Megajolt worth considering?

Post pics of your car in here
Simon
Posts: 145
Joined: August 1st, 2009, 6:55 pm
Location: Leicester
Contact:

Re: Megajolt worth considering?

Post by Simon »

Here's a pic of the Megajolt components destined for my Spider comprising Ford coil pack and EDIS module (defaults to fixed 10deg BTDC if the Megajolt fails), trigger wheel and trigger sensor, and the actual Megajolt ECU. This was all bought some time ago, so the system may have developed a bit since then.
Megajolt Kit - Coil Pack, EDIS Module, Trigger wheel, Pickup and ECU.
Megajolt Kit - Coil Pack, EDIS Module, Trigger wheel, Pickup and ECU.
_IGP6668.jpg (244.21 KiB) Viewed 5471 times
Regarding the difference between the MSD and an Megajolt, the fundamental difference as far as I can tell (never having used the former, but just going on the spec.), and ignoring the multiple spark trigger strategy, is that the MSD is a capacitive rather than inductive discharge unit. Rather than relying on the collapse of the primary coil circuit, either by mechanical contact points opening or electronically switched by a transistor, to induce a high voltage in the coil secondary, a capacitive system uses an oscillator and transformer to step up the 12v car supply to around 400-500V and charge a capacitor (the size of which determines the ultimate spark energy). When triggered (by contact points or electronically as before) the charged capacitor is discharged across the coil primary thus producing a pulse of several thousand volts at the secondary, and the reason they can potentially 'fry' your tacho if you leave it connected to the primary. The inductive systems tends to give a longer duration but lower energy spark, whilst CD systems produce a shorter duration but higher energy spark. I imagine the multiple spark strategy of the MSD system is to address the limitation of the short duration spark of this type of system. I've built my own versions of both types, mostly with optical triggering from the distributor, and have always felt the CD systems give the crispest starting and response, mostly because they are less affected by a low supply voltage when cranking as you are still putting several hundred volts through the primary. CD systems have actually been around for years; my '70 911 has, an albeit primitive, one as standard. The multi spark system isn't even that new (just the application of microprocessor control in recent years); there used to be an advert in the back of Practical Electronics in the '80's for a kit that fired a 'continuous' spark for the entire period that the points were open. Please note that none of the above is intended to question the performance of, or fully explain the exact details of any of the systems mentioned in this thread (which I am sure have all manner of clever design details and refinements their respective engineers have implemented ), but just to add some additional information.
GC_15
Brit01
Posts: 825
Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: Megajolt worth considering?

Post by Brit01 »

What certainly interests me is having a knock sensor as part of the set up. I know the Omex600 has this but this is in a completely different price range.
Guy Croft
Site Admin
Posts: 5039
Joined: June 18th, 2006, 9:31 am
Location: Bedford, UK
Contact:

Re: Megajolt worth considering?

Post by Guy Croft »

Thank you very much Jason, Simon,

some excellent material there which I shall study with interest,

G
Guy Croft, owner
Menios
Posts: 3
Joined: July 28th, 2011, 9:29 am

Re: Megajolt worth considering?

Post by Menios »

When it comes to knock sensing things are not easy if the engine you have was not supplied with knock detection system from factory.
The best you can do to map your ignition curve is to use self calibrating knock detection system such as those sold by Phormula or other more expensive options.
Since I am mapping my car by myself the best knock detection for cheap is to use a modified hearing aid amplifier and a microphone that will be bolted on the engine block as close as possible to cylinders 2&3(where a knock sensor would be bolted on). That way you can hear knock from a speaker or earphones and retard ignition while you do live mapping.


edit:

Regarding Megajolt installation it is worth checking Megajolt 2. If it has direct coil control capability the EDIS module will not be needed. Just the coil pack will do.
Also if it is capable of reading more than 36-1 crank signal paterns it means that you can use other paterns like 60-2, or some other rover or motorbike trigger wheels. You can even go as cheap as 2 bolts spaced 180deg apart on the crank pulley and a hall sensor for 4 cylinder engines, or 3 bolts spaced 120deg apart for 6 cylinder engines.
pastaroni34
Posts: 58
Joined: June 26th, 2006, 10:53 am
Location: Texas, USA
Contact:

Re: Megajolt worth considering?

Post by pastaroni34 »

Regarding MegaJolt 2, this revision is a major update that will work without the Ford components, however, MegaJolt 2 is still under development. I do not expect these to be available for another year. At this time AutoSportLabs is concentrating on launching a different product, RaceCapture.

-Jason
-Jason Miller
Miller's Mule Machine and Design Inc.
Houston, Texas - USA
Post Reply

Who is online

Users browsing this forum: No registered users and 38 guests