leading sparkplug hole modification
01-27-2013, 05:47 PM
#29
you might want to run the idea by your pals at Pettit, given the general issues around the Renesis leading plug as it is I'm banking on this only exacerbating the situation
it never fails that someone has to start proposing old engine ideas that don't really apply to the Renesis
it never fails that someone has to start proposing old engine ideas that don't really apply to the Renesis
01-27-2013, 08:21 PM
#30
Well, speaking of....
Spent the evening reading the Yamamoto Rotary Engine book.
http://foxed.ca/rx7manual/manuals/RE...amoto-1981.pdf
The information in there both shows better idle stability with the plug closer and (and this is the really interesting part!) knock only happens at 45-50deg ATDC ( at the peak pressure point on a properly tuned engine) and right where the trailing plug is ( and right below the stock knock sensor). So the way I'm thinking the only thing hot enough to cause knock there is the trailing spark plug. So using a much cooler plug (BUE) with a hot coil or CDI may do wonders with our engine's survivability. Or you could just plug the trailing hole. Thoughts?
Spent the evening reading the Yamamoto Rotary Engine book.
http://foxed.ca/rx7manual/manuals/RE...amoto-1981.pdf
The information in there both shows better idle stability with the plug closer and (and this is the really interesting part!) knock only happens at 45-50deg ATDC ( at the peak pressure point on a properly tuned engine) and right where the trailing plug is ( and right below the stock knock sensor). So the way I'm thinking the only thing hot enough to cause knock there is the trailing spark plug. So using a much cooler plug (BUE) with a hot coil or CDI may do wonders with our engine's survivability. Or you could just plug the trailing hole. Thoughts?
01-27-2013, 09:32 PM
#31
Rotary Evolution
the trailing plug to me has always been problematic, but for street cars and n/a applications it hardly ever crops up major issues. these are more FI ideas in promoting reliability.
01-27-2013, 10:15 PM
#32
Team--appreciate your suggestion but I am ahead of you. Calling Pettit tomorrow
There is the mazdaspeed washer that is 0.45 thick rather than the 1mm than comes with the plugs. Possibily use no washer--school is still out on that one. You are mandated to run a colder plug if this is done.
This is really nothing new--Thats why Mazdaspeed sells the thinner washers and why Yamamoto speaks of it. To the best of my knowledge no one has messed with it on the Rx8?
E mail already sent to Steve Kan ( tuner) but I dont think moving the plug kernal is going to have that big of an effect on timing--i am already very conservative at 14.5 with oem split. I will follow his lead though.
doing due diligence before I really try this out.
You have to ask questions to learn anything--right?
Harlan That is what I have always heard too. The trailing plug has more affect on detonation than the lead. I run the colder denso 32 plug for trailing.
Interesting idea about plugging the trailing hole--but our engines/computer really doesnt like to run well without the trailing working. For a drag race engine--yes maybe--but not a street engine?
Good position for the knock sensor--right?
I DO WANT TO WARN EVERYONE TO NOT TRY AND DO THIS WITHOUT PROPER DUE DILIGENCE. YOU COULD REALLY MESS YOUR ENGINE UP AND IT MAY BE FOR NOTHING. NO PROVEN GAINS HAVE BEEN FOUND...YET. RESEARCH CONTINUES.
There is the mazdaspeed washer that is 0.45 thick rather than the 1mm than comes with the plugs. Possibily use no washer--school is still out on that one. You are mandated to run a colder plug if this is done.
This is really nothing new--Thats why Mazdaspeed sells the thinner washers and why Yamamoto speaks of it. To the best of my knowledge no one has messed with it on the Rx8?
E mail already sent to Steve Kan ( tuner) but I dont think moving the plug kernal is going to have that big of an effect on timing--i am already very conservative at 14.5 with oem split. I will follow his lead though.
doing due diligence before I really try this out.
You have to ask questions to learn anything--right?
Harlan That is what I have always heard too. The trailing plug has more affect on detonation than the lead. I run the colder denso 32 plug for trailing.
Interesting idea about plugging the trailing hole--but our engines/computer really doesnt like to run well without the trailing working. For a drag race engine--yes maybe--but not a street engine?
