Nitrous spark plug selection question
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Nitrous spark plug selection question
According to most nitrous kit manufactorers, they recommend to step down at least 1 heat range for a 100 - 150 shot and 2 heat ranges over 150 shot.
Now here is my question:
Right now, there are NGK BKR6ES-11 plugs in my engine.
Those are NON-Resistor plugs.. I used to have Resistor plugs in the engine before the rebuild (Autolite 3924).
The NGK BKR6ES-11 cross reference to the Autolite 3923 which are one heat range colder than the 3924's I had before.. I don't understand too much about spark plugs and the benefit etc. of going either with resistor or non-resistor plugs. Any information about that would be appreciated..
I researched and the next colder plugs from NGK would be the BCP7ES which is also a non-resistor plug.
So, I wonder... Can I go with the Autolite resistor plugs or would it be better to go with the non-resistor NGK plugs???? Any input is appreciated!
Another question would be about plug gaps.. I usually run .045 gap but I read that with nitrous, it's better to go with less gap.. Is that true and what gap would be a good starting point?
Now here is my question:
Right now, there are NGK BKR6ES-11 plugs in my engine.
Those are NON-Resistor plugs.. I used to have Resistor plugs in the engine before the rebuild (Autolite 3924).
The NGK BKR6ES-11 cross reference to the Autolite 3923 which are one heat range colder than the 3924's I had before.. I don't understand too much about spark plugs and the benefit etc. of going either with resistor or non-resistor plugs. Any information about that would be appreciated..
I researched and the next colder plugs from NGK would be the BCP7ES which is also a non-resistor plug.
So, I wonder... Can I go with the Autolite resistor plugs or would it be better to go with the non-resistor NGK plugs???? Any input is appreciated!
Another question would be about plug gaps.. I usually run .045 gap but I read that with nitrous, it's better to go with less gap.. Is that true and what gap would be a good starting point?
Last edited by GrandSportC3; Jan 6, 2007 at 09:36 AM.
Drifting
Joined: May 2005
Posts: 1,601
Likes: 0
From: BETHEL PARK PENNSYLVANIA
a resistor plug is designed to keep noise out of your radio. i thought you were to go with a colder plug for nos? i run ar3924 autolites in my 408 with a 125 shot. the ar is a race plug.
vc
vc
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
I mis-typed.. Of course I need colder and not hotter plugs.. Edited the post.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
hmmm.. doesn't it depend on the engine? That plug might be fine for a pump gas engine with nitrous but I doubt that the same applies to a high compression race engine with nitrous that runs on 112 octane race gas..
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Decided to step down 2 heat ranges to heat range 8 (6 right now)...
I also decided to go with racing plugs.. Let's see how those will work out!
NGK R5672A-8
I also decided to go with racing plugs.. Let's see how those will work out!
NGK R5672A-8
Racer
Joined: Jul 2004
Posts: 332
Likes: 0
From: Geneva Ohio
You are going in the right direction. I would say with your DA the -8 would work well on motor and with a small shot.
We usually run NGK -8 on motor and NGK -9 with nitrous. That is with 12.5 compresssion and good gas.
Like John says " read your plugs after every pass". The A/F meter is a valuable tool for tuning the carb but nitrous is a different animal. In our experience you don't want to see A/F ratio higher than 11:1 using the nitrous.
Using the short burst method like you are doing the big thing that you are going to look for is the grey or brown specks on the plug insulator. As you know that indicates pre ignition. If you see them on the plugs you will need to run a colder plug (-9) and/or take out some timing.
Just for your information, I think that you are going to need to bring in about a 150 shot around 2.5 seconds into the run to see a 9 second time slip. Of course that is assuming that you have a fairly tight converter.
But that is my guess. And good luck
We usually run NGK -8 on motor and NGK -9 with nitrous. That is with 12.5 compresssion and good gas.
Like John says " read your plugs after every pass". The A/F meter is a valuable tool for tuning the carb but nitrous is a different animal. In our experience you don't want to see A/F ratio higher than 11:1 using the nitrous.
Using the short burst method like you are doing the big thing that you are going to look for is the grey or brown specks on the plug insulator. As you know that indicates pre ignition. If you see them on the plugs you will need to run a colder plug (-9) and/or take out some timing.
Just for your information, I think that you are going to need to bring in about a 150 shot around 2.5 seconds into the run to see a 9 second time slip. Of course that is assuming that you have a fairly tight converter.
But that is my guess. And good luck
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
You are going in the right direction. I would say with your DA the -8 would work well on motor and with a small shot.
We usually run NGK -8 on motor and NGK -9 with nitrous. That is with 12.5 compresssion and good gas.
Like John says " read your plugs after every pass". The A/F meter is a valuable tool for tuning the carb but nitrous is a different animal. In our experience you don't want to see A/F ratio higher than 11:1 using the nitrous.
Using the short burst method like you are doing the big thing that you are going to look for is the grey or brown specks on the plug insulator. As you know that indicates pre ignition. If you see them on the plugs you will need to run a colder plug (-9) and/or take out some timing.
