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M&W CDI vs Vipec CDI


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I am having a tough time deciding between M&W and Vipec CDI. The main reason is because I am running an old car which uses a distributor system. I only have 1 coil instead of 4.

The issue is the Vipec CDI is intended for 4 sets of coil while I can go for a M&W Pro 10 which is meant for 1 coil. Of course, the Pro10 is cheaper than the Vipec as well (expected since pro10 caters to just 1 coil).

Thus, I don't know if I should invest in the Vipec or the M&W. With the Vipec, I will not be utilising the other 3 outputs at all (its like paying for the features but not utilizing it). With the Pro10 I will get what I paid for but I am afraid of any incompatible issues that might arise (I will be asking my vendor to install for me of course).

Another issue I am concerned with is the compatibility with the coil. I have a brand new Mallory 28880 which is a high current CDI coil. Thus there is a danger than some CDI may not be able to provide enough power to the coil (Mallory specifically mentioned that this coil is for their Hyfire 7 series only, 6 series cannot use). I did ask M&W and they assured me that Pro10 will drive the coil w/o any problems. Will the Vipec drive the coil?

Btw, I am just thinking of this (just a wild idea). What if I combined all the outputs of the Vipec CDI into 1? Feed the ignition 1 of the Vipec into all out inputs of the CDI, enabling the CDI to fire at 4 outputs at once and then join them together and feed into 1 coil. Will I will get 4x the current output (voltage remains the same and boost power? To prevent any reverse flow of the current, I will install a high capacity diode (1200V 100A rated diode) at each output. This way, I can fully utilise the Vipec CDI.

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The XPS-4 CDI is a four channel twin capacitor CDI. While you can use just on channel, it is a bit of a waste of money. The M&W PRO 10 single channel is more suitable. I am very sure it would drive the Mallory coil.

If you are going to run less then 30 PSI then you do not need a CDI. Just use the GM LS1 coil. It has an internal igniter.

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OK, my main aim of running CDI is trying to get a bigger spark gap. I do enjoy the extra low RPM power I get with a bigger gap. However, this limits my boost and I will get misfiring at high RPM. Hence, I am trying to use CDI to resolve the misfiring issue. Of course, I could reduce back the gap but the car does not feel that good at low RPM with a smaller gap.

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Inductive ignitions have a much longer spark burn then CDI ignitions. CDI have a very short powerful spark. While this may light the fuel/air mix at very high boost, it has big problems lighting lean mixtures at cruise. This is why some CDI multi spark.

A CDI that multi sparks often only gives two sparks and only under 3500 rpm. An inductive ignition give one very long spark which is longer then a multi spark CDI.

The difference can be noticed when tuning at light load. With a inductive ignition you can make the engine run much leaner. Also better exhaust emissions. This is why all OEM use inductive.

Ray.

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