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Discussion Starter #1
Hey everyone, I'm just wondering if electronic carburettors can be tuned by altering their controllers. I own a GA16DS and my carburettor is rigged with sensors and wires. The wires go into the interior of the car so I assume there's some kind of electronic controller controlling the carburettor.

My question is, can the settings be altered so that the fuel-air mixture ratio can be changed? Can I somehow force more fuel and air into the cylinders by altering the carburettor settings? Thanks in advance!
 

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I've never seen a GA16DS, but in general, if you want to keep the electronic carburetor you'll have reprogram the ECU with a different fuel map or trick the sensors in some way. The Hitachi carburetors that came on e-series motors are a nightmare when they start having problems, so swapping them out for a non-emission/non-electronic carburetor (such as a weber) is what most people do. They are easier to tune, maintain, and customize to your specific application.
 

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Electronic carbs were a last ditch effort by manufacturers to keep carbs emissions compliant to avoid the costs of going to fuel injection systems...... They tried everything they could, basically this makes the last of the carbed cars nightmares to deal with. BII is right, you really don't want to mess around with the wiring. They are controlled by a rudimentary ECU , less than 1/3 the processing power of even a basic EFI unit.....
 

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Well, Rochester and Weber do make carburetors that have provisions for emissions control, they were better examples of such (there is one that is used on BMW 2002s that is a version of the Weber 32/36 DGV but it is only useful in non-performance applications, like a show car that still needs to pass smog) but nethier will be easily adaptable to a Nissan.

Are you simply looking to replace a malfunctioning carburetor or are you looking for something performance-oriented?
 

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Discussion Starter #5
The GA16DS and the GA16DE is almost the same except that the DS has a carburettor. I'm looking for some peformance. I have read that the GA16DS cannot be converted to EFI so I was wondering if I can squeeze some more out from my engine. I'm not planning on getting another carburettor since it's still running fine. It's just that sometimes I feel that the engine's power output seem restricted. Are there any other way to improve performance on a NA engine besides bolting on a turbo?
 

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youmolo said:
The GA16DS and the GA16DE is almost the same except that the DS has a carburettor. I'm looking for some peformance. I have read that the GA16DS cannot be converted to EFI so I was wondering if I can squeeze some more out from my engine. I'm not planning on getting another carburettor since it's still running fine. It's just that sometimes I feel that the engine's power output seem restricted. Are there any other way to improve performance on a NA engine besides bolting on a turbo?
If you want to convert to EFI it is possible, come visit the B11/B12/KN13 and e-series and GA forums, several members have efi conversion projects going on.

But changing over to a Weber (or similar clone, like dell'orto will give you some gains in performance, it all depends on what other modifications you make and what carbuertor you choose, sometimes picking the wrong one will see a loss in performance or unrealized potential.

In general you want to choose a higher flowing carburetor as your volumetric efficiency increases (you increase VE by making air flow easier). For most of us not running turbos or really high compression (but we have a modifications), a single downdraft carb (dual venturi) with 32mm-38mm venturis is more than adequate.

But if you are looking to gain power, you are thinking horse before the cart. The selection of the carburetor should be the product of (planned/done) VE enhancements, unless you are looking to ditch the current system entirely.
 

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youmolo said:
Hey everyone, I'm just wondering if electronic carburettors can be tuned by altering their controllers. I own a GA16DS and my carburettor is rigged with sensors and wires. The wires go into the interior of the car so I assume there's some kind of electronic controller controlling the carburettor.

My question is, can the settings be altered so that the fuel-air mixture ratio can be changed? Can I somehow force more fuel and air into the cylinders by altering the carburettor settings? Thanks in advance!
Electronic carbs just control the mixture during closed loop operation like during cruse and light throttle. It won't affect WOT when the PWM solenoid goes full duty cycle and it starts to work like a normal carb anyway.
 

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Discussion Starter #8
morepower2 said:
Electronic carbs just control the mixture during closed loop operation like during cruse and light throttle. It won't affect WOT when the PWM solenoid goes full duty cycle and it starts to work like a normal carb anyway.
PWM solenoid? Changing to a bigger bore carburettor will provide more air and fuel, but will it be suitable for the enigne? What other changes must be done to properly install the new carburettor.

Oh, and I'm just curious, is EFI really that MUCH better than carburetted cars?
 

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morepower2 said:
Electronic carbs just control the mixture during closed loop operation like during cruse and light throttle. It won't affect WOT when the PWM solenoid goes full duty cycle and it starts to work like a normal carb anyway.
Some are like this, others are a bit more complex, some could change the size of the venturi(s), some even managed to "rejet" themselves (IIRC the Holley 6200 series had this function). Others controlled the flow of fuel and air based on the readings of the various sensors in use. Moreover, most of these carburetors have the jets, "sealed" in, not allowing the user to change them. Moreover, the ignition system is directly tied in to EEC in many instances.

