does a bigger spark make more power?

[al167]

hello i have just done a search on this site for msd ignitions and found no results. so i thaught its maybe time for one.
i have been looking into getting a good aftermarket ignition system now for a while now and after a few hours researching on the net and talking to my tuner i purchased a msd dis 4 ignition system.

my car is a hiace and its got a vvti 1.5jz engine with gt3540 106 housing turbo my compression ratio is 9.8 to 1 and im using a microtech ltx12 running 3 coils( m and w coils) waste spark.

now, wilst tuning the car at 15psi boost, the spark was blown out at 0.8mm gap and the engine would break up.
i closed the gap to 0.6mm and my problem disapered until 22psi
i then closed the gap to 0.5mm and that fixed the probem until 28psi (now c16)
i then closed the gap to 0.4mm and that fixed the problem and im now at 32psi and it ran sweet on the dyno (no missfires at 0.4 gap) and made 502rwhp.
i know that when there is a high cylnder pressure (under high comp/ high boost) it is harder for the spark to make the jump across the gap.(the figers above prove this)
what would happen if i had 0.8 gap at 32psi with a stronger spark?
will i make more hp (or torque) even though the engine was not missfiring with 0.4mm gap
i will hook it up and dyno tes it in the next few weeks

[oldcorollas]

misfire = spark not able to ionise mixture or arc across gap, OR
misfire = spark not able to effectively and reliably ignite the mixture.

if the mixture is reliably igniting, and the ignition timing is set so the peak cylinder pressure arrives at the right time.. is there much to gain i wonder?

looking forward to your tests

btw, have you compared the graphs for the runs you have done with those different spark gaps, and was the timing optimised for each gap?

edit: it also depends where your spark is being generated..
if you are bending the ground electrode, then the end will be closest together, so the spark will be right at the end, giving great access to the mixture. if you use a plug with parallel surfaces (ground and centre electrodes) then the spark position should change, and may sometimes be shielded somewhat from the mixture?

or are you using platinum or iridium style plugs? they should have less issues with shielding

[wa5]

read something in Street Machine years ago, they reckoned that on cars with a C/R of less than 10.5 to 1 it didnt really matter, above that it made a slight improvement...
I am only repeating what I read years ago..... and make no claims that it is correct or otherwise.

[jeffro ra28]

A common feature of a racing spark plug is to be "gapless". Resulting in the center electrode having almost full veiw of the cylinder below. The ground strap ends before it covers the electrode. So basically being "ungappable" as bending the ground electrode will not increase/decrease the gap. "Champion" plugs offer a wide range of these plugs.
Sorta like this, notice the ground electrode not covering the entire center electrode


From my experience very little improvements are made with spark plugs UNLESS there is a blow out or weak spark issue in the first place.
I have experimented with grinding the entire ground strap off and having the center electrode strike the arc between the surrounding metal ring (see RE series plugs in link below). However a powerfull ignition (in my case MSD8 dual coil ) needs to be used as the spark will not have the required energy to jump from the center electrode to the outer ring. No real horsepower improvements were acheived.

If you are having this issue i reccomend sourcing some HKS spark plugs. They can be used with factory coils and are the easy option before replacing coils, ignition modules etc. They are not designed to be gapped. They range from $30-$90 each but are a must in high boosted high compression engines!

See here, http://209.85.135.104/translate_c?hl...%3Den%26sa%3DG
Sourced from any HKS dealer or direct from the Australian HKS distributor Performance Wholesale Ph: 07 38081986

[tomvale13]

apologies, though he was looking for an msd of which i have a spare new one.

Have re-read first post properly and adjusted mine accordingly.

[jeffro ra28]

all fixed :

[Norbie]

A bigger spark does not necessarily result in more power, but in your case an ignition amplifier is most certainly required. A 0.4mm gap is crazy! I don't know anyone who's tried to run 30+ psi without upgrading the ignition; something like an MSD DIS4 is really a given for a setup like that.

[abently]

You will definitely see a reasonable increase in power from a larger gap over 0.4mm.

Iridium plugs need less energy to make the same jump, so if I were you, I'ld get some Iridium IX's @ 0.8mm Non-projected type. (they come pre-gapped and are not suited to being re-gapped unless you are extremely extremely careful).

Run them @ 0.8mm and see how you go. Other neat trick you can do is to run shorter Ignition cables via relocating the coils closer.

I think you'll be close to getting away with having to upgrade your Ignition system.

[allencr]

Re: does a bigger spark make more power?
Sure it does, especially when it was poor or marginal to begin with and/or combustion pressure has increased.

Here's a 'racin' plug, and everyone 'just knew' that it was a 'racin' plug because it was expensive & would barely start the engine and/or would foul out Very soon, and needed to swap in normal plugs to start & warm up, so that the 'racin' plug would actuall run the F'ing thing.



Thanks for the pic Gordon Jennings. http://www.strappe.com/plugs.html

[al167]

i wired up the msd dis 4 today and it was relitively simple. it was very similar to hooking up an amp for your car stereo. i started the engine and it ran nice i havnt driven it yet though
i agree with norbie that i should have gone to a better ignition along time ago, but i like to use what ive got before i start spending $600 on an ignition amplifier that i may not need . i have tried ngk platnum plugs to no success they cost me $100 for the set too

the plugs i use are ngk bcpr7es and are $18 for 6
my leads are also short the longest is 500mm aprox my 3 coils are mounted on the rocker cover
the msd booklet that came with ignition didnt recomend any type of plug type as it says all engines are different but it did recomend not to use platnum type plugs with the msd
i will try and dyno in the next few weeks.

[Norbie]

Yeah your problems will disappear with the MSD DIS4. I have one of them and it came off an 800hp 2JZ which still used the factory coils.

These things are very powerful, they'd probably vapourise the fragile little electrodes on a platinum plug, which is why they don't recommend using them.

[jeffro ra28]

have you considered running a slightly colder plug? 9.8:1 and 32 psi seems a fair amount. Id be using a cooler plug ?

[al167]

they come standard with a six i think? what do you recomend ie bcpr8es?
new post for types of plugs for high hp 2jz put up