MSD box Instead of the CDI??
11-13-2004, 01:44 PM
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MSD box Instead of the CDI??
Has anyone swapped-out their CDI box and replaced it with MSD?? I see two immediate benefits. Multiple spark for single plug set-ups in performance engines. Then adjustable RPM limiter.
11-13-2004, 01:55 PM
#2
RL Technical Advisor
Todd:
LOL,..I've been doing this one for 30 years. Its a no-brainer on carbureted & MFI-equipped engines and of course, race motors.
A few points:
1) One must use the matching MSD coils. Impedance is critical to proper ignition performance. Bosch & other coils degrade MSD performance and in many cases, cost HP.
2) Proper installation is VERY important. MSD ignitions draw more current than other ignitions and the quality of the power feeds and grounding cannot overstressed. The vast majority of failures are due to poor grounding and power connections.
LOL,..I've been doing this one for 30 years. Its a no-brainer on carbureted & MFI-equipped engines and of course, race motors.
A few points:
1) One must use the matching MSD coils. Impedance is critical to proper ignition performance. Bosch & other coils degrade MSD performance and in many cases, cost HP.
2) Proper installation is VERY important. MSD ignitions draw more current than other ignitions and the quality of the power feeds and grounding cannot overstressed. The vast majority of failures are due to poor grounding and power connections.
11-13-2004, 03:28 PM
#4
Steve - Do you think there is an advantage to the MSD over a properly working stock Bosch box? If so, do you think it is the multiple sparks (which are at rel. low rpms only)?
11-13-2004, 04:43 PM
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I've used MSD boxes on other apps and they have multiple spark all the time regardless of RPM. I see on most of the installs you can pull the total timing back 2-3 degrees because the burn is more efficient.
11-13-2004, 07:26 PM
#7
RL Technical Advisor
Originally Posted by randywebb
Steve - Do you think there is an advantage to the MSD over a properly working stock Bosch box? If so, do you think it is the multiple sparks (which are at rel. low rpms only)?
There are clear differences in performance and drivabilty with MSD's. The advantages are huge with any engine that tends to run richer or leaner in certain RPM ranges where the OEM Bosch systems cannot cleanly fire off an imperfect A/F.
These were a godsend with cars like our 3.5 litre slide-valve RSR's, 935's and even the old 917/10 that we used to run for a client. The Bosch igntions could never prevent plug fouling with any idling and adding a pair of MSD's made them run like CIS engines,...
One thing too,......MSD's permit the wide plug gaps that not only improve idle qualities, but make more HP on the dyno.
Ya can't do that with any Porsche OEM ignitions and the dyno doesn't lie,...
Its the combination of low speed multi-sparking that fires rich mixtures efficiently and the much higher voltage & current that does the job.
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11-14-2004, 06:44 AM
#8
There's no REAL benefit to the multiple spark feature of the MSD unit.
Facts:
1. If there were a benefit all the OEM car manufactures would have bought/used the technology
in a nanosecond. Furthermore, no OEM uses a CDI system. Present design technology
can achieve the desired spark using inductive discharge.
2. By the time the second spark occurs, there's no more charge to burn and the piston has
moved too far down the cylinder to have an effect.
3. The min spark requirements, which the Bosch CDI provides, are;
a. 60-100 millijoules of energy
b. 100-200 microsecond pulse
c. 30-40KV
4. The complex circuitry of the MSD results in much less reliability than the Bosch unit.
5. The additional number of sparks and much higher voltage of the MSD results in additional
ignition stress causing reduced cap & rotor life and wire breakdown.
6. Porsche uses a twin plug system (964/993) versus a multiple spark system
to achieve an improved combustion process that the MSD can't.
7. The MSD unit draws a large amount of current (direct connect to battery),
and as such generates "noise" which can affect other electronics, e.g. the alternator voltage regulator.
A CDI ignition coil does not require impedence matching. A CDI ignition coil is an ignition coil is
an igntion coil. It's basically just a pulse transformer. The only variable is the turns ratio which
determines the final spark voltage. The coil type does become critical in an inductive discharge system.
Check out this web site (www.systemsc.com) on the Technical page under Ignition Systems for
more info.
Bottomline: The MSD multiple spark system is another marketing tool to differentiate
a product with a unique feature. There's no data to backup its' cliams.
Save your money and buy a carbon fiber shift ****. The car will feel like it's going faster.
Note: Above 3000-4000 RPMs, the MSD produces just one spark per cylinder firing.
Facts:
1. If there were a benefit all the OEM car manufactures would have bought/used the technology
in a nanosecond. Furthermore, no OEM uses a CDI system. Present design technology
can achieve the desired spark using inductive discharge.
2. By the time the second spark occurs, there's no more charge to burn and the piston has
moved too far down the cylinder to have an effect.
