ddub

Sweet I'm a pinch hitter

As stated, I think it's more the fact that the people that are always seen as "right" only post in topics they have knowledge of, and make sure what they are saying is the truth using the FSM, archives, searching, etc.

TitosToy

idealistically this is a neat thread to see if the "masters" (quoting blackplauge) have questions but realistically, if they did have any they'd post em up. as for them being right all the time - that's cuz it was their way of doing it that made it work. i'm not trying to knock the thread down i was just putting my 2 cents in.
i will thank them for all the info they've shared. i know i've learned alot sinced i've joined thi forum and it's a short amount of time.



so masters...if you hav any questions...ask away

RETed

First of all, the U.S.-spec Turbo II only comes with two cats.

The first one is a pre-cat - primarily designed to handle cold-start emissions.
This cat is small and the first one upstream the exhaust gases hit.
Due to it's smaller size, it's supposed to heat up faster - heat is GOOD for catalytics.

Second, I dunno what "controls HC and CO" means, but the cats cannot selectively control either by itself...at least I haven't seen one do that.

Short narrative on cats in automotive applications...
The precious metal platinum (and sometimes palladium) is used as the "catalyst".
In most applications, minute particles of Pl are suspended in a ceramic matrix.
The ceramix matrix is used due it's very high resistance to heat.
For some unknown phenomenon, heated Pl turns HC's (hydrocarbons), CO (carbon monoxide), and NOx's (oxides of nitrogen) into less obnoxious H20 (water), CO2 (carbon dioxide), and N2 (nitrogen gas) in it's more efficient operation.
Notice, the elements are all the same - H (hydrogen), C (carbon), O (oxygen), and N (nitrogen).
The hot Pl (catalyst) can rearrange them so they are not as toxic as when the engine first spits them out.

(Man, I hope my memory still works - I'm sure someone else will correct my mistakes. )

BTW, you're still one ignore BP...


-Ted

SJ_chameleon

Sorry to point this out Ted but I think you answered your own question about what HC and CO means. I think Karack was asking which cat controls Hydro Carbons and Carbon Monoxide. please dont kill me.

mwpayne

That's cause you're not always RIGHT, callin' my potential REPU ugly..
Oh, wait, guess it's true. Fuggit, I want one anyway!

White_FC

I think his point might have been that the cats can't 'control' the break down of these products. They can mearly change a set percentage of the gas flow depending on their condition and operating temp.
Playing with semantics really but I think thats what he was getting at.

.. I have been known to be wrong before though..

SJ_chameleon

Yeah that thought crossed my mind as well. You probably are right, I just thought I would point it out in case he missed it.
Thanks though

Kory_yahi

Here is a nice video of what these rotary "gurus" do when they are not working on their FC/FB/FD/Toyota Tercel

http://starterupsteve.com/swf/8bitDandD.html

Parastie

The Pl changing those particles into other particles is not for an "unknown reason". It momentarily binds to to the original particles dropping their entropy thus allowing for another (of the same) particle to bind to it. Entropy is hurtle that keeps things from reacting, catalysists drop the energy required for the reaction making it happen easier.

I actually studied Catalytic Converster in Organic Chemistry in college, but that was a long time ago.

Aaron Cake

iTrader: (1)

Uh huh...Well I can say for one thing that I've never even seen D&D.

BlaCkPlaGUE

I ******* NEW IT!!!!!!

Dude, I have sent you like 5 PM's in the past little while, with no answer. You bastard


Still , im looking for questions guys! Reted, comon, you know you got a question as to why your fc is doin something weird, right?

patman

iTrader: (3)

the precious metals arent really a catalyst in the conventional sense of the term. what they do is provide a site for the reaction to take place. In other words, reactions are more likely to take place on the spots of precious metals. I believe that there are selective cats that are more condusive to one reaction or the other, but i could be wrong about that.

