[rockcrawlerdude]

hi guys i have the opportunity to buy a efi kit to fit to my G16a in my sierra, the kit comes with uncut loom and ecu, fuel tank. what do people think? its only $200 as he just wants it gone, how hard will it be to fit and whats involoved? and whats the pros for it? thanks.

[pezz]

is it pick up or posted?
do you know the guy?

if i remember correctly, there was someone scamming people with a tbi kit


not saying this guy is, just making sure a good guy doesn't get stung

[rockcrawlerdude]

its pickup, is there many pros for it (like more power) and how hard will it be to install, he says there was no wires cut in the process.

[pezz]

im not sure about the install, but if you get it be sure to do a step by step so i can follow it

[Gwagensteve]

rockcrawlerdude wrote:

(like more power)

Really? I'd be surprised if the TBI kit liberates much more power at all out of a G16A. I would have thought the advantages were all about improved drivability rather than any meaningful power increase. 30 seconds of furious googling wasn't able to net me the power quoted for the TBI G16A (Escudo spec) but bear in mind that the Japanese measured power differently than the ADR and their local models all looked a little bit more powerful than what we got here on paper. That might not actually mean the engine produced any more power than a carb one here though. Just food for thought. for $200, the improved drivability should make the swap worthwhile even if power doesn't increase at all.

Steve.

[rockcrawlerdude]

wasnt really after more power just more drivability on big angles, would it take long to instal? i dont know much about this type of injection, i know more about carbies.

[johnmath]

I put a Swift TBI into my G13 SJ50 Sierra. It recently flagged the O2 sensor as needing replacing - I got a new one from eBay for $40. Fuel economy around the city is +40% from 7.8 (carby) to 11.3 km per litre (TBI). I haven't been on a long run since the new O2 sensor fitted, but I am hopeful of 13 - 14 km per litre. I have been getting 12 versus 10 with the carby.

Drivability and cold starting, idle, angles, etc. is heaps better. Power is up considerably - top speed 90 kph up the steep Glen Osmond Road compared to 80 kph with the carby. I wrote some stuff on the pitfalls I found doing the conversion here: viewtopic.php?f=5&t=41393

[Gwagensteve]

I'd be completely amazed if you can pull 7.1l/100km out of a Sierra under any circumstances. Physics doesn't support economy that good whilst cruising. However, your economy looked a bit crook before the install so it's all good.

rockcrawlerdude, I'd highly recommend ensuring you get an Escudo (as in Vitara) TBI kit - by all accounts it's much easier to fit than the Swift version.

Steve.

[johnmath]

In my "other" Suzuki, I get as good as 4.5 lt / 100 km on long highway trips. It is a Cappuccino

[Reubs]

johnmath wrote:

Fuel economy around the city is +40% from 7.8 (carby) to 11.3 km per litre (TBI).

Gwagensteve wrote:

I'd be completely amazed if you can pull 7.1l/100km out of a Sierra under any circumstances.

km/L - not L/100km. Those figures seem about correct for Sierra EFI conversions but when read properly in km/L. Yeah I was confused too when I first read it!

[Gwagensteve]

Yes, but johnmath is expecting 14 km/l which is 7.1 l/100km out of a high top with a tbi 1.3.

I never got better than 10l/100km out of my cappuccino.

[johnmath]

I never said "expecting to get 7.1 l/100k", I said "hopeful of 13 -14 kpl", that is, hopeful of between 7.7 and 7.1 l/100 km. I am already getting 8.3 l/100k on long trips before the new O2 sensor, which has improved city milage by about 15%. If that improvement transferred to highway milage it would become 7.3 l/100k. I will post back once I have some figures. For what it is worth, I have calculated tank fill to tank fill economy for almost every fill for all of the vehicles I have owned for the past 40 years. That's probably nudging towards 1000 of my own personal fuel economy calculations. I am under no illusions about real world fuel consumption.

[Rhinoman]

There isn't any real difference in power because the TBI has around the same cross-sectional area as the carb did. You will need the throttle body and inlet manifold with all sensors and the exhaust manifold with the lambda sensor and the the MAP sensor (bulkhead) with the in-line filter/damper, try and get the rocker cover as well. You will also need a high pressure fuel pump.

[rockcrawlerdude]

Thanks a lot guys!!!! I have decided to stay with carb until it blows then upgrade. Thinking 4ag supercharged version I was also advised to steer away from the kit because parts are hard to find an I won't know if it works until I fit it all. Thanks again guys.

