13B PP Ignition breakup
05-20-13, 02:57 PM
#51
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I have been running PP road racing engines since 1997.
Do you have Mazda Factory Racing PP housings, or do you have street housings that have been made into racing PP housings?
For MFR PP housings, they are made for 20 Deg BTDC timing, both leading and trailing. These housings have the spark plugs located slightly differently than street rotary housings, so their timing requirements are slightly different.
For street housings that have been made into PP housings, I run leading 24 BTDC and trailing 18 BTDC.
I use an '81 - '83 stock distributor, and I dyno at 320 rwhp.
I warm up with 7 or 8 heat range NGKs, and then I use the 11.5 plugs for road racing. The 9 and 10 heat range plug will overheat the tip, which will cause detonation when running on straights longer than 3/8 mile. The hotter plugs will run okay for short bursts, but they engine will break up when running longer, sustained runs. For example, the 10 will run okay for one 1/4 mile pass, but if you turned around and ran 3 back to back 1/4 mile runs with no cool down in between, then the 10 heat range plugs will cause the engine to misfire. I fought this problem for awhile until an experience racer gave me a set of old 11.5 plugs, and that cured most tuning problems with my PP motor.
Also, your spark plug gap is much too wide. For a high rpm PP motor, you should be running 0.65mm gap.
Do you have Mazda Factory Racing PP housings, or do you have street housings that have been made into racing PP housings?
For MFR PP housings, they are made for 20 Deg BTDC timing, both leading and trailing. These housings have the spark plugs located slightly differently than street rotary housings, so their timing requirements are slightly different.
For street housings that have been made into PP housings, I run leading 24 BTDC and trailing 18 BTDC.
I use an '81 - '83 stock distributor, and I dyno at 320 rwhp.
I warm up with 7 or 8 heat range NGKs, and then I use the 11.5 plugs for road racing. The 9 and 10 heat range plug will overheat the tip, which will cause detonation when running on straights longer than 3/8 mile. The hotter plugs will run okay for short bursts, but they engine will break up when running longer, sustained runs. For example, the 10 will run okay for one 1/4 mile pass, but if you turned around and ran 3 back to back 1/4 mile runs with no cool down in between, then the 10 heat range plugs will cause the engine to misfire. I fought this problem for awhile until an experience racer gave me a set of old 11.5 plugs, and that cured most tuning problems with my PP motor.
Also, your spark plug gap is much too wide. For a high rpm PP motor, you should be running 0.65mm gap.
05-22-13, 05:47 AM
#52
Exhaust Manifold Leak
Thread Starter
Nice car, is it stock body with fiberglass fenders or complete fiberglass with tube frame?
I have street housings, I think they are early rx4 13B housings, the ones where there is no 13B casted one them.
as I said, the picture of the plugs I posted is after 1 hour of circuit racing, straights are much about 300-400m long, and lap time is around 1.15 min.
so maybe 50 laps, and the plugs are still dark brown, leadings where wet, no damage at all to the porcelain??
could it be because we run no thermostat? water is maybe 60 degC, also after a few full load pulls, the plugs are still cold and you can easily hold them in your hand.
I have street housings, I think they are early rx4 13B housings, the ones where there is no 13B casted one them.
as I said, the picture of the plugs I posted is after 1 hour of circuit racing, straights are much about 300-400m long, and lap time is around 1.15 min.
so maybe 50 laps, and the plugs are still dark brown, leadings where wet, no damage at all to the porcelain??
could it be because we run no thermostat? water is maybe 60 degC, also after a few full load pulls, the plugs are still cold and you can easily hold them in your hand.
05-22-13, 02:55 PM
#53
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Can you give me details of your carb settings: what size venturies, what size air jets, what size mains?
I would love if my water temps were as cool as 60C. In the deep southern USA where I race, the air temps are pretty warm, so my water temp is usually around 100C. I run a 82C thermostat, to help the engine warm up quicker. My water temps are measured at the hottest part of the system, where the water is leaving the engine at the thermostat location.
Where is your water temp sensor?
I would love if my water temps were as cool as 60C. In the deep southern USA where I race, the air temps are pretty warm, so my water temp is usually around 100C. I run a 82C thermostat, to help the engine warm up quicker. My water temps are measured at the hottest part of the system, where the water is leaving the engine at the thermostat location.
Where is your water temp sensor?
