Calling all FD HKS Twin Power Owners
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Joined: Feb 2009
Posts: 609
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From: Whatsittoya
Calling all FD HKS Twin Power Owners
I recently added the twin power. I was wondering how often the plugs need to be replaced now and if they can be cleaned instead of replaced?
I run 9's and am over 500RWHP...there are people that will tell you that you need colder plugs at my power level. I change my plugs once a year, and put ~3-4k miles per summer. 
FWIW, my twin power added 10RWHP...dyno'd before we installed it and dyno'd immediately after. 
FWIW, my twin power added 10RWHP...dyno'd before we installed it and dyno'd immediately after.
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How many miles per year do you put on your 7? I haven't had any issues with mine fouling, but again it's all about proactive/preventative maintenance. I change mine once per year and drive ~3-4k miles per summer. 
I change mine once per year and drive ~3-4k miles per summer.
You shouldn't need to alter your plug maintenance routine. Yes, you can clean the plugs. However, you need to do that in smaller intervals (i.e. not at every 2000 miles, but probably every 500-1000) as at some point, the plugs will get beyond where a cleaning will do any good. That will make your plugs usable much longer than just running until they foul.
Joined: Jan 2002
Posts: 922
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From: KC, KS
performance and longevity. They are inversely related.
HKS twin power in my experience reduces the life of your plugs and requires more frequent changes. That's not a big deal really. It comes with the territory when you modify a car. I also run the OEM platinum 9 heat range plugs (BUR9EQP). I don't like race plugs. They are expensive and hurt idle quality.
9 is actually a VERY cold plug when you put it in a broader perspective. there are plenty of turbo piston engines with exhaust temperatures close to a rotary that run 7's. Factory plugs on most turbo piston engines is a 6, and 5 for a non turbo.
HKS twin power in my experience reduces the life of your plugs and requires more frequent changes. That's not a big deal really. It comes with the territory when you modify a car. I also run the OEM platinum 9 heat range plugs (BUR9EQP). I don't like race plugs. They are expensive and hurt idle quality.
9 is actually a VERY cold plug when you put it in a broader perspective. there are plenty of turbo piston engines with exhaust temperatures close to a rotary that run 7's. Factory plugs on most turbo piston engines is a 6, and 5 for a non turbo.
It comes with the territory when you modify a car. I also run the OEM platinum 9 heat range plugs (BUR9EQP). I don't like race plugs. They are expensive and hurt idle quality.
9 is actually a VERY cold plug when you put it in a broader perspective. there are plenty of turbo piston engines with exhaust temperatures close to a rotary that run 7's.
9 is actually a VERY cold plug when you put it in a broader perspective. there are plenty of turbo piston engines with exhaust temperatures close to a rotary that run 7's.
9's are a lot more stout (and are a lot colder) than people give them credit for. 
I think the factory 4G63 Evo plug is a 7, and I know for sure that the factory STi plug is a 6. many people have run either of those engines have been run at 25psi on straight pump fuel with no colder than a 7 or 8. and we are talking EGT's of at least 1500-1600 preturbo
http://forums.evolutionm.net/7477844-post12.html
Evo 10's run 23psi from the factory and use an 8 heat range... granted that's much less horsepower than what heavily modified FD's are doing but that's still a lot of boost
http://forums.evolutionm.net/7477844-post12.html
Originally Posted by GST Motorsports
Evo 8:
Iridiums:
Stock heat range:
