***blown Engine***
07-23-08, 12:47 PM
#26
Nub
Join Date: Jul 2008
Location: Arizona
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
Pics coming soon...
I have a theory on why it blew and was wondering if it has happened to anyone else.
My rev limiter is set by "fuel cut" and NOT "ignition cut".
That's where I believe it went wrong.
I had it tuned a few months ago and NEVER redlined it.
I have been racing it without going to the 8000 rpm redline, shifting at 7500 rpm.
I never felt the need to...until I raced this past weekend.
Then at the top of third...BOOM!!!
As soon as it hit rev limiter, it hit it's end.
I have a Haltech E8, and injecting 100% methanol.
~504 whp
~1680 cc injectors ALL AROUND
~(2)Coolingmist S-HSV controlled by the ecu
~(2)12 gph nozzles for meth
The S-HSVs are controlled via "generic pwm" and does NOT have a cut-off option.
Like I said earlier, the "rev limit" is controlled by "cutting fuel", BUT do you guys believe that the meth still spraying is what caused it to go lean and pop?
I expected it to be addressed already that "Meth injection should always be set with an ignition rev limiter."
Either I missed that or I obviously lack that common sense then.
I have a theory on why it blew and was wondering if it has happened to anyone else.
My rev limiter is set by "fuel cut" and NOT "ignition cut".
That's where I believe it went wrong.
I had it tuned a few months ago and NEVER redlined it.
I have been racing it without going to the 8000 rpm redline, shifting at 7500 rpm.
I never felt the need to...until I raced this past weekend.
Then at the top of third...BOOM!!!
As soon as it hit rev limiter, it hit it's end.
I have a Haltech E8, and injecting 100% methanol.
~504 whp
~1680 cc injectors ALL AROUND
~(2)Coolingmist S-HSV controlled by the ecu
~(2)12 gph nozzles for meth
The S-HSVs are controlled via "generic pwm" and does NOT have a cut-off option.
Like I said earlier, the "rev limit" is controlled by "cutting fuel", BUT do you guys believe that the meth still spraying is what caused it to go lean and pop?
I expected it to be addressed already that "Meth injection should always be set with an ignition rev limiter."
Either I missed that or I obviously lack that common sense then.
07-23-08, 01:32 PM
#28
BDC Motorsports
Additionally, timing drifts by a couple of degrees at higher rpm (typically around 2 degrees) so it is most likely running approx 14 degrees of advanced.
That can only be motivated by problems with a trigger as there's no reason for "timing to (just) drift". That's absurd. If there's any kind of spark scatter, the blame is on trigger unless there's something goofed with an ECU and in that case we oughta not even be using the damn thing in the first place. Take a look at the FC: it's notorious for having spark scatter due to the mechanical nature of the crank angle sensor. There's also issues with the older Haltechs and their lack of good trigger filtration when using the internal reluctors for converting our CAS output to a hall-effect type signal and that issue becomes prevelant up at higher RPM. It's why I have people w/ the E6K/E6X not shift above 7krpm. But an FD w/ a crank trigger wheel and dual magnet setup on a PowerFC, with unmodifiable, hardcoded trigger settings? There shouldn't be any "timing drift" especially "drift" that produces a seemingly-consistent amount of retard at high load (wow, what a convenient benefit!).
You should revisit your timing map methology before commenting on timing advance.
Sorry to hijack your thread, Gohan. I hope you get your setup sorted.
B
07-23-08, 02:05 PM
#29
Movie Star
Thread Starter
iTrader: (11)
Join Date: Dec 2003
Location: Fort Wayne, Indiana
Posts: 982
Likes: 0
Received 0 Likes
on
0 Posts
"At 7750 RPM it's injecting roughly 78% duty cycle.
I'm running two nozzles, both are rated at 12 gph or about 750cc/min together.
I'm running four 1600cc injectors of fuel or 6400cc/min together."
i am not clear on your meth injector sizing....
are you running two 12 GPH/756 CC/Min injectors or are you running two injectors that total 12 GPH?
i run two 700 CC/Min injectors on my FJO setup for a 1400 total..
anyway, you have it nailed... the engine went lean when you hit fuel cut and were still spraying meth.
your setup sounds like a real tiger. it must be fun to hang on to.
as to your IGL after peak torque, whether you add a degree or 3 you were toast w the fuel cut.
here's hoping you are back on the road soon... with an ignition cut.
howard coleman
I'm running two nozzles, both are rated at 12 gph or about 750cc/min together.
