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911 CDI+ (3 Pin)

Categories: CDI+ Ignition
911 CDI+ (3 Pin)

Classic Retrofit's revolutionary CDI+ units, proven to deliver power improvements right across the rev range, have become an integral part of the upgrade process amongst 911 engine builders and Porsche aficionados. 

One of the shortfalls of the Bosch CDI is that it has no internal voltage regulation. The coil voltage decreases both with battery (alternator) voltage and also with RPM. 

We overcame this issue in the game-changing Classic Retrofit CDI+ ignition unit by employing a regulated power supply that offers a constant voltage to the coil under all RPM conditions and with battery voltages as low as 8 volts. This means you get the same spark energy under all conditions.

In fact, you get twice the spark energy of a Bosch CDI as our CDI+ units produce two sparks back-to-back, typically at 400us intervals, although it can be adjusted right down as far as the coil will allow: around 200us. This is a significant factor behind the instant 'butt dyno' improvements reported by all of our customers.

The Classic Retrofit CDI+ unit requires no modifications to the original wiring loom harness or metalwork and is 'plug and play'. Our cast aluminium casing sits perfectly in your engine bay for an entirely appearance. All Porsche 911 CDI+ units have a 48 MHz microprocessor onboard to control ignition timing.  Our electronics module can also be retrofitted into an original case by special request (see accessories).

Internal Circuitry Comparison

Inside the Classic Retrofit CDI+ unit with cutting edge electronics:

Classic Retrofit CDI+

Inside an original Bosch CDI unit - electronics from the 1960s:

Bosch CDI Porsche 911

CDI Comparison Video

Here's a video we made of a Bosch CDI and a Classic Retrofit CDI+ under the same test conditions, demonstrating the consistent ignition control that all of our CDI+ owners enjoy. There are many other benefits come with our modern technology, but this is a very visible improvement that is easily felt when driving a classic 911 or any other classic car fitted with our technology. 

We are constantly developing the CDI+ firmware and continue to support the global community that has invested in our UK-built ignition units and all of our other products. Contact us with any questions!


AVAILABILITY - Shipping in 1 - 2 Weeks.

The CDI+ 3 Pin is our direct replacement for Bosch CDI units used in the classic Porsche 911 from 1969 to 1977. Extensive development and rigorous dyno testing has proven our CDI+ unit to be a major improvement over the original Bosch CDI unit, with improved torque right across the rev range.

We have now supplied more than 250 CDI+ units to very happy customers all over the world. We support our units with a lifetime warranty: subject to zero electrical abuse! Check out the online Porsche communities for the many great reviews of our products - they are far superior to the cheaply made and overpriced unreliable alternatives available elsewhere.

CDI ignition was originally fitted to a great many European sports cars of the 1970s and 1980s, including Maserati Ghibli, Alfa Romeo Montreal and are popular with BMW 3.0 CSL racers. Our CDI+ is a great upgrade for all of these applications.


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(See type specs below)

Type Specification

The road unit is a plug and play replacement for the Original Bosch CDI. It is pre-set at the factory (to your specification) and has the following features:

  • Hard RPM limiter
  • Soft RPM limiter
  • Launch RPM limiter
  • Adaptive multi spark at low RPM
  • Dual spark at high RPM
  • Shift Light output
  • Clutch pedal input
  • Tacho calibration

The following parameters can be adjusted using the hidden 'jog wheel'.

  • Hard RPM limiter.
  • Soft RPM limiter.
  • Shift light RPM.
  • Tacho calibration.

The unit comes with a laptop cable which allows adjustment of the following:

  • Ignition advance curve.
  • Soft limiter retard.
  • Hard limiter cut scheme.
  • Max RPM tell tale
  • Engine run time
  • MFI fuel pump cutoff RPM min/max.
  • Multi spark interval.
  • Launch control RPM limit.
  • Firmware updates

The unit works with the existing distributor without modification and can use the weights and springs for the advance curve. It can also be programmed with a custom ignition timing 'map' by connecting a laptop (cable supplied). The ignition map can either work with a locked distributor or by 'overlaying' advance on top of the standard distributor mechanical advance.

The race unit has the same features as the standard unit but incorporates a waterproof programming cable that can be mounted in the car. This allows easier access for frequent tuning/adjustment