Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Reference Material on Programmable Ignition
Goto page 1, 2  Next
 
Post new topic   Reply to topic    924Board.org Forum Index -> Performance Upgrades
View previous topic :: View next topic  
Author Message
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Wed Aug 22, 2012 4:37 am    Post subject: Reference Material on Programmable Ignition Reply with quote

I am seeking a solid set of reference material on how to tune a programmable ignition system. I have read the MegaManual content, and it's a good start on the very basics, but I'd like to get some more detailed information on how to setup an appropriate map, particularly for a forced induction application.

The thing I did not like about the MegaManual content was that it said to test the ignition curve, you basically have to tweak it until you get ping in an area of the curve and then back it off. That might be the only way to go about it, but it seems like "tuning by Braile", and in my way of thinking, there must be a better way.

I currently own "How to Tune and Modify Engine Management Systems" by Jeff Hartman, but was not satisfied with the depth of coverage on the topic of ignition.

I believe Wes referenced the David Walker book "Engine Management: Optimizing Modern Fuel and Ignition Systems" but would like to confirm if anyone else has read this book or can recommend it specifically as it relates to programmable ignition on forced induction applications.

I'm open to other online references as well. Part of my motivation is to determine a well-defined set of requirements for a forced induction application so I can make a more informed evaluation of the alternative solutions (MegaJolt, MegaSquirt, MSD, Reline-Weber, etc.).

On a related note, as I understand it, converting to programmable ignition requires that the ignition distributor have its vacuum and mechanical advance locked out. I've found some how-tos on this for other makes, but was wondering if anyone here has locked out their OEM Bosch distributor.

As I understand it, without adding a trigger wheel, it is possible to use the stock distributor with locked advance mechanisms, and to pick up the VR signal from the dizzy to provide signal to the ignition system, whatever it may happen to be. Looking for validation that I'm on the right path here.
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
WEASEL149  



Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield

PostPosted: Thu Aug 23, 2012 1:47 am    Post subject: Re: Reference Material on Programmable Ignition Reply with quote

ideola wrote:
I am seeking a solid set of reference material on how to tune a programmable ignition system. I have read the MegaManual content, and it's a good start on the very basics, but I'd like to get some more detailed information on how to setup an appropriate map, particularly for a forced induction application.

The thing I did not like about the MegaManual content was that it said to test the ignition curve, you basically have to tweak it until you get ping in an area of the curve and then back it off. That might be the only way to go about it, but it seems like "tuning by Braile", and in my way of thinking, there must be a better way.

I currently own "How to Tune and Modify Engine Management Systems" by Jeff Hartman, but was not satisfied with the depth of coverage on the topic of ignition.

I believe Wes referenced the David Walker book "Engine Management: Optimizing Modern Fuel and Ignition Systems" but would like to confirm if anyone else has read this book or can recommend it specifically as it relates to programmable ignition on forced induction applications.

I'm open to other online references as well. Part of my motivation is to determine a well-defined set of requirements for a forced induction application so I can make a more informed evaluation of the alternative solutions (MegaJolt, MegaSquirt, MSD, Reline-Weber, etc.).

On a related note, as I understand it, converting to programmable ignition requires that the ignition distributor have its vacuum and mechanical advance locked out. I've found some how-tos on this for other makes, but was wondering if anyone here has locked out their OEM Bosch distributor.

As I understand it, without adding a trigger wheel, it is possible to use the stock distributor with locked advance mechanisms, and to pick up the VR signal from the dizzy to provide signal to the ignition system, whatever it may happen to be. Looking for validation that I'm on the right path here.


Good thread topic.

The book I mentioned, "Engine Management: Optimizing Modern Fuel and Ignition Systems" only covers the basics and would not help at all for tuning the ignition map on forced induction applications.
I think the book was mainly launched as a companion to Dave Walker's "Emerald" ECU and management software (which you get on a CD with the book).
It's probably helpful if you decide to go the Emerald route but otherwise I wouldn't recommend it.

