Originally Posted by full_garage (Post 6737580)

Not even close...Steve W is enemy #1

Originally Posted by Lorenfb (Post 6737489)

"If you DID want to make more power you could increase the compression ratio to, say, 10,3 to 1, and then use twin plugs to prevent the detonation that would otherwise result."

As many of us know,
a more advance timing always yields more torque, i.e. up to the point of detonation.
.

Originally Posted by Lorenfb;6736602The purpose of the thread was to present the results of a comparative evaluation of the MSD ignition unit versus the Bosch ignition unit. The intention was not meant to be super robust, but just evaluate both from some key factors of an ignition system.

The results basically concluded that the MSD ignition provides no real benefit over
the Bosch ignition and in some cases my be less desirable,

[B

i dont think i have ever read that anyone claims any major benefits of the MSD, although i stated, several."
1. a more direct power connection to the battery instead of old wiring running through a switch.

2. a direct ground from the coil back to the MSD unit.

3. the components are not old and been exposed to heat for 30 years.

4. more components does not make it worse. the permatune has far less than both of these, does that make it the best.

5. porsche saw the need to put out 350kv, what proof do you have that 450kv is not better? the higher voltage has a better chance of firing a fouled plug, no?
[/B]


it's the responsibility of MSD to prove such and provide the appropriate data to support the claims if there are any.

you say the bosch is better. where are your claims? where is your test data? i talked to MSD, they said to test the 2 units and do a plug comparison. i say do that and do an exhaust gas analysis and post the data.
you have said the pulse width is narrower with the MSD. where is the proof that this matters? once the fuel is ignited, does a few microseconds wider of a pulse make any difference? where is the proof?.

Originally Posted by sc_rufctr (Post 6739488)

This thread reminds me of the threads on audio sites arguing about which turntable is the best. :rolleyes:

Just get out a drive your 911s...

Originally Posted by mercury26 (Post 6739605)

The best turntable is Technic SL-1200 MkII. The gold standard. :)

Originally Posted by Lorenfb (Post 6739767)

"1. a more direct power connection to the battery instead of old wiring running through a switch."

This is a requirement for the MSD since it has 2X the peak current needs of the
Bosch unit. The low current requirement of the Bosch unit versus the MSD's
doesn't present a problem for the ignition switch.

Where are you getting the idea that the MSD has 2X the current requirement? The 8 firings at low RPMs doesn't require any more peak current than does the OEM at max RPM.

"2. a direct ground from the coil back to the MSD unit."

At 300-450 volts and the few milliamps of current flow even a somewhat poor ground return would more than suffice. Unless you're mounting the unit under one of the front seats....

Most 911 Bosch factory installations have 2 grounds.

"3. the components are not old and been exposed to heat for 30 years."

Not a real issue for many, especially since the Bosch unit doesn't use electrolytic
capacitors, like the MSD, which have high failure rates with high temps found
in the engine compartment. So if one is concerned about heat problems, the MSD
is a poor choice.

1.) The reason I sent the OEM CDI from my '78 to you was because it worked fine until it warmed up, or for 5-10 minutes after I sprayed it with freeze mist. Obviously something in there had become heat sensitive as a result of the ~200 miles driven, Seattle to McCall, during battery overcharging.

2.) Had the factory engineers used, KNOWN to use, the distributed capacitance design approach that MSD has used, MULTIPLE electrolytic capacitors "sharing" the load/task, it is likely that the OEM CDI would have been more reliable. My guess is that the Bosch engineers were not of the knowledge that their design would be put to use with the battery "SINK", stabilization, so far removed from the locale.

But yes, electrolytics are often the bain of electronics design, usually the first to fail under heat or just long term use.

But on the other hand their use would most definitely protect the downstream electronics from the voltage spikes inherent in the 911 Porsche alternator circuit...REMOTE battery, no local voltage spike SINK.

"4. more components does not make it worse. the permatune has far less than both of these, does that make it the best."

It's a FACT that as the number of components increase in ANY system, the failure
rate also increases. As can be seen by the image of the inside of the MSD unit,
it has over 5X as many components as the Bosch. It uses more power semiconductors
than does the 911 3.2 DME ECM which also controls the fuel.

On the other hand I would wager some serious money that if one did an actual, knowledgeable, MTBF analysis on the old, mostly now obsolete, components in the OEM CDI vs the MSD the MSD would prove to be sunstantially more reliable.

The Perma-Tune is an inappropriate example as it has a design problem unrelated to its
component count.

Design problems, even unforeseen, do not equate to MTBF analysis, separate issue entirely.

"5. porsche saw the need to put out 350kv, what proof do you have that 450kv is not better? the higher voltage has a better chance of firing a fouled plug, no?"

At idle the Bosch unit puts out about 400KV and at high RPMs the voltage is
about 350KV. It's rise time (the time to go from 0 volts to max volts) that determines
the spark's ability to fire a fouled plug. In both the MSD and the Bosch, the rise
time is way under a microsecond. That was the plus in using the CDI system
in the late 60's versus the early transistorized inductive discharge ignition.
The increased MSD voltage has insignificant advantage over the Bosch unit.

Let's assume, just for the moment, that the voltage required at the plug gap to initiate an arc is 23.5KV....

In order to reach that level let's further assume that a coil primary CURRENT of 20 milliamps is required to reach that voltage level on the secondary. There can be NO QUESTION that applying 450 volts to the primary vs 300 volts will overcome the coil primary inductive reactance sooner, result in a substantial increase in voltage risetime at the secondary.