NGK iridium - BPR7EIX - $7.32/ea @ sparkplugs.com
Denso - IW22 - $11.99/ea @ sparkplugs.com
1/2 step colder:
NGK iridium - BR7EIX - $7.32/ea @ sparkplugs.com
1 step colder:
NGK iridium - BPR8EIX - $8.00/ea @ sparkplugs.com
Denso - IW24 - $11.99/ea @ sparkplugs.com
1 1/2 step colder:
NGK iridium - BR8EIX - $7.32/ea @ sparkplugs.com
Copper:
Gap @ .024-.026
Stock heat range:
NGK - BPR7ES - $2.24/ea @ sparkplugs.com
Denso - W22EPR-U - $2.24/ea @ sparkplugs.com
Autolite - 3924 - $1.90/ea @ Pep Boys or Kragen
1/2 step colder:
NGK - BR7ES - $2.24/ea @ sparkplugs.com
Denso - W22ESR-U - $2.24/ea @ sparkplugs.com
1 step colder:
NGK - BPR8ES - $2.24/ea @ sparkplugs.com
Denso - W24EPR-U - $2.24/ea @ sparkplugs.com
1 1/2 step colder:
NGK - BR8ES - $2.24/ea @ sparkplugs.com
Denso - W24ESR-U - $2.24/ea @ sparkplugs.com
Evo 9:
Iridiums:
Stock heat range:
NGK - ILFR7H - $11.71/ea @ sparkplugs.com
Denso - IKH22 - $11.95/ea @ sparkplugs.com
Autolite - XP5325 - $6.xx/ea @ Kragen
1 step colder:
NGK - R7437-8 - $41.52/ea @ sparkplugs.com
Denso - IKH24 - $11.95/ea @ sparkplugs.com
Evo 10:
Iridiums:
Stock heat range:
NGK - ILKR8E6 - OEM part #1822A021 - $13.23/ea @ mitsubishiparts.net
Iridiums:
Stock heat range:
NGK iridium - BPR7EIX - $7.32/ea @ sparkplugs.com
Denso - IW22 - $11.99/ea @ sparkplugs.com
1/2 step colder:
NGK iridium - BR7EIX - $7.32/ea @ sparkplugs.com
1 step colder:
NGK iridium - BPR8EIX - $8.00/ea @ sparkplugs.com
Denso - IW24 - $11.99/ea @ sparkplugs.com
1 1/2 step colder:
NGK iridium - BR8EIX - $7.32/ea @ sparkplugs.com
Copper:
Gap @ .024-.026
Stock heat range:
NGK - BPR7ES - $2.24/ea @ sparkplugs.com
Denso - W22EPR-U - $2.24/ea @ sparkplugs.com
Autolite - 3924 - $1.90/ea @ Pep Boys or Kragen
1/2 step colder:
NGK - BR7ES - $2.24/ea @ sparkplugs.com
Denso - W22ESR-U - $2.24/ea @ sparkplugs.com
1 step colder:
NGK - BPR8ES - $2.24/ea @ sparkplugs.com
Denso - W24EPR-U - $2.24/ea @ sparkplugs.com
1 1/2 step colder:
NGK - BR8ES - $2.24/ea @ sparkplugs.com
Denso - W24ESR-U - $2.24/ea @ sparkplugs.com
Evo 9:
Iridiums:
Stock heat range:
NGK - ILFR7H - $11.71/ea @ sparkplugs.com
Denso - IKH22 - $11.95/ea @ sparkplugs.com
Autolite - XP5325 - $6.xx/ea @ Kragen
1 step colder:
NGK - R7437-8 - $41.52/ea @ sparkplugs.com
Denso - IKH24 - $11.95/ea @ sparkplugs.com
Evo 10:
Iridiums:
Stock heat range:
NGK - ILKR8E6 - OEM part #1822A021 - $13.23/ea @ mitsubishiparts.net
Last edited by arghx; Dec 2, 2010 at 01:09 PM. Reason: Evo plugs
I think the factory 4G63 Evo plug is a 7, and I know for sure that the factory STi plug is a 6. many people have run either of those engines have been run at 25psi on straight pump fuel with no colder than a 7 or 8. and we are talking EGT's of at least 1500-1600 preturbo
http://forums.evolutionm.net/7477844-post12.html
Evo 10's run 23psi from the factory and use an 8 heat range... granted that's much less horsepower than what heavily modified FD's are doing but that's still a lot of boost
http://forums.evolutionm.net/7477844-post12.html
Evo 10's run 23psi from the factory and use an 8 heat range... granted that's much less horsepower than what heavily modified FD's are doing but that's still a lot of boost
Lets not forget that the leading plugs in an wasted spark Fd fires 3 times as often when comared to any 4 stroke piston engine. They get a cooling off period ours doesn't. Doesn't that account for something?
All 9's are great for a mildly modded twins car, or even single turbo 13b's that push lower boost (10-13psi). Once you start adding water injection and cranking the boost up, race plugs should be high on the priority list.
On my personal car (20B) I saw an immediate 37rwhp gain with the installation of R6725-10.5s from the BUR9EQP's at 12psi. They also made the car capable of boost higher that 15psi without frying plugs ever dyno pull. Our 13b-re Vert gained 16rwhp @15psi , from 435 to 451rwhp with only the addition of a set of 10's.
