FC3AZ

Just have a simple question.......would 2 Bonez high flow cats keep a street ported 13B legal?

Bambam7

It should.
I have a ported motor, and I failed emmisions so bad it was funny (9X the acceptable HCO) I needed a cheap, temp way to lean it out a lot, (My Nox was really, really low, so I could play with leaning out a bit to cut down the HC), and since I am really, really cheap, and a real hack, I disconnected my O2 sensor so the ecu wouldn't read it, and go into failsafe mode, then I actually drilled a hole in my intake hose between the engine and the MAF sensor, and put a piece of cloth over it to filter it.
The ECU thought there was a lot less air going in than actually was, and by playing with the size of the hole, I could get it leaned out to the point where it can pass emmisions, and run somewhat normally to pass the test.
I know, I should be hung for such hack work, but hey, whatever works.
If it runs too lean your Nox will get too high and you can fail on that too (plus combustion temps will be dangersously high when driving to the test)
Anyways, to actually answer the question, porting does increase emmisions a bit, but you should be able to get away with it if things are tuned right, and you have two cats!

niner

i passed emmissions on a streetported motor. HCs were very low too, i think about an 8 (220 is limit, most newer cars get bout 15-30)
but i did inspect it myself. and my muffler wasnt hooked up so a LOT of fresh air was mixing w/ it
but i think that it wouldnt be too hard as long as car is running good

FC3AZ

Reason why I ask, is because I was considering getting a used motor, and getting a mild port done to it. Then buying Bonez dual high flow cats to clean up the exhaust a bit. I am going to keep the stock exhaust manifold and everything. My goal is a street legal (emissions) ported motor. I just think that would be best of both worlds.

RotorMotorRX7

i got a street ported motor and i failed emmisions about 4 times so i siad the hell with it and put a race pipe in my car and pulled the air pump just despite them!! lucky for me i found someone to hook me up with an inspection sticker

Bambam7

You wouldn't really get any worthwhile gains in having a ported motor with full emissions/cats
Since all of the gain is in the high end, the cats wouldn't let the exhaust open up enough to make use of the bigger ports in the motor.
You'd lose low end too, and not gain enough high to make it worthwhile.

Just my 2 cents.

FC3AZ

hmmmm..........very interesting. Thank you all for the help. Would I even lose flow with the Bonez cats?

Ryde _Or_Die

yes

FC3AZ

Well, I dont really have any other option for keeping it street legal though. hmmm...........this has me puzzled. I have no choice for the emissions legal issue though....sorry....

Felix Wankel

Try a Random Technology cat, V8 guys seem to like them. (I'm not a big fan of Bonez anyway).

Bambam7

You will get more gains out of you 6 port motor by doing bolt ons anyways. Porting a near stock 6 port motor is juts not worth the money, time, and work required unless you are going all the way with everything else (no emmission)
With your car the way it is, porting will get you about 10 HP at the high end, and lose a bit (maybe not noticable) in the low end.
If you spend about the same amount of money on bolt ons you get get much better results.
Get headers( maybe), get a custom made pre-cat replecement pipe,(they are useless) a high flow main cat, a nice cat-back, a K/N cone intake filter, get bigger spark plug wires, and an electric fan. That will keep you emmisions legal, and you will have a much faster car (30 hp minimum)

Oh, I almost forgot, with porting, your gas mileage will SUCK! (5 mpg drop for 20 hp sucks!)