[johnmath]

Rhinoman wrote:

There isn't any real difference in power because the TBI has around the same cross-sectional area as the carb did. You will need the throttle body and inlet manifold with all sensors and the exhaust manifold with the lambda sensor and the the MAP sensor (bulkhead) with the in-line filter/damper, try and get the rocker cover as well. You will also need a high pressure fuel pump.

There is difference in power with a TBI over a carburettor. With TBI system there is no need for the restrictive venturi of a carburettor that creates the pressure drop that sucks in the fuel, because the fuel is delivered above atmospheric pressure by the injection system. That means more air/fuel mixture can be delivered to the engine - typically 10-20% - and hence more power is produced. Like I said, the increase in power is enough for +10 kph up a ~6% gradient. And the engine is a LOT more responsive, and more fuel efficient (+40% around the city in my case). I had my carburettor rebuilt three times in six years but I only ever achieved <8 kpl around the city and maxed at 10 kpl on long trips. The last fill in the city was 11.3 kpl.

The SuziStore used to sell a manifold adaptor to fit a Swift TBI to a standard Sierra manifold, which is what I used. I did use a nibbler to enlarge the manifold opening to match the TBI, however.

Most TBI systems use low pressure fuel deliver, typically 3 - 7 psi (0.2 - 0.5 Bar) unlike MPFI systems which are typically 30 - 60 psi (2 - 4 Bar). But yes, for various reasons you do need an electric fuel pump.

To be honest, the reason I bothered doing the TBI conversion was because the engine in my Sierra had been completely rebuilt just before I purchased it, by a reputable engine builder, so it seemed a shame to swap out the motor.

[Rhinoman]

johnmath wrote:

Rhinoman wrote:

There is difference in power with a TBI over a carburettor. With TBI system there is no need for the restrictive venturi of a carburettor that creates the pressure drop that sucks in the fuel, because the fuel is delivered above atmospheric pressure by the injection system. That means more air/fuel mixture can be delivered to the engine - typically 10-20% - and hence more power is produced. Like I said, the increase in power is enough for +10 kph up a ~6% gradient. And the engine is a LOT more responsive, and more fuel efficient (+40% around the city in my case). I had my carburettor rebuilt three times in six years but I only ever achieved <8 kpl around the city and maxed at 10 kpl on long trips. The last fill in the city was 11.3 kpl.

I thought that you swapped a 1.6 throttle body set up onto a 1.3, that would give a good power boost. If you're swapping a good 1.6 carb for a good 1.6 TBI then it isn't going to make any significant difference as they are both designed to flow the same amount of air, an EFI engine may be rated at 2bhp or so more and feel a little better but it also has different cam timing. I am a big fan of EFI but I'm unconvinced that the conversion is worth the effort and expense unless the original carb is shot.

[johnmath]

From Wikipedia: "The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure, while a carburetor relies on suction created by intake air accelerated through a Venturi tube to draw the fuel into the airstream." http://en.wikipedia.org/wiki/Fuel_injection

The suction in a carburettor system is the difference between atmospheric air pressure and internal manifold pressure - there MUST be a drop in pressure across the venturi at wide open throttle or the carburettor simply could not deliver fuel. TBI throttle bodies do not need to have the venturi restriction in them because the fuel is pumped in under pressure. At wide open throttle in a TBI setup there doesn't need to be any pressure drop through the throttle body. Less restriction means more airflow. More airflow means more power. Simple.

[Rhinoman]

johnmath wrote:

From Wikipedia: "The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure, while a carburetor relies on suction created by intake air accelerated through a Venturi tube to draw the fuel into the airstream." http://en.wikipedia.org/wiki/Fuel_injection
The suction in a carburettor system is the difference between atmospheric air pressure and internal manifold pressure - there MUST be a drop in pressure across the venturi at wide open throttle or the carburettor simply could not deliver fuel. TBI throttle bodies do not need to have the venturi restriction in them because the fuel is pumped in under pressure. At wide open throttle in a TBI setup there doesn't need to be any pressure drop through the throttle body. Less restriction means more airflow. More airflow means more power. Simple.

Theoretically that may well be correct however a Vitara TBI has the injector stuck in the middle of the intake throat and has a sizeable venturi at its exit, its not an ideal design for max. power. The simple fact is that a TBI swap on a 1.6 motor will not give any more power. A small pressure drop is usually designed in to allow the EFI to meter the fuel correctly.

