You are right...no fuel to help the spark travel along on because it's a lot leaner out here...maybe I should write a paper on...um...oh yeah, someone already did that.Originally Posted by content22207
Location: North GA
Posts: 6,200
Club(s): (SEDOC) (DCUK)
You are right...no fuel to help the spark travel along on because it's a lot leaner out here...maybe I should write a paper on...um...oh yeah, someone already did that.
Location: North GA
Posts: 6,200
Club(s): (SEDOC) (DCUK)
Really? I see both as confirming what Martin has been saying all along. Doesn't address what I've been saying except for one thing much, increasing the gap alone causing an increase in voltage at the plug (thanks for an accepted references).
"Larger gap spacing results in greater voltage requirements and increased energy in the initial release of the capacitive portion of the discharge." [pg. 62, Emphasis added]
Like I said before, this is nothing new, especially to engineers in 1981:
"SINCE READING in 1960 the first papers dealing solely with cycle-to-cycle combustion variations, I have kept a keen interest in the subject. The "conclusions arrived at them are still valid, although some clarifications of the mechanisms have been shown..." [Pg 63, Emphasis added]
BTW- The paper also says performance includes power and emissions...
Yep. Same exact engine for 10 years
Which has little to nothing (as usual) to do with the questions at hand.
Was it diesels started to out perform gas burners, with no spark gap or coil at all?
======
Well watch is about over. Please continue on with extraneous truths.
CYA!
Last edited by Ron; 08-30-2011 at 06:07 AM.
Posts: 1,068
Yes indeed, with compression ratios almost three times as high.
Which releases more energy: a spring compressed to 1/8 its original length, or a spring compressed to 1/20 its original length?
To be brutally honest Ron, if you don;t understand the difference between gasoline combustion and diesel combustion, you have no business commenting in this thread in the first place.
Bill Robertson
#5939
Posts: 1,068
Back to the thread at hand:
If an owner wants:
- decreased emissions
- more reliable combustion
- more complete combustion
especially in a lean burning engine like the a DeLorean PRV, there is no better way to accomplish that than to increase secondary ignition voltage and spark plug gap.
Engineers from AC Delco, Lucas, Ford, and Champion all agree.
Every American and Japanese car manufacturer came to the same conclusion, and did just that in the 1970's -- a practice that continues to this day (they did so first on the exact same engines that had been running smaller plug gaps with breaker points -- ignition technology that inherently limited secondary voltage and spark plug gaps, then continued doing so on newer designed engines).
A subset of European manufacturers continued using lower voltage ignition and smaller plug gaps, even after breakerless ignition made higher voltage ignition and larger plug gaps possible. Evidence points to a reluctance to redesign the ignition coil -- a necessary step towards high energy ignition.
The PRV, as used in a DeLorean, can benefit greatly from higher voltage ignition. That is why Renault/Chrysler started using higher voltage capacitive coils and a larger plug gap for the 3.0 version of our engines (Autozone shows the 3.0 PRV plug gap as .044", but other online sources show it .030-.035" -- both are wider than the original DeLorean spec).
Bill Robertson
#5939
Location: Leonardtown, MD
Posts: 9,604
My VIN: 03572
In the late 60s the big new thing was capacitive discharge ignition. The problem with gas engines back then was leaded gasoline fouling the plugs. So they decided to burn the plugs hotter and open the gap with capacitive discharge ignition. I don't hear much about that anymore. Unleaded gas was started in the early 70s.
Race engines always needed higher power coils, dual points etc. to run 10000 RPM. That was due to the dwell times are just to short to get the energy into the coils.
I'm still open for info on what advantage there is to using a different spark set up on our low compression engines. What is better, more voltage or more current. Does a higher voltage spark ignite fuel faster than a lower voltage with more current? If it ignites the fuel faster, wouldn't you need more advance timing? So as long as you don't get any miss fires what are the benefits?
Does the higher voltage cause our distributor cap to fail sooner since it was not designed for that voltage.
Posts: 1,068
The higher voltages possible with capacitive coils simply were incompatible with breaker points.
Everything eventually went capacitive after after breakerless ignition. GM was the first in the 1970's, mounting a capacitive coil directly to the distributor cap. Ford went capacitive when they introduced TFI modules in the 1980's (the module mounted to the distributor body). All distributor packs were capacitive. I don't think there has been a new car model with inductive ignition since the mid 1980's.
Bill Robertson
#5939
Location: Baton Rouge, Louisiana
Posts: 3,047
My VIN: 16510 and carbureted
Club(s): (GCD) (SEDOC) (DCUK)
I'm not going to post something saying I've been a mechanic for 30 years, blah blah blah. I'm just going to say facts which I have been doing all along.
About 6 months ago I decided to upgrade my ignition. I purchased a high performance coil, MSD spark plug wires, and new spark plugs.
I gapped my new plugs to .05 and didn't bother to increase voltage going into the ignition coil. I left the resistor grid wired to put 6 - 8 volts into the coil.
The problems were very quick to surface. The car wouldn't alway start and when it did it ran like crap. Many of my friends were quick to blame my fuel system saying the engine was flooded. Also my gas mileage dropped drastically.
I then pulled each plug and regapped them to .026. The car ran perfect after that.
When I got around to redoing the wiring in my engine bay I decided to rewire the resistor grid to provide 12 volts into the ignition coil. Then I gapped my plugs to .05
The car ran perfect at .05 only after I increaed voltage going into the coil.
Ron can post all the foolishness he wants but I am not responding to anymore of his posts on this subject.
Posts: 1,068
I just corresponded with an owner who may have wired his coil backwards: "The input to the coil is about 4.75V and the output is over 7.5V." If that statement is correct, not just written backwards, he definitely has the wires on the wrong terminals.
Why is this such a common problem in the DeLorean community? Bosch coils may be labeled bass ackwards, but Pertronix and MSD coils clearly have their positive and negative terminals labeled with "+" and "-" signs.
Bill Robertson
#5939
Location: North GA
Posts: 6,200
Club(s): (SEDOC) (DCUK)
yes indeed,...was it diesels started to out perform gas burners, with no spark gap or coil at all?
To be brutally honest Ron, if you don;t understand the difference between gasoline combustion and diesel combustion, you have no business commenting in this thread in the first place.
Posts: 1,068
I'm pretty sure Ron and Martin realize they are wrong, and rather than taking their lumps they are just trying to steer this thread off in tangential directions.
In 1981 Bosch ignition stood alone with low voltage coils and small spark plug gaps. That is an uncontestable historical fact.
By 1981 every other ignition manufacturer had already adopted higher voltage coils and larger plug gaps, even for engines that previously used low voltage coils and small plug gaps (the change can not be attributed to new engine designs, although some engines that previously were high compression did have their compression ratios dropped).
I have no idea why Bosch didn't upgrade to HEI.
The number of vehicles running Bosch ignition in the 1980's was an extremely small segment of the global car market. Unfortunately DeLoreans were in that small group.
I find it particularly interesting that Chrysler used higher voltage ignition and wider plug gaps for its 3.0 iteration of the PRV, while Volvo continued to use a Bosch ignition system and .028" plug gaps on the B280 (I have no idea who made Chrysler's 3.0 ignition). Starting in 1988, for the same basic engine, the North American user equipped it with HEI while the European user stuck with earlier spec ignition -- a clear dichotomy if I ever saw one.
Bill Robertson
#5939
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