Quote:
Originally Posted by Pete
Besides all of the above info i would hook your AIR pump directly into the header air tubes,hot wire pump to stay running so it pumps fresh air into your exhaust.
Pete
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I'm fairly certain they test for that, it's the "dilution" number.
The VA test is quite strict. My '90 was right on the limit for HC's with headers and cats on a basically stock 350.
I wonder if the best bet wouldn't be to toss stock manifolds and cats back on. Then you'll have lots of cat, and really good low-throttle O2 feedback to help it get as close as possible to stoichiometric. I have to think at low exhaust flow that the O2 in those huge header collectors really isn't getting a good read on things.
For what it is worth, my HC numbers from just adding headers/cats to a car with an already ported intake went from 13ppm HC's to 48ppm HC's. That's a 3-4x increase. You need to cut your numbers by 3/4 to get down where it's acceptable. I wonder if stock manifolds and cats won't be the best way to do it?