2 or 3 bar MAP best

[I1ULuz]

Which would be best to use a 2 or 3 bar MAP? I plan to run no more than 18 psi.

I have been told that a 2 bar is more accurate, and will read that high. I don't want max it out and hurt the engine by going lean.

Thanks

 

[TurboDave]

Well, in the MAP sensor world, the first bar will be used up by atmospheric pressure, only leaving you with one bar (on a two bar sensor), so if you plan on running more than 15psi, you'll need a 3 bar sensor.

 

[KendallF]

Originally posted by TurboDave
Well, in the MAP sensor world, the first bar will be used up by atmospheric pressure, only leaving you with one bar (on a two bar sensor), so if you plan on running more than 15psi, you'll need a 3 bar sensor.

DFI's manual recommends sticking w/a 2 bar if you're running within a few psi of 1 bar (I'd say 18 is close enough). Their reasoning is the resolution you gain for driveability is worth more than having the extra top range. To compensate, you richen the top cells of the fuel map.

Having said that, if you want to scrounge starter maps off of other people, you'd better run a 3 bar. Most DFI/Felpro users are using the 3 bar because most people spending the $ for aftermarket ECMs are running more than 18 psi.

Good luck!

 

[I1ULuz]

I have it up and running and I think I am only one in the world, and I think I am safe in saying this. running the Speed-Pro on a MR2 turbo. I currently have a 3 bar MAP and have a 2 bar in hand.

I have dyno'd 270 @14psi, I think there is about 30 hp in there, but want to do it safe. Its a 122 cid engine so I don't feel too bad about the HP level I am at. There are others making more power but I want to drive it everyday.

Is there a way to test a 2 bar with an air compressor?

If I use a 2 bar map will I have to change my VE tables?

 

[Craig Smith]

The 2 bar will give you the most resolution for drivability tuning as mentioned above, but the 3 bar is the "proper" way to go if you exceed 15 psi of boost. You would probably be OK with the 2 bar since you aren't exceeding the 15 psi limit by very much... just raise the numbers in the top row.

If you have a table for a 3 bar sensor and switch to a 2 bar sensor (or the other way around) you will need to redo the table. The values in the cells will become different. Sorry.

Enjoy the holiday!

Craig