok but would my system with a muffler first be effective in burning off the noxious emissions?
__________________
Turbo powa!
1977 911s. it's cool
Old 07-22-2020, 02:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered
 
Join Date: Nov 2017
Posts: 538
Quote:
Originally Posted by quattrorunner View Post
ok ok but would my system with a muffler first be effective in burning off the noxious emissions?
Yes

Sent from my Nokia 7.1 using Tapatalk
Old 07-22-2020, 02:17 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,323
Garage
Quote:
Originally Posted by Mixed76 View Post
Many older cars have their catalytic converter pretty far from the engine. They have been moved much closer so the reaction starts as soon as possible after startup. Your cat will work fine after the muffler, but it will take a little longer to get hot than if it was before the muffler.

One additional thought- a fiber packed muffler may clog up a downstream cat and create problems. The channels inside a cat are pretty small.

Sent from my Nokia 7.1 using Tapatalk
Thanks, missed this post

__________________
Turbo powa!
1977 911s. it's cool
Old 07-22-2020, 02:20 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 12:06 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.