Dented rotor faces
10-01-12, 12:28 AM
#1
Dented rotor faces
Well a few weeks ago I spent some coin and bought some 7240 ngk 11heat plugs and went out and started to turn boost up.
Let me state that i have been running this motor the last 3 years hard on 18-22psi... Stock studs. primary port matched to secondarys and earlier opening exhaust porting. CLASSIC rotary aviation apex seals and the rest is all stock oem seals including coolant seals.
Im running 200cc pre turbo injection and little over 700cc's at the throttle body of 50/50
Pump fuel with 1.5 oz to a gal mix ratio. And a monster fuel system.
The turbo is a 6766 precision with custom long runner maifold. 3" exhaust and open wastegate dump.
Well I went out and started to crank the boost up to see how well the motor and seals hold up to some high boost. My aem ems makes this really easy to do with just a few clicks. I started to get into a 4th gear pull while logging. once it hit boost it started to cut out bad even after lowering boost to 18 psi in which i have ran with my egv plugs just fine. Im thinking breakup or spark blowout because im not running a aftermarket ignition amp as i have never needed to with the egv series spark plugs. After a few failed attempts and no way to get the car to run in boost without cutting out i decided to quit for the night.
Im running 12* split in all boost . 17* timing at 15 psi and 5* at 30 psi
Got home and noticed its idling a little lumpy.
I pulled the motor out a few hours ago and noticed the rear rotor face is dented pretty bad but no blown seals.
Question is did heat kill the rotor even tho i didnt do a long pull or can the ignition breakup cause the face to dent? Or too small of exhaust building heat? I noticed the heat wrap on the manifold did not hold up. Its all crispy and flaking apart.
I will post some pics later this week when i tear the block down.
Let me state that i have been running this motor the last 3 years hard on 18-22psi... Stock studs. primary port matched to secondarys and earlier opening exhaust porting. CLASSIC rotary aviation apex seals and the rest is all stock oem seals including coolant seals.
Im running 200cc pre turbo injection and little over 700cc's at the throttle body of 50/50
Pump fuel with 1.5 oz to a gal mix ratio. And a monster fuel system.
The turbo is a 6766 precision with custom long runner maifold. 3" exhaust and open wastegate dump.
Well I went out and started to crank the boost up to see how well the motor and seals hold up to some high boost. My aem ems makes this really easy to do with just a few clicks. I started to get into a 4th gear pull while logging. once it hit boost it started to cut out bad even after lowering boost to 18 psi in which i have ran with my egv plugs just fine. Im thinking breakup or spark blowout because im not running a aftermarket ignition amp as i have never needed to with the egv series spark plugs. After a few failed attempts and no way to get the car to run in boost without cutting out i decided to quit for the night.
Im running 12* split in all boost . 17* timing at 15 psi and 5* at 30 psi
Got home and noticed its idling a little lumpy.
I pulled the motor out a few hours ago and noticed the rear rotor face is dented pretty bad but no blown seals.
Question is did heat kill the rotor even tho i didnt do a long pull or can the ignition breakup cause the face to dent? Or too small of exhaust building heat? I noticed the heat wrap on the manifold did not hold up. Its all crispy and flaking apart.
I will post some pics later this week when i tear the block down.
10-01-12, 01:23 AM
#3
talking head
the dents are from detonation,, common for s5 and FD rotors to do this
im expecting there is just a little too much timing there above 22 psi for the fuel.. regardless of the water/ meth injection ..
not a fan of the mixed AI ,, as some mix by volume , others by weight , and its not a clear science when you introduce especially platinum or irridium plugs which are known to catylise alcohol fuels
water AI is more predictable in its boundary cooling effect without unwanted or unpredictable side effects,, its there to replace mixture normally wasted on boundary quenching and slow down combustion so it remains a propogation and not a detonation event
excessive timing is still defeating the normal propogation
.. ive also added the case before where its all happening in the trailing quench zone and that increasing trailing timing ( narrowing the split ) will reduce effective compression in this zone
im expecting there is just a little too much timing there above 22 psi for the fuel.. regardless of the water/ meth injection ..
not a fan of the mixed AI ,, as some mix by volume , others by weight , and its not a clear science when you introduce especially platinum or irridium plugs which are known to catylise alcohol fuels
water AI is more predictable in its boundary cooling effect without unwanted or unpredictable side effects,, its there to replace mixture normally wasted on boundary quenching and slow down combustion so it remains a propogation and not a detonation event
excessive timing is still defeating the normal propogation
.. ive also added the case before where its all happening in the trailing quench zone and that increasing trailing timing ( narrowing the split ) will reduce effective compression in this zone
10-01-12, 01:41 AM
#4
what gets me is the 7240 plugs could not do the same boost as the EGV plugs without cutting out.... Either that or they were firing the mixture so well that it was just running that lean. And when the EGV plugs fire they are not igniting as well so they make a richer fire. Is this a possibility?