05-22-13, 02:59 PM
#55
05-23-13, 02:49 AM
#56
Exhaust Manifold Leak
Thread Starter
I didnt take the carb apart yet, but the info about the throttle was supplied by the previous owner. the reason why I did not take it apart yet is that it runs quite good afr at wot in the rpm where we drive at the track, at low rpm it is quite rich, but idle is close to lambda 1, so around 14 afr. wot afr is around 13.5 from 5-9k rpm.
our sensor is located in the stock location, below the oil filter pedestral, so you are right at the thermostat housing it will be slightly warmer.
maybe also the exh is to small? it runs 2" (52mm OD) primaries till before the diff, these have resonators (hot dog style) and then it collectes into a 2.5"collector, goes under the diff and then there is antoher 2.5" straight trough muffler..
our sensor is located in the stock location, below the oil filter pedestral, so you are right at the thermostat housing it will be slightly warmer.
maybe also the exh is to small? it runs 2" (52mm OD) primaries till before the diff, these have resonators (hot dog style) and then it collectes into a 2.5"collector, goes under the diff and then there is antoher 2.5" straight trough muffler..
05-23-13, 10:52 AM
#57
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Mine runs richer, close to 12.5 when in the power band, 6000-8900 rpms.
I run twin 2" primary pipes to a merge collector, which necks down to a 2.38" diameter throat, then it has a smooth tapered expansion cone up to 3" diameter. I have a 3" diameter Borla straight thru muffler on the end to knock the noise level down a little. I usually temporarily restrict the very end of the pipe during my morning warm up of the engine, just to keep from irritating the other people in the paddock at the race track.
I race mostly against Porsche 911 RSR with 3.0 liter motors, and occasionally against other RX-7s.
I run twin 2" primary pipes to a merge collector, which necks down to a 2.38" diameter throat, then it has a smooth tapered expansion cone up to 3" diameter. I have a 3" diameter Borla straight thru muffler on the end to knock the noise level down a little. I usually temporarily restrict the very end of the pipe during my morning warm up of the engine, just to keep from irritating the other people in the paddock at the race track.
I race mostly against Porsche 911 RSR with 3.0 liter motors, and occasionally against other RX-7s.
05-23-13, 11:18 AM
#58
Exhaust Manifold Leak
Thread Starter
I think if our rx3 would have 320hp at the wheels a 911 rsr would not have much chance.. as the car is now (runing gguessing max 220hp at the wheels) it is equally fast in the corners, but it lacks oomph on the straights..
seems your exh is almost identical to mine, just you are running a 3"muffler where I a, running a 2.5".
do you think the resonators before the merge collector hurt top end? theyare also 2"
seems your exh is almost identical to mine, just you are running a 3"muffler where I a, running a 2.5".
do you think the resonators before the merge collector hurt top end? theyare also 2"
05-24-13, 01:54 PM
#59
Rotary Freak
I have been running PP road racing engines since 1997.
Do you have Mazda Factory Racing PP housings, or do you have street housings that have been made into racing PP housings?
For MFR PP housings, they are made for 20 Deg BTDC timing, both leading and trailing. These housings have the spark plugs located slightly differently than street roatary housings, so their timing requirements are slightly different.
For street housings that have been made into PP housings, I run leading 24 BTDC and trailing 18 BTDC.
I use an '81 - '83 stock distributor, and I dyno at 320 rwhp.
I warm up with 7 or 8 heat range NGKs, and then I use the 11.5 plugs for road racing. The 9 and 10 heat range plug will overheat the tip, which will cause detonation when running on straights longer than 3/8 mile. The hotter plugs will run okay for short bursts, but they engine will break up when running longer, sustained runs. For example, the 10 will run okay for one 1/4 mile pass, but if you turned around and ran 3 back to back 1/4 mile runs with no cool down in between, then the 10 heat range plugs will cause the engine to misfire. I fought this problem for awhile until an experience racer gave me a set of old 11.5 plugs, and that cured most tuning problems with my PP motor.
Also, your spark plug gap is much too wide. For a high rpm PP motor, you should be running 0.65mm gap.
Do you have Mazda Factory Racing PP housings, or do you have street housings that have been made into racing PP housings?
For MFR PP housings, they are made for 20 Deg BTDC timing, both leading and trailing. These housings have the spark plugs located slightly differently than street roatary housings, so their timing requirements are slightly different.
For street housings that have been made into PP housings, I run leading 24 BTDC and trailing 18 BTDC.
I use an '81 - '83 stock distributor, and I dyno at 320 rwhp.
