cam theory/question

[rickles8099]

so i dont know if its because im on too much crack or what, but heres something i was pondering on yesterday.

would an aftermarket turbo cam with a stock fuel map with the o2 sensor disabled cause a car to run leaner and therefore "cleaner" (emissions wise) or would the cam actually make the car run "dirtier"

[N2HIFI]

two ways to look at it

1- Does the larger lift and duration allowing more air and fuel into the combustion chamber mean that the mixture will burn hotter thus buring everything in the chamber and having less left unburnt fuel left over = less emissions having to be filter by a cat and muffler.

2. Does having more fuel and air in the combustion chamber mean that there is a possibility more unburnt fuel may make it through the motor and out the exhaust which the cat and muffler may not beable to filter out enuff to pass emmissions.



i personally would think that option 1 would be more the case, because with a stock base map and not adding more fuel but adding more air due to the longer intake duration of the new cam would cause a lean senario which would make the motor burn hotter thus burning ALL of the mixture in the combustion chambers which would lead to less exhaust needed be filtered by the cat and muff which on a turbo car there probly would be not car.


just my opinion

chris

[6speedblazer]

so i dont know if its because im on too much crack or what, but heres something i was pondering on yesterday.

would an aftermarket turbo cam with a stock fuel map with the o2 sensor disabled cause a car to run leaner and therefore "cleaner" (emissions wise) or would the cam actually make the car run "dirtier"

now im not a honda guy so bear with me. im going from my gm expericence

on gm cars fuel ammount is based off engine vac. an aftermarket cam will pull less vacuum making the computer think there is a higher load or your at a higher RPM thus making the engine run richer throught the rpm range.

some people argue that a cam will allow for more airflow and that it will get burned off but this is not true. i know if the blaze sits adn idles for a few it will start to load up and i gotta blip the throttle to clear out the cylinders.

i dont see why this wouldnt be the same for any speed density setups

[thsmrtone1]

true... gotta keep in mind the map sensor measures I/M vacuum, not cylinder vacuum... i would think though, that a longer cam durration would create more IM vac... = less fuel

i dont have any proof though....

[6speedblazer]

true... gotta keep in mind the map sensor measures I/M vacuum, not cylinder vacuum... i would think though, that a longer cam durration would create more IM vac... = less fuel

i dont have any proof though....

i can prove my post. i have a large aftermarket cam and at idle i pull 14 in of vac stock was 20

my BLM's went from 128 on the stock cam to 110 on the aftermarket cam there for im pulling less vac and running richer.

the ecu interprets less engine vac as more engine load, more load requires more fuel