Ignition Systems And Limits

[Gareth87]

Really don't have a great understanding of ignition systems. Keen to know more, what's available and how far each with go.

Currently I run a single bosch coil with with an old school electronic distributor on my FJ20. How far will this go before I run out of spark?

What's the next upgrade and when do CDI ignition systems become useful?

G

[discopotato03]

If you can find a way to mount coils directly on the spark plugs and drive them from an after market brain you escape the 80s era distributor and HT leads woes . The trouble with boosting the std system is the cap and leads dramas with high energy ignitions .

Many people mount a gang of four transistor coils somewhere near the cam cover and run short leads to the plugs , almost as good as coil on plug and much better than a dizzy cap and rotor button .

Good reliable ignition system doubly important on forced induced engines , A .

[Gareth87]

Yeah I see that's fairly common running a coil and short lead for each plug, especially with a distributor setup like mine.

When can I expect to see limits with my setup and is it related to boost and RPM?

Will the coil need upgrading and what is the big downside with a setup like mine?

Cheers and sorry for all the Q's, just trying to get my head around what I need to know.

G

[33GTRV]

CDI becomes usefull when it becomes a trailer sailer. Search for cdi vs standard mirrored coil setups. Alot of info on the subject and its pros and cons

[jet_r31]

Yeah I see that's fairly common running a coil and short lead for each plug, especially with a distributor setup like mine.

When can I expect to see limits with my setup and is it related to boost and RPM?

Will the coil need upgrading and what is the big downside with a setup like mine?

Cheers and sorry for all the Q's, just trying to get my head around what I need to know.

G

be related to hp and combustion pressure and a few other things , your asking on the wrong forum going by the answers...Rb30 single cams all have long plug leads, a distributor and a single coil..plenty make 900+ hp on 40+PSI of boost with that with no problems with just a CDI...a cheap analog MSD 6AL or something would probally do the job...and cheap as chips, unless the FJ has some weird probelmsd with its standard setup?

cheers

darren

Edited July 8, 2013 by jet_r31

[33GTRV]

And the 900hp vl's are all 400m cars. You want drivability and reliability? Do a proper cop or cnp conversion with a good quality igniter of at least 10a and a set of Quality coils. I'm sure there is a conversion for an fj for a signal.

[jet_r31]

and the 500-700hp+ plus cars are all street cars.....neverminding all types of other motors that have the same setup

that are fine...Talk about overkill, the starter of thread hasn't even listed power or specs...

or depending on computer outputs you could convert to wastespark

cheers

darren

Edited July 8, 2013 by jet_r31

[Ben C34]

The distributor isn't dead yet!

[Gareth87]

@jet_R31 - FJ20, 400hp ATW, 17psi boost, 8500rpm rev limit. Full house engine build with all the trimmings. Looking to make more HP if possible.

Tuner said to try as it is first with single coil etc but wanting to learn more about ignition setups so I know what to expect and what is possible.

Running old Wolf V4 ECU which isn't helping the drivability at the moment so if I can just go ahead and throw it back on the dyno with what I have, then great.

Cheers for the input so far everyone.

[discopotato03]

The problem is making the spark jump the gap when there is compression plus boost pressure in the chambers , the air density is quite high and if the current can find an easier path to earth it will take it .

Before you even consider the electricals/electronics the rotor turning inside a cap gives issues . Any backlash in the drive gear/jackshaft gear shows up as timing inaccuracy .

The one coil has to fire four plugs instead of one and EVERYTHING hinges of what gets through to the button via the coil lead and carbon brush . Then you have erosion of the four cap contacts and finally the resistance of the four plug leads .

More modern engines use coil on plug or a waste spark system because you need high current to fire todays lean mixtures - and mostly that doesn't even figure in forced induction .

Sadly FJ20s come from the very early 1980s (1981 was 32 yrs ago) when emissions were not as tightly regulated as they are now so the manufacturers didn't have to use super high voltages to fire even turbo engines running 7-10 pounds of boost . Honestly the simplist thing to do would be to run a couple of double ended coils close to the cam cover and four short leads , two coils makes things simller computer and cost wise . If you could crank trigger for the reference pulse you take all the inaccuracies out of the system too .

The whole management and ignition system on an FJ20 needs to go over the shoulder if you want to make serious power because it's all dark ages stuff by todays standards .

It'd kill me to do FJ20s again because there are some pretty good alternatives out there now . By comparison they are lighter more compact and have far better control systems . FJs drive you crazy with two timing chains you can't easily get at that want to rattle and getting at those under bucket valve cap shims is a PITA . Single coil distributor ignition system is just another problem to solve .

People like FJs because they have big strong heavy blocks cranks and heads , fine if you are aiming for 700+ horsepower but way overweight oversize and overkill for 400 horsepower . If serious you're throwing away both manifolds and fabricating better ones . No smarts like variable cam timing either .

I could go one but you et the picture , you need deep pockets and an FJ20 bent to go places with them .

Just my 2c cheers A .

[PSI086]

Best bang for buck is swapping to a set of 4 x LS2 coils with a set of custom leads. They have inbuilt ignitors which the wolf will drive fine and they have a brilliant spark. You can pick up a set of 4 oem surplus coils with loom for a bit over $100 off ebay usa

[Gareth87]

Thanks for the info @Discopotato03. Good to know a little more about the setup. I know the FJ is old school but I've built a tough engine now with every part that could go in the thing and it really does make good power with relatively low boost and plenty more in reserve for when I wind the boost up.

My engine is the same year as the car so it's quite fitting in that respect but I would like to make 450hp at the tyres and call it a day so I'm interested as to what might let me down on my current setup.

@PSI086 - Will search ebay, cheers!

[discopotato03]

I don't remember you upgrades but Alex used to make his own twin scroll steam pipe manifolds and run an external gate . Expensive but an FP GT3076R HTA should do the job from what I hear .

I would try to run EV14 top feed injectors like IDs and if at all possible E85 fuel because it really pushes detonation thresholds down .

Cheers A .