88 adjust MAP vs BARO RBob?
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Car: Pro Stadium Tough Truck
Engine: Buick V6 272 cu in
Transmission: TH350
Axle/Gears: Broken most of the time
88 adjust MAP vs BARO RBob?
I'm looking over the 88 hack info from Moates files. Does 88 adjust the MAP according to what ever altitude the car is at... so even if you are in Denver the ecm will still use the MAP 100 column?
Anyone know why 88 has 4000 (main VE) or 4800 (others) as the rpm limit in many tables instead of higher like in 8D?
Thanks
Anyone know why 88 has 4000 (main VE) or 4800 (others) as the rpm limit in many tables instead of higher like in 8D?
Thanks
Last edited by AtomicTruck; 08-29-2006 at 06:09 PM.
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Car: Pro Stadium Tough Truck
Engine: Buick V6 272 cu in
Transmission: TH350
Axle/Gears: Broken most of the time
Hmmm. I just read a post talking about how you wouldn't be able to reach the high MAP values if you were driving at a high altitude. Was that for something else?
It makes sense though... that must be why the ecm does the Baro tests often?
It makes sense though... that must be why the ecm does the Baro tests often?
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Car: check
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There are no adjustments made to the MAP value. The reason the MAP doesn't go as high as the elevation increases is because the atmospheric pressure is lower.
The vacuum variable is elevation compensated as it is manifold vacuum. Take barometric pressure, sub off the MAP, and manifold vacuum is the result.
RBob.
The vacuum variable is elevation compensated as it is manifold vacuum. Take barometric pressure, sub off the MAP, and manifold vacuum is the result.
RBob.
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Car: Pro Stadium Tough Truck
Engine: Buick V6 272 cu in
Transmission: TH350
Axle/Gears: Broken most of the time
I get it.
I wonder why the GM guys didn't make a method for altitude compensation? They certainly compensated for a bunch of other things. Some of which seem a little overboard.
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I wonder why the GM guys didn't make a method for altitude compensation? They certainly compensated for a bunch of other things. Some of which seem a little overboard.
Thanks
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Car: 1983 G20 Chevy
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They did not need to compensate it for altitude. The VAC parts of the tables are referenced against BARO. BARO self corrects at certain TPS, MAP, RPM limits which are commonly hit during driving. Think OD pull at low RPM with moderate throttle. The MAP decreases as altitude increases, the MAP reading is tied to the fuel and spark tables which advances the timing and cuts fuel. It really doesn't matter whether the MAP reading drops due to altitude or throttle position.
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Car: Pro Stadium Tough Truck
Engine: Buick V6 272 cu in
Transmission: TH350
Axle/Gears: Broken most of the time
hmmmm... Interesting....
In the area of performance tuning though, a big cam engine running in Denver isn't going to get much MAP table to tune, right?
In the area of performance tuning though, a big cam engine running in Denver isn't going to get much MAP table to tune, right?
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Car: Pro Stadium Tough Truck
Engine: Buick V6 272 cu in
Transmission: TH350
Axle/Gears: Broken most of the time
The reason I'm trying so hard to fully understand how all this works is because I race all over the country. Although I haven't been to Denver yet there are some races there that I just might end up at some day.
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Car: 1983 G20 Chevy
Engine: 305 TPI
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Axle/Gears: 14 bolt with 3.07 gears
Performance will drop in Denver, but if you have a properly setup tune at sea level, it shouldn't be too far off at higher altitudes.
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