Originally Posted by "02996ttx50

now i understand. i needed pictures. well, you should've been given a key chain with the tune. apologies to the op, the thread, and all.

Originally Posted by BauerR

I wouldn't go back to a tune using a MAF. Too much power left behind pulling through that $hit MAF.
Talk to Sam, he'll hook you up

Originally Posted by SteveMFr

Brits speak of dog's testes and people today like to say something is ill.

Originally Posted by SteveMFr

Glad you're happy, but simply assuming MAFless is for everyone because of your experience is silly. There's a million roads that lead to Rome and each has advantages and disadvantages. And the MAF itself is not the issue, it's the tubing (as I'm sure you meant to say). There are ways of getting around that: Pete95zhn is running a 997tt airbox with 1 MAF and doubling the values. I will likely either go that route or, possibly MAFless at some point as well.


Sorry to the OP for the continued hijack. To continue your schooling:
https://en.wikipedia.org/wiki/MAFless_Tuning

Originally Posted by EVOMS

There are two schools of thought for this--

The stock Bosch MAF can only see something like 600hp worth of air flow, and the 996TT intake tract is quite long and convoluted. The stock MAF is also a common failure item. Many people feel the solution to this is to go MAF-less, relying on the factory ECU's fallback speed density/Alpha N system (boost pressure x throttle plate angle) to measure load. This system works by saying that at a given air pressure and temperature ahead of the throttle body, X% throttle plate angle SHOULD results in Y air mass should be drawn into an engine based on a calculation of air density (pressure x temperature), a mapped table of pressure differential across throttle body vs. throttle angle, and a mapped table of engine volumetric efficiency.

The reality is that this measuring system is not terribly accurate on this car, as unlike the 997.2 and 991 that come stock running speed density, there is no MAP sensor inside the intake manifold itself so there are a lot of assumptions/calculations made to come up with an air flow figure. This means that fueling and ignition timing is never totally on point, so especially at low load, partial throttle, and under transients the car tends to run richer/leaner than ideal, which reduces power and sharpness of engine response. Most of these cars run ok at full load where all the tuning is done, but the engine management can't really keep up outside of that.

There are other compromises you make when pursuing a MAFless system. There are a bunch of cars running around with 'MAFless' tunes with the stock airbox/inlet system in place. I assume the MAFless tune is done in these circumstances to deal with the limitations of the stock MAF, and you keep an intake tract that functions like stock otherwise--air drawn from the top of the car, no dirt/water ingestion issues, etc. With upgraded inlet ducts, these systems work well up to 800hp or so, but you have the driveability issues outlined above.

However, there are other cars that have the intakes off of the turbos, being drawn through the fender liners or intercooler ducts. This is tricky to do, as you end up sticking the filter some place where it is exposed to dirt or water off of the rear tires, or it takes valuable air flow away from the intercoolers. We've done cars like this before, mostly when we make more than 900hp or so and you don't have any other options to flow that much air. For a street car making 600-700hp, it isn't necessary and you compromise the usability of the car by doing it that way.

We went another direction. The MAF is fantastic because it gives you a direct measurement of airflow under any circumstance. If your MAF sensor and housing are properly calibrated, it is a very accurate and precise way of measuring air flow going into the engine, which makes it very straightforward to do calculate how much fuel needs to be delivered, and how much load the engine is under for calculating ignition timing, torque production, etc.

To get around the limitations of the stock Bosch MAF, we developed a conversion kit for our V-Flow intake to use a Hitachi MAF sensor and a software calibration to work with the new sensor. This sensor is much more robust than the Bosch sensor, and is capable of seeing very high air flow levels. With our V-Flow intake and high flow turbo inlet ducts (https://www.evoms.com/Porsche_Turbo_...kfaid996tt.htm) we build an intake tract that supports over 800hp, and does so with EXCELLENT driveability and consistency. It lets us do things like this, making 660wtq by 3500rpm and a peak of over 700wtq on a GT700 with a built motor. With a fuel pump upgrade, this car does just over 700whp now on the same induction system.



Another benefit is that keeping the MAF sensor in place allows us to maintain almost all of the factory diagnostics, so the car will self diagnose itself should it develop an air leak. Almost every single time we get a >Stage 2 996TT in here that is converted over to our software from other brand, the car starts throwing faults that can be traced back to minor air leaks/mechanical faults that were undiagnosed on the previous tune.

Sam

Originally Posted by "02996ttx50

calling a tune, some spark plugs, and an air filter "the hammer"?

Originally Posted by RDS928S

Its all about the tune & quicker spool time/flow to & from the turbos.
Mafless systems support 600+ HP & much more.

Mafless incorporates larger y-pipe, eliminates factory air box & turbo air supply plenum. Most use fender well intakes.

Originally Posted by SteveMFr

There are ways of getting around that: Pete95zhn is running a 997tt airbox with 1 MAF and doubling the values. I will likely either go that route or, possibly MAFless at some point as well.

https://en.wikipedia.org/wiki/MAFless_Tuning