I warm up with 7 or 8 heat range NGKs, and then I use the 11.5 plugs for road racing. The 9 and 10 heat range plug will overheat the tip, which will cause detonation when running on straights longer than 3/8 mile. The hotter plugs will run okay for short bursts, but they engine will break up when running longer, sustained runs. For example, the 10 will run okay for one 1/4 mile pass, but if you turned around and ran 3 back to back 1/4 mile runs with no cool down in between, then the 10 heat range plugs will cause the engine to misfire. I fought this problem for awhile until an experience racer gave me a set of old 11.5 plugs, and that cured most tuning problems with my PP motor.
Also, your spark plug gap is much too wide. For a high rpm PP motor, you should be running 0.65mm gap.
Thanks for the confirmation.
Eric
05-24-13, 01:59 PM
#60
Rotary Freak
Mine runs richer, close to 12.5 when in the power band, 6000-8900 rpms.
I run twin 2" primary pipes to a merge collector, which necks down to a 2.38" diameter throat, then it has a smooth tapered expansion cone up to 3" diameter. I have a 3" diameter Borla straight thru muffler on the end to knock the noise level down a little. I usually temporarily restrict the very end of the pipe during my morning warm up of the engine, just to keep from irritating the other people in the paddock at the race track.
I race mostly against Porsche 911 RSR with 3.0 liter motors, and occasionally against other RX-7s.
I run twin 2" primary pipes to a merge collector, which necks down to a 2.38" diameter throat, then it has a smooth tapered expansion cone up to 3" diameter. I have a 3" diameter Borla straight thru muffler on the end to knock the noise level down a little. I usually temporarily restrict the very end of the pipe during my morning warm up of the engine, just to keep from irritating the other people in the paddock at the race track.
I race mostly against Porsche 911 RSR with 3.0 liter motors, and occasionally against other RX-7s.
We should communicate more as our power plant setups are very very similar with similar tuning requirements, though I run ITB's.
Eric
05-24-13, 01:59 PM
#61
Exhaust Manifold Leak
Thread Starter
ok, so what could cause the fact that I have dark browm #10 plugs after an hour of track use with an msd 6a and fc leading coils with comparing to you guys quite lean mixture?? also plugs are cold after some WOT pulls?
I read about it that lassa wankel had the same with his 13B PP, which was caused by running alternator. but we are running one and the MSD should have quite a bit more spark energy than a stock inductive setup??
I read about it that lassa wankel had the same with his 13B PP, which was caused by running alternator. but we are running one and the MSD should have quite a bit more spark energy than a stock inductive setup??
05-28-13, 03:44 AM
#62
Exhaust Manifold Leak
Thread Starter
Here 2 photos of the exhaust
header probaly started out as a racingbeat one, thick walled 2" tubing. then 2 hot dog style resonators, and then collect into 2.5" and go to 2.5 " straight trough muffler.
I am panning to make a complete new system, and I also have 54mm tubing (50mm ID), would that be a step forward in comparison to the 2" thick walled tubing which is more like 47mm ID..
header probaly started out as a racingbeat one, thick walled 2" tubing. then 2 hot dog style resonators, and then collect into 2.5" and go to 2.5 " straight trough muffler.
I am panning to make a complete new system, and I also have 54mm tubing (50mm ID), would that be a step forward in comparison to the 2" thick walled tubing which is more like 47mm ID..
05-28-13, 09:41 AM
#64
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on mine there was a big port mismatch between the engine exhaust port exit and the header inlet, the engine is ~48mm and the header is 43mm, since its an RB header there is enough meat to port it, but IMO having a big mismatch right at the engine is pretty big. a stock FC is ~48mm at the engine and 50mm at the manifold inlet...
05-30-13, 10:58 AM
#65
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"I have dark browm #10 plugs after an hour of track use"
It is very hard to tune an engine, based on spark plug color alone. The only way to get a good reading from spark plug color is to cut the engine off while running at full power, push the clutch in, and coast into pit lane without letting the engine idle. Then pull the plugs and read them. If you let the engine idle, then that idle mixture level will influence the color of the plugs.
I really struggled tuning mine until I installed an A/F meter that I could read while driving on the race track.
It is very hard to tune an engine, based on spark plug color alone. The only way to get a good reading from spark plug color is to cut the engine off while running at full power, push the clutch in, and coast into pit lane without letting the engine idle. Then pull the plugs and read them. If you let the engine idle, then that idle mixture level will influence the color of the plugs.
I really struggled tuning mine until I installed an A/F meter that I could read while driving on the race track.
05-30-13, 01:24 PM
#66
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+1 i think i could tune without the AFR gauge, but i'm glad i used it, i know my carb actually delivers a consistent mixture through the whole RPM/load range. the hard part actually is using the AFR and still tuning so the ENGINE runs the best. its very easy to have the gauge in front of you and you try to make it read a number you really like.
