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View Full Version : please explain a wasted spark system?



LSB_11
09-14-2004, 04:09 PM
my mechanic has contacted haltech in australia, he says with the haltech system on the srdet ignitor aplication you have to bridge the #1 and #4 cylinders and #2 and #3 together. i just thought this would make problems, would they still fire at the same time. and he called it a wasted spark, what is that, i dont really understand it. have you heard ways of wireing the haltech E6X with the q45 ignitor chip?

KidZelda
09-14-2004, 04:21 PM
Each coil fires two cylinders simultaneously, one is on its compression stroke and the other is on exhaust stroke. This is called a “waste spark system” because one spark is “wasted” on the exhaust stroke cylinder.


Some benfits are,hotter sparks, cleaner plugs, better engine efficiency.

killjoy
09-14-2004, 04:25 PM
I run wasted spark on my haltech and it works great.

mattmartindrift
09-14-2004, 05:28 PM
ditto, but w/ my Tec2

Hugh
09-14-2004, 06:20 PM
My tec3 runs on wasted spark, and phased injection.

(my injectors and spark plugs are paired)

Kim_Jong_Il
09-14-2004, 07:06 PM
Tec on our FSAE car does too, some OE domestics I believe, MegaSquirt^2 & UMS, and most other aftermarket standalones for the most part run wasted spark. Descriptions above all suffice.

LSB_11
09-14-2004, 09:42 PM
why exactly is this done, why dont they just fire them individiaully. i can see more heat and cleaner plugs like said above. but can this system work as fast or efficiently as single spark, are there any cons for this/or any horror stories.

Nikeboy355
09-14-2004, 09:43 PM
My tec3 runs on wasted spark, and phased injection.

(my injectors and spark plugs are paired)


so does phased injection mean that the injectors fire during the exhaust stroke?... what is the purpose of all this action when the combustion chamber is just trying to expel te burned gas or is there something I am not understanding...

Kim_Jong_Il
09-14-2004, 09:56 PM
Both phased injection and wasted spark are done primarily for simplicity of setting up the system. For sequential injection (and probably) spark the ems needs a signal from the cams as well to determine where the engine is in it's stroke. That seems to be the number one reason why most aftermarket systems don't utilize the setup, a lot of people won't go through the extra work for the benefits (they might be marginal, I'm not really sure).

9591
09-14-2004, 10:44 PM
why exactly is this done, why dont they just fire them individiaully. i can see more heat and cleaner plugs like said above. but can this system work as fast or efficiently as single spark, are there any cons for this/or any horror stories.

I'll not venture my own opinion, but note what others, more knowledgable than me, have found:

1) AEM's RWD drag Civic (6.xx et) runs waste spark;

2) I spoke with Tony Sloan a few weeks ago at an NHRA event in St. Louis (his son, Clay Sloan, was in the process of winning the Pro All-Motor class at the time). He said they'd dyno-compared waste spark and direct-fire arrangements. Waste spark won.

Hugh
09-15-2004, 09:53 AM
Not to mention, just about every major car manufacturer is using waste spark right now. (at least every time I look under the hood of any new cars I keep seeing it)

It's not like old or bad technology. It's very common.

As far as phased injection, the injector is not firing at the precise moment when the valve is open, no. But... the valve is close during the exhaust stroke, so its not like the fuel is spraying in there then. I've been wanting to run full sequential, but it seems the benefits are minimal at best for a lot of extra work and parts.