Injection End Angle
Re: Injection End Angle
Hi all,
Just wanted to share my first « results »
First : I’m not a professional, I have some previous experience with other management systems but this is not my job. My aim is to share experience and test about this topic.
On top of the previously posted vidéos, I also try to gather some info that make sense for me, especially from Holley forum.
Context and setup : this is a « test » car , Mitsubishi lancer Evo 6. Bloc is bone stock with only some add ons. Car is supposed to receive another fully built engine, and for this purpose the fuel system is totally upgraded, and I’m using ID1750 XDS injectors, which are obviously overkill for the currently setup.
I mention that because this topic is highly related to camshaft and fuel injector size. Basically, the less fuel final injection timing is, the more important is the fuel injection end angle.
I did some tests, at idle and while crusing at light throttle (about 2000 and 3000 rpm).
At idle it was, probably due to the very small injection timing I need, quite easy to find out which value seems to be the best.
I was looking first of all for the best « feeling » about how the car was running, and then look at Lambda and MAP.
My hypothesis (according to the info mentionned above) :
MAP value should be the minimum ( -> engine « less effort » to maintain idle rpm)
Lambda value should be the leanest ( -> engine is « burning » more efficiently the fuel available)
From this point it seems that those three « output » were maximized with the same angle (in my case 400 deg).
Then I tried, in another hand, a fully « theorical » approach based on some discussions and feedback from Holley forum :
Basic idea is to avoid, if possible (due the required injector timing), to inject fuel when the exhaust valve is still open. Of course, due to cam overlap, intake valve would be a open (by more or less depending on Cam config) by this time.
For this purpose :
- I determined when my exhaust Cam is supposed to be closed (in my case it was around 23 ATDC)
- then I pick up the fuel final primary value from logs
- then I convert my engine idle rpm in degree per millisecond (in my case 1000 rpm -> 6 deg/ms), by multiply it by the fuel final timing I’m able to say how many degrees of crank are needed for this injection time to complete.
With those data I computed an « end angle » , for example at idle : end angle = inj timing in degree + ex cam close angle + 360 (because syvecs data is based, as mentionned, on firing TDC).
It appears that I get a value very close to what I found above with my test.
Then I used a few logs and the same technique to populate the « injection End angle table », using the correspondant injection timing at the rpm / map from the table. Obviously variations are not extreme from one cell to the other.
I will continu the test, to be clear this affects a Little bit the injection table values as those modifications affect the returning lambda value (tendancy to go leaner in my case).
Will try to dig further, for the time being it was helpful for the car, only tested light load and up to 3500 rpm.
Just wanted to share my first « results »
First : I’m not a professional, I have some previous experience with other management systems but this is not my job. My aim is to share experience and test about this topic.
On top of the previously posted vidéos, I also try to gather some info that make sense for me, especially from Holley forum.
Context and setup : this is a « test » car , Mitsubishi lancer Evo 6. Bloc is bone stock with only some add ons. Car is supposed to receive another fully built engine, and for this purpose the fuel system is totally upgraded, and I’m using ID1750 XDS injectors, which are obviously overkill for the currently setup.
I mention that because this topic is highly related to camshaft and fuel injector size. Basically, the less fuel final injection timing is, the more important is the fuel injection end angle.
I did some tests, at idle and while crusing at light throttle (about 2000 and 3000 rpm).
At idle it was, probably due to the very small injection timing I need, quite easy to find out which value seems to be the best.
I was looking first of all for the best « feeling » about how the car was running, and then look at Lambda and MAP.
My hypothesis (according to the info mentionned above) :
MAP value should be the minimum ( -> engine « less effort » to maintain idle rpm)
Lambda value should be the leanest ( -> engine is « burning » more efficiently the fuel available)
From this point it seems that those three « output » were maximized with the same angle (in my case 400 deg).
Then I tried, in another hand, a fully « theorical » approach based on some discussions and feedback from Holley forum :
Basic idea is to avoid, if possible (due the required injector timing), to inject fuel when the exhaust valve is still open. Of course, due to cam overlap, intake valve would be a open (by more or less depending on Cam config) by this time.
For this purpose :
- I determined when my exhaust Cam is supposed to be closed (in my case it was around 23 ATDC)
- then I pick up the fuel final primary value from logs
- then I convert my engine idle rpm in degree per millisecond (in my case 1000 rpm -> 6 deg/ms), by multiply it by the fuel final timing I’m able to say how many degrees of crank are needed for this injection time to complete.
With those data I computed an « end angle » , for example at idle : end angle = inj timing in degree + ex cam close angle + 360 (because syvecs data is based, as mentionned, on firing TDC).
It appears that I get a value very close to what I found above with my test.
Then I used a few logs and the same technique to populate the « injection End angle table », using the correspondant injection timing at the rpm / map from the table. Obviously variations are not extreme from one cell to the other.
I will continu the test, to be clear this affects a Little bit the injection table values as those modifications affect the returning lambda value (tendancy to go leaner in my case).
Will try to dig further, for the time being it was helpful for the car, only tested light load and up to 3500 rpm.