Just for your information, I think that you are going to need to bring in about a 150 shot around 2.5 seconds into the run to see a 9 second time slip. Of course that is assuming that you have a fairly tight converter.
But that is my guess. And good luck
We usually run NGK -8 on motor and NGK -9 with nitrous. That is with 12.5 compresssion and good gas.
Like John says " read your plugs after every pass". The A/F meter is a valuable tool for tuning the carb but nitrous is a different animal. In our experience you don't want to see A/F ratio higher than 11:1 using the nitrous.
Using the short burst method like you are doing the big thing that you are going to look for is the grey or brown specks on the plug insulator. As you know that indicates pre ignition. If you see them on the plugs you will need to run a colder plug (-9) and/or take out some timing.
Just for your information, I think that you are going to need to bring in about a 150 shot around 2.5 seconds into the run to see a 9 second time slip. Of course that is assuming that you have a fairly tight converter.
But that is my guess. And good luck
Here are a little more details on how I'll run the nitrous:
Safety setup:
1) WOT safety switch (only allows nitorus activation at WOT)
2) fuel pressure safety switch (shuts off if fuel pressure is below 5 psi)
3) MSD window switch. Nitrous will only be activated if the RPM is between 3000 and 6800. The rev limiter is set to 7000 rpm, so I'll avoid hitting the rev limiter with the spray on.
Retard setup:
Right now, I'm running a 4 degree retard pill in the retard system which puts me at a total of 32 degrees with spray. The retard system is activated with the same push button as the nitrous.
Right now, the plan is to spray as soon as I'm in 2nd gear, then go off the spray button when shifting and push it again after shifting into high gear..
What was your best on engine before you used the spray? How big of a shot?
Last edited by GrandSportC3; Jan 7, 2007 at 10:42 AM.
Racer
Joined: Jul 2004
Posts: 332
Likes: 0
From: Geneva Ohio
I don't know what converter you have in there, but usually we shift to second at 6800 just past the 60' mark at about 1.8 to 2.0 seconds. Bringing in the nitrous at about 2.5 seconds allows everything to settle in after the shift. You've got to know that the converter is going to absorb a lot if the initial nitrous hit.
That being said I would not shut the nitrous down between shifts because the converter is just starting to grab with the extra power. Then you are going to release it and start over again. That could be a dangerous mixture for everything concerned including trans, motor and traction.
That being said I would not shut the nitrous down between shifts because the converter is just starting to grab with the extra power. Then you are going to release it and start over again. That could be a dangerous mixture for everything concerned including trans, motor and traction.
Thread Starter
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
I don't know what converter you have in there, but usually we shift to second at 6800 just past the 60' mark at about 1.8 to 2.0 seconds. Bringing in the nitrous at about 2.5 seconds allows everything to settle in after the shift. You've got to know that the converter is going to absorb a lot if the initial nitrous hit.
That being said I would not shut the nitrous down between shifts because the converter is just starting to grab with the extra power. Then you are going to release it and start over again. That could be a dangerous mixture for everything concerned including trans, motor and traction.
That being said I would not shut the nitrous down between shifts because the converter is just starting to grab with the extra power. Then you are going to release it and start over again. That could be a dangerous mixture for everything concerned including trans, motor and traction.
The reason why I don't want to spray during the shift is because the transmission is stronger when in gear then during the shift...
The 1 - 2 shift occurs at about 1.3 seconds into the run. I have a 2.74 first gear and 4.11 rear gears. So, I'll hit the spray at about 1.5 seconds into the run, then I'll shift into 3rd gear early (usually shift at 6500 - 6800 RPM but with the spray I'll shift early) and go off the spray during the shift and then hit it again until the end of the run.
Last edited by GrandSportC3; Jan 7, 2007 at 11:35 AM.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
3.5 to 4 /10's is a lot of e.t. to gain in a mid 10 second car. I have never used the -8's and have had great luck with the -9's.
Your next motor will need -9's or even -10's
I think your plan will gain an appreciable amount of MPH, but not much et. I agree with Daren that you need to put the power to the car as quick as possible to get a 9 sec slip. NA converters are not efficient nitrous converters, granted we are only talking about a 100 shot, but the rule still applies.
Not totally an apples to apples comparison; but when I first ran nitrous in my current car the car would go 9.40's on the motor at 140-141 mph. I made one run that I engaged the nitrous (150 shot) at about 60' and the car went 8.995 at 154.
Your next motor will need -9's or even -10's
I think your plan will gain an appreciable amount of MPH, but not much et. I agree with Daren that you need to put the power to the car as quick as possible to get a 9 sec slip. NA converters are not efficient nitrous converters, granted we are only talking about a 100 shot, but the rule still applies.
Not totally an apples to apples comparison; but when I first ran nitrous in my current car the car would go 9.40's on the motor at 140-141 mph. I made one run that I engaged the nitrous (150 shot) at about 60' and the car went 8.995 at 154.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
I agree that going off the nitrous between shifts could upset the chassis and cause the car to unload and break traction. If you do this be careful, don't want the thing to swap ends on you. The IRS might actually help with this issue.