4-Rotor FC Build
08-01-14, 02:05 PM
#1701
Senior Member
Most mechanics don't even check the emissions john. If you read the book in the correct way it should, but most guys don't.
And if you think the lambda sensor is faulty, compare the values with one of those gas meters used for "APK"
And if you think the lambda sensor is faulty, compare the values with one of those gas meters used for "APK"
08-01-14, 03:30 PM
#1702
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ignore the wideband, use the force. the wideband means well, but the engine will tell you wants.
08-01-14, 05:05 PM
#1703
As requested, a video of cruising around with the 4-rotor. It's totally boring and dull though, maximum rpm in the vid is about 4000, maximum throttle is about 20%
Yeah that might be true, it kindoff sucks though, I'm used to being lazy and adjusting the ecu so the wideband reads a number I like, which has always worked for me.
It's still wierd though, the AFR reads super rich, there is a strong fuel smell coming out of the exhaust, and the fuel consumption is just insane, about 5mpg, but when I lean it out a bit it just bucks, mirfires and make my header glow.
I'll do some messing around, maybe different plugs will help, and I'll try a different wb sensor. Will also try to get some EGT gauges, they might add some usefull information about what is what.
It's still wierd though, the AFR reads super rich, there is a strong fuel smell coming out of the exhaust, and the fuel consumption is just insane, about 5mpg, but when I lean it out a bit it just bucks, mirfires and make my header glow.
I'll do some messing around, maybe different plugs will help, and I'll try a different wb sensor. Will also try to get some EGT gauges, they might add some usefull information about what is what.
08-01-14, 08:06 PM
#1706
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Ohhh... my... ******* God!
How can you not have a big *** smile going from ear to ear?
How can you not have a big *** smile going from ear to ear?
08-02-14, 02:00 AM
#1707
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If he has been to the RDW for that, they do check emissions. When registration is done, you're smog exempt.
I've been to the RDW to ask about this for my 929/rx4 swap
So the RDW guys say that any rotary is exempt. But worst case scenario, if someone doesn't know about the exemption, you would have to pass the 4.5% Mark.
08-02-14, 02:11 AM
#1708
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Mileage will always be a bitch with a PP. Kees Hoebeke built a couple, he had a 2rotor PP in an FC and it did 2km/L.
His 4rotor rx-8 drained the floatbowls of the ida carbs he was running at first, even only going up to 5-6k rpm
If it's smelling rich, but getting hot and bucking, I would think you need to check the timing aswell.
Good luck with the tuning!
Ps. If you happen to feel for a bit longer drive, you know I live closeby :P
08-02-14, 06:48 AM
#1710
At what RPM does it start bucking / smooth out? Looks like you like to keep it in gear as long as possible and then it would start bucking. It looks like it will be fairly streetable even though its PP.
I cant wait to hear this thing open up. Oh and dyno results.
I cant wait to hear this thing open up. Oh and dyno results.
08-02-14, 01:04 PM
#1712
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Yeah that might be true, it kindoff sucks though, I'm used to being lazy and adjusting the ecu so the wideband reads a number I like, which has always worked for me.
It's still wierd though, the AFR reads super rich, there is a strong fuel smell coming out of the exhaust, and the fuel consumption is just insane, about 5mpg, but when I lean it out a bit it just bucks, mirfires and make my header glow.
I'll do some messing around, maybe different plugs will help, and I'll try a different wb sensor. Will also try to get some EGT gauges, they might add some usefull information about what is what.
i did find with mine that i could have used the same AFR targets as mazda did with the stock S4 NA, although it took some experimentation to get there.
mine is maybe simpler though, with the carb i have a choice of a jet that runs, one that doesn't and one that shoots fire at you, so its actually very easy to tune.
mileage should get better, mine is quite good actually. you may find that mileage sucks at low throttle, but gets better @wot
08-04-14, 01:40 PM
#1714
Full Member
Great to see the car running!