I'm running four 1600cc injectors of fuel or 6400cc/min together."
i am not clear on your meth injector sizing....
are you running two 12 GPH/756 CC/Min injectors or are you running two injectors that total 12 GPH?
i run two 700 CC/Min injectors on my FJO setup for a 1400 total..
anyway, you have it nailed... the engine went lean when you hit fuel cut and were still spraying meth.
your setup sounds like a real tiger. it must be fun to hang on to.
as to your IGL after peak torque, whether you add a degree or 3 you were toast w the fuel cut.
here's hoping you are back on the road soon... with an ignition cut.
howard coleman
07-23-08, 02:40 PM
#30
BDC Motorsports
07-23-08, 04:09 PM
#31
Rotary Freak
Join Date: Feb 2001
Location: fort worth, tx, usa
Posts: 1,926
Likes: 0
Received 0 Likes
on
0 Posts
1
It's not garden-variety detonation; it's pre-ignition from firing the plug too early. Sure, trailing can do it, but absolutely yes leading can do it as well. 16*BTDC isn't too much on a high quality race fuel at 1bar and above. Neither is a 7* split with the same lead timing using the same kind of fuel. But trying to do it on a highly volatile pump fuel of varying and unreliable quality? It's firing too early. There's no room for anything to go wrong.
If you think running 16 degrees with your 7 degrees split isn't too much, you should continue to run that setup and see how long your customers car would last. Additionally, split timing will only amplified with S4 rotor housing. I think it's funny that you keep blaming on the quality of gas being poor when it wasn't the case. Sure there are occasionally bad gas from the gas station but 93 octane is more than adequate to run 20psi in a rotary and 16-17psi on 91octane. 16 degrees isn't much at all when the split timing is set conservatively. I also find it funny coming from the same person who thinks running 11.5:1 a/f ratio is ideal on pump gas and anything richer is a waste of gas. What a/f do you tune to now?
... what?
That can only be motivated by problems with a trigger as there's no reason for "timing to (just) drift". That's absurd. If there's any kind of spark scatter, the blame is on trigger unless there's something goofed with an ECU and in that case we oughta not even be using the damn thing in the first place. Take a look at the FC: it's notorious for having spark scatter due to the mechanical nature of the crank angle sensor. There's also issues with the older Haltechs and their lack of good trigger filtration when using the internal reluctors for converting our CAS output to a hall-effect type signal and that issue becomes prevelant up at higher RPM. It's why I have people w/ the E6K/E6X not shift above 7krpm. But an FD w/ a crank trigger wheel and dual magnet setup on a PowerFC, with unmodifiable, hardcoded trigger settings? There shouldn't be any "timing drift" especially "drift" that produces a seemingly-consistent amount of retard at high load (wow, what a convenient benefit!).
You should revisit how trigger works. It's done by magnetic field (V=L*di/dt). There is a propagation delay at high rpm as it passes throught the magnetic field due to the X being the same but less t. Eventhough mazda runs the 12 tooth trigger setup, each tooth it passes through is 30 degrees and will always have a slight error. The only way to eliminate any drift is to have a finer resolution in trigger or use optical setup. You think engineers from Apexi PFC added the 2 degrees of advanced at higher rpm just for the hell of it? They done enough testing to see what I described and added the drift error onto their firmware to offset it.
I don't need to re-visit anything, Steve. I'm well studied in this from the school of hard knocks. I think it's you who should. You run advance too aggressively especially at high RPM. I've seen your spark advance maps I don't know how many times and I've wiped out more of them than I can count because nearly every single time they were firing way too early under heavy load. Personally, I would rather err on the side of caution, bring limits down some, run things more conservatively (namely the spark advance), and have a 5% or even 10% drop in overall power instead of having a blown engine a month or two after the fact.
Sorry to hijack your thread, Gohan. I hope you get your setup sorted.
Read my above comment. if you continue to run your 7 degrees split, you shouldn't run more than 14 degrees in advance. Enough said.
