Does Size Matter?

[Lextreme II]

No! not that. I notice the 2uzfe Tundra COP is about half of the size as the VVTi 1UZFE from the SC400. I wonder does it make any difference from exterior physical size and spark rating.

 

[cjsupra90]

The size can cause a change in spart output if it caused for a substantual change in coil winding... Primary to secondary coil winding ratio and the input voltage are what mainly dictate spark output... If size drastically changes this ratio, then it could have an effect.. a good example would be the CBR pencil coils that Im using.. Thier spark output is so week if used in an inductive system that you have to run them with CDI...

SIDE NOTE:
One thing that a lot of people dont seem to understand with coils and spark output (voltage) is that regardless of what the coil can produce, it only produces what is needed to jump the plug gap... If you go out and buy 50,000 volt coils, this does not mean that you are going to get 50,000 volts at the spark gap. Cylinder pressures have probably the largest effect on requiered voltage for spark jump at the gap... If it is only requiering lets say 24,000 volts to be able to jump the gap, then that is all you your gonna get from your 50,000 volt coil.. This mainly applies with inductive type setups... CDI setups will run at full voltage output all the time because of how it works compaired to inductive type systems. Its all in the system operating principles..

 

[Lextreme II]

Thanks for the detail explaination. So how do we test between the two COP?

 

[cjsupra90]

Im not fully understanding what exactly your asking or what your wanting to test......

the only easy way to tell what kind of differance is to either find out what the coil winding count is for each and or fire them in a real world situation. By this, I mean build a plexiglass chamber that can withstand the pressures and simulate the cylinder pressure and fire a plug with a coil in question and see how the spark output is there are test equipment out there that can monitor the spark voltage but would probably prove to be cost prohibited.. visual check should be enough thought if there is a significant differance and that in itself would be enough to determine if the coil will work for your needs as long as the simulation was accurate enough....

or you could be like John (cribbJ) and just buy a bunch of coils and try them on the engine and see if you notice a differance (best to do it on a dyno though and keep all over veriables at a constant <---- Important part be constant) :wink:

 

[KDog]

Measuring the turns ratio of the coils is quite easy to do. Any electronics tech should be able to do it for you.

Coils used in an inductive system produce more heat then those used in CDI, it is another factor you need to be aware of. In an inductive system COPs tend to be small because they are designed for lower charging times (usually just under 2 millseconds) Vs the 3ms-6ms which a normal external mounted coil endures (although they tend to fire more then one cylinder as well which increases there power requirements).

Size is not necessarily an indicator of power handling ability. There are different construction techniques and material usage which can make a coil more/less efficient.