allora ricerca beneOriginariamente Scritto da Gia
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TI aiuto ioallora ricerca bene
When discussing engine tuning the 'Air/Fuel Ratio' (AFR) is one of the main topics. Proper AFR calibration is critical to performance and durability of the engine and it's components. The AFR defines the ratio of the amount of air consumed by the engine compared to the amount of fuel.
A 'Stoichiometric' AFR has the correct amount of air and fuel to produce a chemically complete combustion event. For gasoline engines, the stoichiometric, A/F ratio is 14.7:1, which means 14.7 parts of air to one part of fuel. The stoichiometric AFR depends on fuel type-- for alcohol it is 6.4:1 and 14.5:1 for diesel.
So what is meant by a rich or lean AFR? A lower AFR number contains less air than the 14.7:1 stoichiometric AFR, therefore it is a richer mixture. Conversely, a higher AFR number contains more air and therefore it is a leaner mixture.
For Example:
15.0:1 = Lean
14.7:1 = Stoichiometric
13.0:1 = Rich
Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.
Let's take a closer look. As the air-fuel mixture is ignited by the spark plug, a flame front propagates from the spark plug. The now-burning mixture raises the cylinder pressure and temperature, peaking at some point in the combustion process.
The turbocharger increases the density of the air resulting in a denser mixture. The denser mixture raises the peak cylinder pressure, therefore increasing the probability of knock. As the AFR is leaned out, the temperature of the burning gases increases, which also increases the probability of knock. This is why it is imperative to run richer AFR on a boosted engine at full load. Doing so will reduce the likelihood of knock, and will also keep temperatures under control.
There are actually three ways to reduce the probability of knock at full load on a turbocharged engine: reduce boost, adjust the AFR to richer mixture, and retard ignition timing. These three parameters need to be optimized together to yield the highest reliable power.
ovviamente il tutto ? preso dal sito di un grosso produttore di turbocompressori....
cos? gli hai risparmiato la faticaTI aiuto io
When discussing engine tuning the 'Air/Fuel Ratio' (AFR) is one of the main topics. Proper AFR calibration is critical to performance and durability of the engine and it's components. The AFR defines the ratio of the amount of air consumed by the engine compared to the amount of fuel.
A 'Stoichiometric' AFR has the correct amount of air and fuel to produce a chemically complete combustion event. For gasoline engines, the stoichiometric, A/F ratio is 14.7:1, which means 14.7 parts of air to one part of fuel. The stoichiometric AFR depends on fuel type-- for alcohol it is 6.4:1 and 14.5:1 for diesel.
So what is meant by a rich or lean AFR? A lower AFR number contains less air than the 14.7:1 stoichiometric AFR, therefore it is a richer mixture. Conversely, a higher AFR number contains more air and therefore it is a leaner mixture.
For Example:
15.0:1 = Lean
14.7:1 = Stoichiometric
13.0:1 = Rich
Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.
Let's take a closer look. As the air-fuel mixture is ignited by the spark plug, a flame front propagates from the spark plug. The now-burning mixture raises the cylinder pressure and temperature, peaking at some point in the combustion process.
The turbocharger increases the density of the air resulting in a denser mixture. The denser mixture raises the peak cylinder pressure, therefore increasing the probability of knock. As the AFR is leaned out, the temperature of the burning gases increases, which also increases the probability of knock. This is why it is imperative to run richer AFR on a boosted engine at full load. Doing so will reduce the likelihood of knock, and will also keep temperatures under control.
There are actually three ways to reduce the probability of knock at full load on a turbocharged engine: reduce boost, adjust the AFR to richer mixture, and retard ignition timing. These three parameters need to be optimized together to yield the highest reliable power.
ovviamente il tutto ? preso dal sito di un grosso produttore di turbocompressori....comunque penso che servit? anche ad altri...
qui mi sembra mossa pero'
Sicuramente questa mappa non ? attiva visto che non abbiamo il tasto sport. Quella modifica, forse la puoi comprendere meglio se gurdi la mappa in tabellare. E stata fatta per evitare di avere dei punti un cui la richiesta di coppia scenda rispetto al valore precedente. Magari e una cosa sbagliata che faccio ed anche le altre mappe DW le ho modificate tenendo presente questa cosa.
Apparte quella mappa da te evidenziata, sotto i 1500rpm non ho modificato nulla
tra l'altro non ? sbagliato il pedale fino a quei valori, anzi, io arriverei fino a 500Nm, poi delle 2 non sono usati dalla ecu perch? limitati o dal limitatore di coppia o da altri limitatori...
con gli anticipi come ti regoleresti?
Quei valori che leggi in tabbellare ( con ecm ) sono anticipi o posticipi. Per esempio se leggi 20 vuol dire 20 gradi prima o dopo il pms?
In teoria dovrebbero essere anticipi, ma allora come mai sono valori positivi?
non preoccuparti del segno, quando sono anticipi sono positivi, quando negativi posticipi. Comunque considera di non andare sopra i 27?*4000rpm, e li regoli a sensazione. La regola corretta sarebbe quella di calcolarsi la durata di iniezione e regolarli in modo che questa si mantenga entro certi limiti dopo il pms.
Ho provato la mappa ed inietta 96,58mm3\ciclo. direi che ci siamo. L'erogazione e migliorata e devo dire che chi vuole prestazioni buone in tutta sicurezza va pi? che bene.
Unico neo! ho dei picchi di pressione di 1,6\1.65 bar per poi scendere a 1,4bar come da mappa obbiettivo. Come potrei correggere questo difetto?
cala la mappa di gestione della geometria variabile nelle ultime colonne, ma vacci piano, un po' alla volta, altrimenti troverai la macchina "morta" per iniziare cala il 2% (200punti) all'ultima colonna.
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