Hi there,

I have just got my MS1 (running extra) driving my gsxr1100 engine. It already had TBI's and I had set the fueling up with an LC-1. It ran very nicely.

So, now I am driving the sparks too, and I have it idling and it revs up a bit. I haven't been out in it, as it is all to horrid out at the moment.

I couldn't find an advance table for this engine, and most spreadsheets and books are based on car engines. So, I have built a table from various tidbits that I could find, and I am looking forward to testing it all out.

So, here's my questions:
1) What are the clues to good timing? apart from detonation!
2) How is the AFR affected when the timing is out?
3) any other top-tips.


I am intending to wire up a "fake NOS" switch, that will allow me to add/remove 3degs of timing at the press of a button, which might help me "feel" for the power.

thanks,


Matt

best ignition just before detonation (can be corrected on that )

afr will alter as not complete combustion

3: still learning myself

woolly

If you get to the stage of detonation you are way over advanced.

(1) Make sure the ignition is not so advanced at cranking speed that it causes problems cold starting --- ie no more than about 5 degrees BTDC below 500 rpm
(2) Listen for pinking at low and medium crankshaft speeds when pulling hard in high gears -- if you get pinking retard timing 2 degrees at a time until it stops.
(3) Maximum ignition total advance an engine will take varies it can be as littles as 28 crank degrees or as much as 38.
The most I have ever seen used was 43 degrees specified by a well known Imp engine builder but it gave no more power than when set to 38btdc.

Even without detonation using too much advance at high speed can put excess stress on the pistons and bearings.

[Edited on 10/12/09 by britishtrident]

The relationship between AFR and timing is weak mixtures burn slower so an engine running weak will run better if given more advanced ignition timing.
However a weak mixture can also cause pinking or detonation.


If the AFR is near correct or over rich it has no effect on timing.

great tips, thanks.

I guess I need to wire-up my advance/retard switch and go for a drive and see if I can feel any power differences.

I have already run into the starting problem. Fortunately the MegaSquirt stuff allows different cranking timing so I played with that.

I have seen 39deg as the recommended maximum advance for a 1D ignition table for the GSXR1100. So I will aim just below that for WOT. For smaller throttle openings I should be able to go a bit higher.

Is there any effect on the measured lambda from early/late timing that is worth looking out for? I know optimal timing is affected by mixture strength and quantity, but I was wondering if I could use my lamba probe to advantage (the fueling is already good as I set it up with the stock ignition unit).

Thanks again,

Matt

quote:

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1D ignition table

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Presumably by that he means without load sensing (tps or map) as you cannot have a ignition system without crank possition which in itself gives engine speed. Although that would be a 2d map. (1d is single value)

As i understand he is running a 3D map however, but has been able to find a copy of a suitable 2D map for the correct engine and is hence able to make some use of that.


Daniel

Sorry for the confusion.

Mr dhutch has guessed correctly.

The stock gsxr1100 has RPM input only. I am using MS to get the benefits of TPS and RPM input (plus the other odds and sods) my only reason for bringing up stock GSXR1100 is that it provides a guide to the values I will need at WOT. Agreed, at lower throttle opening I can put more advance, also I should be able to have a bit more at high RPM above peak torque.

I need to write my own table from scratch, which I have done. My question really was how do I improve this table without a rolling road.

Matt

p.s. Finally a rant about 1d, 2d, 3d.
1d 2d 3d. Its all a bit bogus. Fundamentally what they call 3d mapping is a 2 dimensional array of values. A grayscale picture is a 2 dimensional (2d) array of pixel intensities, we don't call that 3d do we! I know its just marketing but it is annoying that they use this terminology.

And my present draft map.

Stock idle is ~1100rpm. Rev limit is 11k rpm.

Matt
Rescued attachment draft_table.JPG

DON'T USE THE TABLE ABOVE IF YOU ARE RUNNING A GSXR1100W

It isn't right (yet). I will post a table when it is working properly.

Matt