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Car Forum / Honda Cars / March 2006Better MPG with premium spark plugs?
I have an '87 CRX Si that runs great and gets the expected mpg. Will I get better gas mileage with premium spark plugs and wires? Thanks, Greg I would say that decent plugs might do a little....probably better gettin new plugs/wires/rotor etc....BUT DONT spend your money on "split fire" type they are a scam and very expensive. > I have an '87 CRX Si that runs great and gets the expected mpg. Will I > get better gas mileage with premium spark plugs and wires? > > Thanks, > > Greg > I have an '87 CRX Si that runs great and gets the expected mpg. Will I > get better gas mileage with premium spark plugs and wires? > > Thanks, > > Greg My '87 Integra ran best (typical commuter driving, not racing) with the standard NGKs. I tried Bosch Platinums and they performed worse. Never tried premium wires, replaced OEM with OEM. Routinely replaced cap/rotor every 30K, air filters at 20K. I used moderately sporty tires inflated to about 35 psi. My Integra delivered improved mpg with synthetic oil. I could get 36-38 mpg out of it on the highway moving right along with traffic (70+ mph) vs the EPA rating of 30 mpg. Overall, I got about 32 mpg. Probably the best compromise between utility/economy/fun-to-drive I've ever owned. [Crushed like a tin can when a Tarus wagon plowed into it's rear end so I'd have to say safety was also compromised.] YMMV. > I have an '87 CRX Si that runs great and gets the expected mpg. Will I > get better gas mileage with premium spark plugs and wires? Unless your current setup is worn or defective and produces a poor spark, no.  SignatureTeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > I have an '87 CRX Si that runs great and gets the expected mpg. Will I > get better gas mileage with premium spark plugs and wires? > > Thanks, > > Greg it depends on what you mean by "premium". if it's something like ngk iridiums, and the rest of your ignition system is perfect and new, you can get maybe 1-2%. it's probably more important to ensure your distributor cap and leads are in good condition. >From NGK Spark Plugs web site: Frequently Asked Questions Q: How much of a performance improvement can I expect from changing plugs? A: A common misconception is that changing spark plugs will result in a large power increase. In most cases, removing even seriously worn out spark plugs will only result in very modest power gains, typically about 1-2% of total engine output. This could be even less for computer-controlled vehicles, primarily because most newer vehicles have more powerful ignition systems and the vehicle's computer can make adjustments so that vehicle operation seems smoother and more seamless. Many people think that simply supplying more spark to the firing tip can and will combust more fuel. What they don't understand is that most newer cars' engines are so efficient that they are already burning all of the available fuel. Simply adding more spark voltage can't burn more fuel because there is no more fuel to burn. When a stock or near-stock engine is given a fresh set of spark plugs, peak efficiency is restored. The power gains that come from this restored state of tune are usually minimal. Any company that tells you that their spark plug will provide significant gains in power in a stock or near-stock engine is making blanket statements that may not be supportable. >>From NGK Spark Plugs web site: > [quoted text clipped - 16 lines] > of the available fuel. Simply adding more spark voltage can't burn more > fuel because there is no more fuel to burn. eh? you're very confused. mixture ratios vary, and spark energy requirements for complete combustion vary too, by over ten-fold. part of the ability of the plug to deliver those energy requirements are determined by things like electrode conductivity and morphology, i.e. design. hence, different plugs /can/ affect power output. sheesh, go to a library rather than regurgitate garbage off the net will you? > When a stock or near-stock engine is given a fresh set of spark plugs, > peak efficiency is restored. The power gains that come from this > restored state of tune are usually minimal. Any company that tells you > that their spark plug will provide significant gains in power in a > stock or near-stock engine is making blanket statements that may not be > supportable. > >>From NGK Spark Plugs web site: > > [quoted text clipped - 23 lines] > design. hence, different plugs /can/ affect power output. sheesh, go > to a library rather than regurgitate garbage off the net will you? Maybe you should check the total resistance of a modern ignition system. Between the coil, distributor resistor, resistor wires, and plug resistor you can easily end up with over 50000 Ohms. How does a 0.001 Ohm difference in the plug tip matter? It is true that the voltage needs vary vastly with compression and the electrode shape. I am unaware of any modern car that needs a pointed electrode to achieve a proper spark. They all have enough spare voltage and dv/dt to work with a plug that has been mildly worn to a dome. Also, modern low emission engines maintain the proper air/fuel ratio underneath the spark plug even when the rest of the chamber is lean. It's a valve and injector timing trick. I agree with Kevin that a properly working iginition system is well capable of handling the voltage variations needed to spark the gap within the specified service interval of the plug. So changing out