But let's also keep in mind that it is highly likely that other than the above subject the 450 volts used on the primary has no effect on the plug voltage firing level, in our case that remains constant at 23.5KV. The 300 volt application will (eventually) reach the firing voltage just as the 450 volts.

Sidebar: Any energy left within the coil's magnetic field (not, typically, an non-substantial amount) once the arc extinguishes will be "recycled", returned to the discharge capacitor.

Originally Posted by Lorenfb (Post 6739767)

"1. a more direct power connection to the battery instead of old wiring running through a switch."

This is a requirement for the MSD since it has 2X the peak current needs of the
Bosch unit. The low current requirement of the Bosch unit versus the MSD's
doesn't present a problem for the ignition switch.
but the ignition swittch could be a problem for the CD.
have you looked at the MSD schematic? the direct wire to power is a 12AWG that provides power ONLY to the HIGH VOLTAGE part of the MSD. if you can tell me how direct power from the battery to the high voltage section of the MSD is not better than the bosch getting its power through a smaller gauge wire and the ignition switch, i will kiss your ass! i think direct power from the battery is an INCREDIBLE IDEA! the rest of the MSD is powered through the ignition switch and a basic "power supply" inside the MSD, again, a great idea, is there for voltage regulation.
since the MSD needs direct power and a bigger wire for more current, as you claim, and this power source is only used in the high voltage section, then the current, or power out of the MSD must be greater than the bosch, that is better and perhaps the reason for a narrower pulse.


"2. a direct ground from the coil back to the MSD unit."

Most 911 Bosch factory installations have 2 grounds.
i have only seen ground at the boch unit and the neg side of the coil grounded. that leaves a potential the multiple connections to cause problems

"3. the components are not old and been exposed to heat for 30 years."

Not a real issue for many, especially since the Bosch unit doesn't use electrolytic
capacitors, like the MSD, which have high failure rates with high temps found
in the engine compartment. So if one is concerned about heat problems, the MSD
is a poor choice.
where is the proof or the hight failure rate and why do you have a job repairing bosch units along with others on here if the bosch is so relaiable?


"4. more components does not make it worse. the permatune has far less than both of these, does that make it the best."

It's a FACT that as the number of components increase in ANY system, the failure
rate also increases. As can be seen by the image of the inside of the MSD unit,
it has over 5X as many components as the Bosch. It uses more power semiconductors than does the 911 3.2 DME ECM which also controls the fuel.
as an electronic tech, i am usually on the same page, more to break. but unless there is proof that something is bad, i would not put it down based on the number of components, certainly the MSD that has not earned it. this would be one of those opinions i wouod just keep to myself.
if componets are added to add voltage regulation of stability due to heat, i dont think that the number of componts is a bad thing then.

The Perma-Tune is an inappropriate example as it has a design problem unrelated to its component count.

"5. porsche saw the need to put out 350kv, what proof do you have that 450kv is not better? the higher voltage has a better chance of firing a fouled plug, no?"

At idle the Bosch unit puts out about 400KV and at high RPMs the voltage is
about 350KV. It's rise time (the time to go from 0 volts to max volts) that determines
the spark's ability to fire a fouled plug. In both the MSD and the Bosch, the rise
time is way under a microsecond. That was the plus in using the CDI system
in the late 60's versus the early transistorized inductive discharge ignition.
The increased MSD voltage has insignificant advantage over the Bosch unit.
then why did they do it? i called and talked to MSD about it, perhaps you should.

Originally Posted by sc_rufctr (Post 6739488)

This thread reminds me of the threads on audio sites arguing about which turntable is the best. :rolleyes:

...

Originally Posted by quattrorunner (Post 6733422)

But your pictures of the insides make me more happy I use MSD. More modern and seemingly less likely to fault.

Originally Posted by Lorenfb (Post 6736921)

"My statement was based on a twin plug set-up used with one MSD vs two; Read the entire post Loren and respond to the entire post not just one sentence taken out of context."

Ok. Let's try again and the statement is still wrong.

"In a twin plug engine running two coils and one MSD box, effectively cutting the current to the coils in half, a chassis dyno shows a 15 hp loss compared to the same set-up with two MSD boxes driving the coils at full current. There is a correlation between spark voltage and power produced. Mike Bruns has the details and the testing."

1. The total current from the CDI splits but not necessarily equally between the two
coils which depends upon how well matched each coil is. The voltage, though, is the
same across each coil, but the energy transfer is basically half of the initial, again
assuming matched coils. This assumes the coils are in parallel. If in series then
the voltage divides between the coils and mostly likely unequally, and this being
the worst hookup.

2. Again, there is no correlation between voltage (in this case) and power (HP) since
the voltage is the SAME for coils assuming a parallel setup. In any case, connecting
two coils to one CDI is a Mickey Mouse setup whether series or parallel.

Bottom line: So to make a statement about a correlation between spark voltage
and power is totaling incorrect, especially since the thread discusses the abnormally
high voltage of the MSD versus the lower and more normal Bosch spark pulse voltage.

Originally Posted by RWebb (Post 6740120)

Rega?

Originally Posted by mercury26 (Post 6739605)

The best turntable is Technic SL-1200 MkII. The gold standard. :)

Originally Posted by winders (Post 6739647)

The Technics SL-1210M5G with a Dynavector cartridge...

Scott

Originally Posted by RWebb (Post 6740736)

And if it is made in Australia, why do they call it "Cali" burn?