Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

running without a catalytic converter......hypothetically, of course!

Thread Tools
 
Search this Thread
 
Old 07-28-2004 | 02:25 AM
  #1  
low miler's Avatar
low miler
Thread Starter
Banned
 
Joined: Jan 2004
Posts: 847
Likes: 0
From: Indianapolis
Question running without a catalytic converter......hypothetically, of course!

Hypothetically speaking, is it possible to run a GTS without its converter and would it do any good if I did? This question is just for entertainment purposes only.

And secondly, what are the three or four best and cheapest ways to make my car faster?


Last edited by low miler; 07-29-2004 at 01:58 AM.
Old 07-28-2004 | 03:46 AM
  #2  
Rich9928p's Avatar
Rich9928p
Addict
Rennlist Member

 
Joined: Jul 2002
Posts: 2,674
Likes: 35
From: AZ
Default

a. From what I've seen posted, removing catalytic converters doesn't buy you much HP, perhaps 5 HP. The RMB (rear muffler bypass) is said to help with a few HP, most add it to enhance the sound.
The air is bad enough, no need to pollute any more than necessary

b. the cheapest way to make ANY car faster is to remove weight, this gives the most bang per HP.

c. performance chips. From actual dyno, the claims seem to fall short of actual. Chips may reduce the reliability of the engine due to reducing safety margin in the design. Chips are pretty expensive for the HP they say is delivered.

d. Beyond that, there are some exotic exhaust systems (Ott, Devek) etc. that are fairly costly and deliver a few more HP. Anything beyond that is pretty big money and is pretty major work.
Old 07-28-2004 | 11:41 AM
  #3  
Jim_H's Avatar
Jim_H
Banned
 
Joined: May 2001
Posts: 12,264
Likes: 3
From: The Great Northwest
Default

Ott X Pipe, without a doubt the best bang for your $. Ran without cats my GT put 301 to the wheels and the tone is the best I have heard on any car.
It is easy to put cats back on for inspection.
Old 07-28-2004 | 12:17 PM
  #4  
Dave Sz.'s Avatar
Dave Sz.
Addict
Rennlist Member

 
Joined: May 2001
Posts: 125
Likes: 1
From: SE WI
Default

"Ott X Pipe, without a doubt the best bang for your $. Ran without cats my GT put 301 to the wheels and the tone is the best I have heard on any car."

Jim,

Did you leave the rest of the exhaust stock or did you add an RMB also? I'm told that not cats and an RMB is too loud for urban driving with a GT.

Dave Sz.
Old 07-28-2004 | 12:27 PM
  #5  
SteveG's Avatar
SteveG
Rennlist Member
 
Joined: Jul 2001
Posts: 6,520
Likes: 99
From: New York
Lightbulb

Originally Posted by low miler
And secondly, what are the three or four best and cheapest ways to make my car faster?

This has been covered extensively in the archives. Lose weight, go on a diet; I'll never forget my college roommate trying to make (lose) weight in the bathroom!
Old 07-28-2004 | 12:52 PM
  #6  
heinrich's Avatar
heinrich
928 Collector
Rennlist Member

 
Joined: Jan 2003
Posts: 17,270
Likes: 5
From: Seattle
Default

Low, yes. There is much horsepower to be gained from losing the cats. No question. You will need to retain your rear muffler though.
Old 07-28-2004 | 01:13 PM
  #7  
Jim bailey - 928 International's Avatar
Jim bailey - 928 International
Addict
Rennlist Member

Rennlist
Site Sponsor

 
Joined: Jul 2001
Posts: 11,542
Likes: 3
From: Anaheim California
Default

the Ott X-pipe and two high flow mufflers will add nearly 30 HP to an 89 GT . The X-pipe works !! Plus the mixing of the pulses in the X seems to reduce the harshness of the exhaust note compared to an old fashioned H pipe balance tube ....the H is better than nothing but does not compare to an X .
Old 07-28-2004 | 01:28 PM
  #8  
Big Dave's Avatar
Big Dave
928 Engine Re-Re-Rebuild Specialist
Rennlist Member
 
Joined: Oct 2001
Posts: 7,970
Likes: 29
From: Brighton, MI
Default

Happy "x" owner here. Get it!
Old 07-28-2004 | 01:52 PM
  #9  
hacker-pschorr's Avatar
hacker-pschorr
Administrator
 
Joined: Aug 2001
Posts: 1,643
Likes: 2,259
From: Up Nort
Default

6 - 11psi will give the biggest gain over anything else. I say 6-11 because I don't know the specs of the GTS kit:
www.murf928.com
Old 07-28-2004 | 02:08 PM
  #10  
Sab's Avatar
Sab
Addict
Rennlist Member

 
Joined: Jan 2002
Posts: 1,732
Likes: 0
From: Florida
Default

I can tell you from personal expirience, do not take that cats off. Your car wil have no noticeable performance increase and it will stink like an old school buss.
Old 07-28-2004 | 02:44 PM
  #11  
Big Dave's Avatar
Big Dave
928 Engine Re-Re-Rebuild Specialist
Rennlist Member
 
Joined: Oct 2001
Posts: 7,970
Likes: 29
From: Brighton, MI
Default

Originally Posted by Sab
I can tell you from personal expirience, do not take that cats off. Your car wil have no noticeable performance increase and it will stink like an old school buss.

My personal experience contradicts yours. Performance has increased in a very noticeable way for me. There is an odor from the unfiltered exhaust, but I rarely smell it.
Old 07-28-2004 | 02:50 PM
  #12  
Mark's Avatar
Mark
Addict
Rennlist Member

 
Joined: Jan 2003
Posts: 3,537
Likes: 0
From: Mountains of GA!
Default

Originally Posted by Big Dave
My personal experience contradicts yours. Performance has increased in a very noticeable way for me. There is an odor from the unfiltered exhaust, but I rarely smell it.
I agree w/Big Dave! Most BWAAAAHHH for the $

The cats are darn good mufflers by themselves. My sound is sweet. I wouldn't want it any louder - i.e.-RMB. As it is, I can set off car alarms if I want to!
Old 07-28-2004 | 05:18 PM
  #13  
Jack '84 928s's Avatar
Jack '84 928s
Drifting
 
Joined: Apr 2002
Posts: 2,162
Likes: 0
From: Hobbs, NM (or lovington)
Default

I could tell a diffrence when i took my cat off and the porsche mufflers.....
Old 07-29-2004 | 01:49 AM
  #14  
ViribusUnits's Avatar
ViribusUnits
Nordschleife Master
 
Joined: Aug 2002
Posts: 9,010
Likes: 2
From: South Texas
Default

Much depends on the current condition of your cat. And for that, much depends on the current condition of the other emission controls.

If the cat is partly cloged, highly possible on cars this old, you can get substantial proformance improvement. Not only that, but if the cat is poisioned, you'll have no net change in your emissions. One thing that can cause a cloged cat is a defunct or disconnected smog pump. And if you don't have a cat, the smog pump is pretty much pointless on air injection cats.

So, if your going to remove the smog pump, you have to remove the cat, and if your going to remove the cat, you may as well remove the smog pump.
Old 07-29-2004 | 01:56 AM
  #15  
low miler's Avatar
low miler
Thread Starter
Banned
 
Joined: Jan 2004
Posts: 847
Likes: 0
From: Indianapolis
Question

Let me get this straight. If I was to order this X pipe thingy from Devek, I would have to keep my original rear mufler on? I just ordered a rear muffler bypass. Should I send it back, or is it possible to use both?




All times are GMT -3. The time now is 05:13 PM.