We have seen hp increase with all high boost 13b single turbo cars with the installation of 10.5's. Some increases as drastic as 75rwhp @ 24psi. We even tried a set of 10's in an N/A race car and picked up an immediate 10rwhp.
Additionally the colder plugs reduce the likelihood of cracking around the spark plug holes in the rotor housings.
On my personal car (20B) I saw an immediate 37rwhp gain with the installation of R6725-10.5s from the BUR9EQP's at 12psi. They also made the car capable of boost higher that 15psi without frying plugs ever dyno pull. Our 13b-re Vert gained 16rwhp @15psi , from 435 to 451rwhp with only the addition of a set of 10's.
We have seen hp increase with all high boost 13b single turbo cars with the installation of 10.5's. Some increases as drastic as 75rwhp @ 24psi. We even tried a set of 10's in an N/A race car and picked up an immediate 10rwhp.
Additionally the colder plugs reduce the likelihood of cracking around the spark plug holes in the rotor housings.
Last edited by Banzai-Racing; Dec 3, 2010 at 07:05 AM.
Dave @ KDR does not recommend them, after all his years of experience. 
We dyno'd my car time after time after time on 20+ psi, and I ran on these plugs all summer. I have no issues to report whatsoever.
Dave said he's had more problems fouling race plugs, and once they're done they're done (again according to him). The 9's are so much cheaper, and are definitely getting the job done for me while running around on 23 psi, so unless I see a drastic (and consistent) change in performance I'm going to continue to run them.
I suppose it all depends on who you talk to, and what their personal experience with xxx plugs has been.
We dyno'd my car time after time after time on 20+ psi, and I ran on these plugs all summer. I have no issues to report whatsoever. Dave said he's had more problems fouling race plugs, and once they're done they're done (again according to him). The 9's are so much cheaper, and are definitely getting the job done for me while running around on 23 psi, so unless I see a drastic (and consistent) change in performance I'm going to continue to run them.
I suppose it all depends on who you talk to, and what their personal experience with xxx plugs has been.
Joined: Mar 2001
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From: FL-->NJ/NYC again!
TRWeiss, you and I have similar setups and I personally would never run 9s at our boost levels. I also road race the car so for me the cold plugs are where it's at
I'd had the same set of NGK Race 10s in for many thousands of miles, around 3k now. Zero startup problems, zero driveability problems. This on a superb tune by Enzo out on Long Island.
In the past I did have problems w/the race plugs fouling out, and I believe alot of that has to do with the tune.
I'd had the same set of NGK Race 10s in for many thousands of miles, around 3k now. Zero startup problems, zero driveability problems. This on a superb tune by Enzo out on Long Island.
In the past I did have problems w/the race plugs fouling out, and I believe alot of that has to do with the tune.
^ I hear you, and do respect your opinion. I may run them in the future...who knows. I'm simply doing what Dave is suggesting, which is to run the 9's unless I run into some sort of problem. 
I figure his 25+ years of experience with rotaries has got to count for something! 
He just says that in his personal experience he's had a lot of trouble with them, that's all. Though it's quite possible that it's due to him being a conservative tuner, and thus the tunes are fouling out the plugs as you stated.
I'm simply doing what Dave is suggesting, which is to run the 9's unless I run into some sort of problem. I figure his 25+ years of experience with rotaries has got to count for something! He just says that in his personal experience he's had a lot of trouble with them, that's all. Though it's quite possible that it's due to him being a conservative tuner, and thus the tunes are fouling out the plugs as you stated.
Full Member
Joined: Feb 2010
Posts: 63
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From: New Zealand
Here is a real good thread how the Twin Power corrected an ignition issue. https://www.rx7club.com/power-fc-forum-47/high-load-stumble-909607/Keep in mind that, as far as plugs go, fowling is primarily due to oil and fuel, erosion is the ignition system amperage, and capability of spark is related to fuel/air mix pressure.
So:
If you are fowling the plugs look at the tune.
If you are having a plug erosion problem look to a cooler plug or plat plugs.
If you are having an ignition problem (like in the attached thread) look into a stronger ignition system.
So:
If you are fowling the plugs look at the tune.
If you are having a plug erosion problem look to a cooler plug or plat plugs.
If you are having an ignition problem (like in the attached thread) look into a stronger ignition system.