# MAF Sensor HP limits?



## Dowski12 (Nov 2, 2011)

My question is, how much HP can a stock 225 maf sensor support and If I was to use the stock sensor in a 4" housing would it effect the sensor readings? Im gonna be running a precision 5858, shooting for 500hp, and wasn't sure if the stock maf would keep up. Any feed back would be greatly appreciated.


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## Mantvis (Jan 1, 2010)

Dowski12 said:


> My question is, how much HP can a stock 225 maf sensor support and If I was to use the stock sensor in a 4" housing would it effect the sensor readings? Im gonna be running a precision 5858, shooting for 500hp, and wasn't sure if the stock maf would keep up. Any feed back would be greatly appreciated.


All i can say i have APR Stage 3+ with 3in housing, and it does use stock sensor.


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## [email protected] (Jul 1, 2009)

Measurement accuracy with a stock 3" sensor begins to degrade above 270 grams/second. Transplanting that MAF's sensor into a bigger housing will enable more accuracy at that power level, but you need ECU software which is calibrated for the re-scaled sensor voltages.


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## jbrehm (May 16, 2006)

In for this one!

Does anyone know the actual answer to his question? I make more power without my (new) MAF in, but then I saw Doug pull something close to 500wHP with his in  In the stock housing, does anyone know at what g/sec, hp, lb/min, whatever unit the MAF maxes it's 5V reading out at?


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## Dowski12 (Nov 2, 2011)

[email protected] said:


> Measurement accuracy with a stock 3" sensor begins to degrade above 270 grams/second. Transplanting that MAF's sensor into a bigger housing will enable more accuracy at that power level, but you need ECU software which is calibrated for the re-scaled sensor voltages.


Im going to be tunning with maestro, is there a way to rescale for the larger housing using maestro?


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## [email protected] (May 14, 2009)

Dowski12 said:


> Im going to be tunning with maestro, is there a way to rescale for the larger housing using maestro?


Maestro allows you to select different MAF's, like VR6/Audi 4.2 V8 ect.


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## Kacz07 (Mar 4, 2012)

I have the R32 MAF and airbox with an APR Stage 2+ tune, 4 bar FPR, TIP, tubular manifold, and 3" DP and I have no codes.

I don't know if anything has been rescaled, but I know that when the sensor senses slower air, the 4 bar FPR can compensate enough to keep it within reasonable ECU correction values. 

I noticed a difference in spool time. It used to pull hard into midrange and seem to stumble, but now it spools slower and seems to pull harder on the top end.


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## 20v master (May 7, 2009)

Kacz07 said:


> I have the R32 MAF and airbox with an APR Stage 2+ tune, 4 bar FPR, TIP, tubular manifold, and 3" DP and I have no codes.
> 
> I don't know if anything has been rescaled, but I know that when the sensor senses slower air, the 4 bar FPR can compensate enough to keep it within reasonable ECU correction values.
> 
> I noticed a difference in spool time. It used to pull hard on top and seem to stumble, but now it spools slower and seems to pull harder on the top end.


225 MAF to R32 MAF = ~17.4% more cross sectional area in the housing. Going from 3 bar FPR to 4 bar = ~15.5% more fuel pressure. This is why the combo works. Same as going from a 180 1.8T MAF to a VR/225 MAF. The numbers are close enough that the ECU sees a percentage less airflow, and removes a similar percentage of fuel injection time. Increasing the pressure behind the injectors is something the ECU doesn't see, and it just happens to even out. If you have a standard APR file, nothing is scaled for your MAF setup. Your observations however, aren't concrete and are likely placebo. You say it used to pull hard up top, then it seems to pull harder up top. So that sounds like no change at all. Data logs are needed to define a difference. Swapping to the other MAF and airbox lid along with the old FPR would be easy enough to make a nice comparison with some VAG COM logs though. Spool time shouldn't have been affected either way.


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## ModsTTand (Jul 8, 2009)

20v master said:


> 225 MAF to R32 MAF = ~17.4% more cross sectional area in the housing. Going from 3 bar FPR to 4 bar = ~15.5% more fuel pressure. This is why the combo works. Same as going from a 180 1.8T MAF to a VR/225 MAF. The numbers are close enough that the ECU sees a percentage less airflow, and removes a similar percentage of fuel injection time. Increasing the pressure behind the injectors is something the ECU doesn't see, and it just happens to even out. If you have a standard APR file, nothing is scaled for your MAF setup. Your observations however, aren't concrete and are likely placebo. You say it used to pull hard up top, then it seems to pull harder up top. So that sounds like no change at all. Data logs are needed to define a difference. Swapping to the other MAF and airbox lid along with the old FPR would be easy enough to make a nice comparison with some VAG COM logs though. Spool time shouldn't have been affected either way.


