Going to CDI - whats the best way

[andrew_mx83]

so i am thinking about going CDI on my race motor, pissing off the distributor and replacing it with the 7m-gte cam position sensor.

will the msd programmable type boxes take this as their input? or will it need a dedicated CAS? i cant see anywhere that they that need a map sensor... surely there must be some load compensation.


the other idea i am toying with is getting an aftermarket ecu and using it just for spark only (motor is carby fed so it would do little else). at least this way i know its easy to program a proper ignition curve and run a CAS and MAP input, but i was wondering if these things act as a CDI as well or will i still need to run a 6AL type box after it?

[MWP]

Do you have a specific need for CDI?
Will COP, coil-per-plug or wasted spark do the job?
Im just asking as CDI isnt cheap, and you probably dont really need it.

[andrew_mx83]

not a fan of coil on plug, was thinking wasted spark but pushing high RPM and lots of comp i am wondering if i should just do it properly....

im open to ideas though!!

[litldv8]

EDIS and AUII coils are the win

[timbosaurus]

EDIS and AUII coils are the win

Umm... care to elaborate why? we're a technical forum here...

personally I think the complexity and reliability of the EDIS, as well as the need for an additional trigger wheel is a good reason not to use EDIS. I've never used AU2 coils though, so can't comment on them.

Anyways, Andrew, not sure why you want to go for CDI in your application? It's main advantage is shorter charge time over an inductive system. It's disadvantaged in it's cost, and it's shorter spark duration

Shorter charge time is needed on engines that are very high revving (motorbikes), and/or single coil/large-number-of-cylinder motors (V8 race motors), where you may need to charge the coil, say, 4 times per revolution at 8000rpm (~2ms). An inductive coil (~5-6ms) takes too long to charge.

Given yours is a 4 cylinder... and I'm assuming you'll run wasted spark at least (maybe even individual coils?) which will be fine. a quick calc shows a bit over 6ms for 2 coils at 10,000rpm.

I'd just use 2 wasted spark coils. If you're still worried, you can get low resistance coils that charge in half the time, but put more stress on your electronics.

As for control, the simplest/smallest would be something like this...

http://www.diyautotune.com/catalog/m...tem-p-131.html

It's small, it's sealed, and it's full programmable control of two coils directly (wasted spark). If you want to run 4 individual coils, you'll need externally driven coils (like 1zz COP etc).

It gives you all the megasquirt features, and the other bonus is that it DOES have complete injector control as well (for when you see the light at the end of the carb tunnel ).

With the dorra as it is, you'd get the unit, the 8-foot harness, and the external MAP sensor all landed for around $550.

[litldv8]

to start with i will not enter into a fight over this

taken from the above link^^^^

MicroSquirt also has dual channel ignition drivers (BIP373's) as well as both the Variable Reluctor (VR) and optoisolated 'Hall/optical/points' tach inputs

which is what edis uses as well
i like it - you obviously dont
i have never had any reliability problems with edis

is it just me, or does the 'thermostat' in the top pic look like a bong? :s

Re: Rod tight on gudgeon pin

--------------------------------------------------------------------------------

A bit of dowel will help make sure the material is removed evenly.

Also, if you tape a flap of 1200 grit to a drill bit, you can use it as a flap wheel to make the work easy.

for a technical forum these a great bits of advice
neil

[timbosaurus]

No idea who's fighting mate... I'm just prodding for your reasons.

Toymods (and Andrew in particulare) is more substancial than "I like X..." or "Y sux, man...". And I'm a curious type who also wants to understand why you thought EDIS would suit him.

Myself, I don't think EDIS will suit Andrew, as it is not programmable in itself. Without an ECU to control advance, he'll be stuck at a static 10deg BTDC.

Also, they are reputed to have a limit of around 9000rpm. may or may not be an issue here... but Andrew + 20V + motorbike carbs + race cars sounds like a high-rpm recipe.

Depending on which model you pull it your EDIS module from, you'll have 10+ year old transistors that have had a hard hot life. I'd pick a new FET driver anyday.

I haven't heard of EDIS working with any Toyota CAS, so he'd have to fit an additional trigger wheel which seems a bit redundant.

that's why i'm prodding you for more info...

[andrew_mx83]

engine is a 6 cyl with a target redline of 9000rpm... if my math is right (450 charges/second) that is still around 2ms

so this means single coil is definately out of the question?



i had a bit of a look into the EDIS thing, it looks like it would be pretty easy to setup... raid a falcon from the wreckers for coilpack, EDIS module and crank angle sensor. attach a 36 tooth wheel to the crank pulley and buy a "megajolt" box for a couple hundred bucks which will allow 2 10x10 maps of rpm vs load and is laptop programmable

[andrew_mx83]

tim the motor is a destroked and dry-sumped 7m-ge running 40mm deloroto's and big cams but spot on about being a high RPM recepie

[timbosaurus]

Got my Andrews mixed up... thought yours was the 4A. Too many of you running carby race motor's

a 6 cyl makes things a bit more complicated... as the megasquirt range only comes standard with 2 coil drivers. And yeah, 2ms is probably too short for a single induction coil.

So your main options are adding an extra driver (if you're handy with electronics), using an external 3 channel driver, using coils with built in ignitors (eg: COP), or running an EDIS for it's ignitor/sequencing capabilities.

[andrew_mx83]

Too many of you running carby race motor's

cos its the best way! dont worry one day you will see the light at the end of the EFI tunnel lol

[andrew_mx83]

http://www.autosportlabs.net/Megajolt_Lite_Jr.

thoughts?

[litldv8]

i had a bit of a look into the EDIS thing, it looks like it would be pretty easy to setup... raid a falcon from the wreckers for coilpack, EDIS module and crank angle sensor. attach a 36 tooth wheel to the crank pulley and buy a "megajolt" box for a couple hundred bucks which will allow 2 10x10 maps of rpm vs load and is laptop programmable

perfect

i just put the thought out there andrew can look into it and see if it suits him

I haven't heard of EDIS working with any Toyota CAS, so he'd have to fit an additional trigger wheel which seems a bit redundant.

my hilux is running it with the toyota crank angle sensor admittidly i machined off the teeth and fitted a trigger wheel that i had laser cut to it.
works quite well on my setup.

neil

[timbosaurus]

EDIS is rad... do it.

[thechuckster]

EDIS has a built-in limp-home function - if the ECU snuffs it, you still get a spark.

note: rev limit (via spark cut) is a bit difficult with EDIS - from memory and a quick squiz at the megajolt site, you can't drop spark so any rev limiting is 'soft' (massively retards spark).