There will be divided opinions on methods of tuning ignition. As I understand it you aim for the "minimum timing for best torque" (MBT) at the various RPM/Load sites.
With most forced induction, especially turbos, you'll be knock limited and so can't always reach MBT before it knocks.

It's the DIY tuning part that divides opinion. Some will say you must visit a rolling road and others say you don't need to.

I personally wouldn't trust anyone to tune my engine unless I was absolutely certain of their abilities, and at least over here I've heard stories of rolling road tuners who haven't got a clue.

"Euro924S2" probably had the best approach. He had the guy operate the rolling road to hold various loads/speeds whilst he tuned his own engine.

The rolling road also doesn't replicate real-world conditions properly so I would say copious data-logging is the way forward so you can analyse what's actually happening.

Furthermore IMO it's wise to invest in some sort of knock detection such as a knocklite so you have a visual indicator. Euro924S2 and Cedric have had success with this.
At the same time you can make some det-cans as Raceboy did. This apparently gives you the earliest warning, provided you know what knock actually sounds like.

Other than using EGT readings to help you dial the timing in, there's not much else you can do.
Ion sensing is still some way off I believe.

Re using distributor as ignition trigger you're correct. Just lock any advance mechanisms then set up the trigger - it could probably be Hall or VR, it doesn't have to be VR.
This method is still prone to some error, as it's cam driven and not taken directly from the crank but it works - I believe Simsport used the same method on his SC car many moons ago?

The approach I've taken with tuning is to read as much as possible before starting, from as many sources as possible. Just when you think you've learned everything, something else pops up.
To me it's a continuous learning process.
This thread would be a good place to post relevant links though.
_________________
1979 UK 932
Back to top
View user's profile Send private message
leadfoot  



Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia

PostPosted: Sat Aug 25, 2012 9:40 am    Post subject: Reply with quote

Dan,
I had my distributor flyweights locked, also split one of the four trigger tooths to get a reference point, this was required by the ecu, and the timing was set up for 2x cam rotation.
the sent the output signal through a bosch 024 ignition module.
some reading here and a diagram of hookup https://dgtlmoon.com/bosch_bim_024_electronic_ignition_module

swapped coils in the process too.
stu
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...
Back to top
View user's profile Send private message Send e-mail
musicalannette  



Joined: 21 Feb 2012
Posts: 413
Location: UK

PostPosted: Sun Aug 26, 2012 10:50 pm    Post subject: Reply with quote

Dan, that is hows it done, keep advancing untill you get detonation, then back it off. Modern ECU's have a base map, then "learn" the engine with feedback from a knock sensor. On larger engines it gets more complicated with 2 sparkplugs and flamefronts inside the combustion chamber and trying to get all the fuel burnt at peak compression, look into the rolls royce eagle or better still, just best not go there.

If you think about it simply, you want as much compression when you ignite (tdc) to get the power from the fuel, but not before the crank has passed tdc so you are not fighting the flywheel and loosing power. As the rpm picks up you need to ignite it early to get the fuel burnt at tdc, which is why ignition is before top dead center.

Try and keep it simple in you mind, because if you go down the full path of understanding why the ignition is before TDC you will realise it isnt something that can be calculated easily without double checking with lots of actual data from a test engine.

The variables i can remember (fuel/air ratio, flame front speed, spark plug placement, comustion chamber shape, fuel type, fuel spray pattern, fuel concentration in the cylinder, compression, swirl, combustion chamber size, rpm, manifold depresion and in your case pressure charging), you arent going to be able to even monitor all those easily, let alone change many of them without redesgning a new head.

Quite often this what happens, they design, aquire data redesign from a test bench and dyno, then do the same over again for a specific bore/stroke, usually they alter the comustion chamber shape or plug placement, injector placement to create swirl can really help increase power. It depends on what you want the engine to do. Be super lean burn or max power. Ultilmately for a petrol engine, Direct Petrol Injection is probably the way to go.

