RX7Club.com


Go Back   RX7Club.com > Generation Specific > 1st Generation Specific (1979-1985)
Register Forgot Password?

Welcome to RX7Club.com!
Welcome to RX7Club.com,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to start new topics, reply to conversations, privately message other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join RX7Club.com today!


Reply
 
 
 
 
LinkBack Thread Tools Search this Thread Display Modes
Old 06-21-04, 05:06 PM   #1
Absolute Power is Awesome
10 Year Member
 
purple82's Avatar
 
Trader Score: (0)

Join Date: Mar 2001
Location: Lynnwood, WA
Posts: 1,946
What's Facebook? What's Twitter?
Air Pump

I've seen a lot of people say that disconnecting the air pump will burn out the catalytic converter. I don't see how this is possible.

The air pump provides fresh air to the cat to oxydize the HC and CO in the exhaust. The oxidation process is exothermic, it gives off heat. The reason the air pump is there is because there aren't enough O atoms released in the first catalyst (the reducer, NOx to N2 and O2) to oxydize all of the HC and CO atoms and more O2 needs to be introduced.

The only thing that happens when you disconnect the air pump is that there won't be enough O2 to fully oxydize the exhaust and you'll fail emmisions.

Has anyone actually removed the airpump and burned out a cat?
purple82 is offline   Reply With Quote
Old 06-21-04, 05:35 PM   #2
/_\ Rotarized /_\
 
jweather73's Avatar
 
Trader Score: (0)

Join Date: Jun 2004
Location: Grand Prairie, TX
Posts: 210
Send a message via Yahoo to jweather73
I've done the 1st half of disconnecting mine (and it made a HUGE positive power increase on just a typical stock 1st gen GSL) but Ari up at Rotary Performance in Garland, TX told me it would clog it up with carbon. He said depending on the driving habits (really fast in my case) and the condition of the engine, it may be an average of 6k miles or 6 months. I haven't noticed any differences yet and it's been at least 2000 miles since I disconnected mine... I just need to get my new exhaust system in to cut the damn thing off. (the CAT that is)

Also, I've heard in these forums that it will "melt the cat" and clog it up and who knows what else, so, for what it's worth you know as much as I do (and obviously you know more about the oxidation and stuff that I'm clueless about.) Good question though... I'm gonna be watchin' this thread closely.
jweather73 is offline   Reply With Quote
Old 06-21-04, 06:59 PM   #3
Spinner
 
Trader Score: (0)

Join Date: Mar 2004
Location: Holiday
Posts: 223
Send a message via AIM to Illswyn
Well, you said yourself that it needs O2 to oxidize the HC and CO. Where do you think the HC and CO go without that process? CO goed out the tailpipe I suppose, and HC builds up on the catalyst. Eventually it gets clogged, right?
Illswyn is offline   Reply With Quote
Old 06-21-04, 07:08 PM   #4
Absolute Power is Awesome
10 Year Member
 
purple82's Avatar
 
Trader Score: (0)

Join Date: Mar 2001
Location: Lynnwood, WA
Posts: 1,946
What's Facebook? What's Twitter?
There's no reason why the hydrocarbons wouldn't go out with everything else. It's the hydrocarbons that make the uncatylized rotary exhaust so damn stinky.

You need alot of heat for carbon to build up. That's why it builds in the combustion chamber instead of somewhere in the intake.
purple82 is offline   Reply With Quote
Old 06-26-04, 03:11 AM   #5
RX-7 restoration guy
5 Year Member
 
mazdaverx713b's Avatar
 
Trader Score: (90)

Join Date: Oct 2003
Location: Vermilion Ohio
Posts: 14,338
mazdaverx7
Send a message via AIM to mazdaverx713b Send a message via Yahoo to mazdaverx713b
how else do you think it stays cool other than air under it?
mazdaverx713b is offline   Reply With Quote
Old 06-26-04, 05:23 PM   #6
Absolute Power is Awesome
10 Year Member
 
purple82's Avatar
 
Trader Score: (0)