a good old plug at the end of its service life with a good new plug won't give you that much, as NGK stated, 1-2%. > Maybe you should check the total resistance of a modern ignition system. > Between the coil, distributor resistor, resistor wires, and plug > resistor you can easily end up with over 50000 Ohms. How does a 0.001 > Ohm difference in the plug tip matter? This is a very good point, however... > It is true that the voltage needs vary vastly with compression and the > electrode shape. Maybe I'm just being silly, but it seems to me that more voltage is simply better (within reason - if it's enough to breach the ceramic, that's a problem, but assuming that's not gonna happen...) You have two electrodes and an air gap. You need to generate enough voltage to cause a spark to jump that gap. The stronger the spark, the less likely it is that you'll get a misfire. The actual resistance may vary depending on the air/fuel mix floating through the gap at any given time, but in any event, you want a nice hot spark to ignite it: if the mix provides a higher resistance, you need more voltage to create the arc; if the resistance is lower, the arc may occur at a lower voltage and not be hot enough to ignite the mixture - either way, more voltage is better. I can't imagine any instance you'd actually want LESS voltage across the gap. > I am unaware of any modern car that needs a pointed > electrode to achieve a proper spark. They all have enough spare voltage > and dv/dt to work with a plug that has been mildly worn to a dome. True - the shape of the electrodes isn't as much a problem as having the electrode(s) wear down, thus increasing the gap excessively, or having deposits build up on them, thus decreasing the gap significantly, or adding "insulation" to them, thus reducing the spark efficiency. The spark plug is a pretty simple device, after all... its operation and design really hasn't changed that much in the last, oh, hundred years or so... --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0609-3, 03/03/2006 Tested on: 3/4/2006 12:15:03 AM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com >>>>From NGK Spark Plugs web site: >>> [quoted text clipped - 28 lines] > resistor you can easily end up with over 50000 Ohms. How does a 0.001 > Ohm difference in the plug tip matter? ok, make that "thermal conductivity". > It is true that the voltage needs vary vastly with compression and the > electrode shape. I am unaware of any modern car that needs a pointed > electrode to achieve a proper spark. it doesn't much when the plugs are new because the electrodes are nice & square, and those sharp angles have higher emissivity. but those sharp edges quickly erode, so skinny electrodes that can take the thermal/chemical environment make for better spark quality over time. add to that the fact that skinny electrodes have higher emissivity than fat ones day one, and retain it over time, and you /do/ have a better plug. > They all have enough spare voltage > and dv/dt to work with a plug that has been mildly worn to a dome. > > Also, modern low emission engines maintain the proper air/fuel ratio > underneath the spark plug even when the rest of the chamber is lean. > It's a valve and injector timing trick. red herring. | > >>From NGK Spark Plugs web site: I avoid NGK ; wears fstr than NipponDenso / Champion. | > > misconception is that changing spark plugs will result in a | > > large power increase. Bullshit ; changing from plugs with ( 4k ohm ) resistors to plugs w-o will get more amperes i.e. broader sparks, fstr burn, 5% more torque, 2% less noise, enable slower idling & a bigger gap for longer & even broader sparks ( another 1% more torque ). If replaced by plugs with electric wind design, then even fstr burn & more torque. What plugs & wires do you recommend? >>From NGK Spark Plugs web site: > [quoted text clipped - 10 lines] > have more powerful ignition systems and the vehicle's computer can make > adjustments so that vehicle operation seems smoother and more seamless. i definitely noticed a difference in the girlfriends RAV4 once it hit 60k by replacing the OEM platinum plugs with new ones. the idle smoothed out noticeably. Yes, I've noticed the same thing with older plugs. When a difference like that is noticed, you know the factory specified interval has been stretched too long. I personally change plugs 30K miles. But replacing an old but properly working plug at the end of its service life may not give you more than 1-2% improvement with modern ignition system. Of course, how NGK arrivies at 1-2% is a different story. > i definitely noticed a difference in the girlfriends RAV4 once it hit > 60k by replacing the OEM platinum plugs with new ones. the idle smoothed > out noticeably. > I have an '87 CRX Si that runs great and gets the expected mpg. Will I > get better gas mileage with premium spark plugs and wires? not enough to make up the difference in price. the only "premium" wires are OEM, and plugs are whatever ND or NGK the sticker under the hood calls for. youll be better off making sure it stays in proper tune, change the oil every 5k, keep the tires inflated and the air filter clean. > I have an '87 CRX Si that runs great and gets the expected mpg. Will I > get better gas mileage with premium spark plugs and wires? > > Thanks, > > Greg My .02 is that it's WAY more important to gap the OEM replacement plugs to the correct gap than it is to buy some trendy exotic split-fingered ones. |
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