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Old 01-26-2006, 11:21 AM   #1
kaisersouse
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Default Bigger plug spark...is it doable? Does it hurt things? Is it worth it?

Is is possible to get more beefier coil packs (I guess thats what its called...where the plug wires connect to) and increase the plug gap to get a bigger spark? Would a bigger spark increase performance and would it kill gas milage?
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Old 01-26-2006, 12:14 PM   #2
kaisersouse
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hmmm i have seen the phrase "Diamond Coil Pack" being passed aroundon Google. Cant find a manufacturer site tho...
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Old 01-26-2006, 01:05 PM   #3
solbey11
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Um...don't even bother. During normal driving, your ignition system isn't even working up to it's full potential. Your ECM is controlling ignition timing and dwell time on every engine stroke. Your car doesn't need a huge spark every time a cylinder fires. It will create to much heat in the coil pack and it's just a waste. Your ECM creates the perfect spark every time to ignite the A/F mixture in your engine.
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Old 01-27-2006, 10:47 AM   #4
Hayes
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Waste of your money & time in my opinion. Many are running highly modified Suby engines using the stock ignition.
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Old 01-27-2006, 11:16 AM   #5
kxmx51
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not trying to thread jack... but what about one step colder plugs for every increase of 75 hp? ive heard its a good mod that can actually add an increase in hp
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Old 01-27-2006, 02:07 PM   #6
Patrick Olsen
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Quote:
Originally Posted by Hayes
Waste of your money & time in my opinion. Many are running highly modified Suby engines using the stock ignition.
That doesn't mean they wouldn't see an improvement if they used a better ignition system.

This subject comes up every once in a while, and the response is always, "The stock ignition system is more than enough, don't waste your money!" I have yet to see any actual testing that shows that an aftermarket ignition is worthless. I know I've seen posts on here in which guys stated they're running an MSD DIS box, and at least a couple people have adapted an MSD coil pack from Mitsu/Dodge 4-cyl cars. I actually have one of those MSD coil packs, but my initial attempt to get it to work failed - I think I need to reverse two of the wires on the harness connected to the coil pack, but I haven't had a chance to fiddle with it more.

It's on my list of "Things to Try with the Subaru" now that I have access to dyno facilities again.

Pat Olsen
'97 Legacy 2.5GT sedan
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Old 01-27-2006, 05:29 PM   #7
solbey11
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Quote:
Originally Posted by Patrick Olsen
That doesn't mean they wouldn't see an improvement if they used a better ignition system.
But if the ECM is controlling all ignition timing with a stock coil pack, it's going to control an aftermarket setup the same exact way. It's just like upgrading an RS fuel pump to a WRX fuel pump. You aren't going to see any effects at all because your ECM is controlling your injectors. Sure you may have a higher fuel pressure, but your pressure regulator will bleed any excess pressure off and your ECM will compensate for any extra fuel flow through the injectors.

Your ECM is programmed to have the proper A/F ratios in each cylinder under all different engine loads. It's also controlling the spark to allow proper burn of the A/F mixture. So just upgrading these parts isn't going to have any effect on your car's performance.

Whenever you start to get into a lot more HP then you will have to think about upgrading and getting an ECM reflash. But on a basic modded 2.5L NA engine, you won't notice any performance improvements with upgraded componants.
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Old 01-27-2006, 05:51 PM   #8
kaisersouse
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but I thought the ECU just controlled the sparks TIME....not how big the spark is itself. I've read that a bigger/hotter spark causes a more efficient fuel burn, which in my opinion would mean a small HP gain but also better gas milage as the fuel itself if burning more efficiently.

So if you have a coil pack pushing more energy...you can open the gap on the plugs more (since they will travel the increased distance in the same amt of time since there is more energy to push them)... therefore creating a bigger spark....making a more efficient explosion. Thats what I've come to understand anyways.

This would prob also mean I'd need beefier plug wires and possibly better plugs...
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Old 01-27-2006, 07:35 PM   #9
solbey11
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The ECM controls spark timing and dwell timing. Dwell timing is how long the coil pack saturates before it sends current down the plug wire. The longer the coil pack saturates, the hotter it gets and the less efficient it becomes. So the ECM takes in all sensor readings and determines the proper dwell time for the coil pack. And it sends enough current to the plug to ignite the A/F mixture in the cylinder. So your ECM is basically limiting the ability of the ignition system. If it wanted to, it could create a bigger and longer spark, but it would just be a waste due to the A/F mixture present. So if you go with a bigger turbo/fuel system, you will have more air and fuel in the cylinder. Therefore you would need a better ignition system that could handle the added A/F mixture.

I agree with you when you talk about the larger gap better explosion. But your stock engine was already designed to maximize the spark potential. Unless you start heavily modifying it, you really won't have to upgrade the ignition system.
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