Buckaroo Banzi

Anyone from California pass smog with an after market mild Cam?
Looking for numbers or feedback pro's and con's before I consider purchasing
a sponsors product.

thanks in advance


-BB

Buckaroo Banzi

Anybody???

Bump..

Trucho-951

Would you mind posting the cam specs? e.g. duration #'s @ 0.050", I think that would give folks something to comment on.

Laust Pedersen

I guess an indirect answer is better than none, so here we go:

My Jalpa 3.5L, V8, 64 deg valve overlap (@zero lift), 4 double horizontal Webers smog pump, two cats passed CA smog every time, each time to the amazement of the technician. There is no doubt that cats were the saviors. Before they were warmed up the exhaust smelled badly and when they were hot you could breathe the exhaust for hours.

In other words, I am quite sure that you with a good catalytic converter will be able to pass with a different cam. However it may require a dedicated chip to ensure optimum AFR. If your area does not require a load based smog check, then a dedicated chip may not even be necessary for passing smog, but still be a good thing for optimum performance.

Laust

Trucho-951

Laust, yes I agree, the importance of a really really good cat cannot be overstated.

My experience with a recent CA smog test lead me to understand that there is a tidder-todder relationship between HC's and NOx. Even with a MAF, I had to play around with the piggyback settings because if I went lean to reduce HCs, the NOx would shoot up exessively. So I had to find the "sweet spot" to get just enough fuel to keep low HCs, but not cause an undue raise in NOx. I'm not sure a dedicated chip can do the job, unless the chip is developed specifically to pass smog. I think a fuel management system, e.g. piggy back computer is a must.

I wonder, if we had a NOx pre-cat cat, like the new cars do, maybe our 951's would have an easier time at the smog check station?

Laust Pedersen

Rande, I forgot to mention that you shouldn't change your valve lift, since it may convert your non-interference engine back to an interference engine.

And now that I am here: Our catalytic converter is quite far downstream, meaning that they can be difficult to get it started (light-up), especially if it is old or a newer aftermarket unit, which use less catalyst (platinum, palladium, rhodium). Less catalyst is in some ways good, since it makes the cat more resistant to internal melt-down.
It is always a good idea to take a "spirited drive" just before the emissions test is done and also ask to have the actual test done as quickly after the drive as possible.

Laust

KuHL 951

A 10-15% mix of xylene in a 1/4 full tank does wonders for a borderline car. If you are uncomfortable with the xylene just fill the tank after you get it smogged. personally I like to drive mine harder after the transfusion of xylene just for the fun of it. I go strictly to "Test Only" facilities with a hot cat and have never failed one yet. My newest car is a 91 which says a lot right there.

Tom M'Guinn

So, on the subject of good catalytic converters, I recently got the SFR version and was surprise how small it is -- darn easy to R&R though. Anyone know how these compare to the factory unit in terms of emissions effectiveness?

Edit: sorry if this is a slight OT hijack -- the reason I ask here is that I am also considering a cam, but my current car is always borderline on NOx -- which is one of the reasons for the new cat. Curious if the new cat might allow more room for error with a cam.

PEvans

If you are running the original cat in a 20 y/o car you have to figure there isn't much left. Newer cats are more effective and last longer. If you live someplace where they put the car up on a treadmill and test for NO, you will eventually have to replace the cat. After that there should be plenty of head room for whatever fun stuff you want.

wi54545

Tom,

I have a fabspeed race cat and it is very small, I passed emissions with flying colors. Very low emissions considering the year of the car.