MAP-4 in a Bantam

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Mmw
Posts: 2
Joined: Mon Mar 03, 2025 11:50 am

MAP-4 in a Bantam

Post by Mmw »

Hello
I am thinking about replacing my VDO Tacho/Hobbs in my Bantam with a Blaze MAP-4. I have already installed a Blaze ASV-2 so I have a spare hole.
I have a few questions..
Will I be able to use the existing RPM pickup on the Jabiru 3300 engine? If not, what is commonly used as a replacement?
Is the unit supplied with a temperature sensor? If not, what is commonly used?
I would like to measure fuel pressure instead of manifold pressure. Is this possible and if so what pressure transducer to use?
That's it for now.

MMW
rainier
Site Admin
Posts: 727
Joined: Fri Aug 28, 2020 7:03 pm

Re: MAP-4 in a Bantam

Post by rainier »

The map sensor is usually used with a temperature sensor based on the common electronic sensor LM335. Yes there is one included in the box.
You can try using the standard Jabiru pickups (which are just a coil with a magnet on the flywheel). If this coil is open (nothing else connected) you should have sufficient signal for the RPM signal - ensure you have set the MAP-4 to maximum sensitivity. Also switch the noise filter off as we are dealing with a very short pulse that pretty much looks like noise. It's all in the manual...
Normally on Jabis our RPM pickup is one of the A/C leads to your regulator/rectifier. This usually works fine unless the signal is messy for some reason. In this case a good idea is to use a small 600 ohm audio transformer (smallest you can find is just fine). Connect one end to the A/C coil and the other side one connection to ground and the other is the RPM signal - advantage of this approach is that you get a nicely DC decoupled and somewhat filtered signal.
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