Standard MAP sensor maximum boost and alternatives?

Evo

Member +
Hi I'm sure I'll be too this has been covered but it can't search for 3 letter words on this forum like MAP so it's hard to find an answer.

So

What is the max boost I can run on the standard MAP sensor on a 1993 EP82?

And

Are there any plug and play 3 bar sensors I can run with a Jam ECU?

Thanks

Christian
 

dac69er

Super Moderator
they read anywhere up to about 1.15bar where i live in the uk according to the 2 i have had on my power fc. but like any sensor reading at its max, the accuracy will obviously be iffy at those pressures.

i dont know if the jam ecu has any type of fuel cut at all, but a 3 bar sensor would have the wrong voltage range so your fuelling and timing would be all completely to cock.
 
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Evo

Member +
Thanks for your reply matey.

The Jam ECU has a fuel cut at 1.3 bar.

So if I got the Jam FCC (FCD) would I be able to run above what the standard MAP sensor reads to?

Not really sure what the function is of the MAP sensor apart from telling the ECU what the pressure is in the inlet manifold.

If you force it to boost above what the MAP sensor can read then will the ecu just max out the injectors or retard timing or something?

And is there not a map sensor that reads to a wider range than the standard but at the same voltage or would the ecu not know what to do with it?

The reason I'm asking is because Kon managed to run 1.7 bar through a Jam ecu for a year or so.
 

dac69er

Super Moderator
a jam fcd would clamp the voltage at under standard starlet fuel cut (unless you adjust it internally) so you would gain nothing by doing that.

without knowing the exact scaling of the ecu, it is hard to tell, but as with anything, it can be done. you can run 2 bar on a standard ecu if you wanted too.


standard map sensor has a 2 bar range that is scaled between 0-5v, 0-2bar absolute or -1bar to +1bar relative to atmospheric pressure.
the sensor can read over or under that amount depending on where you live and the atmospheric pressure on the day. height above sea level and pressure changes in the weather affect this. you can often see as much as a 0.05bar swing day to day depending on weather systems.

anyway. if you get a map sensor with a larger range, but still with the normal 0-5v output that the ecu needs, then the voltage the ecu sees with be different for a given pressure. this will mess your map up. you can correct this with a rrpfr and a safc or similar. but it wont be ideal.

personally, if you want to run anything over 1.2 bar, i would get a piggyback that can take a wider ranged map sensor, or go stand alone.
 
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weeJohn

Lifer
Keep checking the fueling as you raise the boost, when it stops being safe, stop raising boost. Jam will always slightly overfuel anyway, so there is a little scope for more boost.
 

weeJohn

Lifer
More boost can be ran, I ran 1.4 bar with a stock map sensor on a Blitz ecu, as long as the fuelling is ok, it will not do any harm.

Thinking back to that time, the car made only about 10 bhp less than when I went to a Power FC, mpg was a little less but there was very little hassle involved in tuning and changing set ups with that ecu. The quest for more power and what is considered the best way to do things is a little misguided sometimes I think!
 

dac69er

Super Moderator
More boost can be ran, I ran 1.4 bar with a stock map sensor on a Blitz ecu, as long as the fuelling is ok, it will not do any harm.

Thinking back to that time, the car made only about 10 bhp less than when I went to a Power FC, mpg was a little less but there was very little hassle involved in tuning and changing set ups with that ecu. The quest for more power and what is considered the best way to do things is a little misguided sometimes I think!
its not all about peak power, its the overall increase across the whole range. a large amount of "engine tuners" just tune to get you a high peak figure, but don't worry about the overall power the car can produce. I gained considerable torque when I went to a power fc from a jam ecu.

you could run 1.5bar on a stock engine and a big turbo only using a rrfpr and larger injectors using a diode to trick the map sensor signal to get a good max power figure. will run crappy otherwise though and the engine wont last long.

as everyone always says, its not what ecu you use, its who tunes the car that matters.
 

sventz

Member
my stock MAP won't go above 0.8bar with my turbo setup...fuel cut comes there...never had that issue when running a ct12 turbo on stock exhaust manifold...maybe the turbo i have now pushes way more than map can handle?!
 

Rev

Member +
My 2c. Bigger exhaust is needed with larger boost. Ct12 has plenty of air but to access it needs cool temps. The stock map can be fooled to handle more boost and obtain more air (eg my safc2 gave 22psi ) but the ct12 is at 60% efficiency at highest boost so will be running hot without an excellent FMIC and extra cooling help. The ecu can't be fooled with regard to air temperature so If you are content with moderate power the ct12 is fine especially as it can also give extra low rev boost due to its extra flow with the right setup.

Enlarging the exhaust and going for power boost at higher revs will be easier with a turbo that has better high end efficiency. That being said i was hoping to get more efficiency out of a ct12 compressor by using a much lighter blade with high flow shape and maybe 6 blade
like high flow blitz blades, not sure if this has been done successfully but there are a few new billets blades out there.
 
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SKINY

Lifer
I was always told the quicker you can get the exhaust gasses out the better on turbo charged cars, I've went down the straight through route to a back box with most of my turbo cars :) the GT will be 2.5 from the turbo back with the new kit on, its currently 2-2.5 into the Nur spec box
 
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