Plugs: 9s all around or mix 9s (leading) and 10s (trailing)
12-04-10, 08:14 AM
#1
Plugs: 9s all around or mix 9s (leading) and 10s (trailing)
Right now my car has B10EGV's all around. My trailing plugs always look fine, but the leading plugs typically are covered with a lot of carbon after only a couple thousand miles. The coils and everything seem fine, so it looks to me like the 10s are just too cold.
I went with 10s because the car was running close 500rwhp and I thought I needed them. Now I tuned the car down a bit, added a HF cat and running less boost, and am wondering if I should stick with the 10s.
Should I just go 9s all around, or should I just go with 9s (B9EGVs I guess) for the leading plugs and 10s for the trailing?
Thanks
I went with 10s because the car was running close 500rwhp and I thought I needed them. Now I tuned the car down a bit, added a HF cat and running less boost, and am wondering if I should stick with the 10s.
Should I just go 9s all around, or should I just go with 9s (B9EGVs I guess) for the leading plugs and 10s for the trailing?
Thanks
12-04-10, 09:57 AM
#2
Original Gangster/Rotary!
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What boost levels?
Based on your post, I'd say say go with BUR9EQ(P) all around. Those are proper rotary plugs, I'm not a fan of the ones that require the modded socket, are too short, and have no resistor.
Based on your post, I'd say say go with BUR9EQ(P) all around. Those are proper rotary plugs, I'm not a fan of the ones that require the modded socket, are too short, and have no resistor.
12-04-10, 10:05 AM
#3
I'm running 15-16 psi right now, and I would guess I'm right at a peak of 400-415 rwhp (just a guess; the car made 475 rwhp at 17.5 psi with a straight exhaust, as you know
). Yeah the modded socket is annoying as hell to deal with, it takes a lot of finesse to get the plugs in and out.
12-04-10, 12:11 PM
#4
Racing Rotary Since 1983
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simple...
if your plugs are blackish they are running too cold.
move warmer til they look light brown. the engine will run alot better. BTW, even w premix the FD will generate the proper plug color w the right heat range plug. if you can cope w the EGVs (special socket) they come in half heat ranges which can be helpful.
so you were right in your initial statement when you used the "cold" word.
anyone's engine will tell them the right heat range w plug color.
howard
if your plugs are blackish they are running too cold.
move warmer til they look light brown. the engine will run alot better. BTW, even w premix the FD will generate the proper plug color w the right heat range plug. if you can cope w the EGVs (special socket) they come in half heat ranges which can be helpful.
so you were right in your initial statement when you used the "cold" word.
anyone's engine will tell them the right heat range w plug color.
howard
12-04-10, 05:40 PM
#7
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I cannot tell you that I am a fan of 9's all around.
There is a reason the factory send the cars out w/ 7's and 9's. The rotor housing in the trailing plug location has a smaller hole as we all know. This smaller hole creates more heat and is why the colder plug is used in the trailing. If you are running 9's all around you are essentially running a hotter trailing plug due to the smaller hole.
Is this what you are trying to accomplish?
There is a reason the factory send the cars out w/ 7's and 9's. The rotor housing in the trailing plug location has a smaller hole as we all know. This smaller hole creates more heat and is why the colder plug is used in the trailing. If you are running 9's all around you are essentially running a hotter trailing plug due to the smaller hole.
Is this what you are trying to accomplish?
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12-05-10, 08:59 AM
#10
I cannot tell you that I am a fan of 9's all around.
There is a reason the factory send the cars out w/ 7's and 9's. The rotor housing in the trailing plug location has a smaller hole as we all know. This smaller hole creates more heat and is why the colder plug is used in the trailing. If you are running 9's all around you are essentially running a hotter trailing plug due to the smaller hole.
Is this what you are trying to accomplish?
There is a reason the factory send the cars out w/ 7's and 9's. The rotor housing in the trailing plug location has a smaller hole as we all know. This smaller hole creates more heat and is why the colder plug is used in the trailing. If you are running 9's all around you are essentially running a hotter trailing plug due to the smaller hole.
Is this what you are trying to accomplish?
12-05-10, 09:18 AM
#11
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there is no doubt that the best aftermarket rotary plugs are the NGK R6740's (Greddy RE## plugs) followed by the NGK R6725's. They are both pricy though, however I think the ideal setup for you would be the leading BUR 9's with trailing 10's.
12-05-10, 09:19 AM
#12
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I sold my single turbo car a month or so ago. The day I sold it the turbo let go and had to be replaced. It was making high 300's w/ a very poorly rebuilt turbo from a local rebuilder, I didn't realize how bad it was til it let go. I was running 9's L and 10.5 T at 16 PSI on 91 with a large street port. The turbo has since been changed to the turbo you are running and I have retuned the car for the new owner on the street. I would say he is pretty close to 430 now from feeling the car in comparison to others I have built/rode in. I'll have a dyno for it in a couple weeks.
My current car is a boring old twin turbo car.
Why would you not change the trailings when changing the leading?
My current car is a boring old twin turbo car.
Why would you not change the trailings when changing the leading?