I have never seen a GA16DS, so I'm not sure what kind of carburetor it uses. Nonetheless, youmolo, if you increase the size of the venturi, you increase torque at higher RPM, but you lose throttle response. I've never seen an EEC with replacable venturis (a lot of the Webers do however), but you might be able to find a velocity stack that will fit however.

And yes EFI is much better and the most desirable.
 

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bII said:
Some are like this, others are a bit more complex, some could change the size of the venturi(s), some even managed to "rejet" themselves (IIRC the Holley 6200 series had this function). Others controlled the flow of fuel and air based on the readings of the various sensors in use. Moreover, most of these carburetors have the jets, "sealed" in, not allowing the user to change them. Moreover, the ignition system is directly tied in to EEC in many instances.

I have never seen a GA16DS, so I'm not sure what kind of carburetor it uses. Nonetheless, youmolo, if you increase the size of the venturi, you increase torque at higher RPM, but you lose throttle response. I've never seen an EEC with replacable venturis (a lot of the Webers do however), but you might be able to find a velocity stack that will fit however.

And yes EFI is much better and the most desirable.
You mean the holley 6200 had mixture control at WOT? How is that posible when o2 sensors at the time were only accurate around stoic? Did it work off of a ECU MAP in open loop like EFI? If so, I didnt know that. Are you sure it changed metering orface size or did it just meter fuel to the emulsion tubes via a PWM solenoid like a typical feedback carb?

There was a holley/weber varible venturi POS carb in the late 70's early 80's that had a vacume controled slide venturi thing and a needle valve that was like an SU carb but mounted verticaly like a conventional V8 carb. Ford used them oin small block V8's, it didnt have WOT electronic control. Is that the carb you are talking about?
 

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morepower2 said:
You mean the holley 6200 had mixture control at WOT? How is that posible when o2 sensors at the time were only accurate around stoic? Did it work off of a ECU MAP in open loop like EFI? If so, I didnt know that. Are you sure it changed metering orface size or did it just meter fuel to the emulsion tubes via a PWM solenoid like a typical feedback carb?

There was a holley/weber varible venturi POS carb in the late 70's early 80's that had a vacume controled slide venturi thing and a needle valve that was like an SU carb but mounted verticaly like a conventional V8 carb. Ford used them oin small block V8's, it didnt have WOT electronic control. Is that the carb you are talking about?
That was one variable, I think Hitachi also made one. And as far as the 6200, I don't remember how it "rejeted" themselves (hence for the quotes), I know a user-controlled dial was an available option, that let you override the normal function.

One (really annoying) way some systems limit fuel/air is by limiting how far the butterflys, even if you floor it. I'll have to pull a shop manual tonight, I don't have a lot of expierance with these systems, other than trying to troubleshoot and then finally ditching the damn things. As anyone can imagine, these are not popular carburetors.
 

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bII said:
That was one variable, I think Hitachi also made one. And as far as the 6200, I don't remember how it "rejeted" themselves (hence for the quotes), I know a user-controlled dial was an available option, that let you override the normal function.

One (really annoying) way some systems limit fuel/air is by limiting how far the butterflys, even if you floor it. I'll have to pull a shop manual tonight, I don't have a lot of expierance with these systems, other than trying to troubleshoot and then finally ditching the damn things. As anyone can imagine, these are not popular carburetors.
Yeah the Hitachi was a copy of the SU. I agree those carbs sucked. Hard to get running right, not even running well when new. Remember when emmission controls were not fully wired in the 70-80's? Those cars sucked.
 

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morepower2 said:
Yeah the Hitachi was a copy of the SU. I agree those carbs sucked. Hard to get running right, not even running well when new. Remember when emmission controls were not fully wired in the 70-80's? Those cars sucked.
Yeah, many of us with carbureted e-series powered sentras swap them out for webers or something similar when the eec or a component thereof fails (or we want to take advantage of modifications). The Webers allow you to modify and tune all the curcuits and there's a weber for every application and every power level. In fact IIRC there was a Honda (CRX or something) that put out like 380HP running two DCOE's. I think the guy's name who drove it was something Robinson.
 

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Discussion Starter #14
owh, okay. i don't plan on getting a new carb or changing to efi because the car is quite old already and i'm going away soon. any other mods that can be done to boost a carb's performance besides changing a new one? I've done a CAI already and it sounds good. i'm looking for a new exhaust system soon. new headers,straight pipes and a muffler. what do you people think?
 

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youmolo said:
owh, okay. i don't plan on getting a new carb or changing to efi because the car is quite old already and i'm going away soon. any other mods that can be done to boost a carb's performance besides changing a new one? I've done a CAI already and it sounds good. i'm looking for a new exhaust system soon. new headers,straight pipes and a muffler. what do you people think?
I own a NX with a GA16DS. I've searched a lot for performance upgrades, but found zero. Exhaust is def. an option, but don't expect too much gain.. I suppose 4-5 HP.
I a'm wondering how you did that CAI. I'm seaching my a** of on the internet how to put that on my GA16DS if it is possible at all.

Can you tell me hou you did it/show some pics?

Cheers from holland :thumbup:
 
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