Thats not true all cars has to take the idle test, only the high rpm test has not to be taken by rotary after 1992
He mentioned that he wanted the 4-rotor registered, so it would be legal.
If he has been to the RDW for that, they do check emissions. When registration is done, you're smog exempt.
I've been to the RDW to ask about this for my 929/rx4 swap
So the RDW guys say that any rotary is exempt. But worst case scenario, if someone doesn't know about the exemption, you would have to pass the 4.5% Mark.
If he has been to the RDW for that, they do check emissions. When registration is done, you're smog exempt.
I've been to the RDW to ask about this for my 929/rx4 swap
So the RDW guys say that any rotary is exempt. But worst case scenario, if someone doesn't know about the exemption, you would have to pass the 4.5% Mark.
08-04-14, 02:49 PM
#1715
holy cow that thing sounds awesome! its perfect...
i did find with mine that i could have used the same AFR targets as mazda did with the stock S4 NA, although it took some experimentation to get there.
mine is maybe simpler though, with the carb i have a choice of a jet that runs, one that doesn't and one that shoots fire at you, so its actually very easy to tune.
mileage should get better, mine is quite good actually. you may find that mileage sucks at low throttle, but gets better @wot
i did find with mine that i could have used the same AFR targets as mazda did with the stock S4 NA, although it took some experimentation to get there.
mine is maybe simpler though, with the carb i have a choice of a jet that runs, one that doesn't and one that shoots fire at you, so its actually very easy to tune.
mileage should get better, mine is quite good actually. you may find that mileage sucks at low throttle, but gets better @wot
You might be right about the mileage thing, the pulsewidth and VE at highway speeds is not that different from idle, which is wierd. I need to turn the overrun fuel cut on though, I think that will make a big difference, at the moment it plows out a lot of raw fuel when I let go of the gas.
08-04-14, 05:34 PM
#1716
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I
You almost make me regret going with EFI You might be right about the mileage thing, the pulsewidth and VE at highway speeds is not that different from idle, which is wierd. I need to turn the overrun fuel cut on though, I think that will make a big difference, at the moment it plows out a lot of raw fuel when I let go of the gas.
You almost make me regret going with EFI
You might be right about the mileage thing, the pulsewidth and VE at highway speeds is not that different from idle, which is wierd. I need to turn the overrun fuel cut on though, I think that will make a big difference, at the moment it plows out a lot of raw fuel when I let go of the gas.EFI should end up being better, its just going to take longer
08-05-14, 11:03 AM
#1718
Senior Member
08-05-14, 11:22 AM
#1719
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my Tr3 had a pair of SU's and a single SU is like an S4 FC, now imagine trying to get 2 S4 FC ecu's in synch?
08-05-14, 04:45 PM
#1720
Senior Member
Can you adjust when fuel is injected? Restrict the exhaust flow to experiment?
Or just direct inject?
08-05-14, 06:00 PM
#1721
It's not really rpm related, it's load related, at the moment it doesn't like low loads. Anything under 8% or so causes it to buck, but 8% throttle is about 140kmh, so it's not really possible to drive at a normal steady speed without it bucking, so I have to give it some gas and load it a bit, untill I'm driving too fast, and then I'll let it coast for a while, and then get on the gas again. Very annoying, but I think I can fix it with tuning.
I think thats just the nature of a peripheral port. You can look at what the OEMs did to make their tiny P-port wankels more consumer friendly.
NSU put a torque converter in front of their MANUAL transmission to dampen the engine bucking.
Norton disabled spark on 1 of 2 rotors at light load so the working rotor was under more load to alleviate bucking.
Mercedes 4 rotor C111 did not enter production, but they placed direct injectors at the spark plugs.
Likewise, Mazda's new peripheral intake rotary has the injectors at the spark plugs so the exhaust only sucks air not fuel/air.
------------
All the p-port fueling/ running issues will make much more sense when you realize the rotary overlap dynamic.
At all rpms is the exhaust is sucking the intake/fuel out.
When the throttle plates are closed limiting total intake flow the exhaust first sucks the available intake/fuel out as per the normal overlap dynamic.