B
If you think running 16 degrees with your 7 degrees split isn't too much, you should continue to run that setup and see how long your customers car would last. Additionally, split timing will only amplified with S4 rotor housing. I think it's funny that you keep blaming on the quality of gas being poor when it wasn't the case. Sure there are occasionally bad gas from the gas station but 93 octane is more than adequate to run 20psi in a rotary and 16-17psi on 91octane. 16 degrees isn't much at all when the split timing is set conservatively. I also find it funny coming from the same person who thinks running 11.5:1 a/f ratio is ideal on pump gas and anything richer is a waste of gas. What a/f do you tune to now?
... what?
That can only be motivated by problems with a trigger as there's no reason for "timing to (just) drift". That's absurd. If there's any kind of spark scatter, the blame is on trigger unless there's something goofed with an ECU and in that case we oughta not even be using the damn thing in the first place. Take a look at the FC: it's notorious for having spark scatter due to the mechanical nature of the crank angle sensor. There's also issues with the older Haltechs and their lack of good trigger filtration when using the internal reluctors for converting our CAS output to a hall-effect type signal and that issue becomes prevelant up at higher RPM. It's why I have people w/ the E6K/E6X not shift above 7krpm. But an FD w/ a crank trigger wheel and dual magnet setup on a PowerFC, with unmodifiable, hardcoded trigger settings? There shouldn't be any "timing drift" especially "drift" that produces a seemingly-consistent amount of retard at high load (wow, what a convenient benefit!).
You should revisit how trigger works. It's done by magnetic field (V=L*di/dt). There is a propagation delay at high rpm as it passes throught the magnetic field due to the X being the same but less t. Eventhough mazda runs the 12 tooth trigger setup, each tooth it passes through is 30 degrees and will always have a slight error. The only way to eliminate any drift is to have a finer resolution in trigger or use optical setup. You think engineers from Apexi PFC added the 2 degrees of advanced at higher rpm just for the hell of it? They done enough testing to see what I described and added the drift error onto their firmware to offset it.
I don't need to re-visit anything, Steve. I'm well studied in this from the school of hard knocks. I think it's you who should. You run advance too aggressively especially at high RPM. I've seen your spark advance maps I don't know how many times and I've wiped out more of them than I can count because nearly every single time they were firing way too early under heavy load. Personally, I would rather err on the side of caution, bring limits down some, run things more conservatively (namely the spark advance), and have a 5% or even 10% drop in overall power instead of having a blown engine a month or two after the fact.
Sorry to hijack your thread, Gohan. I hope you get your setup sorted.
Read my above comment. if you continue to run your 7 degrees split, you shouldn't run more than 14 degrees in advance. Enough said.
B
07-23-08, 04:17 PM
#32
Movie Star
Thread Starter
iTrader: (11)
Join Date: Dec 2003
Location: Fort Wayne, Indiana
Posts: 982
Likes: 0
Received 0 Likes
on
0 Posts
I have a solenoid plumbed just prior to each nozzle.
07-23-08, 04:34 PM
#33
Junior Member
Join Date: Dec 2005
Location: Yorkshire United Kingdom
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
If there was total fuel cut under boost how much meths would need to be in the combustion chamber to cause problems? I'm sure i read on here somewhere that you needed 50% fuel in the combustion chamber to get a viable burn. From memory this was something Peter from rice racing posted in the racelogic group buy thread when questioned about the saftey of fuel cut.
Kevin
Kevin
Kevin
07-23-08, 04:40 PM
#34
Rotary Freak
Join Date: Feb 2001
Location: fort worth, tx, usa
Posts: 1,926
Likes: 0
Received 0 Likes
on
0 Posts
On gasoline, it's approximately 35%. I'm not too sure on just Methonal
07-23-08, 04:47 PM
#35
Junior Member
Join Date: Dec 2005
Location: Yorkshire United Kingdom
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
So if running a ratio of 80:20 fuel meths it should be safe to have a hard cut as meths is supposedly a harder mix to ignite in the combustion chamber?
Kevin
Kevin
07-23-08, 05:03 PM
#36
Rotary Freak
Join Date: Feb 2001
Location: fort worth, tx, usa
Posts: 1,926
Likes: 0
Received 0 Likes
on
0 Posts
I couldn't answer that since meth has a totally different property than gasoline but I think you should be safe.
