Yet another ignition question… 6.0L dizzyless... Ignition curve/map

I’ve been searching this forum and a numerous amount of sites on the web for an ignition curve/map for a later 6.0L engine, the one without any dizzy…

The car is running on a MS3X, runs very well but would like to get the ignition map a better tune but is seems like there are no numbers what so ever… before anyone says “get it on a dyno”… yes I will when I find someone close by that doesn’t charge me USD1000….

Only numbers I found so far is for the HE engine… using the 18 degrees at 3000rpm and 0 degrees at idle as a base, but… how much is the vacuum advance… never minding the absurd amount of delay vales etc…. what is the maximum advance, I’m now running at max 24 degrees to avoid knock at WOT (running on high RON pump gas)

I know there a few here running MS on HE engines… anything to share?

BR//Tobmag

I have some maps but there is a complicating factor in that I run lpg which is a very high octane fuel and my heads are skimmed to about 13.5:1, not the 11.5:1 you are expecting. Worse than that, they have some sort of aftermarket camshaft which seems to love huge amounts of advance at idle rpms.

Philip Lochner also has maps, but he lives at high altitude.

I think Greg Meboe had his 6l on a rolling road and that may be the best starting point.

As I understand it, one poster said that the ignition ecu language for this is a derivative of javascript, so it may be able to interrogate the oem ecu.

kind regards
Marek

Thanks Marek.

If you would like to share your map it would be great just to see the basic nubmers you have in there.
Phil is living in ZA J-burg so yes high altitude but as I remember he uses 2 MAP sensors to take care of the altitude issues so hopefulle he will read this as well :slight_smile:

Lets see if Greg comes by as well and hopefully can share his tuning as well.

I dont have any control units from the Engine at all so have nothing to read out from…

BR//Tobmag

Like I said, it’ll not really be suitable for you, but it mostly works for me.

kind regards
Marek

Hi Marek.

seems like we have about the same WOT numbers in but you are pulling way more advance at cruising than I do at the moment.

Tobmag

Road tuning timing for a high compression engine is actually rather “easy”. For every operating point, advance till you hear detonation (ping), then retard 3 degrees. This is how I do it. “Don’t do this at home - or on the road” :slight_smile: This method is based on the ASSUMPTION that max torque is delivered just before detonation sets in - which is often not the case. Rover V8’s will happily produce more torque long after detonation has begun.

Note that intake air temp (and barometric pressure) plays a big role when it comes to detonation. I was often frustrated by my Rover V8s happily pinging when I off-road in the hot Zimbabwean bush whereas at home I have no issues.

Megasquirt allows one to retard/advance timing as a function of intake air temp. At times I’ve had to pull back 8 degrees, in those conditions, to stop the pinging!!!

I find it impossible to road tune timing for a low compression engine simply because they are much less prone to detonation than high compression engines. A braked dyno is then really the only way. I have found that they tolerate WAY more advance than high compression engines.

My low compression 7.2L V8 in my Jensen gave me 8km/L on numerous long trips. The best I get of from the high compression engine is 7Km/L. I concluded that the low compression engine is more fuel efficient due to more advance, but the high compression is certainly more powerful at full throttle.

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Something I’ve always wondered: In a low compression engine, is it possible to dial in too much advance without it pinging? IOW, the torque begins to drop off even though the engine is not pinging?

I don’t have scientific evidence to support my view, but I believe so - that you can have too much advance without pinging, losing out on torque.

The reason I say so, is on the basis of my Jensen low compression engine’s behaviour. I had that engine advancing into the mid 50’s ON VERY LIGHT THROTTLE (0 - 20%) around 2000rpmm where the car cruises and I never got pinging. This very possibility is what made me dial the advance back to a self imposed 50. Because the plug sits on the very edge of the combustion chamber on the 440, it seems logical that the flame front should take twice as long to reach the other side (and hence will tolerate more advance) compared to a head where the plug sits right in the middle.

This is why it is my view that a low compression engine can only really be well mapped on a braked dyno where you can see the immediate result of a change in timing advance.

good thing you are not programing a Hi boost forced induction engine , ignition curves can really get complicated, 15 PSI in the inlet and melt a piston before knock will happen before max torque is reached!

for my lowly V12 9.2 compression,Pre HE flat chamber , at present i’m at 24 BTDC at 950/1000rpm no vac, vac applied and it runs to damn rough at idle! throttle response is great tho!
max advance is right around 50* BTDC, all in at 3000rpm, all the way to past 6500rpm!
peak torque 4200, i drop it about 3* till past 44/4500 rpm, then bring it up to 50 again at full throttle.

now most do not realize the Heron Quiescent chamber you cannot hear detonation NA!
thus the Quiet chamber!

and YES in todays performance world a GOOD wheel dyno and tuner,has become a must for serious tuning!
all of the best parts ,pistons, cams, heads,etc, and gadgets will be NO better than the final tuning.
ron

DSCN8693 .

i’m really old school with my SDS EFI system,with dizzy and a Summit weight/spring setup, but it works for me.
ron

That smartphone app that calculates HP based on acceleration and vehicle weight won’t do?