Then the increasing volume of the intake stroke starts to suck throttle restricted intake/fuel.
Because of the restriction of the throttle plate the normal overlap dynamic reverses as it becomes easier for the increasing intake stroke volume to suck in exhaust instead.
-------------------
A carb on a P-port is going to be "easier" to tune for light load as it continuously meters fuel into the air going past the jets.
It lets the exhaust suck air/fuel out the exhaust and also has air/fuel available for the intake stroke.
versus
Fuel injection will not constantly meter fuel into the intake during these events- you get one shot at it.
If you inject your fuel during the overlap phase its going out your exhaust.
You can time injection event later so it corresponds to the later part of the intake stroke if you have sequential injection.
You can move the injectors onto the rotor housing for semi-direct injection (same idea, larger operating window as you are not depending on intake port being open).
You can move the injectors into the combustion chamber (true direct injection).
I apologize if this is elementary to you.
I think thats just the nature of a peripheral port. You can look at what the OEMs did to make their tiny P-port wankels more consumer friendly.
NSU put a torque converter in front of their MANUAL transmission to dampen the engine bucking.
Norton disabled spark on 1 of 2 rotors at light load so the working rotor was under more load to alleviate bucking.
Mercedes 4 rotor C111 did not enter production, but they placed direct injectors at the spark plugs.
Likewise, Mazda's new peripheral intake rotary has the injectors at the spark plugs so the exhaust only sucks air not fuel/air.
------------
All the p-port fueling/ running issues will make much more sense when you realize the rotary overlap dynamic.
At all rpms is the exhaust is sucking the intake/fuel out.
When the throttle plates are closed limiting total intake flow the exhaust first sucks the available intake/fuel out as per the normal overlap dynamic.
Then the increasing volume of the intake stroke starts to suck throttle restricted intake/fuel.
Because of the restriction of the throttle plate the normal overlap dynamic reverses as it becomes easier for the increasing intake stroke volume to suck in exhaust instead.
-------------------
A carb on a P-port is going to be "easier" to tune for light load as it continuously meters fuel into the air going past the jets.
It lets the exhaust suck air/fuel out the exhaust and also has air/fuel available for the intake stroke.
versus
Fuel injection will not constantly meter fuel into the intake during these events- you get one shot at it.
If you inject your fuel during the overlap phase its going out your exhaust.
You can time injection event later so it corresponds to the later part of the intake stroke if you have sequential injection.
You can move the injectors onto the rotor housing for semi-direct injection (same idea, larger operating window as you are not depending on intake port being open).
You can move the injectors into the combustion chamber (true direct injection).
I apologize if this is elementary to you.
08-05-14, 06:27 PM
#1722
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hmm actually i've found that anything you can do to reduce intake vacuum makes the engine run better (less bucking) so therefore the low RPM dynamic is actually that the exhaust gasses get taken up into the intake stroke.
if you look at the engine apart, you will see this is almost obvious, the rotor basically scoops toward the intake. also you need to factor in that the intake is at a vacuum and the exhaust is not, and there is also decent flow between them
in the middle and higher rpms, things change as everything is moving faster and the gasses have more inertia.
if the bucking bothers you, drill a small hole in the throttle plate, or lower intake vacuum by some other means.
if you look at the engine apart, you will see this is almost obvious, the rotor basically scoops toward the intake. also you need to factor in that the intake is at a vacuum and the exhaust is not, and there is also decent flow between them
in the middle and higher rpms, things change as everything is moving faster and the gasses have more inertia.
if the bucking bothers you, drill a small hole in the throttle plate, or lower intake vacuum by some other means.
08-05-14, 06:35 PM
#1723
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I have zero knowledge of PP intake/exhaust dynamics. But sounds to me like a real challenge to alliviate gas consumption at lower RPMs because of the outrageous overlap. From your description, most of the fuel must be going the opposite direction at low RPM.
Can you adjust when fuel is injected? Restrict the exhaust flow to experiment?