07-24-08, 04:00 AM
#37
registered user
iTrader: (1)
Join Date: Jan 2006
Location: San Diego
Posts: 2,469
Likes: 0
Received 0 Likes
on
0 Posts
The only thing suspect is using the Generic pwm map for aux injection. I'm not too sure if it still continues to spray after 7750rpm. There were no adjustment for rpm range so 7750 is the highest it would go. We nevered tuned it past 7700rpm when it was tuned using the dyno pak (it limits how far to go). If the meth injection did shut off after 7750rpm, it would lean out by approx 14% off fuel and could damage the engine.
07-24-08, 08:23 AM
#38
Racing Rotary Since 1983
iTrader: (6)
steve: i assume when you talk the timing you are using the numbers you are referring are the logged number rather than the mapped number since you need to allow for the two additional degrees the PFC guys programmed in. am i correct?
if i understand this correctly you are spraying 1512 CC/Min of alcohol. you are running 4 1680 CC/Min injectors at 70-something duty cycle. you hit a fuel cut and approx 5000 CC/Min of base fuel is withdrawn probably leaving you with 1512 CC/Min of alcohol. given alcohol's flash ability i wouldn't be surprised that it could cause the problem.
OTOH:
after a month of working thru various aspects of my FJO twin solenoid (think fuel injector) setup i may also have another idea for you. our setups are somewhat similar in that they function entirely different than the traditional nozzle-pump speed governed systems.
your setup, if i understand it correctly, has 2 solenoids and a pump. something, i suppose your ECU, tells the solenoids when to pulse open.
two factors determine specific output: ontime and pressure.
depending on how your pump is directed you may have a pressure problem. your AI rail pressure could have been 14 psi rather than above 100.
the FJO unit has provision for logging rail pressure. we discovered that when using 100% alcohol that the pump, if continuously cycling at the ready, developed a methanol gas pocket. (this does not happen w water or 50/50 mix). as a result the pump is now directed in a stand down until needed fashion which works fine.
perhaps, this might have been the problem... i found pressure dropped to 14 psi w the gas bubble. fortunately i had not tuned up at that point. i dyno next tuesday.
good luck,
howard
if i understand this correctly you are spraying 1512 CC/Min of alcohol. you are running 4 1680 CC/Min injectors at 70-something duty cycle. you hit a fuel cut and approx 5000 CC/Min of base fuel is withdrawn probably leaving you with 1512 CC/Min of alcohol. given alcohol's flash ability i wouldn't be surprised that it could cause the problem.
OTOH:
after a month of working thru various aspects of my FJO twin solenoid (think fuel injector) setup i may also have another idea for you. our setups are somewhat similar in that they function entirely different than the traditional nozzle-pump speed governed systems.
your setup, if i understand it correctly, has 2 solenoids and a pump. something, i suppose your ECU, tells the solenoids when to pulse open.
two factors determine specific output: ontime and pressure.
depending on how your pump is directed you may have a pressure problem. your AI rail pressure could have been 14 psi rather than above 100.
the FJO unit has provision for logging rail pressure. we discovered that when using 100% alcohol that the pump, if continuously cycling at the ready, developed a methanol gas pocket. (this does not happen w water or 50/50 mix). as a result the pump is now directed in a stand down until needed fashion which works fine.
perhaps, this might have been the problem... i found pressure dropped to 14 psi w the gas bubble. fortunately i had not tuned up at that point. i dyno next tuesday.
good luck,
howard
07-24-08, 12:50 PM
#39
Rotary Freak
Join Date: Feb 2001
Location: fort worth, tx, usa
Posts: 1,926
Likes: 0
Received 0 Likes
on
0 Posts
I just looked at the halwin again. v1.62, v1.71, and v1.82b under "option", "variable rpm point setup". I didn't see an option for generic pwm map. Where on halwin would the generic rpm load pwm configuration be?
07-24-08, 12:59 PM
#40
Rotary Freak
Join Date: Feb 2001
Location: fort worth, tx, usa
Posts: 1,926
Likes: 0
Received 0 Likes
on
0 Posts
Howard,
The PFC firmware has a build-in 1 and 2 degree advance based on rpm. It does it automatically and you can see it on the log.