10-01-12, 02:04 AM
#5
talking head
the 7420s are irridium,,like platinum , is known to catalyse with ethanol and methanol
the egv are gold paladium.. paladium also being a handy catalyst ... but not known especially so with alcohol
its always been noted that platinum and irridum plugs can do funny things with those fuels .. but i dont blame them entirely
i look at the wide split .. and maybe just a little too much timing in the 22+ psi region -especially if a CAS engine ,, where a little wobble is normal and should be accounted for at this end of the sharp stick
..and the possibilty you dont always have equal AI to both runners at certain airflows,
the egv are gold paladium.. paladium also being a handy catalyst ... but not known especially so with alcohol
its always been noted that platinum and irridum plugs can do funny things with those fuels .. but i dont blame them entirely
i look at the wide split .. and maybe just a little too much timing in the 22+ psi region -especially if a CAS engine ,, where a little wobble is normal and should be accounted for at this end of the sharp stick
..and the possibilty you dont always have equal AI to both runners at certain airflows,
10-02-12, 11:21 AM
#7
I bet you had 3mm seals...? Anyway, I would go with 100% water injection if you don't want to worry about your IAT's in the engine. Other than that you'll have to monitor your knock levels and up the fuel or up the water injection to combat the situation.
I'm not sure why people do methanol injection if they have a big fuel system. The cooling effect can't match water and if you need more fuel you can just add it into the map. Again, I would switch over to 100% water injection.
I'm not sure why people do methanol injection if they have a big fuel system. The cooling effect can't match water and if you need more fuel you can just add it into the map. Again, I would switch over to 100% water injection.
Trending Topics
10-02-12, 11:31 AM
#8
Thats a shame.....Your car was running strong for quite some time. Good info to know. I'll be switching over to Water only as well. I have enough pump/injectors to deliver a pretty high volume. But i'll be running the 7425's heat ranges 10 leading and 10.5 trailing.
10-02-12, 12:12 PM
#9
Yea I ran the car hard for 3 years now. And 30 psi on pump gas and stock studs......hehe
I ran 50/50 to try it. I will stick with just water in the future.
I had rotary aviation 2mm CLASSICS. That all i have ran for the last 8 years with no customer combacks from a damaged or spit out apex seal. I have not taken the motor apart to see if they warped but i will keep this updated.
As for plug gap I dont remember off the top of my head.
Im going to go with a 20b in the car and low boost. 500hp on 10-12 psi should be fine for a street car not to mention the extra tourque will be nice as well.
I will have a ton of parts going up for sale soon to fund buying a 20b from
japan2la
Plus i was gonna sell the car and get a terminator cobra cuz I honestly cant stand the sound of a 2 rotor lol. A 20b sounds better than a v8 Imo
I ran 50/50 to try it. I will stick with just water in the future.
I had rotary aviation 2mm CLASSICS. That all i have ran for the last 8 years with no customer combacks from a damaged or spit out apex seal. I have not taken the motor apart to see if they warped but i will keep this updated.
As for plug gap I dont remember off the top of my head.
Im going to go with a 20b in the car and low boost. 500hp on 10-12 psi should be fine for a street car not to mention the extra tourque will be nice as well.
I will have a ton of parts going up for sale soon to fund buying a 20b from
japan2la
Plus i was gonna sell the car and get a terminator cobra cuz I honestly cant stand the sound of a 2 rotor lol. A 20b sounds better than a v8 Imo
10-02-12, 12:38 PM
#10
^ BEFORE YOU DO!! make sure you go check out the Bad guy transactions japan2la has held against him. Seems he's Jipped a lot of people in the past few months.... a couple people baught motors and never got them.. might be something to consider before you put any money down
10-02-12, 12:54 PM
#11
heat, detonation and faulty ignition.
this is one reason i don't run the cheapo plugs versus the real race $25 versions. at least for leadings, trailings aren't quite as necessary.
a light lack of internal lubrication or weak oil cooling can attribute to it, the rotors are cooled internally so if the oil isn't high enough in volume or isn't cooled well enough then the rotor cooling being lax weakens the metal enough so that it can be pushed in with enough force. hopefully you're not running the single oil cooler and run the better plugs.
