sd101
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sd101 [2010/08/19 06:31] twdorris |
sd101 [2024/03/15 11:16] (current) |
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| In calculating fuel requirements for an engine, the amount of air (n in the above equation) is the critical piece of data we need to solve for. To solve for that, we need to know absolute pressure, absolute temperature and volume. | In calculating fuel requirements for an engine, the amount of air (n in the above equation) is the critical piece of data we need to solve for. To solve for that, we need to know absolute pressure, absolute temperature and volume. | ||
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| ===== Pressure and Temperature ===== | ===== Pressure and Temperature ===== | ||
| - | Pressure and temperature are easy enough to measure in our application using off the shelf sensors like the GM IAT for temperature and the GM 3-bar sensor for pressure. Other pressure sensor options are listed on our [[externalsensorlist|Aftermarket Sensor List]]. These include the GM 3.3-bar, AEM 3.5-bar and AEM 5-bar sensors. Other sensors listed on that page can be logged, but are not suitable for SD operation because they do not provide a reliable **absolute** pressure reading. | + | Pressure and temperature are easy enough to measure in our application using off the shelf sensors like the GM IAT for temperature and the [[https://www.ecmtuning.com/product_info.php?cPath=28&products_id=47|4-bar sensor]] we provide on our site for pressure. Other pressure sensor options are listed on our [[externalsensorlist|Aftermarket Sensor List]]. These include the GM 3-bar, GM 3.3-bar, AEM 3.5-bar and AEM 5-bar sensors. Other sensors listed on that page can be logged, but are not suitable for SD operation because they do not provide a reliable **absolute** pressure reading. We also offer a [[https://www.ecmtuning.com/product_info.php?cPath=28&products_id=50|Speed Density bundle]] on our site as well, which includes the standard 4-bar pressure sensor and the IAT sensor along with necessary pigtails and bung. |
| For air temperature, the only supported sensor is the GM IAT sensor (AEM IAT sensor is actually the same thing). You can get part number information off the [[externalsensorlist|Aftermarket Sensor List]] page. | For air temperature, the only supported sensor is the GM IAT sensor (AEM IAT sensor is actually the same thing). You can get part number information off the [[externalsensorlist|Aftermarket Sensor List]] page. | ||
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| A typical SD VE table might look something like the following (click to enlarge). | A typical SD VE table might look something like the following (click to enlarge). | ||
| - | {{ http://www.ecmtuning.com/images/forums/sddata/sdtable.png?446x244 }} | + | {{ https://www.ecmtuning.com/images/forums/sddata/sdtable.png?446x244 }} |
| It may seem intimidating at first, but it's really not as bad as it looks. We provide a number of tools and helpers to make dialing the VE table in on your own car pretty easy. And, honestly, most people may find that they can just drop the "stock" VE table we provide into their car and basically fire it up and drive around. There's no doubt some amount of dial-in will be necessary, of course. But for basic driveability, it should work fine. | It may seem intimidating at first, but it's really not as bad as it looks. We provide a number of tools and helpers to make dialing the VE table in on your own car pretty easy. And, honestly, most people may find that they can just drop the "stock" VE table we provide into their car and basically fire it up and drive around. There's no doubt some amount of dial-in will be necessary, of course. But for basic driveability, it should work fine. | ||
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| Because we know this concept may be not be mainstream, we offer the following datalogs that have *no* air temperature compensation. All the temperature compensation in both these logs is based on coolant temperature. | Because we know this concept may be not be mainstream, we offer the following datalogs that have *no* air temperature compensation. All the temperature compensation in both these logs is based on coolant temperature. | ||
| - | [[http://www.ecmtuning.com/images/forums/sddata/hotidle-noiat.elg|Hot idle - no IAT]] \\ | + | [[https://www.ecmtuning.com/images/forums/sddata/hotidle-noiat.elg|Hot idle - no IAT]] \\ |
| - | [[http://www.ecmtuning.com/images/forums/sddata/coolidle-noiat.elg|Cool idle - no IAT]] | + | [[https://www.ecmtuning.com/images/forums/sddata/coolidle-noiat.elg|Cool idle - no IAT]] |
| These were captured minutes apart from each other on the exact same car idling in the exact same spot in our parking lot. In one, air temperature varies from 172F to 130F while in the other it's only 70F the whole time. | These were captured minutes apart from each other on the exact same car idling in the exact same spot in our parking lot. In one, air temperature varies from 172F to 130F while in the other it's only 70F the whole time. | ||
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| However, at wide open throttle, the air temperature seen by the IAT sensor quickly takes over as the primary factor in determining air density. We have logs showing this effect as well with measured A/F ratio dipping to 8.3:1 with IAT at 133F compared to A/F ratio of 9.1:1 at 65F with boost around 20psi. These logs can be found below. | However, at wide open throttle, the air temperature seen by the IAT sensor quickly takes over as the primary factor in determining air density. We have logs showing this effect as well with measured A/F ratio dipping to 8.3:1 with IAT at 133F compared to A/F ratio of 9.1:1 at 65F with boost around 20psi. These logs can be found below. | ||
| - | [[http://www.ecmtuning.com/images/forums/sddata/coolwot-noiat.elg|Cool pull - no IAT]] \\ | + | [[https://www.ecmtuning.com/images/forums/sddata/coolwot-noiat.elg|Cool pull - no IAT]] \\ |
| - | [[http://www.ecmtuning.com/images/forums/sddata/hotwot-noiat.elg|Hot pull - no IAT]] | + | [[https://www.ecmtuning.com/images/forums/sddata/hotwot-noiat.elg|Hot pull - no IAT]] |
| As before, these logs were taken minutes apart from each other on the same car. The only difference between them is air temperature. In the first, air temperature averaged 65F while in the second, it was 133F. | As before, these logs were taken minutes apart from each other on the same car. The only difference between them is air temperature. In the first, air temperature averaged 65F while in the second, it was 133F. | ||
| However, unlike the idle logs, measured A/F ratio in these actually *did* change, suggesting that air temperature in these log actually did have an impact on airflow entering the engine. | However, unlike the idle logs, measured A/F ratio in these actually *did* change, suggesting that air temperature in these log actually did have an impact on airflow entering the engine. | ||
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sd101.1282213894.txt.gz · Last modified: 2010/08/19 06:31 by twdorris
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