It would be of very limited help unless it can plot HP vs speed (which you then need to translate to rpm)

It would certainly be of no value at any operating point other than full throttle.

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Of course they plot HP vs. speed, and they plot HP vs. RPM too, I think.

Good question about part-throttle data, though. On a dyno, do you set the throttle at some fixed position and then vary the timing to see where you get the best performance? Are you looking for torque or fuel consumption at that point? I guess they’d both be optimized at the same point.

Kirby, there are three scenarios:

  1. Fuel & timing maps manifold pressure based:
    In this case you will tune partial throttle by getting the operating point (rpm vs manifold pressure) at each point on your map (regardless of actual throttle position) and then you will tune fuelling and timing until you get max torque at that point. If your map has 10 rows and 10 collumns, you have 100 points to tune. Well, not really, realistically, above 4000rpm, you are likely to be at full throttle, so you only need to tune the full throttle points there. Between idle and about 3500rpm it makes sense to spend a lot of time on partial throttle tuning.

  2. Fuel & timing maps MAF based.
    Similar to the above - I think. I’ve never done a MAF, so can’t speak with authority on this.

  3. Fuel & timing maps TPS based.
    This becomes necessary when you have throttle bodies and hot cams where manifold pressure is not a feasible method of determining engine load. Like I said before, at low RPMs, very little throttle (20%- 30%) can effectively put the engine at “Full Throttle” because it already allows “all the air the engine wants” into the engine despite the smallish throttle opening. Even in this case, you will still aim to find the most torque by tuning both fuelling and timing at each operating point of the map.

Fuel saving comes about as the result of having optimised torque over the entire map. When , driving normally (using the partial throttle part of the map - which can be 80% or more of the entire map), the driver will at all times, demand just enough torque to get the car to do what he wants. Having optimised torque, all over the map, the driver would tend to seek less throttle, which will lead to lower throttle openings, and hence less fuel being consumed, having optmised the partial throttle area of the map.

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Just a note on tuning fuel for the partial throttle area of the map. Even there, you will provide as much fuel as needed, not more, not less, to get max torque, regardless of the actual air-fuel ratio.

So you are not chasing an AFR of 14.7 eg. That is not the objective. You are chasing max torque by providing whatever fuel and timing delivers the max torque at every operating point.

Unless you are a manufacturer. Then you have your eyes on the “emissions gauge” and THAT has the final say in matters. Then, “optimisation” is focussed on meeting emissions targets, not torque (and hence fuel consumption) targets. Whatever torque the engine is left with, is what the consumer gets.

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Tobmag.

Here is the timing map for the Cobra I built, with standard 12.5:1 CR 5.3 Jag V12.

Note that I have created the table to have much more resolution from idle to 2000RPM, with lesser resolution above 2k, and even less above 4k.

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Thanks for all the replies.

Im very well aware of all tuning parameters, fuels, cr, rod-ratios, combustion chamber design etc… working alot with my XJ12 Pre-HE with a MSII that today is running very well.

To squeeze out the last HP there is no other way than on a dyno…

Thanks Philip. I’ll drop in your numbers to see how she reacts… not shure if I can go up on 28 degrees WOT, I hade to pull down to around 25 but that was on a really hot day… 30 degrees C.

BR//Tobbe

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I’m not familiar with these charts. Can you please explain the vertical scale that goes from 20 to 100? And why does the 20 line get special treatment, far more retarded timing?

Kirb, its a new world of performance tuning, some of us old timers are being left in the dust!

i have next door to me a guy getting into MS 3 and he has been trying to set it up/tune it for 6months !

i hear him always reving and driving , come back and sits in seat pushing compter key board(with a few adjectives added).
ron

and i dont know how they can get a 12.5 comp. ratio to ever use more than 28/30 using more than part throttle , as soon as vac goes down ping starts up! plus that squishy HE chamber is designed to run on the edge of detonation,barely, lotsa dropped valve seats for those engines!
you can ping for short periods but rarely for long hiway runs, steady!
ron