Eventually, I will have to smog my cam and heads car in a little over a year. What got me started thinking was the post from someone about passing smog with a 224/230 cam.

I have heard of people with the LT4 Hot cam being able to pass with no problems. I have a comp XE 230/236-112 cam. Taking a look at the total duration (0.006 lift) numbers, my cam is only slightly larger than a Hot cam. It's in the 0.05 numbers that it's bigger. That's the whole idea of the XE cams - to cram as much lift and duration as possible onto a cam.

The numbers are:
LT4 Hot cam
0.006" lift duration - 279/287
0.050" lift duration - 218/228
LSA - 112
ICL - 108
Calculated degrees of overlap: 59

Comp XE 230/236
0.006" lift duration - 282/288
0.050" lift duration - 230/236
LSA - 112
ICL - 108
Calculated degrees of overlap: 61

Comp "306" cam (just for comparison)
0.006" lift duration - 290/307
0.050" lift duration - 230/244
LSA - 112
ICL - 108
Calculated degrees of overlap: 74.5

Given that overlap is what supposedly kills you for smog, I wonder if the 230/236 could pass with a smog tune. I'd just like to have to avoid swapping the cam for smog if I don't have to.

Any ideas? What about swapping to say some 1.3 ratio break-in rockers to reduce the effects of higher lift and overlap? Anyone ever try this?

BRAD

 

I'd like to know also, from what I've been reading lately that Cali has changed the laws again and has now made the hotcam hard to pass. I read a post or two on it, so I can't say for sure if its true, but I sure would like to be able to pass with mine, which is smaller than yours. You might have to get it smoged to see

 

i've toyed with the idea of putting a extra cat in the catback right at the start of it. If that is illegal hide it in a muffler. I've also wondered if a person could wire their air pump to run while they are testing. The solution for polution has always been diluting it. I don't have emissions now but i if we do i think if a person pulled every trick in the book they could get it to pass. Like a tune, special fuel.

 

My air care is in 2 more years, so i'm not to worried right now. I think it will also take some extensive tunning.

 

I think you may be a little mistaken. Plus 12* intake and 8* exhaust duration is significantly larger than the hotcam, and couple that with the much larger lift for both than the hotcam. I'm not going to say a definitive NO, but it's highly doubtful that the 230/236 will pass emissions. The proverbial snowballs chance in hell.

 

well, its been done

It basically takes some good emmissions tuning plus the general well maintenance and a few tips/tricks (drive it around for a good hour before you bring it in, etc) I forget exactly who it was that passed emissions with this cam, but if you do a search the post may sstill be there...

 

I've thought of this as well, although the PCM would have to stay in closed loop but all that extra O2 would make the cats work better and dilute the ppm counts as stated.
FWIW I found out with the OBD2 plug-n-play emissions, rear O2 sims pass with flying colors.

 

The numbers I was looking at were the total duration numbers. On those two, the hotcam has only 3 degrees less intake and 1 degree less exhaust. I know the 230/236 opens faster and stays open more/longer. In terms of overlap, the two are only 2 degrees apart.

On both cams, during overlap, both the intake and exhaust valves are open but only a very small amount. For example, it takes the Hot cam about 30 degrees to go from 0.006 lift to 0.050 lift (and another 30 degrees at the other end to go back down from 0.050 to 0.006).

Maybe that's not even a valid point. If nothing else, it shows how much more abrupt the XE series is.

I had thought of using the AIR pump full time during the test. It is supposed to reduce emissions by completing the combustion of unburned hydrocarbons in the exhaust during cold startup, when the engine is in enrichment mode to warm up. Then again, injecting all that air in closed loop could cause a lot of problems with the O2 sensors.

Well if that fails, I may just have to use "other means", or just swap back to the stock cam for smog.

BRAD