Author Topic: Turbo ignition timing  (Read 9116 times)

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Offline sabat

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Turbo ignition timing
« on: June 19, 2008, 03:04:55 PM »
I now have an adjustable ECU, and will go to the dyno next week to tune. All I've worked with in the past (on a carb bike) was a on/off retard box, but in seaching the web for turbo timing info, I've seen some strange ignition maps, and I wonder if anyone could post experience, or suggest some reading, or make general suggestions.

The motor is a 2006 Kawasaki ZX10, intercooled turbo, CR 10.5:1, event gas, 15-22 psi boost.  I was thinking to start by retarding a 2-5 degrees around torque peak, and maybe bring some back before redline, but I won't have all day (or week) on the dyno to experiment. A


Thanks,
Dean

 

Offline dieselgeek

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Re: Turbo ignition timing
« Reply #1 on: June 23, 2008, 02:58:52 PM »
Dean, the way we do it is start with WAAY more retarded timing than we estimate we'll be running, and we make short pulls that go past peak torque, but not necessarily "all the way to redline"

Then we add 2-4 degrees at a time and note the power increase.   You'll see the increase per degree start to fall off with increasing steps, that's how you know you are in the ballpark of proper timing.   Between pulls look for signs of detonation on the plugs, etc. especially if you are treading ground where others haven't gone (i.e., if you have no idea where you'll run into detonation issues).   

What ECU are you using?

Offline sabat

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Re: Turbo ignition timing
« Reply #2 on: June 23, 2008, 04:36:57 PM »
DG, I'm using an OEM Kawasaki race ECU used for Superbike and Supersport classes. It allows +5 and -15 deg timing control according to RPM and throttle position. I had run with stock timing at 16psi on C-16 with no signs of detonation, non-intercooled, so I think I'm pretty safe, but as the boost goes up I'd like to take out a few at least.

What I'm concerned with is giving up power near redline, past torque peak, when possibly I don't need to, so I'm curious if other folks are doing something similar. Do you retard all the way to redline?

Thanks,
Dean

Offline dieselgeek

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Re: Turbo ignition timing
« Reply #3 on: June 24, 2008, 04:39:07 PM »
DG, I'm using an OEM Kawasaki race ECU used for Superbike and Supersport classes. It allows +5 and -15 deg timing control according to RPM and throttle position. I had run with stock timing at 16psi on C-16 with no signs of detonation, non-intercooled, so I think I'm pretty safe, but as the boost goes up I'd like to take out a few at least.

What I'm concerned with is giving up power near redline, past torque peak, when possibly I don't need to, so I'm curious if other folks are doing something similar. Do you retard all the way to redline?

Thanks,
Dean

Usually I don't retard with increasing RPM, instead I add timing because if the fuel burn rate is consistent, at higher RPM you'd need to increase advance to maintain peak cylinder pressure around the 10-15 ATDC position of the crank...

instead, the retard should be more proportional to boost increase.  I would do a sweep (on a chassis/wheel dyno) to make sure you aren't giving up power at that kind of advance even if not detonating.  It's possible to be too advanced for "mean best timing" but not hit detonation yet.
« Last Edit: June 24, 2008, 04:41:53 PM by dieselgeek »

Offline sabat

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Re: Turbo ignition timing
« Reply #4 on: June 25, 2008, 02:20:44 PM »
Gotcha - so I can try putting back some timing after torque peak, as I approach redline.  Retard around highest boost accel, not boost magnitude. Cool.

Offline ddahlgren

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Re: Turbo ignition timing
« Reply #5 on: June 29, 2008, 07:01:28 AM »
Be careful with thinking burn rate is constant combustion speeds can and do change with rpm and air flow in the chamber. As air speed increases a lot of so called constants go out the window. This happens more often in small bore engines which the ZX10 fits into very easily.
Dave

Offline dieselgeek

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Re: Turbo ignition timing
« Reply #6 on: June 30, 2008, 11:16:40 AM »
Be careful with thinking burn rate is constant combustion speeds can and do change with rpm and air flow in the chamber. As air speed increases a lot of so called constants go out the window. This happens more often in small bore engines which the ZX10 fits into very easily.
Dave

Makes sense to me!  Given his circumstances then, what is the easiest way to find best timing at WOT?   

Offline ddahlgren

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Re: Turbo ignition timing
« Reply #7 on: July 05, 2008, 07:34:19 AM »
Make a few pulls on the dyno with a modest amount of timing at boost less than the final number using slightly less than OEM timing and good gas. I work a lot with VP gas only for the reason it is very common on the east coast where I am and they deliver it to most all the shops i work with. I would start with C16 it makes a good turbo fuel and you have to do something really stupid to hurt the engine with it. With the a/f ratio correct make 3 pulls baseline timing -2 degrees if it makes more power everywhere keep going in that direction if not try +2 degrees keep good notes and compare the pulls it should become obvious what the engine wants.The whole key is charge air temperature, the more it goes up the more timing that needs to be taken out.
Dave