High Energy Ignition (HEI)

[AdmiralSenn]

At the risk of feeding the fire (and because I have a genuine interest in the topic) I switched to HEI when I first worked on the car. I had done a tune-up previously but the car was still acting funny, so I switched to a Blaster 2 and widened the plug gaps (I was already running MSD wires).

I can't say if it made a huge difference in performance as the car was still acting funny but it certainly helped it start faster. Combined with a new starter, the car usually fires before it even turns over a full revolution. Even with the old starter, the ignition improvement significantly shortened the number of turns before the engine caught.

I am running an MSD-specific ballast resistor instead of the factory setup, as the datasheet for my coil specified using it if there was a resistor in the car originally.

[David T]

Everyone seems to be overlooking the fact that messing with the ignition system has an effect on emissions. It may not matter to any of us now but DMC had to make an engine package that was certifiable by the US EPA. To do that required intense testing with a certain configuration of components. Once certified that configuration was "set in stone" and couldn't be changed easily and without more testing. There is another factor. 30 years later we know some things we didn't know then and there are things available now that weren't back then. For instance the stuff they call gasoline thesedays. There are also performance parts. Anyway there is some potential for improvement in the ignition system but you have to experiment and hit on the right combination and then you have to fine tune it so it will stay in tune for an extended period. As an example, spark plug gaps change over time. Comparing Bill's car to other Deloreans is difficult with all of the modifications he has done to his car. A dyno would be a good, objective test with the least amount of variables. Dyno time costs money. Put your money where your mouth is, I say. Seat-of-the-pants testing is too subjective and is meaningless.
David Teitelbaum

[content22207]

Everyone seems to be overlooking the fact that messing with the ignition system has an effect on emissions.

According to the Society of Automotive Engineers, increasing secondary voltage and widening the plug gap (and lengthening spark duration) "reduce the cyclic combustion variation and the unburned HC."

Does anybody bother the read the scientific studies I post, or do you all reflexively stick your heads in the ground and cry "don't mess with John DeLorean's masterpiece!"

You all are laboring under the mistaken impression that DeLorean ignition was optimized. It wasn't. It was good enough -- that's it. There is plenty of room for improvement, if only to bring it up to 1981 Mustang standards.

Bill Robertson
#5939

I am running an MSD-specific ballast resistor instead of the factory setup, as the datasheet for my coil specified using it if there was a resistor in the car originally.

Go back and re-read the instructions carefully -- it is possible your coil handle full charging voltage (the Bosch ECU, however, is a different story, although mine is handling whatever comes out the far side of 12.5 primary OK).

This is a Pertronix coil on my 1969 Lincoln engine (transplanted into a 1979 vehicle):
PertronixCoilFullVoltage.jpg
Primary voltage is only 12.5 because the engine is idling about 600 RPM -- it'll jump up to 13.8 when rev'ed.

Bill Robertson
#5939

[AdmiralSenn]

Go back and re-read the instructions carefully -- it is possible your coil handle full charging voltage (the Bosch ECU, however, is a different story, although mine is handling whatever comes out the far side of 12.5 primary OK).

This is a Pertronix coil on my 1969 Lincoln engine (transplanted into a 1979 vehicle):
PertronixCoilFullVoltage.jpg
Primary voltage is only 12.5 because the engine is idling about 600 RPM -- it'll jump up to 13.8 when rev'ed.

Bill Robertson
#5939

I'm sure it will handle it - in fact I ran the car for a few weeks that way before I found that line in the directions, and nothing bad happened. But I figured that it really isn't hurting anything and the part was cheap enough that I was happier following the manufacturer's directions.

Maybe if/when I switch to controlling spark through my MS ECU I might drop the extra resistor but the worst consequence of installing it is a blistered fingertip from when I poked it by mistake.

[content22207]

What is your primary voltage? My DeLorean runs .25 ohms of resistance, which knocks the primary side down to 12.5 volts when charging (10-11 volts while cranking IIRC). As stated, my Bosch ECU hasn't had any problems with that yet. Of course a Pertronix coil must have more internal resistance than a Bosch coil simply due to the increased number of windings, so the ECU may be seeing similar voltage on the far side.

Bill Robertson
#5939

[AdmiralSenn]

I have no idea off the top of my head, honestly. I'd measure it but without battery cables it's a little hard to start the car.

