I’ve seen ads in many magazines recently about the Pulstar spark plug:
Is this a legitimate automotive advance, or just the latest fad? It claims to increase both performance and efficiency / gas mileage.
Does anyone have direct experience with these plugs? Do they live up to their hype?
Is there independent data documenting real advantages for these plugs?
Are they worth the extra money?
Thanks,
J.
Don’t know about pulstar, but I’ve read about the Halo plugs, which are supposed to have much the same effect. And I’ve found a cite for trials demonstrating at least some improvement (~6%) in fuel economy:
http://www.ontop.nu/england/official_test_of_the_halotm_spar.htm
Warning: Link has sound! http://www.halo-sparkplugs.com/index.html
The thermodynamics is valid at least: if you can get the charge in the cylinder to burn faster, you’ll extract more energy from the expanding gas. To take proper advantage, you should alter the ignition timing appropriately.
Will the computers in modern engines adjust their timing to reflect this change? Your link seems to imply that the computers were adjusting the timing.
Do I have any direct experience with this item? No. Have I seen similar items in the past? Yes. Did they work? Nope they don’t.
Do I believe they work? No.
Do they live up to their hype? I doubt it.
Are they worth the money? IMHO no.
To get the charge to burn faster, you are going to have to change the fuel, or the compression ratio or the temperature in the cylinder. Changing the spark plug is not going to change the speed at which the mixture burns.
I would also note that since the advent of OBDI cars, timing is not adjustable on auto engines any longer. It is a computer controlled function. So even if there was a valid demonstrable effect from using such a plug, you could not take advantage of it without reprogramming the ECM in the car.
I’m quite skeptical about these. The website says they “incorporate an internal capacitor to deliver a spark 10 times more powerful than a spark plug.” I wonder how they define “more powerful.” What I’ve always heard is that the voltage delivered by the plug is no more than what’s required to ignite the fuel mixture, up to the limitations of the ignition components. And modern ignition components essentially never are taxed to their limits. The coil may be capable of generating 75kv, and the plug capable of delivering it, but if the mixture ignites with 20kv that’s all that will be coming from the coil and going through the plug.
It may be that these gizmos can deliver more voltage than other spark plugs, but I seriously doubt that they will.
Not sure. That’s certainly the claim on the halo site. I’m kind of wondering now though, with single-point ignition, where the advantage is. The Halo may get things going faster, so it can have a bigger flame kernel at TDC, but a conventional plug would have the same effect just by firing earlier. I can see why dual spark plugs help, but I’m missing something here.
And on preview, with Rick and GaryT’s comments, I’m even more skeptical!
Good point.
Regardless of how much voltage the coil is capable of delivering, the actual voltage will only be what is required to jump the dominate gap in the system.* At idle on a properly running engine that is about 8-12,000 Volts.
Modern system are capable of generating between 35,000 and about 100,000 Volts. Why so much if they only need 12,000? Two reasons, first as the cylinder pressures go up with the throttle being opened, the required voltage goes up. Secondly, that extra energy translates into a spark that lasts longer for more complete combustion of the fuel. This results in lower emissions.
I am very wary of the the 50 watt figure that the Pulstar people kept harping on. I seriously doubt that a current vintage ignition system has the same total energy as an old fashioned points and condenser system.
*The dominate gap is the biggest gap in the system, it is usually the spark plug, but it can be the rotor to cap gap, or a broken spark plug wire.
But…but look at how much brighter the spark is on the Pulstar plug on the website!
Wouldn’t a spark tend to jump the smallest gap in the system?
What about those gap-less plugs? They were sold from ads like tha in the 1980’sthey had no electrode-the spark jumped across a flat surface. The damn things didn’t work any better than the standard plugs. incidentally, spark plugs are good for 100,000 miles today-so many new car owners never change them. I can remember when the sp change interval was 10,000 miles.
The gaps are in series.
As cornflakes said the gaps are in series.
Let’s look at a typical distributor system. If all is well, you have two gaps in the system. the distributor rotor to cap, and the spark plug gap.
The gaps will probably take the following amounts of energy to ionize or jump the gap.
Rotor to cap 3 KV.
Spark Plug 10 KV
If you put this engine on a scope the firing voltage will show 10KV
Now let’s take a worn engine
Rotor to cap 8 KV
Spark plug 15 KV
1 Bad spark plug wire 20 KV
putting this engine on a scope will show 15 KV on all cylinders except the one with the bad wire that will be at 20 KV.
If you do a test to take the plugs out of the circuit you would see the 8KV at the cap and rotor.
Once you have enough energy to jump the biggest gap, it will jump all the rest.
Back in the 1970s, a company called Asssociated Engineering Developments, LTD of Cawston, Rugby had the plasma plug which supposedly increased mileage by a few percent. In the early '90s AC Delco came out with Rapidfire plugs and one of the other big plug makers came out with the Splitfire plugs. I don’t know anything about the plasma plug, but I tried both the Rapidfire and Splitfire plugs in the car I had at the time (1980 Jeep Cherokee Laredo with a 360 AMC motor) and found that the Rapidfire plugs did make a very slight improvement, while the Splitfires just made my wallet a lot lighter. (Something like $32 in 1990s money which works out to about $320 in todays money.)