[johnmath]

The aperture in a TBI setup can be as large or as small as the designer wants, but the one thing it DOESN'T NEED BY DESIGN is an airflow restriction, unlike a carburettor which NEEDS BY DESIGN an air flow restriction to work. In Suzuki TBI's the fuel is calculated by measuring manifold air pressure (MAP) and and revs, not by flow through the throttle body. You are entitled to your view, but you say you haven't done a TBI swap. I have done a swap and I can say unequivocally it made a big boost to power in my case, with original cams and manifolds. The extra grunt is even quite audible in the exhaust sound.

[Rhinoman]

On a MAP based system air flow is calculated by subtracting manifold pressure from atmospheric pressure, which is the pressure drop across the TBI. If there is no pressure drop then its not possible to calculate airflow, a small pressure drop is usually engineered into the throttle body design to improve the measurement resolution at WOT. This is one of the reasons why OEMs prefer MAF based systems on performance engines because there is no need to add an artificial restriction.
You swapped a 1.3 carb for a 1.6 TBI which will give you around a 20% increase in flow, thats why you get a power increase, the OP is talking about swapping a 1.6 carb with a 1.6 TBI.

[toopy]

Hi Rhinoman,

Any news on your new ECU interface cable as yet? Really need one soon

[johnmath]

Rhinoman wrote:

On a MAP based system air flow is calculated by subtracting manifold pressure from atmospheric pressure, which is the pressure drop across the TBI. If there is no pressure drop then its not possible to calculate airflow, a small pressure drop is usually engineered into the throttle body design to improve the measurement resolution at WOT.

This is not correct. MAP actually stands for manifold ABSOLUTE pressure, The air/fuel mixture that flows into the cylinder is a function of how much push there is (the MAP) and how fast the cylinders are moving (the RPM). The relationship is only approximate and is different for every engine and worked out during engine development. My "other" Suzuki is a turbo car and the MAP sensor measures manifold pressure above and below atmospheric pressure, depending whether it is on boost or not, and still works out the fuel requirement based on MAP and RPM as described above.

Quote:

You swapped a 1.3 carb for a 1.6 TBI which will give you around a 20% increase in flow, thats why you get a power increase, the OP is talking about swapping a 1.6 carb with a 1.6 TBI.

If is that easy, why doesn't everybody do it? It would be the cheapest 20% HP upgrade on the planet! The twin chokes of the original carburettor actually have more open area at WOT than the single throttle of the TBI system I replaced it with. The gain in flow is through not needing the venturi pressure drop (which is a drop between atmospheric air pressure and manifold air pressure needed to suck in the fuel). In a carburettor engine, the maximum MAP is atmospheric air pressure minus venturi pressure drop. In a MAP / TBI engine there is no need for a venturi pressure drop, so the maximum MAP at WOT can be and should be atmospheric air pressure, i.e. higher pressure than a carburettor engine and therefore move mixture is delivered to the cylinders and more power developed.

Some other fuel injection systems do use venturis or vanes to measure airflow, but MAP based fuel injection systems do not need to restrict the airflow and nor airflows sensors based on hot wire need to be restrictive. The downside of MAP systems is relatively crude fuel calibration, compared to EFIs that actually measure the airflow directly. This compensated when running in closed-loop by the O2 sensor and feedback control.

[Rhinoman]

Both manifold pressure and atmospheric pressure are measured in absolute terms, to simplify the maths the initial fuel calculations are performed assuming baro is 1bar and then a correction is put in later using the measure value. To try and explain this another way, if you don't have any restriction then manifold pressure will always be atmospheric pressure, this is usually the case on motorcycle engines, however because they cannot measure airflow at high loads they have to switch to a TPS based algorithm, the Vit ECU does not have that capability hence a small restriction is required to maintain measurement resolution
The throttle body on a vit is the opposite of a venturi the TB has a smaller area entry and exit and a much larger bore, this is done to slow air velocity behind the injector, in a high pressure air stream the fuel 'cone' is compressed into a narrower pattern, slowing the air allows a more even mixture. In a carburetor the venturi gives a lower pressure but the velocity increases which means that the airflow will be the same, however the faster velocity increases the Pitot effect, after the venturi the airflow will slow and the pressure will increase again.
I don't know why more people don't do this upgrade, I think its because many are put off by the amount of wiring and because the 1.6 upgrade is simpler and gives a lot more torque. A 1.6 carb and manifold swap used to be fairly common over here but its now very difficult to find a good carb.
A hot wire sensor is not restrictive when properly sized, the only issue with them is that airflow data is not published so they are usually discarded on an engine where the airflow is much higher than stock.