Okay, here are my thought's on speed density......"please remember, you can turbocharge anything, it is just a matter of flexibility."
Speed Density: a Speed Density system still has no sensors that directly measure engine airflow, all the fuel mapping points must be preprogrammed, so any significant change to the engine that alters its VE requires reprogramming the computer. Your map on the ford mustang is more then likely a 1 bar, to increase your boost level's, you can buy another bar sensor of 3 bar.
Your speed density ECU has preprogramed standard's installed, therefore, it tries to assume that your engine will always be within these parameters.
Maf Set up: Mass Air Flow (MAF) systems use a sensor mounted in front of the throttle body that directly measures the amount of air inducted into the engine. The most common type of mass-flow sensor is the hot wire design: Air flows past a heated wire thatâ€™s part of a circuit that measures electrical current. Current flowing through the wire heats it to a temperature that is always held above the inlet air temperature by a fixed amount. Air flowing across the wire draws away some of the heat, so an increase in current flow is required to maintain its fixed temperature. The amount of current needed to heat the wire is proportional to the mass of air flowing across the wire. The mass-air meter also includes a temperature sensor that provides a correction for intake air temperature so the output signal is not affected by it. The MAF sensorâ€™s circuitry converts the current reading into a voltage signal for the computer, which in turn equates the voltage value to mass flow. MAF systems also use additional sensors similar to those found in Speed Density systems. Once the electronic control module (ECM) knows the amount of air entering the engine, it looks at these other sensors to determine the engineâ€™s current state of operation (idle, acceleration, cruise, deceleration, operating temperature, and so on),
(((then refers to an electronic map to find the appropriate air/fuel ratio and select the fuel-injector pulse width required to match the input signals.))) This to me, is what is important in a great tune and increased boost levels, to safely maintain your engines preformance.
Now, this is a fact on the speed density systems when comparing them to a maf system: Speed Density systems wonâ€™t tolerate major engine changes without computer reprogramming, which usually requires the services of an outside specialist, or an aftermarket ECU. Without the upgrade to an aftermarket set up, Speed Density system will have difficulty due to an erratic or insufficient manifold vacuum signal.
To me, if you truly want a nice turbo set up, Mass Air is the way to go, due to its superior accuracy and greater tolerance for engine changes. In the past there was a problem on high-horsepower engines because larger-capacity MAF sensors were scarce and prohibitively expensive. Nowadays, oversize MAF sensors are available from Pro-M, Granatelli Racing, and other sources that are compatible with Ford engines and computers. Custom MAF calibration keyed to the specific vehicle, engine, and injector size is also available. With a correctly calibrated oversize meter, reflashing the Ford computer usually isnâ€™t required. (However, before you run out for a larger Ford MAF meter, Fast Track Performance points out that the first limiting factors are the puny Ford 19 lb/hr injectors, which can only support about 320 hp.)
Please try to remember, all i am doing is trying to give information based on my limited knowledge on power adding. I have been involved with turbocharging for a few year's now, and by all account's i am still a novice to this hobby. If i was really good, i wouldn't own a car that only get's into the 12's @ 6200' above sea level, it would be more into the 8's or 9's.
I am just trying to give information based on how i understand ECU car's and what would be the best money spent for building your turbocharged engine, so that it can be enjoyed for years to come.
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