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Is soem of this cam emission leagal?

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Old 03-14-2017, 09:55 AM   #1
n_brio
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Default Is soem of this cam emission leagal?

I have a stock Ls2 ttix on e85 is anyone of this cam going to pass emission?

227/231 | .625"/.605" | LSA114+4

228/235 .605/.609 116+5

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Old 03-14-2017, 11:28 AM   #2
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Define "pass emission". What tests are required in your area?
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Old 03-15-2017, 02:32 PM   #3
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CO Max 0.5
CO 2500 rpm 0.3
HC max 100
Lambda 0.96-1.25
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Old 03-17-2017, 01:32 PM   #4
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bump
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Old 03-18-2017, 03:06 AM   #5
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If you don't have to measure emissions at idle (but at 2500...3000 rpm), it will be ok, assuming your tuner knows how to tune GM PCM's.
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Old 03-18-2017, 05:22 AM   #6
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CO Max 0.5 and HC max 100 is at idle is this possible?
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Old 03-19-2017, 11:33 AM   #7
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I'm hardly a camshaft expert, but I am pretty familiar with passing a smog test.
Without the cats, either are likely to fail.
With properly functioning cats and a reasonable tune, the second one seems likely. My reading of the specs say wide LSA=low overlap=fairly clean on the HC.
It compares pretty closely to my 224/236 .649/.649 on 117+4. 2 local tuners said "why, that's smaller than my smog cam!" (California smog)
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Old 03-19-2017, 06:47 PM   #8
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Quote:
Originally Posted by n_brio View Post
CO Max 0.5 and HC max 100 is at idle is this possible?
With cats fitted, both will be almost zero. So yes it would be very easy to pass on such vehicles with an appropriate cam.

Even with a very mild cam and no cats, that would be doable.

But go too far with the cam and even with cats that will be difficult.

That said...both of those cams are probably pushing things a bit, and would most certainly need cats to have any chance of passing.
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Old 03-19-2017, 07:13 PM   #9
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Takes a pretty fresh engine and careful map to idle below 1/2%CO and still be smooth enough to read below 100ppm HC, even with a factory stock cam. Raising the idle helps a bunch!
With good cats and not a bunch of overlap, should read pretty close to 0 on both, but doesn't take much 'misfire' to overpower the cats and spike the HC.
NOx is the tough one... but doesn't sound like it's tested there. Lucky bastard!
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Old 03-20-2017, 05:12 AM   #10
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we dont messur NOx here in sweden =)
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Old 03-20-2017, 07:30 AM   #11
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Is it possible to have a cam that passes my emissions with out cats an the car? im on e85.
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Old 03-20-2017, 05:42 PM   #12
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Someone please correct me if I'm wrong with this.... but .5%CO is right at stoich?
Too much leaner than that will make the HC rise ("lean misfire"), so needing to be leaner than that to pass CO will elevate the HC... and 100ppm at idle without a cat is already pretty tough. It's going to be a pretty fine dance on the mapping!
I think I'd pass on that challenge.
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Old 03-20-2017, 07:07 PM   #13
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it's not quite as straightforward as that...but 0.1% CO on paper is around 14.7:1 AFR gasoline

0.5% would be around 14.3:1

But that would be with a proper gas analyser, a lambda sensor may not always match

Havent a clue about E85 though and how it performs
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Old 03-21-2017, 09:42 AM   #14
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Working from memory, all the O2 sensor cars wanted to hover right around the .5% mark pre-cat. But it's been a long time since we needed to make those routine adjustments!
It would be a fun challenge to see just how clean you could make this one... but I don't think clean enough. Theoretically, E85 will help with the HC, but zero first hand experience.
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