Do Spark Plugs Matter? CHEAP vs EXPENSIVE | Engine Masters | MotorTrend

Did any of these test results surprise you?

So get regular plugs and open the gap a tiny bit.

Testing and comparing different parts on this channel are my favorite episodes 🙌

I've always had the best luck with regular NGK plugs. Smoother running,fewer misfires..overall better. They just work like a spark plug should..I've tried quite a few other plugs,and always go back.

O'reilly's manager here... I NEVER have NGK or ACDelco brought back with problems. Other, cheap brands, have had issues. Last week a guy brought back a set of autolight APP65 that lasted 5,000 miles and the electrodes were GONE. Ground straps ghosted. All of them. He replaced ACdelco plugs after 90,000 miles.

I run a 1974 Nova with original Gen I 350. I installed O2 sensors on a dual exhaust header combination. This allows me to monitor performance and fuel economy and know whether the problem is isolated (plugs, etc.) or general like carb, distributor, etc. Using a carb I also run a vacuum gauge. This system has served me well. I do open plug gaps routinely and get enhanced performance in every situation.

im so glad engine masters is back on youtube, its been years since ive watched one, also, missing the coolest sparkplug which is a pulseplug with built in capacitor, also plugs wont really shine unless you and increase the pressure inside the cylinder until it cant jump the gap. also other factors to consider is the sparkplugs ability to light up ultrarich or ultra lean mixes, some plugs will perform better than others depending on its design and how it creates hot spots in the cylinder

I would have really liked to see spark plug indexing explored. Maybe in a future episode?

This video earned +sub. Thank you. 33 yrs working with and being around cars and I'm still learning new and valuable information.

Chris Jacobs in his book on ignition systems points out that the main concern is the flame kernel. A wider gap requires more wattage to jump and produces a bigger and hotter flame kernel. The multi electrode plugs just mask the kernel from various directions. He goes into much greater depth than this but for the purpose of this post, it's pertinent. The simple Autolite plug with the wider gap produced the most power. And cheap(ish)!

I've always ran the Autolites and change them often. A cheap fresh plug is much better then an old expensive one!

I actually noticed this gap thing with plugs on an old Saturn that I had. I was trying to eek out a bit more power from that little 4-banger, but things that make power often translate to MPG and I consistently got better mileage with that car when I ran bigger plug gap. My setup was Accel coil packs and NGK plugs with I think 0.055" gap (it's been over a decade so forgive my poor memory but I do know it was significantly more than the OEM spec of 0.040"). I tried this with the factory coils and it would not run right with those so I know the higher voltage coils made a difference. On a highway trip shortly after I did the mods this car got 42 mpg, which is pretty good considering that those cars are EPA rated for 32. I don't know if power changed at all but it did feel faster. I read from some people who know more than me about those cars that the tune was a bit rich from the factory, so maybe the extra gap was helping get more complete combustion on that rich AFR. I don't know exactly why but the results were way better than I expected, especially the mpg. I did some other mods to that car, which was quicker than you'd think due to its lightness, but that plug gap/coil upgrade thing was a big surprise for me. It yielded the best results.

Forgot to add that you CAN make more power with side gapped Autolite Racing plugs, but they don't last long on the street as the gap opens as they wear because it eats the edge of the electrode off.

It doesn't happen often, but I learned literally nothing from this episode. I'm actually quite surprised at that. So in the interest of education, I will provide a little. The reasoning behind the multiple grounding straps is to give the arc a greater chance of developing, reducing the possibility of misfire. Tip for your old copper plugs when you open the gap, you can leave your gap coin in between the strap and plug and using pliers you can push the strap back over to the center while maintaining the gap (only works with gap coins).

Love these engine masters shows

I found that using Autolite Platinum and Double Platinum spark plugs gave the best power and fuel economy at part throttle operation. When I used the Autolite plugs in 7k watt Honda generators that were running air conditioners at a remote site 24/7. The tank of fuel would last 8.5hrs, up from 6hrs with the standard plug. Running Mobil 1 oil instead of conventional multigrade oil, added another hour to the run time. On the dyno, what were the differences with the BSFC?

Could you test longevity by supplying constant voltage until failure? You could also supply higher current with constant voltage to shorten duration of test. Be careful though as this could cause explosive and/or other dangerous results

great episode boys! While a larger gap will net you a bit of power on a NA setup, the same cannot be said once you go boosted. Why? Spark kernel strength! Keeping a larger gap can, effectively 'blow the spark out' as you add boost. For example, you might have shrink your plugs from 32 thou down to 28 or 24 thou once you've increased boost. I think the rough rule was 4 thou for every 50 HP, and swapping to a colder range plug also helped. Would love to see you guys explore spark plug gap on a boosted setup as well! Cheers, - rains

What I'd like to see tested is: Strain on the ignition system due to wider plug gap. More gap means higher voltage needed to strike the arc. Also what affect does gap have in boosted applications. Does gapping more or less effect power, potentially because of spark blow out.

in one of david vizard RECENT books he says a small amount of plug resistance is best ie 200ohms they often come with thousands of ohms. lets be even more clear he measured the resistance in the plugs and leads combined. ignition is VERY important if you have a chamber that is hard to light up.