Syvecs Forums

All,

I have had Tip-In issues from the beginning and no matter how I changed the Transient Fueling properties it always felt hesitant on blips from Idle.
I noticed that my Injection End Angle was set to 540 degr. as that was in the basemap from the start and I didn't fiddle with it.
Afterwards I got some other data and I noticed an Injection End Angle of 360 degr. was used. I changed the 540 degr. for 360 degr. accross the whole RPM range and was pleasantly surprised with very crisp response on blips straight from Idle. AFRs have changed though and I believe I need to redo a bit of Fuel mapping.

The question is though how to properly derive the best Injection End Angle for each RPM breakpoint. Am I correct in saying the Injection End Angle should be different based on Injector size as the Inj. ms. will be very different for the same requirement making the start angle completely different vs. the same eng angle? I believe the best Injection End angle would be to have the injection started when the Intake valves open so atomisation is at it's best due to piston speed, etc. Spraying too early or too late may prevent Fuel from being directly drawn into the cylinder making it going out of suspension and onto runner walls. I also understand that Injection End Angle does not make ANY difference when IDCs are nearing 100% as the injectors are spraying continuously and do not stop.

I am looking forward to some more in depth tech info on this as I believe this is the key to get the best response and also probably can enhance fuel consumption A LOT. Thanks in advance!

Best Regards,

Jasper Kopinga
CS Racing
Taiwan.

I am looking for the same info as well. I have never experienced myself but I have heard some people gets very good improvements from injector timings. I have friend running fiat coupe turbo running 90 degree.

So far I have been reading different things:

- Some people seem to say to tune the end angle to get the richest AFR at a certain RPM point with the same amount of Injector MS. (read amount of fuel) being injected. The theory seems to make sense as the same amount of injected fuel would use up the most amount of available oxygen hence displaying the richest AFR. The question is whether this rich AFR is really a lack of oxygen or unburned hydrocarbons that show up. This can only be confirmed with a 4 or 5 gas analyzer which most people do not have.

- Some people seem to say to tune the end angle in such a way that the injection event takes place into an open intake valve. Personally I feel this is not the case

- Some people seem to say to tune the end angle in such a way that the injection event has FINISHED before the intake valve opens relying on a heated valve to evaporate the fuel even further before being drawn in. This seems OKish.

I need to know first of all how the Syvecs interprets the Injection End angle. The adjustment range is from 0 to 719 degr. Question is where is ZERO degr. at referring to the strokes of a 4-stroke engine. Is ZERO at the beginning of the Intake Stroke? I guess not. Is ZERO at the beginning of the Power stroke? This seems to make more sense. When I went from 540 degr. to 360 degr. things got a lot better as far as transient response off idle was concerned.

If ZERO is indeed the start of the Power stroke then 180 degr. would be start of Exh. stroke and 360 degr. would be start of Int. stroke and 540 degr. would be the start of the Compression stroke.


So far a value of 330 seems to work very well at low RPM / IDLE. Question is whether to advance or retard when RPMs rise. I have seen both methods but I guess it depends on how the actual ZERO is defined. Looking forward what others have to say.

Cheers,

Jasper.

Just bumping this up, as it's a hugely interesting subject.

I played with injection timing by adjusting it at various fixed load points for richest Lambda readings. After this I trimmed the fuelling map to where it was. The engine uses noticeably less fuel, and is definitely more responsive off boost (RB26DETT with 280 degree cams). I see what Jasper K is saying about a 5 gas, luckily I have one, I will have a play with it next time I get some time to "play"!

That's very interesting.
My off-boost needs some more work (but we did have some problems after the mapping on the dyno *cough*oil pressure*cought*), the economy isn't amazing. I see the same MPG as I did in stock form with the sequential twins on the motorway, around 23mpg on the motorway, at around 75mph.

Here is an interesting thread on the Motec site discussing injection timing:

http://www.motec.com.au/forum/viewtopic ... mbda#p3583

RichardB wrote:Here is an interesting thread on the Motec site discussing injection timing:

http://www.motec.com.au/forum/viewtopic ... mbda#p3583

Many thanks, Richard. Great article.

Here is a small excerpt from a scientific paper looking at the effect of injection time. I can't see the whole paper, but the abstract seems to indicate that injecting onto a closed inlet valve has benefits.
http://resources.metapress.com/pdf-prev ... ze=largest

Very interested in this also.

I have been playing around with inj angle to get my DW 1300cc injectors idling steadily at 14.7:1 AFR.

I have reduced angle from 540 to 400 degrees at 500-1500 rpm and this has resulted in a much more stable idle.

Here is quite a useful diagram I stumbled across which clarifies reference angles on a four stroke engine. It would appear that an end angle of 540 as per the base map favours the injector event taking place place whilst the intake valve is closed.

http://www.linkecu.com/support/document ... iagram.pdf

The following link also suggests injecting onto a closed inlet valve has validity

http://bbs.22b.com/cgi-bin/ultimatebb.c ... 564#000003

Also a useful article

http://bbs.22b.com/cgi-bin/ultimatebb.c ... =20#000774