Join Date: Mar 2001
Location: Lynnwood, WA
Posts: 1,946
What's Facebook? What's Twitter?
Quote:
Originally posted by mazdaverx713b
how else do you think it stays cool other than air under it?
Huh? The air injected by the air pump is meant for oxidation, it INCREASES the temperature within the cat. It's not a cooling system.
purple82 is offline   Reply With Quote
Old 06-26-04, 05:52 PM   #7
Yeah, shutup kid.
10 Year Member
 
coldy13's Avatar
 
Trader Score: (0)

Join Date: Mar 2002
Location: Columbus, OH
Posts: 1,684
Send a message via AIM to coldy13
Carbon DOES buildup in the cat if you disconnect the airpump. When I bought my car the previous owner had the airpump tube disconnected. The car didn't run. What was the problem? The cat was so damn clogged with carbon that the exhaust gasses couldn't even get through anymore. I hollowed out the cat and the car ran great.
coldy13 is offline   Reply With Quote
Old 06-26-04, 05:56 PM   #8
It Runs!
10 Year Member
 
Anex 570's Avatar
 
Trader Score: (0)

Join Date: Aug 2003
Location: PA
Posts: 955
Send a message via AIM to Anex 570
By the time the air reaches that Cat, it would be nearly 150 degrees. The acv itself would get to that temp or more. This itself would progress the longer its ran and would be nearly the temp of the cat itself (which would be really hot do to eaxust gas). The only thing that the pump is going to do is suply with mostly oxygen and some gas fumes possibly do to its fed from the air cleaner. There would be no way to "cool" the cat enough to make any differece, except mabye water, which cools the best on contact.
Anex 570 is offline   Reply With Quote
Old 06-28-04, 03:23 PM   #9
New Member
 
Trader Score: (0)

Join Date: Jun 2004
Location: Oklahoma
Posts: 14
Send a message via AIM to 85 GSL-SE
what if you take your cat off? It is possible it will clog anything inbetween the muffler and header?
85 GSL-SE is offline   Reply With Quote
Old 06-28-04, 03:36 PM   #10
Lorem ipsum dolor sit ame
10 Year Member
 
cdrad51's Avatar
 
Trader Score: (0)

Join Date: Nov 2003
Location: The Net
Posts: 3,262
Send a message via AIM to cdrad51 Send a message via MSN to cdrad51 Send a message via Yahoo to cdrad51
Nah.
cdrad51 is offline   Reply With Quote
Old 07-01-04, 11:02 AM   #11
/_\ Rotarized /_\
 
jweather73's Avatar
 
Trader Score: (0)

Join Date: Jun 2004
Location: Grand Prairie, TX
Posts: 210
Send a message via Yahoo to jweather73
how exactly do you "hollow out a cat"?? (catalytic converter, that is.... I can see a bunch of "cat" jokes comin' on....
jweather73 is offline   Reply With Quote
Old 07-01-04, 11:06 AM   #12
Got Boost?
10 Year Member
 
fatboy7's Avatar
 
Trader Score: (0)

Join Date: Feb 2002
Location: Watertown, MA
Posts: 1,064
1) Insert broom stick
2) beat like hell.
fatboy7 is offline   Reply With Quote
Old 07-01-04, 05:41 PM   #13
Absolute Power is Awesome
10 Year Member
 
purple82's Avatar
 
Trader Score: (0)

Join Date: Mar 2001
Location: Lynnwood, WA
Posts: 1,946
What's Facebook? What's Twitter?
So it looks like no one has actually "burned out" a cat by removing the air pump.
purple82 is offline   Reply With Quote
Old 07-01-04, 06:24 PM   #14
FKITALL
10 Year Member
 
The Wankler's Avatar
 
Trader Score: (14)

Join Date: May 2004
Location: Dublin Ca.
Posts: 3,589
No need to hallow out the cat, just buy a pre-silencer...
The Wankler is offline   Reply With Quote
Old 07-01-04, 06:24 PM
RX7Club
Mazda RX7




Paid Advertisement


 
 
 
Reply

Tags
3rd, air, airpump, car, diagram, discharge, disconnected, fumes, gen, heat, mazda, on, pump, rx7

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 10:37 AM.
All content Copyright 2007 by Internet Brands, Inc.

Contacts