Injection End Angle

[Johnny G]

Had some worthwhile results on a hub dyno a couple of weeks back, moving the Injection End Angle on my 2JZ to 374 degrees at 1000rpm, 373 at 1400rpm, with small reductions to 4000rpm, then no gain. All in the aim of refinement.
Obviously, different cams and injector setups will vary.

[Hugh]

Have searched long and hard on the forum, internet and Manuals for an answer on how Syvecs is set-up with respect to injection angle.

For me the 4-stroke cycle is :- Induction, Compression, Power, Exhaust, so based on that if you wanted to inject through an open valve, an injector closing time between 100° and 200° would deliver that.

Injecting on to the back of a closed inlet valve would therefore be 300° or later.

Please can someone confirm if Syvecs considers the inlet valve to close somewhere in the region of 200°

Thanks

Hugh

[stevieturbo]

The table is ATDC as far as I know, which would be based on 0deg as the cylinder firing TDC point.

It will really be up to your own camshafts as to when the valves open and close. So IVC points probably more in the 380-420deg range for most camshafts ?

[Hugh]

Thanks stevieturbo.

Can you answer the question on whether 0° on Syvecs = the start of the Induction stroke or the power stroke, they are 360° apart?

Perhaps I could find the answer in my SCal file if I knew where to look.

The example you show has the power stroke at 0° which is not what I expected.

[stevieturbo]

I see 0deg as the cylinder firing, and as it is called...TDC.

That was the only graph I could find, so ignore bottom numbers hence why I mentioned the 380-420 as you can see this would be IVC.

0deg is the start of a cycle, 720 ( or maybe 719 ) being the end of the cycle.

So scale at the bottom of that graph should go from..


360 - 0 - 360

to

0 - 360 - 720

if in any doubt, remove all plugs except cylinder 1, and spin the engine over and pull a crank trigger oscilloscope and you will be able to see that cyl1 TDC compression/firing relates to 0deg on the cycle.

[Slowie]

.

[Hugh]

I see 0deg as the cylinder firing, and as it is called...TDC.

That was the only graph I could find, so ignore bottom numbers hence why I mentioned the 380-420 as you can see this would be IVC.

0deg is the start of a cycle, 720 ( or maybe 719 ) being the end of the cycle.

So scale at the bottom of that graph should go from..


360 - 0 - 360

to

0 - 360 - 720

if in any doubt, remove all plugs except cylinder 1, and spin the engine over and pull a crank trigger oscilloscope and you will be able to see that cyl1 TDC compression/firing relates to 0deg on the cycle.

Thanks stevieturbo, but I just don't get it, your engine has to draw in air on the induction stroke between 0° and 180° before it can fire on the power stroke 360° to 540°, so makes no sense to me why it would be the way you describe.

Areed that it will be either 0° or 360° that is the nominal start of the inlet valve opening, but cannot see how your oscilliscope test would identify which one it is, since this in an internal reference from the ECU and only described in the "injection end angle table".

Given that the spark has to be timed 360° later than inlet valve opening, there must be some way to establish how this has been set-up in the ECU.

[RICE RACING]

0 is referenced not in 0-720 4 stroke cycle (or 0-1080 deg wankel or 0-360 two stroke etc etc) but rather 0 TDC compression stroke, done this way most likely to cover all engine operating principles my best 'guess'.

[stevieturbo]

Thanks stevieturbo, but I just don't get it, your engine has to draw in air on the induction stroke between 0° and 180° before it can fire on the power stroke 360° to 540°, so makes no sense to me why it would be the way you describe.

Areed that it will be either 0° or 360° that is the nominal start of the inlet valve opening, but cannot see how your oscilliscope test would identify which one it is, since this in an internal reference from the ECU and only described in the "injection end angle table".

Given that the spark has to be timed 360° later than inlet valve opening, there must be some way to establish how this has been set-up in the ECU.

0 deg on the syvecs oscilloscope trace is cyl1 TDC firing/compression.

So on the very right of the chart shown it would be TDC/Firing which is effectively either 0 or 720, however you want to look at it. I guess strictly speaking it can only really be 719 and then back to zero.

I think I did mess up a little looking at the graph. It would make more sense that as IVO would be in the 300-360deg region ATDC, this is where end of injection should be, as most seem to suggest it is best to inject against a closed valve, certainly at higher loads.

The induction stroke would only start around 360ish then run through to say 600ish degrees at which point compression starts ready for firing again at 719/0deg ( ignoring actual spark timing )

The oscilloscope test will show where cyl1 TDC is in reference to the Syvecs 720 cycle. If there was no cam trigger then it would only be a 360 cycle, but as there will be a cam trigger and you already have this correct in the ecu, it should display the 0-720 trace and you will see cyl1 slow down as it rises to compression so you can be 100% certain the trace is correct.

[stevieturbo]

This chart is numbered a bit better ?