Good position for the knock sensor--right?
I DO WANT TO WARN EVERYONE TO NOT TRY AND DO THIS WITHOUT PROPER DUE DILIGENCE. YOU COULD REALLY MESS YOUR ENGINE UP AND IT MAY BE FOR NOTHING. NO PROVEN GAINS HAVE BEEN FOUND...YET. RESEARCH CONTINUES.
01-29-2013, 11:49 AM
#34
Rotary Evolution
+1
this is a rather involved experiment, although many people have tried it before yet the results haven't really been proven that i have seen to date. i have seen many types of spark plugs used and in some cases the plugs did contact the apex seals and caused engine damage to occur.
02-08-2013, 06:21 PM
#35
Ok --lets see what happens.
I did this modification and ran my engine for approx 600 miles without washers around the lead sparkplug.
I had to take them out...................... why?
They were causing lean a/f's at certain repeatable points of my powerband. Thats right--they were. By that-- I mean a very noticeable difference. Like from a normal of 11.1 to a new 12.2-12.4!!
Now how did that happen? I have my ideas--but would like to hear from others too.
I did this modification and ran my engine for approx 600 miles without washers around the lead sparkplug.
I had to take them out...................... why?
They were causing lean a/f's at certain repeatable points of my powerband. Thats right--they were. By that-- I mean a very noticeable difference. Like from a normal of 11.1 to a new 12.2-12.4!!
Now how did that happen? I have my ideas--but would like to hear from others too.
02-08-2013, 09:58 PM
#37
Good call--but it's not that because it corrects itself as the rpms climb. It is only lean during rpms of 6-7.2K then after that the a/f's get rich again.
Now first I thought --uh oh bad injector/s--something. But i reinstalled the washers and those spots went away.
Now first I thought --uh oh bad injector/s--something. But i reinstalled the washers and those spots went away.
02-09-2013, 09:00 AM
#38
Interesting. If you wish to continue playing with fire, see what happens when you run 2 washers under each plug. Will the a/f go "rich"?
Why is this happening? A type of misfire. The a/f charge is moving in the chamber, away from the leading plug. If the spark is at the surface of the chamber, the initial burn is also moving with the charge. That delays (relative to e-shaft position) the lighting of the trailing charge. However the plug recess provides a pocket where a portion of the a/f mixture is stopped or slowed, it creates a torch, lighting a band of the main charge rather than just a point. <<--- speculation on my part. One would have to work out burn speeds and such to see if it makes sense.
Why is this happening? A type of misfire. The a/f charge is moving in the chamber, away from the leading plug. If the spark is at the surface of the chamber, the initial burn is also moving with the charge. That delays (relative to e-shaft position) the lighting of the trailing charge. However the plug recess provides a pocket where a portion of the a/f mixture is stopped or slowed, it creates a torch, lighting a band of the main charge rather than just a point. <<--- speculation on my part. One would have to work out burn speeds and such to see if it makes sense.
02-09-2013, 07:17 PM
#40
Lol--seems that way doesnt it?
Maybe I will go Isuzu...
But all I know is
1-my engine starts faster--this makes sense
2- my vacuum seems to be a little higher--i wish i have a more accurate way of checking it other than the boost/vac gauge i have been looking at for 6 years..
Does this mean anything?
lead sparkplug with washer on:
rpm 1201--1228 ( i idle at 1200)
maf no higher than 7.87
iat 68
washers off:
rpm 1200-1227
maf 8.1 no lower than 8.01
iat 87
coolant temps identical.
but better to be safe than sorry--right? So i have new denso's WITH washers on them until my tuner gets into town again. Then we can approach this in a more evidence ( or not) finding fashion.
Maybe I will go Isuzu...
But all I know is
1-my engine starts faster--this makes sense
2- my vacuum seems to be a little higher--i wish i have a more accurate way of checking it other than the boost/vac gauge i have been looking at for 6 years..
Does this mean anything?
lead sparkplug with washer on:
rpm 1201--1228 ( i idle at 1200)
maf no higher than 7.87
iat 68
washers off:
rpm 1200-1227
maf 8.1 no lower than 8.01
iat 87
coolant temps identical.
but better to be safe than sorry--right? So i have new denso's WITH washers on them until my tuner gets into town again. Then we can approach this in a more evidence ( or not) finding fashion.