Or just direct inject?
Can you adjust when fuel is injected? Restrict the exhaust flow to experiment?
Or just direct inject?
once its tuned its going to be much better
08-05-14, 07:29 PM
#1724
hmm actually i've found that anything you can do to reduce intake vacuum makes the engine run better (less bucking) so therefore the low RPM dynamic is actually that the exhaust gasses get taken up into the intake stroke.
You are mistaking cause and effect.
Here I am saying the same thing. Intake vacuum is the restriction of the throttle plate creating a low pressure area as the volume of the intake stroke increases.
Decreasing vacuum is increasing load or intake flow.
It is only because of the flow limits of the throttle plate that the intake stroke finds it easier to "suck" exhaust gas up instead of intake charge.
so therefore the low RPM dynamic is actually that the exhaust gasses get taken up into the intake stroke
No, the exhaust scavenging is not dependent on rpm- but rather load (throttle restriction). Whack the throttle open and you lose intake charge to the exhaust at all rpms.
if you look at the engine apart, you will see this is almost obvious, the rotor basically scoops toward the intake. also you need to factor in that the intake is at a vacuum and the exhaust is not, and there is also decent flow between them
No, you have high velocity exhaust gas moving along the rotor flank on the bottom and out the exhaust port through a large opening (bottom of exhaust port to apex seal) and above that you have a smaller opening 33 degrees to the exhaust flow (top of exhaust port to apex seal) leading to a volume of low velocity intake.
That is the strong exhaust siphon of rotary overlap.
in the middle and higher rpms, things change as everything is moving faster and the gasses have more inertia.
If this were true the overlap of the p-port would not show the increases in volumetric efficiency in all rpms that it does over the lower overlap side port.
if the bucking bothers you, drill a small hole in the throttle plate, or lower intake vacuum by some other means.
Yes, allow the intake to flow more so that it can feed the exhaust port and the intake stroke.
In order to keep the rpm down you may have to actually introduce load such as having the engine move de-activated rotor chambers such as in the Norton.
You are mistaking cause and effect.
Here I am saying the same thing. Intake vacuum is the restriction of the throttle plate creating a low pressure area as the volume of the intake stroke increases.
Decreasing vacuum is increasing load or intake flow.
It is only because of the flow limits of the throttle plate that the intake stroke finds it easier to "suck" exhaust gas up instead of intake charge.
so therefore the low RPM dynamic is actually that the exhaust gasses get taken up into the intake stroke
No, the exhaust scavenging is not dependent on rpm- but rather load (throttle restriction). Whack the throttle open and you lose intake charge to the exhaust at all rpms.
if you look at the engine apart, you will see this is almost obvious, the rotor basically scoops toward the intake. also you need to factor in that the intake is at a vacuum and the exhaust is not, and there is also decent flow between them
No, you have high velocity exhaust gas moving along the rotor flank on the bottom and out the exhaust port through a large opening (bottom of exhaust port to apex seal) and above that you have a smaller opening 33 degrees to the exhaust flow (top of exhaust port to apex seal) leading to a volume of low velocity intake.
That is the strong exhaust siphon of rotary overlap.
in the middle and higher rpms, things change as everything is moving faster and the gasses have more inertia.
If this were true the overlap of the p-port would not show the increases in volumetric efficiency in all rpms that it does over the lower overlap side port.
if the bucking bothers you, drill a small hole in the throttle plate, or lower intake vacuum by some other means.
Yes, allow the intake to flow more so that it can feed the exhaust port and the intake stroke.
In order to keep the rpm down you may have to actually introduce load such as having the engine move de-activated rotor chambers such as in the Norton.
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08-06-14, 12:53 AM
#1725
Exhaust Manifold Leak
Yep, cylinder deactivation is now common on piston engine, or lean burn where the throttle is open as power is regulated with fuel, but I think in a practical way cutting fuel on 2 of 4 rotors at light load could be the easiest way. But even a 2'rotor PP with decent overlap will buck at low load..