Injector timing

[KMud]

Just a general wondering for those who roll their own tunes, have you explored injector timing? In particular, B3702? Most setups on here are pretty similar, and I'm wondering what gains were seen from typical monaro/vxr8 setups. Maybe not numbers, but more stable AFR on idle, better low-end feel. Cam specs would be helpful.

[KMud]

stevieturbo said:

Unless you're using a gas analyser when tuning, or testing on a dyno for the upper rpm's, just leave them as is.

My AFRs bounce around a lot when idling, and so I'm tempted to fiddle a little bit +/- as I have read of AFRs being more stable with a minor tweak. That said, I'm about to do intake/TB/injectors, so I'm not fiddling with the little things until my tune is somewhat back together!

edit to add: I think you're probably right that it's hard work to analyse the gains up top.

Edited by KMud on Monday 26th January 23:04

[KMud]

stevieturbo said:

The chances of any tuning issues you are having being down to injection timing using GM values....are almost zero.

I have no major issues, just optimising - thanks for the input though. I've seen some tune files for fairly brutal cars with stock values, although they may just have not known better! I've bought more injector than I need to be honest, so I'm antsy to get it running well. With relatively lower duty cycles it might be more sensitive.

[KMud]

There's a good hptuners thread I have been reading advocating just that Gelf - did you find it made any difference?

[KMud]

Daft question, but is the monaro stock LS1 camshaft the same as the GTO, i.e., ~197/207-116? If that's correct I'll shift my injector timing ~16.5 degrees.

[KMud]

Hmm, those numbers are different. I am confused - I know Monaro LS1s have some LS6 bits, but is MY01 LS6 the correct cam?

[KMud]

I was taking IVO as: [intake @ .05]/2 - (LSA - advance)

[KMud]

stevieturbo said:

And as you can see IVO is almost identical with them all..

Really...you're thinking far too much into it all, and without hundreds of hours on a dyno and with a gas analyser to quantify results....you wont really get anywhere.

Up top I don't question it's pretty academic (my profession...), but down low interests me. I'd be thinking less if the EFI live tables didn't appear to be slightly messed up (or at least the associated documentation)!

edit: I think you think I want to stray from ending injection on intake valve opening - right now I'm running a cam with IVO ~16 degrees earlier, but stock injector timing (so at least partially spraying onto an open valve)...I am just looking to align the events again really.

Edited by KMud on Wednesday 28th January 00:10

[KMud]

Silly things like idle quality and fuel smell?

[KMud]

SturdyHSV said:

This to me seems like something sensible to aim for. GM spent plenty of time setting the timing of EOI compared to IVO, it was presumably set where it was for a reason. So if you've changed IVO because of a different cam, it'd make sense that you need to shift EOI too.

However, we are assuming that EOI is timed where it is based exclusively on IVO, whereas perhaps there are other factors that influence its timing as well?

Interesting thread anyway, any posts I have to read a couple of times to make sure I understood are a good thing as far as I'm concerned

There are more tables on the later OSs, but I think just timing offset with respect to ECT on LS1B. HP tuners have another value for the boundary between cycles (basically IVC I think) which EFI live lacks.

[KMud]

I'm glad someone's on the case