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Author Topic: ME7.5 adjust ignition per gear is it possible?  (Read 13810 times)
professor
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« on: October 30, 2012, 03:08:42 AM »

High loads on low gears can exploit more advance for power delivery but higher gears with high ignition can cause struggle on revving up, especially on setups who works over 191.25% loads for half of the rev range and regular gasoline.
Is there a way to adjust ignition per gear on ME7.5?
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prj
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« Reply #1 on: October 30, 2012, 05:09:20 AM »

Huh???
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elRey
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« Reply #2 on: October 30, 2012, 05:17:14 AM »

I think he is talking about spool via timing advance
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professor
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« Reply #3 on: October 30, 2012, 05:20:36 AM »

Ignition vs Gear i am asking  Smiley

Yes it can be done closer to what am asking via igntion vs IAT, but there is ignition vs gear  on ME7.5?
« Last Edit: October 30, 2012, 05:22:29 AM by professor » Logged

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prj
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« Reply #4 on: October 30, 2012, 05:58:35 AM »

I think he is talking about spool via timing advance

I think what he is talking about makes no sense at all.

professor:
Care to elaborate maybe? You are making some really bold statements which IMO have nothing in common with real world scenarios.
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Gizmo20VT
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« Reply #5 on: October 30, 2012, 06:22:15 AM »

So basically you want timing maps to change when selecting different gears to change the "power band per gear"?
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prj
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« Reply #6 on: October 30, 2012, 06:41:59 AM »

Basically on high load the engine is knock limited the entire time, so this entire thing seems completely pointless to me.
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professor
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« Reply #7 on: October 30, 2012, 06:54:33 AM »

So basically you want timing maps to change when selecting different gears to change the "power band per gear"?

Well sort of.
Let me to describe the scenario i faced and based on what i talk about:
Conservative ignition request on wot for a car which works at 191.25% load from 3500 till redline. Lets say 18 degrees KFZW and 19.5 KFZW2 (12 tappering to 18 and 13.5 tappering to 19.5 after 4500rpm).
On 1st, 2nd and 3rd gear car dont pulls back ignition. On 4th and more on 5th gear ignition retards is reaching 4-6 degrees on each cylinder after 5000rpm. IAT is about +12oC from ext temperature and those results are similar in many continuous logs.

So i am wondering how to overcome this issue?
We can request a bit aggressive ignition on lower gears and pull back ignition on higher gears?

« Last Edit: October 30, 2012, 06:56:17 AM by professor » Logged

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Gizmo20VT
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« Reply #8 on: October 30, 2012, 07:06:13 AM »

This may be a silly answer as Im not really sure where you current power band is or spec turbo.

You could run less timing up top if your out of the efficiency range of the turbo, what octane are you running?
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Gizmo20VT
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« Reply #9 on: October 30, 2012, 07:07:13 AM »

What about less boost request on Higher RPM?

Sorry for double post.
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professor
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« Reply #10 on: October 30, 2012, 07:17:07 AM »

Less boost request isnt a option, via bc perhaps, since car runs over 26psi stable boost till redline.
Gasoline is strictly 100RON.
Turbo is GT3071 and engine is forged 1.8T20V with stock head.

As prj claims perhaps its pointless since ecu takes control and reduces timing accordingly put perhaps lowering requested ignition on high gears and lowering the timing retard can give us better top end power delivery and of course higher safety levels.


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rajivc666
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« Reply #11 on: October 30, 2012, 07:27:58 AM »

You can take the code for KfZW and kfzw2 only from http://nefariousmotorsports.com/forum/index.php?topic=1556.90 and use the gear as the counter for switch, it is easy and can be done.
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phila_dot
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« Reply #12 on: October 30, 2012, 07:34:35 AM »

There is a reason there isn't a table for this...it is unnecessary.

This is handled by load. Rescale the axis if you have to.
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prj
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« Reply #13 on: October 30, 2012, 08:17:15 AM »

Well sort of.
Let me to describe the scenario i faced and based on what i talk about:
Conservative ignition request on wot for a car which works at 191.25% load from 3500 till redline. Lets say 18 degrees KFZW and 19.5 KFZW2 (12 tappering to 18 and 13.5 tappering to 19.5 after 4500rpm).
On 1st, 2nd and 3rd gear car dont pulls back ignition. On 4th and more on 5th gear ignition retards is reaching 4-6 degrees on each cylinder after 5000rpm. IAT is about +12oC from ext temperature and those results are similar in many continuous logs.

So i am wondering how to overcome this issue?
We can request a bit aggressive ignition on lower gears and pull back ignition on higher gears?

Let me start by saying that what you want to do is a very bad idea, and this is because you will melt the engine doing what you are doing.
The reasons you are seeing more ignition retard are as follows:
1. The cylinder charge is probably higher due to higher boost in higher gears.
2. The EGT's go up, making the combustion chamber hotter and more prone to detonation.

Now, what you are doing by retarding timing in higher gears is going to spike the EGT's even more.
You need to control your EGT's properly and enrich the mixture.

As phila_dot said, the reason this is not done is because this is inventing a solution to a problem which does not exist.

If you are capping out the load axis in the map, then underscale your load up top, and you can specify the ignition angle for every load as needed.
I also don't see how reducing advance is EVER going to make anything better under load.

Reduced timing - lower efficiency, more waste heat, higher EGT's, less torque, less power and so on.
This has nothing to do with Motronic per se, it seems that you have a few core principles of the internal combustion engine wrong.
« Last Edit: October 30, 2012, 08:20:30 AM by prj » Logged

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professor
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« Reply #14 on: October 30, 2012, 10:50:51 AM »

Load is adjusted to meet engine load with different boost levels, but load on peak boost level is same for 3rd 4th and 5th gear, so on wot it follows same ignition map line.
Its same cause via bc its works 5% more wg dc on 3rd, 0% on 4th and -4% on 5th gear.
Also it works with max 800-810oC at 5th gear redline (on down pipe) with rock stable lambda 11.6:1.
But retards are higher especially on 5th gear as result of combustion higher temps and engine stress.

So would be best to lower the boost more on 4th and 5th gear and adjust the ignition if needed closer to 2-3 retard.

Thanks for the answers.

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