I do know that the last time I checked voltage at the coil it was lower than it should have been, something like 10.6 volts, but given the issues I'm correcting with the wiring, that number is artificially low. I don't remember what it was prior to the resistor but it wasn't much higher.

I think the resistor I have is .8 ohms. When my battery cables get here and I rewire the car I'll be able to measure it again, and it'll be accurate this time.

[DCUK Martin]

I've actually never argued that Bill's car isn't faster than a stock DeLorean. It almost certainly is. The Alpine GTA Atmo with slightly different cams, ignition timing (advance weights) and a twin Solex carb setup but otherwise identical transmission and ignition systems is a heap quicker than a DeLorean - 156hp IIRC. They didn't have the mpg or emissions figures to hit that DMC did. I'm pretty sure Bill's current setup wouldn't meet those either.

My beef is Bill's claims that any of his mods are "better" without qualifying, in accurate specific terminology why. ("Because Ford used it for years" doesn't count).

I agree with the others -- Not by changing out a good stock coil alone. The stock coil can supply all the energy the stock plugs need to fire correctly. The perfect coil will only produce enough energy to fire the plug, no matter how many gazillawatts it has "in reserve".

And *that* is my single reason for doubting Bill's many claims. I experienced many a headache trying to get my turbo engines to ignite properly under boost and the only coil that'd do it was a stock one. The plugs were changed for NGK BP7EFVS's which are a cold plug used by the GTA boys. HT leads were correct Bougicords (the dizzy cap has different connectors than the DeLorean).

Bill's crowing about better coils means nothing without taking the performance to the point where it fails. Anything up to that point will work fine, but won't actually be any better than a properly working stock system in an engine being accurately fuelled. I add this last caveat because in a rich-running engine, a hotter spark will ignite the mixture more readily, but that doesn't make the ignition system "better".

[content22207]

Bill's crowing about better coils means nothing without taking the performance to the point where it fails. Anything up to that point will work fine, but won't actually be any better than a properly working stock system in an engine being accurately fuelled. I add this last caveat because in a rich-running engine, a hotter spark will ignite the mixture more readily, but that doesn't make the ignition system "better".

Obviously you haven't bothered to read the SAE paper I posted. They proved that increased spark energy ignited LEAN mixtures better.

You stick with your chicken bones and tea leaves -- I'm going with the scientists.

Bill Robertson
#5939

[DCUK Martin]

No I didn't bother wading through the link you posted because on the occasions I have bothered I usually discover that you mis-read or misunderstood it anyway. Let's call it a less-than-optimum mixture condition then.

So you'd fix a lean-running engine by fitting "better" ignition?

I really wish you would "go with the scientists". We wouldn't argue anything like as much.

[content22207]

That paper was published on the eve of widescale HEI adoption over here. In its historical context, manufacturers for the North American market were just beginning to adopt leaner fuel mixtures. It is no accident that HEI caught on like wildfire.

Compared to nearly every one of its North American contemporaries, DeLorean ignition specs are woefully out of date. Both coil voltage and spark plug gap more closely resemble 1971 practice than 1981 practice.

Bottom line: the ignition system used by DeLorean is quite badly matched to its lean mixing fuel system.

That is not mere opinion -- it is SAE research, vetted by Lucas, Ford, and Champion Spark Plugs, and historical comparison of DeLorean against all of its North American contemporaries.

Bill Robertson
#5939

No I didn't bother wading through the link you posted because on the occasions I have bothered I usually discover that you mis-read or misunderstood it anyway. Let's call it a less-than-optimum mixture condition then.

Authors' [AC Delco engineers] conclusions, found on page 60 (14th page of the scan):

"The conclusions reached as a result of this investigation are summarized below. Even though these conclusions are based on tests obtained with one basic engine, the trends observed should be similar to what would be expected of all modern engines.
1) The cyclic work measurement, in conjunction with measurement of emission levels, provides one satisfactory method for evaluating engine performance.
2) Extended gap locations, wider gap size, and higher spark energy levels [my emphasis] are the most significant parameters that reduce cyclic combustion variation and unburned HC. Smaller electrode side shows similar effects, but these effects are less pronounced.
..."

The rest of the paper is just boring data that verifies the above, and commentary from Lucas, Ford, and Champion Spark Plug agreeing with the authors' findings.

Bill Robertson
#5939