3. The min spark requirements, which the Bosch CDI provides, are;
a. 60-100 millijoules of energy
b. 100-200 microsecond pulse
c. 30-40KV
4. The complex circuitry of the MSD results in much less reliability than the Bosch unit.
5. The additional number of sparks and much higher voltage of the MSD results in additional
ignition stress causing reduced cap & rotor life and wire breakdown.
6. Porsche uses a twin plug system (964/993) versus a multiple spark system
to achieve an improved combustion process that the MSD can't.
7. The MSD unit draws a large amount of current (direct connect to battery),
and as such generates "noise" which can affect other electronics, e.g. the alternator voltage regulator.
A CDI ignition coil does not require impedence matching. A CDI ignition coil is an ignition coil is
an igntion coil. It's basically just a pulse transformer. The only variable is the turns ratio which
determines the final spark voltage. The coil type does become critical in an inductive discharge system.
Check out this web site (www.systemsc.com) on the Technical page under Ignition Systems for
more info.
Bottomline: The MSD multiple spark system is another marketing tool to differentiate
a product with a unique feature. There's no data to backup its' cliams.
Save your money and buy a carbon fiber shift ****. The car will feel like it's going faster.
Note: Above 3000-4000 RPMs, the MSD produces just one spark per cylinder firing.
Last edited by Lorenfb; 11-15-2004 at 06:02 AM.
11-14-2004, 07:43 PM
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Wow, I was planning on going to a MSD 6al system this winter, along with magnecor wires. I would also like to eliminate my points and re-curve my dizzy. Short of all that the electromotive system is also an option. Any other opinions??
11-14-2004, 09:11 PM
#10
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Steve Sez:
Loren sez:
Now I am confused! It seems these guys are at opposite ends of the same issue. How do I sort it out? Both their cases seem to make sense but which one is the "answer"?
sign me
There are clear differences in performance and drivabilty with MSD's. The advantages are huge with any engine that tends to run richer or leaner in certain RPM ranges where the OEM Bosch systems cannot cleanly fire off an imperfect A/F.
These were a godsend with cars like our 3.5 litre slide-valve RSR's, 935's and even the old 917/10 that we used to run for a client. The Bosch igntions could never prevent plug fouling with any idling and adding a pair of MSD's made them run like CIS engines,...
One thing too,......MSD's permit the wide plug gaps that not only improve idle qualities, but make more HP on the dyno.
Ya can't do that with any Porsche OEM ignitions and the dyno doesn't lie,...
Its the combination of low speed multi-sparking that fires rich mixtures efficiently and the much higher voltage & current that does the job.
These were a godsend with cars like our 3.5 litre slide-valve RSR's, 935's and even the old 917/10 that we used to run for a client. The Bosch igntions could never prevent plug fouling with any idling and adding a pair of MSD's made them run like CIS engines,...
One thing too,......MSD's permit the wide plug gaps that not only improve idle qualities, but make more HP on the dyno.
Ya can't do that with any Porsche OEM ignitions and the dyno doesn't lie,...
Its the combination of low speed multi-sparking that fires rich mixtures efficiently and the much higher voltage & current that does the job.
There's no REAL benefit to the multiple spark feature of the MSD unit.
Facts
1. If there were a benefit all the OEM car manufactures would have bought/used the technology
in a nanosecond. Furthermore, no OEM uses a CDI system. Present design technology
can achieve the desired spark using inductive discharge.
2. By the time the second spark occurs, there's no more charge to burn and the piston has
moved too far down the cylinder to have an effect.
3. The min spark requirements, which the Bosch CDI provides, are;
a. 60-100 millijoules of energy
b. 100-200 microsecond pulse
c. 30-40KV
4. The complex circuitry of the MSD results in much less reliability than the Bosch unit.
5. The additional number of sparks and much higher voltage of the MSD results in additional
ignition stress causing reduced cap & rotor life and wire breakdown.
6. Porsche uses a twin plug system (964/993) versus a multiple spark system
to achieve an improved combustion process that the MSD can't.
A CDI ignition coil does not require impedence matching. A CDI ignition coil is an ignition coil is
an igntion coil. It's basically just a pulse transformer. The only variable is the turns ratio which
determines the final spark voltage. The coil type does become critical in an inductive discharge system.
Check out this web site (www.systemsc.com) on the Technical page under Ignition Systems for
more info.
Bottomline: The MSD multiple spark system is another marketing tool to differentiate
a product with a unique feature. There's no data to backup its' cliams.
Save your money and buy a carbon fiber shift ****. The car will feel like it's going faster.
Note: Above 3000-4000 RPMs, the MSD produces just one spark per cylinder firing.
Facts
1. If there were a benefit all the OEM car manufactures would have bought/used the technology
in a nanosecond. Furthermore, no OEM uses a CDI system. Present design technology
can achieve the desired spark using inductive discharge.
2. By the time the second spark occurs, there's no more charge to burn and the piston has
moved too far down the cylinder to have an effect.
