ProjectRESuperG

Hi guys,

Just need to know if premixing will mess up my catalytic converter. I have heard it does, and I have heard it doesn't and actually make the car run cleaner. So I need a definitive answer, yes or no.

On a side note, I have also asked which replacement cat on the market is the best, in terms of durability and performance (high flowing and emissions friendly), but never really got a good answer. I realize that maybe high flowing and being able to pass emissions with flying colors might not be possible, so I am looking for the best compromise.

I have a TII (87), and since the stock cat is too costly, I am looking at aftermarket replacements, since I live in CA, and will need to pass smog.

Thanks in advance!

Dokta

I'm curious about premix clogging the cat also. I know that 2 stroke exhausts get real nasty buildup on them after a while. I didnt want that to happen to my cats. I was looking at some high quality premixes like klotz (sp?), and redline. I was hoping that maybe these would burn cleaner, but people on the forum are always saying just to get the cheapest stuff you can find.

As far as cats go, im not too familiar with the aftermarket alternatives. But I do know what to look for. Try to find a catalytic converter that tapers very gently from the piping diameter, to the major diameter of the cat, then tapers gently back to the piping diameter. The biggest flow lost in a cat is the turbulence caused because of a rapid opening and closing of the piping diameter. When the diameter opens to the size of the cat is the worst. There is massive flow separation there. If you can find a cat that is designed properly, there is little to be gained by removing it.

Sammytom

Sense two cycle is meant to burn, I would think it would be better on the cats. But one thing I know, is that you will not pass smog while premixing.

chic7

it depends on if omp able/disable and what ratio you use my cats are gutted and look better know than they did when i first started to premix just what i've seen

ProjectRESuperG

Ok, so no premixing before doing a smog, check! Thanks for letting me know Sammytom!

marlaman

you guhave really searched. there is a good thread on premix and it's effects on the workings of your car. There is premix that doesn't affect your cats but it has to be rated for it. i'm not sure on the rating system myself so i suggest you search for it and you'll find it if you look.

Matt

ddub

That's a flat out lie. You CAN pass smog while premixing, it just might be harder. I passed with flying colors with only an airpump and cat and while premixing, no other emissions equip and no rats nest/solenoids.

ddub

Oh yah, and my passing was just a one day type of thing. Cat and air pump went on for test, came off afterwards.

RETed

It won't hurt cats.
It should pass smog (sniffer).
Your engine burns dirtier trying to burn engine oil.


-Ted

jacobcartmill

iTrader: (6)

why does everybody think that running premix is like the nastiest thing you can do to the ozone? its not like you're running 25:1 gas oil mix or something...

Parastie

Crank oil is not designed to be burned and leaves larger particles then an oil designed to be burned would.

dDub, how did you have your air pump connected for the smog test?

Sammytom

Its posable to pass while premixing. If you still have the airpump and cats, and you dont put to much premix in your gas. I removed my Oil meter pump, and I am pure premix. Theres noway Im passing smog.

pmr2000

I would think you would really need a lot of 2 cycle to fail emissions from premixing. I've been premixing about 8 oz. per tank on a first gen and second gen for 15 years and have never failed NYC emissions. Here's my '88 vert (stock except for hiflow cat and K&N intake kit, 106,000 miles) results:

4/17/04 limits and results
pollutant limit results
HC 0.80 0.12
CO 15.0 0.70
NOx 2.00 0.22

Sammytom

Well 8oz is nothing. Im using 22oz per tank on a tii. 1.5oz per gallon.

pmr2000

No 8 oz. is something, it is 8 oz., I said stock and still have a functioning MOP. That works out to about 1:256 in addition to what the MOP is adding per tank which is good as insurance with a functioning MOP, and I can still pass strict emissions.

Sammytom

No my cats are fine, but I dont come close to passing smog. I went from from passing to nowhere near passing by going to premix.

RETed

Why are you using so much premix???
All it does it suppress octane and dirties the exhaust unnecessarily.
Are you racing or something?
There is such thing as overdoing it.

http://www.thecarricos.com/ACRE/
New-tech90-7-12.pdf

Even at 6kRPM, Mazda has figured out 80 cc/*HOUR* as adequate engine oil injection to keep the apex seal happy.


-Ted

tri_tam

i think i use to much it would smoke for 1 to 2min happen right after start up to 30 sec after start up. that is premix thingy right?
i hope my motor is not giving up.

Etrips

how can you put too much??? its not rocket science here.... most people put 1oz for every gallon of gas into the car. so 10 gallons = 10oz... not hard. enjoy

ddub

The cat had the split air pipe going up into the engine bay still. So with my ACV gone and just my air pump in I had a straight shot to the pipe. Just got the largest heater hose I could find and clamped it onto the airpump outlet and the pipe inlet, bam all of a sudden my car was "clean"

This will kill ur cat if you leave it on for very long, though, I only did this for 1 day to pass my smog test and then I took the cat and air pump back off.

Oh yah and I did this with a bonez high flow cat

cruise HC 73 limit 160
cruise CO% 0.01 limit 1.1
idle HC 86 limit 220
idle CO% 0.05 limit 1.2

jhillyer

We'll get a lot of opinions on this.

I was experimenting with drier high-octane fuels, supplementing with lubricants, either non-synthetic or synthetic, also metallic, dissolved into the fuel, on a the Audi ATQ, a 5 valve/cyl normal breather at 10.6:1 CR with 4 catalytic cells and 4 wideband O2 sensors.

This fuel-borne lubricant tripled soot deposits in the exhaust, which mildly fouled the downstream O2 sensors. The upstream seemed to bake clean. The OBD II stats hinted the soot was likely depositing at open throttle low RPM (high load, such as bogging at standing starts and late downshifts uphill). I did not inspect the lower cats, but they're likely getting this soot. The soot is not waxy or sticky, however, just a fine powder so I'm not concerned.

RETed

I dunno how this applies to this thread.
Although initially it would look like it's applicable, you really need this engine to burn engine oil and compare that result with the pre-mix stuff.
You're also comparing a piston motor, which inherently burns a lot cleaner than a rotary due to the exhaust port timing, to the rotary engine, which usually spits out a lot of emission.


-Ted