simplified answer :beer:


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## Kacz07 (Mar 4, 2012)

20v master said:


> 225 MAF to R32 MAF = ~17.4% more cross sectional area in the housing. Going from 3 bar FPR to 4 bar = ~15.5% more fuel pressure. This is why the combo works. Same as going from a 180 1.8T MAF to a VR/225 MAF. The numbers are close enough that the ECU sees a percentage less airflow, and removes a similar percentage of fuel injection time. Increasing the pressure behind the injectors is something the ECU doesn't see, and it just happens to even out. If you have a standard APR file, nothing is scaled for your MAF setup. Your observations however, aren't concrete and are likely placebo. *You say it used to pull hard up top, then it seems to pull harder up top. So that sounds like no change at all. * Data logs are needed to define a difference. Swapping to the other MAF and airbox lid along with the old FPR would be easy enough to make a nice comparison with some VAG COM logs though. Spool time shouldn't have been affected either way.


I meant to say used to pull hard into midrange and then stumble on top. Like it was spiking and then overboosting.


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## Dowski12 (Nov 2, 2011)

So would it be benefitial to upgrade to a different MAF, such as the R32, or does it really even matter? Sounds like I can use the stock MAF either way, but I have to buy a new maf, so if it would be better in the long run to upgrade, i'd rather do it now. Thoughts?


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## Marcus_Aurelius (Mar 1, 2012)

On a stock turbo, most likely not needed because you're well within the range of accuracy. On big turbos that flow over 300 G/s, it is probably a good idea to get proper readings. The OEM TT sensors (two different ones for AMU and BEA engine codes) are reported to loose accuracy pass 275 G/s and max out at about 335 G/s. 

If you are flowing more than 335 G/s, want to run a MAF, and don't have access to Maestro, you can run a bigger housing and adjust fueling to accordingly. It will lower the MAF values recorded by the margin increased in the housing. This effectively, when done properly, keep you in the range of accuracy of the sensor and help avoid hitting the limit. This hack works but you need to be aware that your actual and calculated load values, as well as torque reported to the ECU are also off by a margin. 

This whole thing can work to your advantage or against you. I have been running a turbo S4 housing with stock TT sensors effectively on my stock turbo for various reasons. Fueling is adjusted and AFR curve is spot on after some tweaking. The actual MAF readings (loads and TQ values as well) are low... but when your driver TQ request is unchanged (based on pedal position) this is not a bad thing for the ECU to ask components to work harder to meet request. 

If you run Maestro, it's really easy because there are various MAF housing/sensor that are preset and can be chosen on the fly. If you're on an off the shelf file, you need to pick the appropriate cross sectional increase that will fit your airflow and find a strategy to correct the fueling (increasing the pressure is not ideal for all situations, especially if running big boost). :beer:


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## 01ttgt28 (Jun 23, 2009)

I don't know if I can explain this correct a couple years ago at water fest after I dyno my car 
Their was a guy from Canada that won the dyno pulls with 740 whp or close to it.he came up to me
And asked about my set up so we talked he told me that he runs a cheese cloth in front of the maf ? I'm
Not 100% but if some one knows what I'm talking about please correct me


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## Dowski12 (Nov 2, 2011)

Marcus_Aurelius said:


> On a stock turbo, most likely not needed because you're well within the range of accuracy. On big turbos that flow over 300 G/s, it is probably a good idea to get proper readings. The OEM TT sensors (two different ones for AMU and BEA engine codes) are reported to loose accuracy pass 275 G/s and max out at about 335 G/s.
> 
> If you are flowing more than 335 G/s, want to run a MAF, and don't have access to Maestro, you can run a bigger housing and adjust fueling to accordingly. It will lower the MAF values recorded by the margin increased in the housing. This effectively, when done properly, keep you in the range of accuracy of the sensor and help avoid hitting the limit. This hack works but you need to be aware that your actual and calculated load values, as well as torque reported to the ECU are also off by a margin.
> 
> ...


Thanks Max, 
I already have Maestro so that works out perfect. Easy is the name of the game at this point, after so many hiccups over the past year, the easier the better.


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## Kacz07 (Mar 4, 2012)

I know Maestro is my answer, but I just haven't come across a good deal to get it. Plus, this car feels as fast as my 300whp/300wtq Caliber SRT4 (fwd, no mechanical LSD), at certain times in the powerband. For this reason and suspension mods, I'm complacent about moving forward and content to drive.:laugh:


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