3. The min spark requirements, which the Bosch CDI provides, are;
a. 60-100 millijoules of energy
b. 100-200 microsecond pulse
c. 30-40KV
4. The complex circuitry of the MSD results in much less reliability than the Bosch unit.
5. The additional number of sparks and much higher voltage of the MSD results in additional
ignition stress causing reduced cap & rotor life and wire breakdown.
6. Porsche uses a twin plug system (964/993) versus a multiple spark system
to achieve an improved combustion process that the MSD can't.
A CDI ignition coil does not require impedence matching. A CDI ignition coil is an ignition coil is
an igntion coil. It's basically just a pulse transformer. The only variable is the turns ratio which
determines the final spark voltage. The coil type does become critical in an inductive discharge system.
Check out this web site (www.systemsc.com) on the Technical page under Ignition Systems for
more info.
Bottomline: The MSD multiple spark system is another marketing tool to differentiate
a product with a unique feature. There's no data to backup its' cliams.
Save your money and buy a carbon fiber shift ****. The car will feel like it's going faster.
Note: Above 3000-4000 RPMs, the MSD produces just one spark per cylinder firing.
sign me
11-14-2004, 09:15 PM
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I'm a big fan of MSD for over 30yrs.
Try keeping an off-shore racer's plugs clean on any other ignition besides MSD and your fouling before the inlet.
The book says multiple sparks below 3k rpm.
It may draw 10amps+ at times so very clean connections and big wires to hot and cold are imp imo.
I just installed a Pertronix in the dizzy terminating to a connector block on the rear elec panel. Back-up Pertronix and points are pre-wired in length for a wham bam R&R.
fwiw, I've also installed the MSD on very worn engines and the difference in starting,idleing, and operation is very noticable. I'm not a pro.
Try keeping an off-shore racer's plugs clean on any other ignition besides MSD and your fouling before the inlet.
The book says multiple sparks below 3k rpm.
It may draw 10amps+ at times so very clean connections and big wires to hot and cold are imp imo.
I just installed a Pertronix in the dizzy terminating to a connector block on the rear elec panel. Back-up Pertronix and points are pre-wired in length for a wham bam R&R.
fwiw, I've also installed the MSD on very worn engines and the difference in starting,idleing, and operation is very noticable. I'm not a pro.
11-14-2004, 09:44 PM
#12
RL Technical Advisor
Loren:
I've learned from experience reading this and the Pelican forum that you do not have an open mind.
I'm not going to reply to your post as its, IMHO a waste of time. I'll just mention for the benefit of others who might read this that I've been racing RSR's and 935's for many years (as well as others) and our engine dyno doesn't lie.
You are clearly a very bright fellow who could REALLY learn a lot from others who have different experiences from you, IF you kept an open mind,....
The scientific method suggests that everyone in those disciplines always learn something new, every day.
Have fun,
I've learned from experience reading this and the Pelican forum that you do not have an open mind.
I'm not going to reply to your post as its, IMHO a waste of time. I'll just mention for the benefit of others who might read this that I've been racing RSR's and 935's for many years (as well as others) and our engine dyno doesn't lie.
You are clearly a very bright fellow who could REALLY learn a lot from others who have different experiences from you, IF you kept an open mind,....
The scientific method suggests that everyone in those disciplines always learn something new, every day.
Have fun,
11-14-2004, 09:51 PM
#13
Rennlist Member
Steve, what do you think of Mallory's equivalents to the MSD boxes? Mallory does make an awesome unilite distributor for the type 1/4 / porsche 914 (can be fitted to a 12v 356/912) that is fully adjustable and I was wondering if their ignition boxes were up to par.
11-14-2004, 11:26 PM
#15
"The advantages are huge with any engine that tends to run richer or leaner in certain RPM ranges where the OEM Bosch systems cannot cleanly fire off an imperfect A/F."
- Steve -
Totally ridiculuous! That's why the Porsche factory uses the MSD in all their race cars, NOT.
Address the 6 facts I've presented. All I hear is; "It seems to run better.".
"I've learned from experience reading this and the Pelican forum that you do not have an open mind."
- Steve -
I've got an open mind to realistic facts and data.
To fire fouled spark plugs, it's a function of the voltage rise time. To fire most completely
the cylinder's charge requires a min energy level. Both of which the Bosch unit has.
Bottomline: Do a little technical reading about ignition systems and present some facts.
- Steve -
Totally ridiculuous! That's why the Porsche factory uses the MSD in all their race cars, NOT.
Address the 6 facts I've presented. All I hear is; "It seems to run better.".
"I've learned from experience reading this and the Pelican forum that you do not have an open mind."
- Steve -
I've got an open mind to realistic facts and data.
To fire fouled spark plugs, it's a function of the voltage rise time. To fire most completely
the cylinder's charge requires a min energy level. Both of which the Bosch unit has.
Bottomline: Do a little technical reading about ignition systems and present some facts.