Outer Limits 4x4 Board

david123 wrote: Lets say that your average engine brand new, produces 70% of its capable power, this is from the manufacture not using the very best possible.

Now up the anti some, add a good exhaust, a bigger better carby, so she gets rid of the crap far better, and drinks the juice far faster, and in theory we have upped the power to a possible 90% of the unopened new power, but, we have a stock ignition system, trying to handle 20% more power than it was designed for.

Power gains, yes you have upped the power, but not by much because the whole thing is held back by a less than adequate ignition system.

Now add a hot spark, one that is more than capable, instant uptake in power.

I know what your trying to say and this I find plausible. The overall upgrade package works together to provide gains. I think carburation has more than anything to do with it. Basically doing the other mods without the ignition system will create too rich a mixture for the existing spark system, hence wasted fuel (running too rich). The upgraded system may allow for burning of the extra fuel, but only up to the stoichiometric ratio, after this it (extra spark energy) would definitly be a waste of time.

However I imagine that doing this may very well increase performance gains, but must be detrimental to fuel efficiency as you are simply burning more fuel.


Mightmouse, thanks for the bit on why mutli-sparks were developed, that makes sense.

know on my Crane CDI unit the multi spark is onl from idle to 3000rpm then it creates one big fat spark and it seams that this is where the most gains ae in the higher RPM.

Abit of a grave dig but I've just fitted a MSD 6470 offroad with the msd SS coil that I got cheap off ebay. I've only just fitted it today so haven't tried it out properly yet but it does make cold starts alot easier and I didn't even need the choke on to drive when cold. My carby isn't the best at the moment so I dunno if I'll get any extra ponies out of it but the if the cold starts stay as good as this it's a worth while mod!

Yes that's a very likely benifit of any multispark setup - which by the way is not unusual from the factory now days.

In reality there isn't time for multiple sparks at higher RPM so it really is a low RPM thing.

A good article on multispark systems can be found at http://www.dtec.net.au/Tech%20Articles.htm

As a side issue spark plug electrode geometry also can make a surprising difference to engine performance and bottom end - some engines and plug electrode geometries just don't get along.

That article is pretty informative thanks mightymouse. Do you know if zooks can benefit from anything other than the standard spark plug? I've just got the standard NGK ones. I did try an apparently old trick where the electrode is cut in half so the spark isn't being shielded by the electrode, but I didn't get any benefits that I could notice.

try going 1 heat range colder, indexing plugs always helps and the right size plug gap is a must.

Glad you liked it Kitika - a lot of experience went into its creation.

I'm not in a position to advise on plugs for zook engines - I know just what's required to determine suitability but past that......

What I CAN say is that the long life platinum and platinum/iridium plugs will pay for themselves over time due to the lack of need to replace and the more consistent performance caused by lack of plug "wear".

Yep grave dug it again How long will a Stock standard 1.3L coil stand up to being fired through an MSD? Also by the 2nd or 3rd spark will the power from the stock coil be very weak because the coil can't build up power fast enough?

That's actually a very complex question..... and very dependend on the actual operating conditions of the motor.

How long will it last - depends on the energy being dumped into it by the MSD and the coils thermal perfomance - you can measure the energy dump - theres another article on the DTec web site on just that, but as you don't know the original coils thermal characteristics its not going to be very helpfull overall.

Matching coil to ignition is absolutley critical to achieving optimum output without damaging the coil by thermal overload.

As per the second bit.......

i'd suggest using an engine analyser to view the primary waveform - it will give you the ability to view the secondary and tertiary spark intervals and waveform.

From that you'll see if its really worthwhile. If you like you can measure the time delay till the second spark, convert it to degrees of engine rotation and decide if its happening at a point in the operating cycle where its usefull.

THe easist solution would be to run a coil suggested by MSD - or trash the whole lots and do the BOSCH conversion as described on the DTec web site. That way you KNOW that you are getting the best bang for your buck.