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Correct place for MAP Sensor

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Hi!

This is my first post.

Im From portugal and we have a small drift team.

Yesterday in dyno we read near the turbo 1.35 bar and in intake manifold 0.8bar

This is a BMW E36 with M30b35 engine with T04e Turbo.

Where is the correct place to put MAP SENSOR?

In my own drift car, BMW E21 with M20B20 engine Turbo, if i put the MAP Sensor befora butterfly i cant read Vacuum and if i put in manifold i have the correct vacuum values?

Where is the right place?

Sorry about my bad English

Thanks

I don't know what your ECU is, but the MAP sensor is usually used for the engine load calculation and the airflow calculation. You want to put it in the intake manifold.

The pressure from the turbo will decrease through the system. It will be highest at the compressor outlet, and lowest in the intake manifold. For your purposes, the engine doesn't "see" the pressure in the compressor outlet. It only "sees" the pressure in the intake manifold.

Raymond is bang on, you should be measuring the pressure in your inlet manifold, as that is what the engine is actually getting. I think you've identified another problem however, a pressure drop of 0.45Bar is pretty large, you might want to check out the rest of your intake system for restrictions. If you can get some temperature measurements of compressor outlet, and intake manifold air temp that might help you out too.

Hi!

Many thanks guys!! The map sensor is inside of intake manifold and the IAT sensor is measuring around 40 Celsius degrees.

Another question... What the good size for all lines turbo to intake manifold?

Thanks again

.4 Mach is the point at which air becomes turbulent and losses in efficiency start to occur exponentially. The key is to stay under that speed. You want to use the smallest piping possible that still flows enough to meet your needs. Larger than necessary piping increases lag time with no measurable gain

The velocities are in miles per hour and mach, and the flow rates are in cfm. Measurements for the piping are in inches.

2" piping

1.57 x 2 = 3.14 sq in

300 cfm = 156 mph = 0.20 mach

400 cfm = 208 mph = 0.27 mach

500 cfm = 261 mph = 0.34 mach

585 cfm max = 304 mph = 0.40 mach

2.25" piping

3.9740625 sq in = 1.98703125 x 2

300 cfm = 123 mph = 0.16 mach

400 cfm = 164 mph = 0.21 mach

500 cfm = 205 mph = 0.26 mach

600 cfm = 247 mph = 0.32 mach

700 cfm = 288 mph = 0.37 mach

740 cfm max = 304 mph = 0.40 mach

2.5" piping

4.90625 sq in = 2.453125 x 2

300 cfm = 100 mph = 0.13 mach

400 cfm = 133 mph = 0.17 mach

500 cfm = 166 mph = 0.21 mach

600 cfm = 200 mph = 0.26 mach

700 cfm = 233 mph = 0.30 mach

800 cfm = 266 mph = 0.34 mach

900 cfm = 300 mph = 0.39 mach

913 cfm max = 304 mph = 0.40 mach

2.75" piping

5.9365625 sq in = 2.96828125 x 2

300 cfm = 82 mph = 0.10 mach

400 cfm = 110 mph = 0.14 mach

500 cfm = 137 mph = 0.17 mach

600 cfm = 165 mph = 0.21 mach

700 cfm = 192 mph = 0.25 mach

800 cfm = 220 mph = 0.28 mach

900 cfm = 248 mph = 0.32 mach

1000 cfm = 275 mph = 0.36 mach

1100 cfm max = 303 mph = 0.40 mach

3.0" piping

7.065 sq in = 3.5325 x 2

300 cfm = 69 mph = 0.09 mach

400 cfm = 92 mph = 0.12 mach

500 cfm = 115 mph = 0.15 mach

600 cfm = 138 mph = 0.18 mach

700 cfm = 162 mph = 0.21 mach

800 cfm = 185 mph = 0.24 mach

900 cfm = 208 mph = 0.27 mach

1000 cfm = 231 mph = 0.30 mach

1100 cfm = 254 cfm = 0.33 mach

1200 cfm = 277 mph = 0.36 mach

1300 cfm max= 301 mph = 0.39 mach

In order to convert from Lb/Min to CFM for the equation above, you take the flow rate in Lb/Min for your turbo (generally an educated guess based on the pressure ratio and power created) and multiply it by 14.27. That will yield the CFM flow for your setup.

For Example:

T3/T04e 57trim .63ar @ 21psi makes 452 whp

This turbo is known to have a 50lb/min compressor wheel which will make ~500bhp. Since we're using whp above, we can assume this turbo is pretty close to its max of 50lb/min.

Now to convert that to CFM, you take 50lb/min x 14.27 = 713.5 CFM. When you refer to the table above, you can see that we're starting to max 2.25" piping, but we're still in the "good" range for 2.5"

but it also depends on how smooth the piping is inside... and all the bends. this i would say is " perfect piping conditions" and if you would pick a number to upsize your piping at it would be when you hit about the .3 maximum .35 mach region

Vlad, what a fantastic post. Great information.

Vlad, very valuable information provided. What kind of literature did you get this from ? Thanks