Yay! Martin is going to read two pages of the paper!
SAE_14.jpg SAE_15.jpg
(Remember: 7:1 is *LOWER* compression than 11:1).
Bill Robertson
#5939
Posts: 1,068
Yay! Martin is going to read two pages of the paper!
SAE_14.jpg SAE_15.jpg
(Remember: 7:1 is *LOWER* compression than 11:1).
Bill Robertson
#5939
Location: DeLorean Cars, UK
Posts: 593
You are confusing flame propagation with spark energy.
Those pages talk about the requirement for longer spark duration in lower compression and "lean burn" engines.
The DeLorean engine does not run lean, nor is it a particularly low compression engine.
Martin Gutkowski
-------------
Very part time DeLoreaner...
Posts: 1,068
Compared to a Eurospec PRV, the North American version is low compression and lean burn.
You need to look at HEI in its historical context. The 1972 Clean Air Act changed the North American automobile manufacturing landscape radically. For example, in 1972 manufacturers dropped compression on every single engine they manufactured. Whereas 10:1 to 11:1 compression ratios were very common in the 1960's, you could not buy a new production vehicle with an engine with higher than 8.5:1 compression after 1972 -- period. It was a radical change, noted in all the automobile magazines of the time. Automobile manufacturers also started jetting their carburetors leaner, partly for emissions and partly for fuel economy -- especially after the 1973 oil crisis.
HEI was developed to optimize combustion in the low compression lean burn North American engines of the 1970's, of which the DeLorean PRV definitely is one.
And of course, with the exception of turbocharging. engines have continued to run in low compression lean burn guise ever since, which is why ignition components such as coil voltage and spark plug gap never went back to their breaker point specs. Regarding turbocharging, which does consume more fuel and produces more pollution, remember that manufacturers have to meet what is known as Corporate Average Fuel Economy -- their entire fleet meets governmental targets. Turbocharged models are offset by econo models. For every Mustang there are multiple Foci. For every Camaro there are multiple Volts. Etc. Forced induction is the exception, not the rule.
Bill Robertson
#5939
You have to read the entire page, Martin:
UnderlinedForMartin1.jpg
Bill Robertson
#5939
Location: DeLorean Cars, UK
Posts: 593
(typing this through gritted teeth)
Get your terminology right. "Lean Burn" refers to very specific, very rare types of spark ignition piston engines which are designed to run at AFRs greater than 14.7:1.
The PRV, whatever flavour, is not one of them.
Your document, and those parts you have underlined proves nothing with regard any advantage on the DeLorean engine.
Bottom line, there is nothing wrong with the DeLorean ignition system as designed!
No, it has a lower static compression ratio and runs closed loop fuel control meaning it stays around stochiometry. This is not "lean"!Originally Posted by content22207
HEI was developed to optimize combustion in the low compression lean burn North American engines of the 1970's, of which the DeLorean PRV definitely is one.
Bollocks. Per hp, a forced induction engine is actually cleaner and more efficient than a naturally aspirated equivalent. Forced induction increases the volumetric flow of the engine and a turbocharger uses what would otherwise be wasted energy to do it.Regarding turbocharging, which does consume more fuel and produces more pollution,
For now.... but trust me, in a few years you'll see smaller and smaller engines with larger and larger, more elaborate turbochargers, mirroring what has happened with diesels over the past 20 years.Forced induction is the exception, not the rule.
Martin Gutkowski
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Very part time DeLoreaner...
Posts: 12
Through gritted teeth indeed. I normally lurk but the amount of misinformation and ignorance in the thread by this guy is appalling.
Location: North GA
Posts: 6,200
Club(s): (SEDOC) (DCUK)
He has all of the information...he just chooses to ignore or re-interpret it.
=====
And compared to a bean can full of burning gasoline it isn't! -- That's not a DeLorean engine either!
OK !!!
......
You supplied the information to prove yourself wrong!
Lets look at the conversation between the experts, Ray and Tom, that YOU posted.
The very first thing YOU underlined is where Ray is clearly referring to "cars these days" and "for the past decade or so", when he said "Right." to Tom!
Ray continues with, "Now that spark plugs need much higher voltages for more complete combustion (and therefore fewer emissions)," -- 1981 is not "Now", but over three decades earlier!
As already said, the other papers you posted clearly show engineers were aware of all this, as do the papers they refer from the 1960s! DeLorean would have used one of many other coils readily available in those days -- There is nothing wrong with the stock coil on a stock DeLorean. And again, changing the coil alone does not change the resistance from the coil to the plug, so the energy used will remain the same! It uses what it "wants" NOT what you "push" through it.
According to the DeLorean Workshop Manual (A:01:01), Vehicle Specification Data: Compression ratio = 8.8:1
According to the DeLorean Workshop Manual (A:02:01), Engine Tuning Data: CO = 1%
Facts all of your wild comparisons and historical facts can not change:
8.8 > 8.5
1% = 0.01
CO can be equated to air/fuel ratio -- 0.01 percent CO is equivalent to 14.7:1 air/fuel ratio.
14.7:1 is Stoic, neither rich NOR lean!
Last edited by Ron; 09-11-2011 at 01:11 PM.
Location: DeLorean Cars, UK
Posts: 593
Darn, missed that one
Anyway static CR tells you nothing about the actual volumetric compression ratio under load. It's only useful for comparing engines with identical valve timing, it gives no absolute reference point.
Martin Gutkowski
-------------
Very part time DeLoreaner...
Posts: 1,068
1) Trend: If lower voltage ignition jumping smaller plug gaps performed better than higher voltage ignition jumping larger plug gaps, manufacturers would have gone back to them. They didn't. Manufacturers went to ever higher voltages and ever larger plug gaps. It is common now to see COP voltages as high as 100,000 volts and plug gaps as large as .08".
2) PRV specific: Renault itself jetisoned Bosch ignition, and the small plug gaps it can support, and went to higher voltage ignition and larger plug gaps on the 3.0 redesign.
Is it possible Martin had problems with his high winding coil simply because he wired the poor thing up backwards? For some reason that seems to be an endemic mistake among DeLorean owners. As I've said all along, if you want HEI performance, you need a complete HEI setup, including correct polarity in/out of the coil.
Bill Robertson
#5939
Location: DeLorean Cars, UK
Posts: 593
The optimum plug gap depends on a whole heap of variables. Wider gaps with higher voltages are not simply "better". There are modern cars with 0.7mm gaps just like there're older cars with larger gaps.
No they didn't. To say Renault "jetisoned" Bosch on their inability to support larger plug gaps is frankly laughable.2) PRV specific: Renault itself jetisoned Bosch ignition, and the small plug gaps it can support, and went to higher voltage ignition and larger plug gaps on the 3.0 redesign.
The switch from Bosch to Renix was more to do with politics and Renault's deal with Bendix as they moved towards EFI.
All the PRV cross-ref plugs I can find are gapped at 0.6-0.7mm, same as DeLorean. (Renault 25 V6, Safrane V6, Espace V6, Laguna V6, Alpine A610 (turbo), Alpine GTA V6 turbo - all pre-1995. Feel free to look 'em up yourself).
Martin Gutkowski
-------------
Very part time DeLoreaner...
Posts: 1,068
UnderlinedForMartin2.jpg
EaglePremierPlugGap.jpg
Bill Robertson
#5939
Last edited by content22207; 09-11-2011 at 02:00 PM.
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