The PFC firmware has a build-in 1 and 2 degree advance based on rpm. It does it automatically and you can see it on the log.
steve: i assume when you talk the timing you are using the numbers you are referring are the logged number rather than the mapped number since you need to allow for the two additional degrees the PFC guys programmed in. am i correct?
if i understand this correctly you are spraying 1512 CC/Min of alcohol. you are running 4 1680 CC/Min injectors at 70-something duty cycle. you hit a fuel cut and approx 5000 CC/Min of base fuel is withdrawn probably leaving you with 1512 CC/Min of alcohol. given alcohol's flash ability i wouldn't be surprised that it could cause the problem.
OTOH:
after a month of working thru various aspects of my FJO twin solenoid (think fuel injector) setup i may also have another idea for you. our setups are somewhat similar in that they function entirely different than the traditional nozzle-pump speed governed systems.
your setup, if i understand it correctly, has 2 solenoids and a pump. something, i suppose your ECU, tells the solenoids when to pulse open.
two factors determine specific output: ontime and pressure.
depending on how your pump is directed you may have a pressure problem. your AI rail pressure could have been 14 psi rather than above 100.
the FJO unit has provision for logging rail pressure. we discovered that when using 100% alcohol that the pump, if continuously cycling at the ready, developed a methanol gas pocket. (this does not happen w water or 50/50 mix). as a result the pump is now directed in a stand down until needed fashion which works fine.
perhaps, this might have been the problem... i found pressure dropped to 14 psi w the gas bubble. fortunately i had not tuned up at that point. i dyno next tuesday.
good luck,
howard
if i understand this correctly you are spraying 1512 CC/Min of alcohol. you are running 4 1680 CC/Min injectors at 70-something duty cycle. you hit a fuel cut and approx 5000 CC/Min of base fuel is withdrawn probably leaving you with 1512 CC/Min of alcohol. given alcohol's flash ability i wouldn't be surprised that it could cause the problem.
OTOH:
after a month of working thru various aspects of my FJO twin solenoid (think fuel injector) setup i may also have another idea for you. our setups are somewhat similar in that they function entirely different than the traditional nozzle-pump speed governed systems.
your setup, if i understand it correctly, has 2 solenoids and a pump. something, i suppose your ECU, tells the solenoids when to pulse open.
two factors determine specific output: ontime and pressure.
depending on how your pump is directed you may have a pressure problem. your AI rail pressure could have been 14 psi rather than above 100.
the FJO unit has provision for logging rail pressure. we discovered that when using 100% alcohol that the pump, if continuously cycling at the ready, developed a methanol gas pocket. (this does not happen w water or 50/50 mix). as a result the pump is now directed in a stand down until needed fashion which works fine.
perhaps, this might have been the problem... i found pressure dropped to 14 psi w the gas bubble. fortunately i had not tuned up at that point. i dyno next tuesday.
good luck,
howard
07-24-08, 01:08 PM
#41
Racing Rotary Since 1983
iTrader: (6)
steve,
yes, i am aware of the 1 and 2 degree (stepped) add on the PFC v the map. i was just asking which timing you were referring to when you were talking numbers. i am pretty sure you were talking the real numbers, that is the logged numbers...
hc
yes, i am aware of the 1 and 2 degree (stepped) add on the PFC v the map. i was just asking which timing you were referring to when you were talking numbers. i am pretty sure you were talking the real numbers, that is the logged numbers...
hc
07-24-08, 01:30 PM
#42
Rotary Freak
Join Date: Feb 2001
Location: fort worth, tx, usa
Posts: 1,926
Likes: 0
Received 0 Likes
on
0 Posts
Yes, at least that's how I interpret it and also from what I tested on the dyno with a timing gun and an O-scope.
07-24-08, 02:14 PM
#43
registered user
iTrader: (1)
Join Date: Jan 2006
Location: San Diego
Posts: 2,469
Likes: 0
Received 0 Likes
on
0 Posts
Open the map in text view:
Maps (tab) chose a map, then chose text view...
Next go to the edit tab and remove the check box from "lock variable points"
Now in the text view you can edit at will both the RPM points and the map points.
