Leave it alone. You're going to open a huge can of worms, especially if you live where they have emissions testing. It amazes me how many people get taken in by the hype over cold air intake systems. Liquid gasoline does not burn. It goes out the tail pipe, wasted, without producing any power. The goal of all intake systems is to warm the air to promote more efficient fuel vaporization so it will burn efficiently.
Diesel engines need to use air coolers because they don't have a throttle blade. They are wide open to as much air as the pistons can draw in, and if that air is cooled, it will be condensed and more goes in, then more fuel can be injected when maximum power is needed. The extreme heat from the high compression is more than sufficient to ignite the fuel, regardless how much it was just cooled. With a gas engine, you only get maximum power at wide-open-throttle, but you're limited by the fact you need to maintain the correct fuel / air mixture. That isn't true with diesel engines. They always get all the air they can pack in. Speed and power are controlled by the amount of fuel that's injected.
Automotive marketing is extremely competitive. If a manufacturer could advertise one more cubic foot of storage space, one more inch of leg room, one more cup holder, or one more horsepower, you can be sure they would do it. They know there is a limit to what they can produce without trading reliability, driveability, fuel mileage, or emissions. You aren't going to improve on those.
You have to remember too that everything about your engine is tied to a number of computers. A higher-lift camshaft does not bring more air into the engine. That's a factor of the size of the cylinders. A camshaft with a higher lift or longer duration had a huge effect on older engines where we relied on air flow through the carburetor to suck fuel in. Varying those aspects changed the personality of the engine. That's how a Chrysler 360 c.I. Could effectively send a police car from 0 to 60 mph like a putsy four-cylinder, then launch it from 60 to 90 mph like a rocket, or the same engine with a different camshaft could get a huge motor home moving from a stop sign.
With all fuel injected engines except Chrysler products, fuel metering calculations are based on the weight of the air going through the mass air flow sensor, then that calculation is modified by readings from the intake air temperature sensor and the other sensors. If the Engine Computer sees air that's colder now, it's going to up the fuel calculations a little. This will result in more air and more fuel. The rest of us do the same thing by pressing down another 1/4" on the accelerator pedal.
If your new camshaft has a longer duration, it's going to have increased overlap. That used to make for the loping, rumbling engines of the '60s and '70s. Since the intake and exhaust valves were open at the same time for a longer period, the momentum of the incoming air and fuel helped push the exhaust gases out of the cylinders. That resulted in a lot more power, but the trade-off was a lot of that fresh air and fuel went right through to the exhaust without ever being compressed or burned in the cylinder. Your eyes would burn if you were near the tail pipe from the excessive unburned fuel. A lot of those cars had a hard time getting ten miles per gallon. That will be cleaned up on your car by the catalytic converters, until that fuel burning in them causes them to overheat and the catalyst melts and blocks exhaust gas flow. The computer will see that rich condition and make adjustments to how long it pulses the injectors open in an attempt to get the fuel / air ratio back to where it should be.
You already have an exhaust system that can flow more than it needs to for any driving conditions. Besides the computer watching the unburned air in the exhaust system, it also monitors what the catalytic converters are doing. If you look at the list of diagnostic fault codes that can be set related to the four oxygen sensors, you'll see there's about two dozen different codes. Every one of them could be reporting something that could adversely affect emissions, and those are the codes that must turn on the Check Engine light. The computer will suspend some of the tests it runs constantly if the oxygen sensor readings are needed for reference, so you can develop a totally unrelated running problem with no fault codes to tell you where to start looking. Also, a relatively minor problem, like a misfire that you can't even feel, can go undetected, and if that is causing too much unburned fuel to go into the exhaust system, it will overheat and destroy the catalytic converter.
There's just too many other things that are going to have to be modified to build a street racer. Too often these projects end up with a "For Sale As Is" sign in the window because the owners destroyed what the engineers researched and developed, and no one can straighten out the mess they created. You also have to remember there's a lot of emissions-related recalls that pop up all the time, and no dealer is going to work on your car because doing so holds them responsible to anything related to emissions compliance. They aren't going to take on that liability. We read here too often when people buy these project cars and are trying to put them back to original, and none of us know where to start.
Sunday, August 9th, 2015 AT 3:04 AM