Last edited by olddragger; 02-09-2013 at 07:31 PM.
02-09-2013, 08:12 PM
#41
Rotary Evolution
the shape of the leading plug opening may not compliment the closer spark plug. creating more apex seal lift instead of allowing the seals to skim over the smaller pocket. ultimately fouling the incoming intake charge.
just a guess.
next question is is the charge density the same with the leaner figure or is it less? that may be difficult to verify, especially now that you know you were pushing it a little too far past the edge unless you have many logs for comparison.
the IAT difference is probably just heat soaking from changing the plugs, i would find it difficult to swallow that the IAT was lower as a result of the plug location.
but i'm really curious how much air the engine is taking in under the same circumstances before and after. leading us to knowing if the engine was making more or less power.
just a guess.
next question is is the charge density the same with the leaner figure or is it less? that may be difficult to verify, especially now that you know you were pushing it a little too far past the edge unless you have many logs for comparison.
the IAT difference is probably just heat soaking from changing the plugs, i would find it difficult to swallow that the IAT was lower as a result of the plug location.
but i'm really curious how much air the engine is taking in under the same circumstances before and after. leading us to knowing if the engine was making more or less power.
Last edited by Karack; 02-09-2013 at 08:16 PM.
02-10-2013, 09:31 AM
#42
I included the iat because i was comparing the maf grams per sec. The air temp influences the grams per sec the maf sees and I wanted to show that there was only 1 degree difference.
It seems to be taking in slightly more at idle. As the rpms increase it is approx the same--i dont see much difference in maf numbers.
During those lean times I actually see less grams per sec.
I wish I had the equipment and skill to properly evaluate this modification.
It seems to be taking in slightly more at idle. As the rpms increase it is approx the same--i dont see much difference in maf numbers.
During those lean times I actually see less grams per sec.
I wish I had the equipment and skill to properly evaluate this modification.
02-10-2013, 03:08 PM
#44
completely agree. I wanted to pursue this modification in as safe of a manner as possible --just to see if there was any measurable difference in the cobb metrics. I saw a few. Unfortunately, the subjective impression was more visible ie: faster cranking etc.
So --i have seen enough to stop. It does change SOMETHING. At this point I can only speculate.
IMHO I do believe if done properly with full diagnostics available during the development--there would be a positive measurable result.
At the first opportunity I want to speak to Cam and Rick about this.Perhaps they can take it further--or who knows --maybe they already have?
So --i have seen enough to stop. It does change SOMETHING. At this point I can only speculate.
IMHO I do believe if done properly with full diagnostics available during the development--there would be a positive measurable result.
At the first opportunity I want to speak to Cam and Rick about this.Perhaps they can take it further--or who knows --maybe they already have?
02-12-2013, 08:33 PM
#45
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Don't know enough to know if good idea - pros/cons but came across these and thought about this thread.
"Forced induction spark plugs"
Mod Edit: Banned Vendor Link Removed
"Forced induction spark plugs"
Mod Edit: Banned Vendor Link Removed
02-13-2013, 06:10 AM
#49
R is a designation for a "Resistor" spark plug.
7240 is the NGK part number
https://www.dragtimes.com/parts/NGK-...519140473.html
I assume this is what they are talking about
7240 is the NGK part number
https://www.dragtimes.com/parts/NGK-...519140473.html
I assume this is what they are talking about
02-13-2013, 09:32 AM
#50
R is a designation for a "Resistor" spark plug.
7240 is the NGK part number
https://www.dragtimes.com/parts/NGK-...519140473.html
I assume this is what they are talking about
7240 is the NGK part number
https://www.dragtimes.com/parts/NGK-...519140473.html
I assume this is what they are talking about
BUR9EQP (5255): http://www.rotary13b1.com/p/1346/BUR...park-Plug.html
BUR7EQP (4764): http://www.rotary13b1.com/p/1345/BUR...park-Plug.html
Last edited by HiFlite999; 02-13-2013 at 09:45 AM.