B) look down the carb while its idling, if its dripping from the boosters, it'll run fine, but at idle it'll be intermittently rich
C) tuning the WOT mixture takes like 5 minutes, its everything else that takes time. basically it means the main fuel jet is right, however everything else can be wrong
D) the 48IDA has its limits, and you may find you have a "street" and a "track" jetting. mine runs really nicely, and its really streetable, however it could probably use more fuel (think apex seal lube) on decel, and this would require a bigger idle jet, which WILL (i tried 60-70-80 idle jets) make it an angry fire breathing monster.
B) look down the carb while its idling, if its dripping from the boosters, it'll run fine, but at idle it'll be intermittently rich
C) tuning the WOT mixture takes like 5 minutes, its everything else that takes time. basically it means the main fuel jet is right, however everything else can be wrong
D) the 48IDA has its limits, and you may find you have a "street" and a "track" jetting. mine runs really nicely, and its really streetable, however it could probably use more fuel (think apex seal lube) on decel, and this would require a bigger idle jet, which WILL (i tried 60-70-80 idle jets) make it an angry fire breathing monster.
05-30-13, 02:29 PM
#67
Exhaust Manifold Leak
Thread Starter
hmmz, my wot afr is really nice around 13.5-13.2:1 from 5000 till redline, cruising is around lambda one and idle is also really good.. therefor I find it strange that the plugs look so dark even after a WOT pull. but you guys are right it always idle a short time before pulling them
actually the car drives also good on the street, just situations like traffic jams it will probaly not like, and very light load also not, basicly it just wants to be driven hard
I'll open the carb and see whats in there once I find the time
actually the car drives also good on the street, just situations like traffic jams it will probaly not like, and very light load also not, basicly it just wants to be driven hard
I'll open the carb and see whats in there once I find the time
05-30-13, 02:39 PM
#68
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07-03-13, 04:49 AM
#69
Exhaust Manifold Leak
Thread Starter
It's been a few races now, car generally behaved well, and gapping the plug closer to .65-.7mm seemed to improve the feeling of the car by a bit.
last race the qualification was in the rain, so wheelspin in 3rd with the slightest hint of throttle. unfortunately we ran this with the #9 rx8 plug, which for sure wetted them out.
then on the race days the weather was nice, altough after warming up with hot plugs, the first 3 laps it would still misfire alot above 6000 rpm, I think because of the wet leading plugs. after some laps it recovers and runs perfect for the rest of the day.
Would it make sense to try to use the leading coils in series on the msd 6al? now they are parralell.
last race the qualification was in the rain, so wheelspin in 3rd with the slightest hint of throttle. unfortunately we ran this with the #9 rx8 plug, which for sure wetted them out.
then on the race days the weather was nice, altough after warming up with hot plugs, the first 3 laps it would still misfire alot above 6000 rpm, I think because of the wet leading plugs. after some laps it recovers and runs perfect for the rest of the day.
Would it make sense to try to use the leading coils in series on the msd 6al? now they are parralell.
07-04-13, 03:00 AM
#70
Exhaust Manifold Leak
Thread Starter
Some action vidoes
As one can see, plug screw the race, first 3 laps of the race massive misfire at high rpm. then they clear and it pulls really well. sucks to lose the race this way. My dad is the driver (don't know if thats a good thing :p)
As one can see, plug screw the race, first 3 laps of the race massive misfire at high rpm. then they clear and it pulls really well. sucks to lose the race this way. My dad is the driver (don't know if thats a good thing :p)
07-17-13, 11:57 AM
#71
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How new is your ignition 12 volt wiring? Are you using an old switch and an old fuse block to power your ignition?
That was a problem I had in the past. When I put in a new dedicated ignition switch and fuse and wiring, then my intermittent ignition problems went away.
That was a problem I had in the past. When I put in a new dedicated ignition switch and fuse and wiring, then my intermittent ignition problems went away.
09-01-13, 05:14 PM
#73
Exhaust Manifold Leak
Thread Starter
Ditched the shitty msd 6al and used stock ignition x2. so 4 pickups and 4 igintiers and 4 stock coils. works super, no more wet plugs. this weekend the car ran 3 sec faster on the same track and we won in our class.. we had some bad luck during he qualification 4th gear synchro broke (ford type9 box) but it got repared over night and we could still manage to join the race.
will post pics of the ignition setup later!
09-02-13, 09:58 AM
#75
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i like that ignition setup! simple!