But adjust any of the list and its back to the drawing board for the timing. Remember, with modern electronic the timing can go when you want it too for a specific rpm, not just limited to bob weights and a vacume diaphram on a dizzy.

Most people never get to see igintion swirl in the chamber on a dyno! So a knock sensor is the way to go for most of us. But this can also be handy for combustion camber design.

It is probably why the A series is such a fantasticly efficient design, they did it over and over. For a pushrod engine, coupled to an equally well developred SU carb it was a shock when I owned one. I had a 1275 austin metro and driving in it at 60mph on a long trip I saw 52miles per gallon (uk gallons), it has just been around so long and been so refined. Amazing considering there is no electronics. I think toyota ought to use it as a starting point for the prius as the 1000 metro is even more economical!

It used to be that you could only really look into engine timing if you were lucky enough to have an engine dyno and a load of test gear, you could always build a dyno and someone i know is in the process of doing that. But that a bit of overkill just for ignition timing.

Really what you want is attach a knock sensor to the engine (these are fitted to wide variety of modern engines with adjustable ecu timing), it detects the shock inside the engine, then the crystals convert this shock into an electrical signal, it then goes through a band pass filter, then if you monitor the signals you can check for detonation, adjusting the timing so it goes away for varying levels of load (manifold depression), rpm and as it sounds like you have a turbo, you will be wanting to add a boost modifier into the mix.

Try and think about simply and monitor the results as it is nearly impossible for most of us to monitor much more than knock, otherwise you might tie yourself up in so many knotts you dont do any knitting.

Hearing for a ping is pretty acceptable on a four cylinder if you know what to look (or should i say listen for) AND your hearing is ok, but when you have more cylinders it isnt, then you have to use the knock sensor to tell you. Definately cant tell with a v12 jag and you will struggle with a v8.

hope this helps
_________________
I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Mon Aug 27, 2012 3:55 am    Post subject: Reply with quote

I've acquired the KnockSense setup, which is what I'll be using. Obviously, what I'm interested in is tuning for power, so it seems that some reading on the topic of "mean best torque" is in order. Still would love to find some specific reference material...
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
musicalannette  



Joined: 21 Feb 2012
Posts: 413
Location: UK

PostPosted: Mon Aug 27, 2012 5:48 am    Post subject: Reply with quote

im sorry that i cant offer you any reading material, but for peak power it will mean putting it on a dyno and going up in 250 rpm stages or whatever you choose and "adjusting" the advance for peak power at different monifold pressures whilst checking you dont have any knock output from the sensor.

im not sure this will be easy on a rolling road and will probably want to be done on a bench dyno for accurate readings.

very very best of luck.
_________________
I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Wed Aug 29, 2012 11:38 am    Post subject: Reply with quote

Quote:
Spark Tuning

Unfortunately for the backyard tuner, developing a good spark map isn't as straightforward as tuning the fuel with a wideband oxygen sensor. Ideally, a spark map should be developed on a chassis-loading dyno. The car is run on the dyno and for every RPM and load bin (the spot on the spark map), the ignition timing is advanced until torque starts to drop off. The point right before the torque drops off is called MBT or mean best torque.

There are a couple of problems with this method. One is the cost of renting a dyno for hours on end. It could easily cost a fortune to get it nailed. But the biggest problem with this method is that many engines (especially high-compression and forced-induction) will encounter knock before reaching MBT. Most engines will ping before reaching MBT.
Engine Tuning Basics Spark Plugs

Because of this, we must keep an ear out for knock while tuning. While knock can be heard, it's much safer to rely on a knock sensor to serve this duty. It's safest to make only changes where needed to the spark map. Typically, the low-load ignition timing that the engine uses stock is best. It's really only under high load and with higher-compression pistons, etc. that other areas in the spark map might need to have some ignition advance removed.

When tuning ignition timing with a knock sensor, you simply reduce the timing advance under those conditions that you encounter knock. There are numerous to control ignition advance. We've listed a few ways and some other terms that will help you.