and i also lean more on water only AI in most anything above 20psi on pump gas. as i always say, if you're going to inject fuel through a garden hose you have to expect inconsistencies. water only AI in the upper range does require a slightly touchy tuning hand though, your tuning window becomes quite narrow.
i would also strongly suggest an ignition amp, this will allow you to push more fuel more safely as a starting point.
you gotta pay to play. i have tested all the cheap methods and while some work they are almost never ideal. overbuild it, key point. E85 would be quite more forgiving in this scenario short of the stockish ignition system.
i also don't really see anything wrong with those timing figures, less split has proven to be more problematic in my builds but the timing up high is too retarded. additionally you can add in more timing after peak torque which generally hits at about 5650 RPMs.
on a side note i have never seen a single dented series 4 rotor, even the high CR turbo engines that spat seals, cracked plates or anything else that killed them.
this is one reason i don't run the cheapo plugs versus the real race $25 versions. at least for leadings, trailings aren't quite as necessary.
a light lack of internal lubrication or weak oil cooling can attribute to it, the rotors are cooled internally so if the oil isn't high enough in volume or isn't cooled well enough then the rotor cooling being lax weakens the metal enough so that it can be pushed in with enough force. hopefully you're not running the single oil cooler and run the better plugs.
and i also lean more on water only AI in most anything above 20psi on pump gas. as i always say, if you're going to inject fuel through a garden hose you have to expect inconsistencies. water only AI in the upper range does require a slightly touchy tuning hand though, your tuning window becomes quite narrow.
i would also strongly suggest an ignition amp, this will allow you to push more fuel more safely as a starting point.
you gotta pay to play. i have tested all the cheap methods and while some work they are almost never ideal. overbuild it, key point. E85 would be quite more forgiving in this scenario short of the stockish ignition system.
i also don't really see anything wrong with those timing figures, less split has proven to be more problematic in my builds but the timing up high is too retarded. additionally you can add in more timing after peak torque which generally hits at about 5650 RPMs.
on a side note i have never seen a single dented series 4 rotor, even the high CR turbo engines that spat seals, cracked plates or anything else that killed them.
Last edited by RotaryEvolution; 10-02-12 at 01:14 PM.
10-02-12, 03:31 PM
#12
Great points
I was running greddy brand 7240 race plugs when this all started. 45$ a plug
They def needed a amp thats for sure lol
The timing figures are at peak tq and i add a few degrees till peak power.
Yea im thinking of running s4 na rotors in the 20b build and low boost. It should make good power and have strong rotors.
I will def do e85 or c16 if i ever run a 2 rotor at high boost again.
Thanks for the input guys.
I was running greddy brand 7240 race plugs when this all started. 45$ a plug
They def needed a amp thats for sure lol
The timing figures are at peak tq and i add a few degrees till peak power.
Yea im thinking of running s4 na rotors in the 20b build and low boost. It should make good power and have strong rotors.
I will def do e85 or c16 if i ever run a 2 rotor at high boost again.
Thanks for the input guys.
heat, detonation and faulty ignition.
this is one reason i don't run the cheapo plugs versus the real race $25 versions. at least for leadings, trailings aren't quite as necessary.
a light lack of internal lubrication or weak oil cooling can attribute to it, the rotors are cooled internally so if the oil isn't high enough in volume or isn't cooled well enough then the rotor cooling being lax weakens the metal enough so that it can be pushed in with enough force. hopefully you're not running the single oil cooler and run the better plugs.
and i also lean more on water only AI in most anything above 20psi on pump gas. as i always say, if you're going to inject fuel through a garden hose you have to expect inconsistencies. water only AI in the upper range does require a slightly touchy tuning hand though, your tuning window becomes quite narrow.
i would also strongly suggest an ignition amp, this will allow you to push more fuel more safely as a starting point.
you gotta pay to play. i have tested all the cheap methods and while some work they are almost never ideal. overbuild it, key point. E85 would be quite more forgiving in this scenario short of the stockish ignition system.
i also don't really see anything wrong with those timing figures, less split has proven to be more problematic in my builds but the timing up high is too retarded. additionally you can add in more timing after peak torque which generally hits at about 5650 RPMs.
on a side note i have never seen a single dented series 4 rotor, even the high CR turbo engines that spat seals, cracked plates or anything else that killed them.
