Capacitive Discharge Ignition, Any benifits to using the MSD system? |
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Capacitive Discharge Ignition, Any benifits to using the MSD system? |
Driver174 |
Jul 30 2018, 08:33 PM
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#1
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Member Group: Members Posts: 106 Joined: 2-February 17 From: Nevada Member No.: 20,806 Region Association: None |
914-4 2L race engine, 10.3:1 compression ratio and twin Weber's
Anyone have experience with the MSD systems on a Type IV? I'm thinking there may be benifits to having the higher spark voltages when compression ratio is relatively high. MSD claims plug gaps of .050 - .060" are possible, and that multiple sparks at lower RPM's improve throttle response. Thus, makes sense, but does anyone have real world experience that support these claims? |
McMark |
Aug 1 2018, 10:38 AM
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#2
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Mark, my thoughts center around the idea that there is a certain amount of 'spark' that is sufficient to ignite the mixture. Any upgrade in potential (CDI or MSD, etc) is essentially wasted after that. If 12,000 volts reliably ignites the mixture, adding 30,000 volts won't ignite it any better.
The Type 4, even at higher compression, seems to ignite pretty easily. I can't begin to approximate why because I don't know enough of the science. Perhaps the 911 found success with the CDI because of the hemispherical combustion chamber. Perhaps Porsche simply opted to install it because it was 'safer' technology. Or perhaps it was more along the lines of trickling down from race success. Also 911 engines turn much higher RPM than typical Type 4. The Type 4's basically flat top pistons and wedge-style combustion chamber may be much easier to ignite, and our redline is relatively low. Len? You still reading this? What're your thoughts on combustion chamber shape, piston dome, and how difficult those different factors are to ignite? Also, Len, what's your redline on that engine? |
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