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running coil on plugs in "wasted spark mode"
NS Dev - 14/4/11 at 08:48 AM

Using another trusty old MBE 956 ecu on a vauxhall XE, would like to use coil on plugs for neatness, can I just fire them in pairs off the wasted spark setup, using the internal amps in the ecu? My concern is overloading the amps, but I don't know if two small pencil coils will be any more demanding than 1 bigger coil in the normal coil pack......any ideas?

lsdweb - 14/4/11 at 09:15 AM

Are the coils designed to run as wasted spark? i.e. are they able to 'recover' quickly as they may be firing twice as often as 'normal'.

I ask because we always had suspicions that my coils on the R1 were struggling at high revs as I was running wasted spark off the Emerlad ECU - in the end I sent the ECU off to Emerald for an upgrade. That was over two years ago and I've not had it back yet....!

Wyn

NS Dev - 14/4/11 at 09:23 AM

hmmmm, I suspect that I may be opening a coil shaped can of worms!!

Am waiting to spk to Steve Broughton as apparently he's done one like this on an XE, but one of the other guys at SBD said that is does depend on the type of stick coil used!

I will only be using 8000rpm though

[Edited on 14/4/11 by NS Dev]

lsdweb - 14/4/11 at 09:33 AM

I'm no expert! But it is something I'd be concerned about and a really tricky one to deal with - my coils were getting really hot - I never had trouble on the track but on the rollers it may have been a problem....


quote:

I will only be using 8000rpm though
Only :-) I guess if the coils are only designed for sequential, then firing them twice as often at 8000 rpm may not be good!


Steve Broughton is your man!

Regards

Wyn

britishtrident - 14/4/11 at 09:39 AM

You can get plug top coils that fire 2 cylinders ---- the 2nd cylinder connected via a short plug lead, not as neat as 1 coil per cylinder.
Or you could use 2 double ended coils as used on a lot of motor cycles and the Rover MG TF VVC which had them mounted on the bellhousing end of the cylinder head.

britishtrident - 14/4/11 at 09:42 AM

See ebay Item number: 180640698781

matt_gsxr - 14/4/11 at 11:37 AM

why not use COP from a bike engine that revs to 16000rpm, at 8kRPM it won't know any different (some R1 rev to 13750 from memory, which isn't far off).

zilspeed - 14/4/11 at 11:41 AM

quote:
Originally posted by lsdweb
Are the coils designed to run as wasted spark? i.e. are they able to 'recover' quickly as they may be firing twice as often as 'normal'.



Wyn



That's something I read about very recently.
The recovery time of the COP is incompatible with wasted spark due to the very nature of it firing twice as much as is actually required.