this is one reason i don't run the cheapo plugs versus the real race $25 versions. at least for leadings, trailings aren't quite as necessary.
a light lack of internal lubrication or weak oil cooling can attribute to it, the rotors are cooled internally so if the oil isn't high enough in volume or isn't cooled well enough then the rotor cooling being lax weakens the metal enough so that it can be pushed in with enough force. hopefully you're not running the single oil cooler and run the better plugs.
and i also lean more on water only AI in most anything above 20psi on pump gas. as i always say, if you're going to inject fuel through a garden hose you have to expect inconsistencies. water only AI in the upper range does require a slightly touchy tuning hand though, your tuning window becomes quite narrow.
i would also strongly suggest an ignition amp, this will allow you to push more fuel more safely as a starting point.
you gotta pay to play. i have tested all the cheap methods and while some work they are almost never ideal. overbuild it, key point. E85 would be quite more forgiving in this scenario short of the stockish ignition system.
i also don't really see anything wrong with those timing figures, less split has proven to be more problematic in my builds but the timing up high is too retarded. additionally you can add in more timing after peak torque which generally hits at about 5650 RPMs.
on a side note i have never seen a single dented series 4 rotor, even the high CR turbo engines that spat seals, cracked plates or anything else that killed them.
10-02-12, 06:31 PM
#13
try the R6725-105 leading plugs, they are about a quarter a piece, not cheap but also not nearly as expensive as that. i've even run stock BUR9EQ trailings up to 500WHP without even so much as a hiccup. they are only 10.5 heat range(6725) but that should still do the job.
i see many people staying with the mentality that mazda incorporated which is strong trailings, which i have not observed when bumping things up considerably. leadings require focus the most, spend the money there and just make sure the trailing is picking up the slack as it should be.
if you do run a high CR engine alcohol/race fuel is a must. these engines do not like much boost when running much higher than the stock FD 9.0:1CR. 14psi is pushing it even with water/meth AI with 9.4:1 rotors on pump gas, 20psi may be doable on lots of water but it may kick you in the nuts before even getting that far. the responsiveness is quite nice but they are also very unforgiving.
i see many people staying with the mentality that mazda incorporated which is strong trailings, which i have not observed when bumping things up considerably. leadings require focus the most, spend the money there and just make sure the trailing is picking up the slack as it should be.
if you do run a high CR engine alcohol/race fuel is a must. these engines do not like much boost when running much higher than the stock FD 9.0:1CR. 14psi is pushing it even with water/meth AI with 9.4:1 rotors on pump gas, 20psi may be doable on lots of water but it may kick you in the nuts before even getting that far. the responsiveness is quite nice but they are also very unforgiving.
Last edited by RotaryEvolution; 10-02-12 at 06:37 PM.
10-02-12, 06:31 PM
#14
talking head
s5 and FD rotor dent because the internal arrangement of the ribs supporting the rotor face has been altered and narrowed
s4 rotors that cop the same level of det will break something else instead , usually corner seals or the tip of the long section of the apex seal
s4 rotors that cop the same level of det will break something else instead , usually corner seals or the tip of the long section of the apex seal
10-02-12, 06:50 PM
#15
talking head
the dent is purely there as a result of the compression wave from the collision of two flame fronts .. heat has nothing to do with it ,,, the sort of heat needed to soften the cast iron would have carbonised the oil...
it pretty clear that mazda added the trailing plug and alters it timing so as to time the collision of a flame front from the leading plug to that propogating from the trailing plug
if that trailing spark is late.. then compression in the trailing quench zone can build . and be set off under sympathetic compression and superheating from the approaching leading wavefront
evidence of this supercompression and detonation is in the trailing area of the rotor face ,, ABOVE the rotor bath.. a dent..
bringing the trailing spark earlier will set the wavefront from the trailing plug in normal propogation towards that of the leading plug... the ignition happens BEFORE the trailing end of the rotor gets to superheat and supercompress
the dents in the rotor are CLEAR evidence of this ,, the position of the dent shows you that supercompression happens beyond the shape of the bath... the pretty obvious solution is to initiate that flame EARLIER when combustion pressures are still normalised
IE.. reduce split
and the only consequences of having too narrow a split are the flame front cancelling each other out before they have time to burn to the outside edges of the rotor ( evidence of this is in those SAE papers )
and if you build enough engines,, and you see some of them used on ecus without a split ( like on some older motechs etc )
then you see a copper stripe on stat bearing in an unusual spot,, evidence that twin firing the plugs all the time can be detrimental to the stat bearings
-- only an issue on those engines running NO split ALL the time
it pretty clear that mazda added the trailing plug and alters it timing so as to time the collision of a flame front from the leading plug to that propogating from the trailing plug
if that trailing spark is late.. then compression in the trailing quench zone can build . and be set off under sympathetic compression and superheating from the approaching leading wavefront
evidence of this supercompression and detonation is in the trailing area of the rotor face ,, ABOVE the rotor bath.. a dent..
