I have a GT with a stroked 3.1. Nothing too fancy. Not a race car. I am pulling and changing out plugs this afternoon, and just curious as to what we use? I do know that I have AC Delcos in there, but not what number designation.
I suppose that I should look at the plugs before asking this, but curiosity and conversation...
I have read many posts that recommend the original equipment: Delco R42TS copper. They work great in my car, but it's curious that all the newer technologies do not work as well in the 2.8, and I would think the added displacement would not make a difference. A sensitive motor I guess.
I have always used Bosch platinum's in all my cars & trucks including my V6 Fiero. they are said to be good for 100k + miles. I have never had to replace them, ever. No problems at all with the Fiero ignition...
Me I prefer: ACDELCO 1 Professionnel; Rapidfire® because they have a corrosion resistant plated shell. OR the : ACDELCO 41809 {#88901015} Professionnel; Double Platine because they have a corrosion resistant nickel plated shell. The 3 spark plugs on firewall side tend to rust after few time that's why I prefer those spark plug plated.
Nickle Plated and other base shell types resist corrosion is a must because "water" get in thru deck lid gap etc on Fiero then on plugs and exhaust. Even then check the shells for rust every year at minimum so can replace before shells rot. Note: Even if you have a "rubber seal" on the deck lid edge... Try not to open when lid is wet and engine is hot. All water gets dumped on exhaust, plugs, etc. that attack them by crash cooling. That can break the exhaust and cause other problems.
HEI and DIS are made to have normal or "Copper" plugs. Platinum plugs are ok and does last longer and most have plated shells as above. If you find copper w/ plated shell is good too. Note that "Copper" plugs in only copper core to the center tip to "reduce resistance" and maybe heat control at the tip. Is kind of funny because most street engines require resistor plug types.
Double platinum is useless unless you have a DIS engine like 87 and up L4. DIS engine Hate Gimmick plugs and plugs can/will die fast.
You won't "improve" HEI and other systems will them either but waste money at minimum. Bosch +2 and +4 and other iffy plugs from big names are just Gimmicks same as others like SplitFire that got sue by FTC etc and basically out of business now but others are Big Companies that "eat" any lawsuit costs as "Cost of doing business." Example: Osram Sylvania sued for false ads/labeling saying Silverstar is so much better and cost 2+ times the price and often doesn't last more then a year or two. Now Osram selling LED "upgrades" like many others hiding behind "off road use only" knowing 98+% will be used illegally on US EU etc. roads. (Osram has owned Sylvania for over a Decade but you only see Sylvania brand in the US.)
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
I have NGK UR6 plugs, since they're supposed to be the same as stock, but a heat range colder, for my souped-up engine build.
I would like if someone had a list of recommended spark plugs as a function of engine horsepower, for the 2.8.
Doesn't exist. HP doesn't matter to plug type. Now if you change cylinder compression, use super/turbo charge, etc. that often can change plug heat range or not depending on a lot of other things including using exact fuel type.
I thought that HP was a convenient proxy for the amount of heat entering the spark plug's center electrode, and thus the amount of heat sinking the centre electrode needs to maintain the correct temperature.
I am interested in the discussion of what plug heat range is the best. My 3.1 is a mild street build. I really try to keep her running premium at all times. I pulled my plugs after about 20,000 miles and all looked very good. They are the run of the mill Delcos that come up when you hit up Oriely's. I heard good about the NGK's often.
Heat range is generally used to keep the center electrode insulator clean, and prevent fouling due to contamination from oil entering the combustion chamber. In performance engines there are more considerations, as detailed in the linked article.
Originally posted by Tony Kania: I pulled my plugs after about 20,000 miles and all looked very good.
If the plugs look good, then all is well, and don't mess with a winning recipe! Your engine is close to stock, so it makes sense that the stock heat range would work well.
In my build, I hope to add another 100 hp or thereabouts, so that's a lot more heat going into the centre electrode; heat that needs to be conducted to the head, lest the electrode overheat and cause preignition.
I suppose I'll be pulling the plugs somewhat often when I get my Fiero on the road, so I'll be able to see if the NGK UR6 makes for a good fouling vs. overheating compromise, and adjust if necessary. If I have to choose though, I think I prefer to err on the side of fouling plugs.
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Originally posted by olejoedad:
Heat range is generally used to keep the center electrode insulator clean, and prevent fouling due to contamination from oil entering the combustion chamber. In performance engines there are more considerations, as detailed in the linked article.
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