Nikki carb
09-14-10, 07:01 PM
#3
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no there isn't. you need a wideband and an assortment of jets, and then the next day it'll be off, cause its a carburator
09-14-10, 07:10 PM
#4
14.0:1 where? Perfect when? 14.0 is perfect under certain load conditions?
14.7 Perfect stoich
13ish good for WOT.
Need a wideband and jets for cruise/WOT
Need a wideband and a screw driver for idle if you're going for numbers. Otherwise adjust idle per Sterling and Vacuum.
14.7 Perfect stoich
13ish good for WOT.
Need a wideband and jets for cruise/WOT
Need a wideband and a screw driver for idle if you're going for numbers. Otherwise adjust idle per Sterling and Vacuum.
09-15-10, 12:16 AM
#5
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Open up the exhaust side and the A/F will be perfect all by itself. Otherwise, jets and emulsion tubes changed by the season await you if you want to maintain that "perfect" ratio "all the time" on an ancient Nikki carburetor.
09-15-10, 10:48 AM
#7
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1985 is now 25 years ago....anything made 5 years after that date will be superior unless a fellah like Sterling does his magic on the ancient Nikki carburetor.
Simple as that.
Simple as that.
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09-15-10, 11:30 AM
#8
It's impossible to perfect a carb unless operating conditions stay absolutely the same... and that includes engine RPM and load. The AF mix that comes out of a carb is always an imperfect estimation of requirements based on poorly-sensed conditions.
A carburetor is a mechanical analog computer that attempts to model and compensate for varying operating conditions, but it's hampered by the complexity of what it's trying to model, and the limits of what it can measure.
Even the most modern computerized fuel injection can't maintain "perfect" mixture control at all times; response lag and imperfect sensing (can't know ALL the variables all the time, nor can you act on sensed conditions with zero lag) doom them to just being a much more accurate estimation.
The first-gen Nikki's also had to contend with new, and rapidly changing, environmental restrictions that were frequently working at crossed purposes, like trying to minimize both NOX and HC emissions while also trying to maximize burn efficiency (fuel mileage) across a wide range of temperatures, pressures, and humidities. Not to mention inconsistent fuel compositions. Or the need to run richer than stoich in order to feed the thermal reactors or early-style cats required to get the exhaust gases down.
Nikki's are pretty solid carbs for their day, but their design goal list was long, and often contradictory, and "maintaining perfect stoich" wasn't even on the list.
A carburetor is a mechanical analog computer that attempts to model and compensate for varying operating conditions, but it's hampered by the complexity of what it's trying to model, and the limits of what it can measure.
Even the most modern computerized fuel injection can't maintain "perfect" mixture control at all times; response lag and imperfect sensing (can't know ALL the variables all the time, nor can you act on sensed conditions with zero lag) doom them to just being a much more accurate estimation.
The first-gen Nikki's also had to contend with new, and rapidly changing, environmental restrictions that were frequently working at crossed purposes, like trying to minimize both NOX and HC emissions while also trying to maximize burn efficiency (fuel mileage) across a wide range of temperatures, pressures, and humidities. Not to mention inconsistent fuel compositions. Or the need to run richer than stoich in order to feed the thermal reactors or early-style cats required to get the exhaust gases down.
Nikki's are pretty solid carbs for their day, but their design goal list was long, and often contradictory, and "maintaining perfect stoich" wasn't even on the list.
09-15-10, 01:36 PM
#9
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the other thing to consider is the engine, not every combustion event is the same, there is an element of randomness, even in a laboratory test. the rotary engine is probably more susceptible to this too, due to the high amount of exhaust gasses that get carried over from the exhaust stroke to the combustion, like a really really big EGR valve. mazda calls it "internal egr".
so the engine, particularly at low rpm, actually needs a mixture richer than 14.7:1 to run without misfiring. a misfire basically = very high HC and CO emissions, and this would never pass any emissions. mazda's solution is to use an air pump...
this is a long winded way of saying, you really don't WANT to run 14.7:1 all the time.
so the engine, particularly at low rpm, actually needs a mixture richer than 14.7:1 to run without misfiring. a misfire basically = very high HC and CO emissions, and this would never pass any emissions. mazda's solution is to use an air pump...
this is a long winded way of saying, you really don't WANT to run 14.7:1 all the time.
09-15-10, 07:57 PM
#10
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This is all good information thanks guys. It does answer a lot of my questions but is there like an ideal seting for the nikki carb so it will function the engine at a constent? I guess what I'm trying to say is that is there a way to adjust the car so it will run good but have good or kinda decient gas milage? I know its a rotarty and ur not suppose to get the best gas milage but I have heard of better gas milage for this car then 10mpg
09-16-10, 12:45 AM
#12
This is all good information thanks guys. It does answer a lot of my questions but is there like an ideal seting for the nikki carb so it will function the engine at a constent? I guess what I'm trying to say is that is there a way to adjust the car so it will run good but have good or kinda decient gas milage? I know its a rotarty and ur not suppose to get the best gas milage but I have heard of better gas milage for this car then 10mpg
09-16-10, 01:49 AM
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tookey bird
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yea ive checked out sterlings site but doesnt he take off some of the needed emisions for the carb? i live in CA and i dont feel like messin with the emisions
09-16-10, 11:09 AM
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my STOCK SA would get 23-25mpg on the freeway
09-16-10, 02:16 PM
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Stock Nikki, stock engine, stock exhaust, unfindable tiny vacuum leak - 18 mpg
Stock Nikki, stock engine, new custom exhaust, 2.5" pipe from stock exhaust manifold to 2.5" high-flow cat exhaust to really nice muffler set up from Rx-7Doctor, unfindable tiny vacuum leak - 20 mpg
Work the exhaust.
Stock Nikki, stock engine, new custom exhaust, 2.5" pipe from stock exhaust manifold to 2.5" high-flow cat exhaust to really nice muffler set up from Rx-7Doctor, unfindable tiny vacuum leak - 20 mpg
Work the exhaust.
09-16-10, 03:23 PM
#19
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You need a friend in the car to do this, however since this is the 1stgen Tech section and not the New Member tech section, here's the part where I have to say that this info is best found using the search engine.
Thread closed.
Thread closed.
