Cam effects on CO and HCO
12-26-2007, 06:34 PM
#1
Staging Lane
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Cam effects on CO and HCO Hey all, my home state recently changed our emissions testing. I am building a iron block ls1 (boring a 5.3 motor) to be installed in my 87 RX7. The new testing here is an idle only test (either idle or 2500rpm with no dynos) and they are only testing for hydrocarbons and carbon monoxide.
So if you go with a bigger cam what parts of emissions testing are greatly affected? I found people are getting 224/224 cams to pass cali emissions, which are quite a bit tougher than where I am at I believe. Are there any tricks to getting a bigger cam to pass CO and HCO like maybe running denatured alcohol(did this with my rotary and it helped me pass).
So if you go with a bigger cam what parts of emissions testing are greatly affected? I found people are getting 224/224 cams to pass cali emissions, which are quite a bit tougher than where I am at I believe. Are there any tricks to getting a bigger cam to pass CO and HCO like maybe running denatured alcohol(did this with my rotary and it helped me pass).
12-28-2007, 04:14 PM
#4
Anything with positive overlap is going to cause the HCs and CO to climb. The more overlap, the worse it gets. Pulling the cats off, obviously make this worse.
Theres no real secret really. There is some tuning that can be done to REDUCE the amount of emissions, but overlap will always cause raw fuel to be present in the exhaust.
Yes, running any kind of alcohol will help.
My advice would be to pick a cam with negative overlap, keep your cats, and have it running well when you get tested.
Or run ALOT of alcohol.
Theres no real secret really. There is some tuning that can be done to REDUCE the amount of emissions, but overlap will always cause raw fuel to be present in the exhaust.
Yes, running any kind of alcohol will help.
My advice would be to pick a cam with negative overlap, keep your cats, and have it running well when you get tested.
Or run ALOT of alcohol.