12-05-10, 12:14 PM
#13
I run all stock 9's all around and trailing plugs are running too hot... I decided to buy Iridium R7420-9 and R7420-10 plugs (Greddy plugs) for track use next year. Best deal I found was on http://www.clubplug.net Get over $150 and get free shipping, I through a set of stock 9's in the order.
Btw, I beleive the R6725's are the platinum versions but are the same price...
Btw, I beleive the R6725's are the platinum versions but are the same price...
12-05-10, 01:07 PM
#14
I sold my single turbo car a month or so ago. The day I sold it the turbo let go and had to be replaced. It was making high 300's w/ a very poorly rebuilt turbo from a local rebuilder, I didn't realize how bad it was til it let go. I was running 9's L and 10.5 T at 16 PSI on 91 with a large street port. The turbo has since been changed to the turbo you are running and I have retuned the car for the new owner on the street. I would say he is pretty close to 430 now from feeling the car in comparison to others I have built/rode in. I'll have a dyno for it in a couple weeks.
My current car is a boring old twin turbo car.
Why would you not change the trailings when changing the leading?
My current car is a boring old twin turbo car.
Why would you not change the trailings when changing the leading?
The more I think about it, and the more reading Ive been doing, the more I agree with you. Especially since my trailing plugs are working out so well now. I'm going to stay with 10s in the trailing and go down to 9s in the leading. I also came across a thread that linked to the hks website and it said not to use non-resistor plugs with their twin power unit. I've been doing that for 2+ years
. The BURs do not come colder than 9, I don't want to spend $120+ on plugs, so now I'm thinking of going with BR10EIX and BR9EIX. As far as I can tell they are basically the same as the EGVs but with a resistor and Iridium, and a different gap size.
Is anyone using these, are they rotary friendly?
12-06-10, 10:29 AM
#16
Original Gangster/Rotary!
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Matt, the issue with noise and the HK$ tp is one reason to use a resistor plug. The other reason is the FD's Crank Angle Sensor pickup.
Ari and Chris over at RP/rx7.com recommend only resistor type plugs for this reason.
Glassman/Jules, nothing against Mr. Weiss and his uber-fast car, but just because the power is there and seems ok for now, doesn't mean it's a good idea. Tear down enough engines and you start to see trends, namely cracking in the rotor housing around the spark plug holes on high power/boost cars running 'warm' plugs.
Ari and Chris over at RP/rx7.com recommend only resistor type plugs for this reason.
Glassman/Jules, nothing against Mr. Weiss and his uber-fast car, but just because the power is there and seems ok for now, doesn't mean it's a good idea. Tear down enough engines and you start to see trends, namely cracking in the rotor housing around the spark plug holes on high power/boost cars running 'warm' plugs.
Last edited by GoodfellaFD3S; 12-06-10 at 10:32 AM.
12-06-10, 11:39 AM
#17
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The more I think about it, and the more reading Ive been doing, the more I agree with you. Especially since my trailing plugs are working out so well now. I'm going to stay with 10s in the trailing and go down to 9s in the leading. I also came across a thread that linked to the hks website and it said not to use non-resistor plugs with their twin power unit. I've been doing that for 2+ years .
The BURs do not come colder than 9, I don't want to spend $120+ on plugs, so now I'm thinking of going with BR10EIX and BR9EIX. As far as I can tell they are basically the same as the EGVs but with a resistor and Iridium, and a different gap size.
Is anyone using these, are they rotary friendly?
. The BURs do not come colder than 9, I don't want to spend $120+ on plugs, so now I'm thinking of going with BR10EIX and BR9EIX. As far as I can tell they are basically the same as the EGVs but with a resistor and Iridium, and a different gap size.
Is anyone using these, are they rotary friendly?
12-06-10, 07:47 PM
#19
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I'm running 11s on my setup, HKS TP with TII coils, T04S running 16 to 18 lbs boost, 100 octane unleaded. Connected the battery and fired her up last night after sitting since August or so of this year. Fires right up, even in the cold 40 to 50 degree air right now. I've had good luck with race plugs and this motor, going on 6 years with this setup.
I do find that it helps to be going track only and full on the gas all the time, I don't know how this would do in street form. I did use 10s and 10.5s for the street all year round in the old days.
I do find that it helps to be going track only and full on the gas all the time, I don't know how this would do in street form. I did use 10s and 10.5s for the street all year round in the old days.
12-07-10, 05:42 PM
#20
Matt, the issue with noise and the HK$ tp is one reason to use a resistor plug. The other reason is the FD's Crank Angle Sensor pickup.
Ari and Chris over at RP/rx7.com recommend only resistor type plugs for this reason.
Glassman/Jules, nothing against Mr. Weiss and his uber-fast car, but just because the power is there and seems ok for now, doesn't mean it's a good idea. Tear down enough engines and you start to see trends, namely cracking in the rotor housing around the spark plug holes on high power/boost cars running 'warm' plugs.
Ari and Chris over at RP/rx7.com recommend only resistor type plugs for this reason.
Glassman/Jules, nothing against Mr. Weiss and his uber-fast car, but just because the power is there and seems ok for now, doesn't mean it's a good idea. Tear down enough engines and you start to see trends, namely cracking in the rotor housing around the spark plug holes on high power/boost cars running 'warm' plugs.
Isn't it true that any "R" in a spark plugs part number means it's a resister plug?
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