LT1 with 3-bar MAP?
Thread Starter
Joined: Oct 2005
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From: Fairfax, Virginia
LT1 with 3-bar MAP? I will be using my stock 94 pcm (OBDI) and Speed Density once I finish the car. I bought a 3-bar map sensor. Even though I plan to run around 15psi of boost, I may be able to push a few more PSI. So that's why I went ahead and got a 3 bar so it will read past 15psi. But I have seen tid bits of information saying the LT1 computer cannot read a 3-bar map sensor. Is that true?
Is it because the computer won't read past 15psi or it won't read the sensor all together?
Another thing. Has anyone had a chance to tune Racetronix's 79lb high impedance injectors? I know they are fairly new to the market so I didn't know how they would handle for low speed street driving. I'm just afraid I'll max out 60's.
Is it because the computer won't read past 15psi or it won't read the sensor all together?
Another thing. Has anyone had a chance to tune Racetronix's 79lb high impedance injectors? I know they are fairly new to the market so I didn't know how they would handle for low speed street driving. I'm just afraid I'll max out 60's.
Thread Starter
Joined: Oct 2005
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From: Fairfax, Virginia
But I wonder if it only worked because your using the MAF. I don't have a MAF so it's relying on the MAP and IAT only. So you are using a 3-bar MAP?
It ain't easy.........
Thread Starter
Joined: Oct 2005
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From: Fairfax, Virginia
Good info. If I'm not mistaken, do you have to cut it by 1/3 with 3-bar because the voltage varies 3 times as fast as a 1-bar? Something like that?
I'm still iffy whether to use 60 or 79lb injectors. I don't know if 60's will support 700hp with a single walbro 255... maybe if I boost reference it.
I'm still iffy whether to use 60 or 79lb injectors. I don't know if 60's will support 700hp with a single walbro 255... maybe if I boost reference it.
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Good info. If I'm not mistaken, do you have to cut it by 1/3 with 3-bar because the voltage varies 3 times as fast as a 1-bar? Something like that?
I'm still iffy whether to use 60 or 79lb injectors. I don't know if 60's will support 700hp with a single walbro 255... maybe if I boost reference it.
I'm still iffy whether to use 60 or 79lb injectors. I don't know if 60's will support 700hp with a single walbro 255... maybe if I boost reference it.
You have to cut it by 1/3 because you're referencing 3 bar in the same amount of voltage as the 1 bar. Has nothing to do with how fast it varies.
Both are 5 volt referenced. The way it's set up, it's measuring 1 bar. You want it to measure 3 bar. The voltage will be no different.
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The value that is represented by each tenth of a volt increase will be more. For and example on a 1 Bar MAP the range will be minus 14.7 PSI to 0 PSI, on a 2 Bar the range will be minus 14.7 PSI to plus 14.7 PSI since they both have an avaliable output range of 0 to 5 volts, the 1 bar sensor will output 1 tenth of a volt change for every 0.294 PSI of pressure change, where the 2 Bar sensor will output 1 tenth of a volt change for every 0.588 PSI of pressure change, if you threw a 3 Bar sensor in to the mix it will output 1 tenth of a volt change for every 0.882 PSI of pressure change As you use a sensor with more range you lose the resolution, since each voltage increase represents more change, so you shouldn't use a 3 Bar, if a 2 bar will do the job, or use a 2 Bar in the motor is NA
Thread Starter
Joined: Oct 2005
Posts: 1,687
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From: Fairfax, Virginia
The value that is represented by each tenth of a volt increase will be more. For and example on a 1 Bar MAP the range will be minus 14.7 PSI to 0 PSI, on a 2 Bar the range will be minus 14.7 PSI to plus 14.7 PSI since they both have an avaliable output range of 0 to 5 volts, the 1 bar sensor will output 1 tenth of a volt change for every 0.294 PSI of pressure change, where the 2 Bar sensor will output 1 tenth of a volt change for every 0.588 PSI of pressure change, if you threw a 3 Bar sensor in to the mix it will output 1 tenth of a volt change for every 0.882 PSI of pressure change As you use a sensor with more range you lose the resolution, since each voltage increase represents more change, so you shouldn't use a 3 Bar, if a 2 bar will do the job, or use a 2 Bar in the motor is NA