bringing the trailing spark earlier will set the wavefront from the trailing plug in normal propogation towards that of the leading plug... the ignition happens BEFORE the trailing end of the rotor gets to superheat and supercompress
the dents in the rotor are CLEAR evidence of this ,, the position of the dent shows you that supercompression happens beyond the shape of the bath... the pretty obvious solution is to initiate that flame EARLIER when combustion pressures are still normalised
IE.. reduce split
and the only consequences of having too narrow a split are the flame front cancelling each other out before they have time to burn to the outside edges of the rotor ( evidence of this is in those SAE papers )
and if you build enough engines,, and you see some of them used on ecus without a split ( like on some older motechs etc )
then you see a copper stripe on stat bearing in an unusual spot,, evidence that twin firing the plugs all the time can be detrimental to the stat bearings
-- only an issue on those engines running NO split ALL the time
10-02-12, 10:01 PM
#16
if you say so
one engine i pulled apart had dents on all 6 faces, it coincidentally had lost all lubrication as well and was run until it shut down. maybe splitting hairs but this was a 100% stock FD running stock boost and as far as i know was not even being pushed when it blew.
the rotors are as susceptible to heat as any material, just many tend to think they see some insane temperatures like you see in the exhaust stream EGTs which is nowhere near true, take away that cooling and it is very nearly true. but at that point you have more to worry about, because the rotor sides are bonding to the irons at that point.
point is don't discount internal rotor oil volume and cooling as a consideration. the side seals, apex seals and everything in and around the rotor relies on that cooling to do it's job.
the rotors lack structural rigidity since they were designed to be lighter, unfortunately that created the weakness, heat does play a role but i wouldn't place most blame on it being the main cause but part of it.
one engine i pulled apart had dents on all 6 faces, it coincidentally had lost all lubrication as well and was run until it shut down. maybe splitting hairs but this was a 100% stock FD running stock boost and as far as i know was not even being pushed when it blew.
the rotors are as susceptible to heat as any material, just many tend to think they see some insane temperatures like you see in the exhaust stream EGTs which is nowhere near true, take away that cooling and it is very nearly true. but at that point you have more to worry about, because the rotor sides are bonding to the irons at that point.
point is don't discount internal rotor oil volume and cooling as a consideration. the side seals, apex seals and everything in and around the rotor relies on that cooling to do it's job.
the rotors lack structural rigidity since they were designed to be lighter, unfortunately that created the weakness, heat does play a role but i wouldn't place most blame on it being the main cause but part of it.
Last edited by RotaryEvolution; 10-02-12 at 10:17 PM.
10-02-12, 10:17 PM
#17
******
iTrader: (7)
Join Date: May 2009
Location: miami
Posts: 901
Likes: 0
Received 0 Likes
on
0 Posts
Great points
I was running greddy brand 7240 race plugs when this all started. 45$ a plug
They def needed a amp thats for sure lol
The timing figures are at peak tq and i add a few degrees till peak power.
Yea im thinking of running s4 na rotors in the 20b build and low boost. It should make good power and have strong rotors.
I will def do e85 or c16 if i ever run a 2 rotor at high boost again.
Thanks for the input guys.
I was running greddy brand 7240 race plugs when this all started. 45$ a plug
They def needed a amp thats for sure lol
The timing figures are at peak tq and i add a few degrees till peak power.
Yea im thinking of running s4 na rotors in the 20b build and low boost. It should make good power and have strong rotors.
I will def do e85 or c16 if i ever run a 2 rotor at high boost again.
Thanks for the input guys.
yes go e85 . you will have lots of fun with it
this is why i dont used s5/s6 rotors .
i stick to s4 turbo rotors and s4 na rotors which love the e85
Last edited by flaco; 10-02-12 at 10:19 PM. Reason: more
Thread
Thread Starter
Forum
Replies
Last Post
[For Sale] Scratch & Dent, Used, and Open-Box Sale!
SakeBomb Garage
Vendor Classifieds
5
08-09-18 05:54 PM