After your done you must put the check back on "lock variable points" or it won't save the changes you have made.
This works for any haltech map that can be expressed in a text view.
Maps (tab) chose a map, then chose text view...
Next go to the edit tab and remove the check box from "lock variable points"
Now in the text view you can edit at will both the RPM points and the map points.
After your done you must put the check back on "lock variable points" or it won't save the changes you have made.
This works for any haltech map that can be expressed in a text view.
07-24-08, 02:58 PM
#44
"Elusive, not deceptive!”
Pics coming soon...
I have a theory on why it blew and was wondering if it has happened to anyone else.
My rev limiter is set by "fuel cut" and NOT "ignition cut".
That's where I believe it went wrong.
I had it tuned a few months ago and NEVER redlined it.
I have been racing it without going to the 8000 rpm redline, shifting at 7500 rpm.
I never felt the need to...until I raced this past weekend.
Then at the top of third...BOOM!!!
As soon as it hit rev limiter, it hit it's end.
I have a Haltech E8, and injecting 100% methanol.
~504 whp
~1680 cc injectors ALL AROUND
~(2)Coolingmist S-HSV controlled by the ecu
~(2)12 gph nozzles for meth
The S-HSVs are controlled via "generic pwm" and does NOT have a cut-off option.
Like I said earlier, the "rev limit" is controlled by "cutting fuel", BUT do you guys believe that the meth still spraying is what caused it to go lean and pop?
I expected it to be addressed already that "Meth injection should always be set with an ignition rev limiter."
Either I missed that or I obviously lack that common sense then.
I have a theory on why it blew and was wondering if it has happened to anyone else.
My rev limiter is set by "fuel cut" and NOT "ignition cut".
That's where I believe it went wrong.
I had it tuned a few months ago and NEVER redlined it.
I have been racing it without going to the 8000 rpm redline, shifting at 7500 rpm.
I never felt the need to...until I raced this past weekend.
Then at the top of third...BOOM!!!
As soon as it hit rev limiter, it hit it's end.
I have a Haltech E8, and injecting 100% methanol.
~504 whp
~1680 cc injectors ALL AROUND
~(2)Coolingmist S-HSV controlled by the ecu
~(2)12 gph nozzles for meth
The S-HSVs are controlled via "generic pwm" and does NOT have a cut-off option.
Like I said earlier, the "rev limit" is controlled by "cutting fuel", BUT do you guys believe that the meth still spraying is what caused it to go lean and pop?
I expected it to be addressed already that "Meth injection should always be set with an ignition rev limiter."
Either I missed that or I obviously lack that common sense then.
Have you taken it apart yet? What broke? What seals are your running? What do the housings look like around the spark plugs?
I think you need a good engine teardown and failure analysis before you and others jump to any conclusions. This information can help the whole community.
“Soapbox” We are a small group of rotary engine enthusiast. The only way that we can push the envelope effectively is if all work together.
Engine teardown pictures please,
Barry
07-25-08, 06:01 PM
#45
Movie Star
Thread Starter
iTrader: (11)
Join Date: Dec 2003
Location: Fort Wayne, Indiana
Posts: 982
Likes: 0
Received 0 Likes
on
0 Posts
Gohan3rdrift, sorry about your engine.
Have you taken it apart yet? What broke? What seals are your running? What do the housings look like around the spark plugs?
I think you need a good engine teardown and failure analysis before you and others jump to any conclusions. This information can help the whole community.
“Soapbox” We are a small group of rotary engine enthusiast. The only way that we can push the envelope effectively is if all work together.
Engine teardown pictures please,
Barry
Have you taken it apart yet? What broke? What seals are your running? What do the housings look like around the spark plugs?
I think you need a good engine teardown and failure analysis before you and others jump to any conclusions. This information can help the whole community.
“Soapbox” We are a small group of rotary engine enthusiast. The only way that we can push the envelope effectively is if all work together.
Engine teardown pictures please,
Barry
I've been preoccupied with other things so I haven't had time to tear into it yet.
I have some family coming over this weekend so I wont be able to get it apart until next weekend.
Sundays are my only days off so it'll be apart August 3rd and pictures will be posted that night.
My anniversary is the 2nd though so don't yell if I take a while.
