Need Spark Plug Recommendation
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Need Spark Plug Recommendation
Hello everyone. I have a 1985 Corvette that made 344 rwhp and 343 rwtq. The engine set up is as follows: TPIS Miniram, TPIS flat tappet cam (224*/224* duration @ 0.050", 0.528"/0.528" total valve lift with 1.6 RR, 112* LSA), 58mm throttle body, AFR 195 Eliminator Cylinder Heads, 10:1 compression, 0.052" quench, 1 3/4" long tube Hooker headers, 1.6 comp cam roller rockers, Corsa 2 1/2" true dual exhaust with H-pipe, MSD 6AL2 ignition box, and other minor mods.
So the plugs that I am currently using have worked really well for me. They have never fouled out even with prolonged idling. They also don't appear to be overheating either. The ones I am using are stock spec AC Delco for a 1990 Corvette. They are AC Delco FR5LS.
I just purchased a nitrous kit and I want to run a 100 shot. But I don't want to change plugs every time that I want to use it. So I need a plug that won't foul out on me during normal driving but that also won't detonate or preignite during nitrous use. So can I get a recommendation on what spark plug to use for this?
Thank you very much.
So the plugs that I am currently using have worked really well for me. They have never fouled out even with prolonged idling. They also don't appear to be overheating either. The ones I am using are stock spec AC Delco for a 1990 Corvette. They are AC Delco FR5LS.
I just purchased a nitrous kit and I want to run a 100 shot. But I don't want to change plugs every time that I want to use it. So I need a plug that won't foul out on me during normal driving but that also won't detonate or preignite during nitrous use. So can I get a recommendation on what spark plug to use for this?
Thank you very much.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
If A/F ratio is correct you won't foul plugs. I would stay with what you have until after you get NO2 set up. It should only take a few runs to know if you need a hotter or colder plug. Pre-ignition and detonation don't require spark plug it's self ignition. NO2 can require higher secondary ignition voltage to prevent misfiring.You do want to make sure you coil and plug wires are able to perform without misfiring.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Thanks for the response.
I have been doing some research on many threads and asked questions from NGK and some of my friends. The research totals at about 6 hours or more for this. I have determined that an NGK plug in the heat range of #6 will probably be the best for what I am doing.
I ran NGK BKR6E spark plugs in 2014, and I cannot find any evidence of me saying anything negative about them, other than me over tightening and cracking them and my old spark plug wires causing misfires. I could find no evidence to suggest that they were fouling on their own. I ran these with the same engine set up that I have now, with some slight insignificant differences.
When I contacted NGK, they recommended a heat range of 6, but told me to use some crazy spark plug that was a terrible combo for nitrous use.
The research I have done has shown that a lot of people with 383s and AFR 195 heads are using NGK #6 plugs. Lots of mentions of the TR6 plugs with nitrous, and lots of mentions of BKR6E on a 383.
So I think that a #6 or a #7 is going to be right for me. And with a non-projected tip, given that it will decrease spark plug operating temperature slightly further, I think that a 7 would be the best to start with. I would be able to see if it fouled under colder engine temps and idling/no load conditions. However, I really think that a #6 is going to be perfect.
Not sure at this point what to do, do I get the 6? Can someone say confidently that the 6 will probably be perfect, or do I get the 7 first?
Also, the factory recommended plugs for an 85 from AC Delco have a heat range of 3, I am using a heat range of 5 from AC Delco now (which is hotter on their scale). Stock NGK recommendation is a 5 heat range on NGK's scale.
They say to back off 1 heat range for every 100 hp, I have added about 175 hp over stock, so I should probably be using a NGK 7 heat range now according to that and then with the 100 shot of nitrous I should be running an NGK 8 heat range. That just seems too cold to me. My friend is using a NGK 7 heat range plug on a twin turbo LT1 with an estimated 800 rwhp.
This is the spark plug that I am interested in at the moment. Thanks.
http://www.summitracing.com/parts/ngk-4922/overview/
I have been doing some research on many threads and asked questions from NGK and some of my friends. The research totals at about 6 hours or more for this. I have determined that an NGK plug in the heat range of #6 will probably be the best for what I am doing.
I ran NGK BKR6E spark plugs in 2014, and I cannot find any evidence of me saying anything negative about them, other than me over tightening and cracking them and my old spark plug wires causing misfires. I could find no evidence to suggest that they were fouling on their own. I ran these with the same engine set up that I have now, with some slight insignificant differences.
When I contacted NGK, they recommended a heat range of 6, but told me to use some crazy spark plug that was a terrible combo for nitrous use.
The research I have done has shown that a lot of people with 383s and AFR 195 heads are using NGK #6 plugs. Lots of mentions of the TR6 plugs with nitrous, and lots of mentions of BKR6E on a 383.
So I think that a #6 or a #7 is going to be right for me. And with a non-projected tip, given that it will decrease spark plug operating temperature slightly further, I think that a 7 would be the best to start with. I would be able to see if it fouled under colder engine temps and idling/no load conditions. However, I really think that a #6 is going to be perfect.
Not sure at this point what to do, do I get the 6? Can someone say confidently that the 6 will probably be perfect, or do I get the 7 first?
Also, the factory recommended plugs for an 85 from AC Delco have a heat range of 3, I am using a heat range of 5 from AC Delco now (which is hotter on their scale). Stock NGK recommendation is a 5 heat range on NGK's scale.
They say to back off 1 heat range for every 100 hp, I have added about 175 hp over stock, so I should probably be using a NGK 7 heat range now according to that and then with the 100 shot of nitrous I should be running an NGK 8 heat range. That just seems too cold to me. My friend is using a NGK 7 heat range plug on a twin turbo LT1 with an estimated 800 rwhp.
This is the spark plug that I am interested in at the moment. Thanks.
http://www.summitracing.com/parts/ngk-4922/overview/
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
I would think you go one number colder with spray.
I would start with stock and hook up a laptop to see how it runs with the current plug. I would also think that you'd get the car working 100% perfectly for a few months before you go sticking more complexity on it, but my point is wasted.
I would start with stock and hook up a laptop to see how it runs with the current plug. I would also think that you'd get the car working 100% perfectly for a few months before you go sticking more complexity on it, but my point is wasted.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
I would think you go one number colder with spray.
I would start with stock and hook up a laptop to see how it runs with the current plug. I would also think that you'd get the car working 100% perfectly for a few months before you go sticking more complexity on it, but my point is wasted.
I would start with stock and hook up a laptop to see how it runs with the current plug. I would also think that you'd get the car working 100% perfectly for a few months before you go sticking more complexity on it, but my point is wasted.
