Right i was reading another thread and something that i took from that was if you have to much air and not enough fuel you will melt your pistons from running to lean. Now my question is if you put a after market air filter on your car like i have Jeff. and in my case the air filter size and potentally the cubic inch of air intake over the norm set up is greatly increased is there a chance of this? i now you said my car was pluged into a cunzult after doing a cambelt but can you explane to us thickes how this works? and why there is no threat of the melt down. what stops that is it your set up or is it something else . ? thanks.

The air meter and the ecu regulate the air to fuel mixture. Where the issue comes is when, you expand beyond that set tolerance. The addition of a larger air filter simply allows the air that's going in to pass in easier, only a tiny proportion at stock levels, this does not exceed that tolerable range. When this becomes important is when you again go beyond that window, the car cannot suck in the same amounts as easy as it did at stock, so needs to breath easier.

More fuel and more air needs to breath in and out more, so everything increases. Simply fitting an exhaust or air filter will have very little gain on your hp figures despite what some manufactures will tell you. That's why they are often labled supporting mods, they are the things that help your proper mods. Things like upping the boost.

Its all about balance mate.

Running lean, too much timing, fuel with too low an octane rating & spark plugs of too high a heat range can cause issues due to detonation and preignition.

 

In the case of the Zed which uses a hot wire air flow meter, additional air and the ease at which the engine ingests it is compensated for up to a point (hence the need for correct mapping). Running lean isn't the main issue, too much timing advance is. I've worked with cars that were running 13.5:1 AFR (Air Fuel Ratio) on full boost, but with a very retarded timing map and forged components, the engine stayed together in one piece.

 

Fitting larger diameter intercooler pipework is the modification that caused the largest change in AFR I've found so far. I had to increase fuelling throughout the rev range by a significant amount, which also highlights the actual gains that were made.