Read more: http://www.importtuner.com/tech/0612_impp_engine_tuning_basics/viewall.html#ixzz24tIaQ8TP


OK, great, if you have a baseline map to start with...but adding in a programmable ignition to a car that never had one? How do you build such a map without a dyno???? How do you know where to even begin???
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
!tom  



Joined: 28 Aug 2006
Posts: 1874
Location: Victoria, BC Canada

PostPosted: Wed Aug 29, 2012 2:04 pm    Post subject: Reply with quote

ideola wrote:
OK, great, if you have a baseline map to start with...but adding in a programmable ignition to a car that never had one? How do you build such a map without a dyno???? How do you know where to even begin???

The stock dizzy advance curve.
_________________
78 924 NA
5-lug
Back to top
View user's profile Send private message Visit poster's website
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Wed Aug 29, 2012 2:12 pm    Post subject: Reply with quote

!tom wrote:
ideola wrote:
OK, great, if you have a baseline map to start with...but adding in a programmable ignition to a car that never had one? How do you build such a map without a dyno???? How do you know where to even begin???

The stock dizzy advance curve.

And how does one go about getting that info?
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Wed Aug 29, 2012 3:04 pm    Post subject: Reply with quote

Here's an old thread with (frustratingly) lots of missing images.
http://www.924board.org/viewtopic.php?t=18911
But still some indication of how others here have done it...
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
!tom  



Joined: 28 Aug 2006
Posts: 1874
Location: Victoria, BC Canada

PostPosted: Wed Aug 29, 2012 6:40 pm    Post subject: Reply with quote

ideola wrote:
And how does one go about getting that info?

I found this from the FSM for a N/A. I'd expect you'd be able to find the equivalent for the 931 somewhere.

_________________
78 924 NA
5-lug
Back to top
View user's profile Send private message Visit poster's website
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Wed Aug 29, 2012 11:06 pm    Post subject: Reply with quote

Ahhhh, yes, I don't have my FSM on this laptop (traveling), will have to check the 931 stuff when I get home. Thx!
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
kcoyle  



Joined: 16 Jan 2011
Posts: 714
Location: Long Island, NY

PostPosted: Thu Aug 30, 2012 10:31 pm    Post subject: Reply with quote

For future reference.


_________________
1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.
Back to top
View user's profile Send private message
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Sat Sep 01, 2012 2:22 am    Post subject: Reply with quote

My version of FSM has all of the US model years, but interestingly, not the Euro NA stuff. The first image below are the graphs printed in Haynes (will attempt to do my own scan later so we can get the Euro stuff in higher resolution):


The following graphs are clipped from the FSM:

1976-1977.5 NA Centrifugal Advance Curve


1976-1977.5 NA Vacuum Advance Curve


1977.5-1979 NA Centrifugal Advance Curve


1977.5-1979 NA Vacuum Advance Curve


1980 NA Centrifugal Advance Curve


1980 NA Vacuum Advance Curve


1981-on NA Centrifugal Advance Curve


1981-on NA Vacuum Advance Curve


1979-1980 931 Centrifugal Advance Curve


1979-1980 931 Vacuum Advance Curve


1981-on 931 DITC Performance Graph


1981-on 931 DITC IAT Correction


1981-on 931 DITC IAT Resistance-Temperature Curve


It's frustrating that the DITC charts are not labeled on the X-Y axes.
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Mon Sep 03, 2012 11:04 am    Post subject: Reply with quote

leadfoot wrote:
Dan,
I had my distributor flyweights locked, also split one of the four trigger tooths to get a reference point, this was required by the ecu, and the timing was set up for 2x cam rotation.
the sent the output signal through a bosch 024 ignition module.
some reading here and a diagram of hookup https://dgtlmoon.com/bosch_bim_024_electronic_ignition_module

swapped coils in the process too.
stu


Stu
Which distributor were you using? Also, what coil?
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> Performance Upgrades All times are GMT + 11 Hours
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group