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? |
HAM Inc |
Aug 1 2018, 03:04 PM
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#2
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Senior Member Group: Members Posts: 846 Joined: 24-July 06 From: Watkinsville,GA Member No.: 6,499 Region Association: None |
We all know the hemi chamber with dome pistons is a bitch for flame propagation, no doubt about that. I can definitely see the CDI helping in that design.
Our shift point was around 7800, but at Roebling Road I did stretch 3rd to 8100 or so. One of the things that puzzles me about the multiple spark discharge concept when using a distributor is, how broad a crank angle can the rotor distribute spark in a given firing cycle. Without a special rotor, I don't think it could be as many as 20 crank degrees, which IRRC is what MSD advertised. |
Mark Henry |
Aug 1 2018, 04:04 PM
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#3
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
We all know the hemi chamber with dome pistons is a bitch for flame propagation, no doubt about that. I can definitely see the CDI helping in that design. Our shift point was around 7800, but at Roebling Road I did stretch 3rd to 8100 or so. One of the things that puzzles me about the multiple spark discharge concept when using a distributor is, how broad a crank angle can the rotor distribute spark in a given firing cycle. Without a special rotor, I don't think it could be as many as 20 crank degrees, which IRRC is what MSD advertised. I agree, I was always dubious about jacobs ignition claims, basically it was just a multi spark CDI and at speed there's only time for a few sparks. Evidence points that it likely it does help low speed issues, but once over say 3000rpm it has little, if any, effect. I would think the hotter spark helps with the initial firing, probably more important on the /6 chamber, but little more To me it's much like the sequential and batch firing of injectors arguement. At low rpms where watercooled cars can run it will make a difference in fuel economy, but little effect on car that normally runs at 3000+rpm. Only so much can be achieved at higher piston/rotation speeds. |
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