MAP sensor in aircooled engine bay

[paul_f]

I have fitted my GM style MAP sensor in the engine bay.

The engine cooling fan uses a lot of air, and I think at high revs and high speed there is probably a depression in the engine bay.

Before I fit the throttle bodies I was thinking about measuring the depression however looking at the MAP sensor it seems to be externally referenced (which makes sense), ie the pressure measured is relative to the pressure the sensor is sitting at - therefore the only way I could measure the depression would be to hook a pipe up to the the sensor and put the other end outside of the engine bay - so an increase in MAP would show the depression.

However am I going to have problems with tuning because of this depression?

Cheers
Paul

[rob@vems.co.uk]

How are you metering the air - AlphaN or Speed Density?

[paul_f]

I was intending on using speed density

[paul_f]

After thinking about it a bit more, I am wondering whether some aren't externally referenced as people have been using them for baro correction