HC= Unburnt Hydrocarbons (doesnt matter what kinda cat, the heat causes them them combust.)
CO= carbon monoxide (reacts with hydrogen and oxygen to form carbon and water) also other oxides of carbon do the same.

pat

Parastie

D&D is not something you can see since it's traditionally a Pen&Paper or table top RPG, it has no pieces besides your imagination.

Unless you're nuts...

RotaryEvolution

iTrader: (30)

yeah i know how catalysts work, i'm just trying to hunt down why my HC and CO readings are still high, i hate emissions so i never got into it. i guess i should pull off the MP to see what condition the latter 2 cats are in.

RETed

Sorry, it should've been unknown-reason-to-me.
I wasn't sure of the exact process which the gases undergo, so I just put down "unknown reason" just to make it simple.

Yeah, two semester of OC here too, but that was almost 12 years ago!

The majority of my understanding of how Pl works in the automotive catalytic was through an old National Geographic article on platinum itself.
There was a really nice diagram showing which molecule going where before and after a catalytic.
Did you know all the worlds platinum can fit in a 14 cubic foot square???
Makes me want to go invest in platinum futures...


-Ted

RETed

Hmmm...I swear that some of the HC's do breakdown through the cat...
I know that HC's are elevated in non-cat exhaust systems.
So it's pure heat that surpresses the "high" HC?


-Ted

RETed

First of all, work on the high HC count.
HC's is one of the easiest variables to control for emissions.
Leaning out the idle mixture will minimize HC count.
If the HC count is through the roof (over 1000+), then it's very likely your cats are just junk and need to be replaced.


-Ted

patman

iTrader: (3)

the exact advice of my engineering professor...lol

RotaryEvolution

iTrader: (30)

i tuned it on the smog machine, lowest i could reach with the HC before it would start to lean misfire and rise again was at about 200 HC ppm which is what makes me wonder if my main cat is even still in one piece. i have been noticing my boost creep rising lately but i thought it was because i ported my new rotor housings even larger than the last set but i will only be able to really tell by pulling the pipe and inspecting their conditions.

patman

iTrader: (3)

freer flowing exhaust will always mean more HC. Restriction in the exhaust causes higher temps, which gives the unburnt fuel a chance to burn instead of just blowing through. Another thing to consider is if you are burning any oil at all it will bump your HC way up.

pat

RotaryEvolution

iTrader: (30)

it's a rebuild with about 500 miles on it, not smoking but it is running premix which shouldn't skew the numbers much. the exhaust is all stock but the cats are old and worn out, it is possible i have a leaking injector causing some of it, the car is a PITA to start even right after a shutdown and it sounds like a secondary injector is bleeding off after i shut down and listen to the rails but it could just be fuel boiling in the rails.

i would like to get it to pass without buying a new set of cats but i should check their conditions before ruling that out as an option. only reason i am reluctant is because the whole exhaust system is coming off the minute i get home after passing emissions and a brand new 3" turboback will be replacing it with a WG port job on the side.

Bob_The_Normal

Would a high-flow cat-back be that bad for emissions since you're still restricted up until after the cat? And maybe I'm actually getting less flow because of the greater volume it has to try and move through AFTER it gets through the cat?

I plan to switch to a high-flow cat but before I do that I want to pass smog... don't want to go making it WORSE before trying to pass lol.

And if I'm running way rich right now will that matter if the cat is in good working condition?

HAHA! This thread got jacked.

--Gary

Andrew.

iTrader: (4)

This is why: https://www.rx7club.com/general-rotary-tech-support-11/wtf-rotorhousing-question-gurus-381160/

I can't believed it when i saw it "question to the guru's" jeeez

RotaryResurrection

iTrader: (8)

yeah, I hear ya...

Perhaps I should have worded it "question to the *other* guru's".

Note that I got no really useable replies other than just wild guesses. I guess if the question were going to be answered, I would have answered it myself, as I seen to have seen inside more engines than just about anybody here (around 300 now, I guess).

RotaryEvolution

iTrader: (30)

didn't get to see the pics since they are gone now but my guess is the rotor housings were probably flawed in the casting process, there is probably a batch of them floating around out there somewhere with similar problems as that one had.