ausmini :: View topic - dizzy mapping

Hi,before I offer my opinion I will do a disclaimer , so you can decide whether my answer is biased as I make and sell performance ignition systems with long duration spark,
Yes, the correct map for your engine will improve performance. The problems are that most people have no idea of the map they need, and being able to work out which one is correct from the dozens on offer and then precisely determining performance changes , its terribly hard. It may be fun to play, but getting it wrong can be tough on engine life.
Many distributors with mechanical advance will have a curve thats suitable, BUT they do not have a good enough spark to properly burn ULP. This includes many of the expensive distributors, beautifully made but again lacking quality spark. Generally road minis do not have efficient hi temperture combustion chambers , and need a big fat spark at the correct time and the best thing I have seen is a longer duration spark of approx 20 degrees of crankshaft duration.
I see from many posts of what users of adjustable systems set their timing at, there is an extreme reluctance to give them enough base timing, probably based on the 2 or 3 degrees that bmc often used. 10 degrees base timing is not enough. Cheers Lindsay Siebler

Author:	p7676 [ Mon Mar 23, 2020 9:10 pm ]
Post subject:	dizzy mapping
Question , does the mapping improve performance ? Allen

Author:	9YaTaH [ Tue Mar 24, 2020 6:33 am ]
Post subject:	Re: dizzy mapping
Yes!

Author:	drmini in aust [ Tue Mar 24, 2020 6:43 am ]
Post subject:	Re: dizzy mapping
Definitely! For example, the original curve in a Cooper S dizzy is nowhere near correct for 98 unleaded fuel. Even more so if running a sportier cam.

Author:	FNQ [ Tue Mar 24, 2020 8:57 am ]
Post subject:	Re: dizzy mapping
Hi Allen A good map will improve your performance, BUT you need to know what you want first. The black box users, ( megajolt stealth etc) and the programmable users ( CSI and 123) will be able to share the key parts of the curves that work for them. If you are planning to tinker yourself, i would just make sure your dizzy cam isnt too wide ( say 11 or 13 but not 15 dizzy degrees)and know what the vacuum is doing ( if you have one). Just as an example, , , go to the CSI ignition website and nose around in the technical info area. Here are some of their curves http://www.csi-ignition.nl/bestanden/mi ... curves.pdf As an example of the important bits of the curve ---------Below I am now talking about timing light degrees Static 10degrees Rapid rise , so i am at 22degrees at 2000rpm More gradual to be all in ( maximum advance 30degrees) at anywhere above 4000rpm I have a 1310 cc mild road motor ( 260 camshaft) with an early non vacuum CSI dizzy and find curves 11 and 13 work pretty well. I am not worried by maximum advance at 32 because i rarely if ever get up to 6000rpm. IMO a number of these curves ( and those in the 123) are unsuitable mainly because they are too slow to advance. When i change something on that motor ( eg different carbs), i use the curves and an AFR to 'optimise' - but apart from that i use one curve.... you only need one , but it needs to be the right one

Author:	lomin [ Tue Mar 24, 2020 8:00 pm ]
Post subject:	Re: dizzy mapping
Hi,before I offer my opinion I will do a disclaimer , so you can decide whether my answer is biased as I make and sell performance ignition systems with long duration spark, Yes, the correct map for your engine will improve performance. The problems are that most people have no idea of the map they need, and being able to work out which one is correct from the dozens on offer and then precisely determining performance changes , its terribly hard. It may be fun to play, but getting it wrong can be tough on engine life. Many distributors with mechanical advance will have a curve thats suitable, BUT they do not have a good enough spark to properly burn ULP. This includes many of the expensive distributors, beautifully made but again lacking quality spark. Generally road minis do not have efficient hi temperture combustion chambers , and need a big fat spark at the correct time and the best thing I have seen is a longer duration spark of approx 20 degrees of crankshaft duration. I see from many posts of what users of adjustable systems set their timing at, there is an extreme reluctance to give them enough base timing, probably based on the 2 or 3 degrees that bmc often used. 10 degrees base timing is not enough. Cheers Lindsay Siebler

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dizzy mapping https://ausmini.com/forums/viewtopic.php?f=2&t=99780	Page 1 of 1

Author:	9YaTaH [ Wed Mar 25, 2020 8:34 am ]
Post subject:	Re: dizzy mapping
lomin wrote: Hi,before I offer my opinion I will do a disclaimer , so you can decide whether my answer is biased as I make and sell performance ignition systems with long duration spark, Yes, the correct map for your engine will improve performance. The problems are that most people have no idea of the map they need, and being able to work out which one is correct from the dozens on offer and then precisely determining performance changes , its terribly hard. It may be fun to play, but getting it wrong can be tough on engine life. Many distributors with mechanical advance will have a curve thats suitable, BUT they do not have a good enough spark to properly burn ULP. This includes many of the expensive distributors, beautifully made but again lacking quality spark. Generally road minis do not have efficient hi temperture combustion chambers , and need a big fat spark at the correct time and the best thing I have seen is a longer duration spark of approx 20 degrees of crankshaft duration. I see from many posts of what users of adjustable systems set their timing at, there is an extreme reluctance to give them enough base timing, probably based on the 2 or 3 degrees that bmc often used. 10 degrees base timing is not enough. Cheers Lindsay Siebler Nailed it!

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