injector capacity
- Thread starter tomwest
- Start date
I totally forgot you were installing a K6.
If you're running the usual bolt-ons, (4-2-1 manifold, cat back etc), as well as the carb bodies you'll exceed 80% duty on the standard injectors no problem. I'd recommend considering starting out with a set of the larger GA16 198cc/min injectors.
If you're running the usual bolt-ons, (4-2-1 manifold, cat back etc), as well as the carb bodies you'll exceed 80% duty on the standard injectors no problem. I'd recommend considering starting out with a set of the larger GA16 198cc/min injectors.
OP
OP
working on an idea for mani. running standard inlet and exhaust but no back box and side exited. the carbs are sat in my garage as the car has to have the K6 up and running and done by today! the carbs are an extra that it can go without for a few weeks. thanks for the injector choice though! will most likely use them when the carb bodies are on.
frank
Club Member
the middle one is the signal wire tom, the outer 2 are heating iirc
solarice
Ex. Club Member
When using the emanage on mine setting the CG injectors to 148cc and the GA16's 198cc (performing injector upgrade correction) produced the better results. The CG's set at 135cc made it run lean / idle weird 
But as you say try both...would be good to get another yay or nay.
But as you say try both...would be good to get another yay or nay.
I have heard that the bigger injectors (in general) might need more fuel pressure to get proper/smaller droplet size on lower rpms. Have you had such experiences?
I have a GA16 injectors (with stock ECU) in my CG13DE and it seems that the air fuel mixture is not igniting properly on low rpms even though the wideband lambda is keeping the AFR close to 15. I am not able to increase fuel pressure until I get shorter injector duration by changing higher capacity MAF, but hopefully I can make that change soon.
I have a GA16 injectors (with stock ECU) in my CG13DE and it seems that the air fuel mixture is not igniting properly on low rpms even though the wideband lambda is keeping the AFR close to 15. I am not able to increase fuel pressure until I get shorter injector duration by changing higher capacity MAF, but hopefully I can make that change soon.
frank
Club Member
mine ran too rich low down with GA16 injectors, and i would have to pull the fuelpump fuse just to get it to start,
but the QG 15/18 topfeed ones didnt overfuel as bad for some reason.
the current SR20 ones are fueling very nice at the reduced pressure from the rising rate fuelreg.
i had expected worse fuel milage from the reduced atomisation, but i think petrol is so flammable that it makes no difference, unlike diesel, which would suffer badly i guess, and with durations over 30% you,re spraying petrol onto a closed inlet valve anyway eh (no atomisation if you,re sucking it back off the inlet mani wall !)
the key to getting a bigger t/b to work, is to increase the fuel ONLY at wider throttle openings eh, and i think most ecu,s only have a fueltrim that extends to 25%, so once you excede that it will start throwing wobblies
but the QG 15/18 topfeed ones didnt overfuel as bad for some reason.
the current SR20 ones are fueling very nice at the reduced pressure from the rising rate fuelreg.
i had expected worse fuel milage from the reduced atomisation, but i think petrol is so flammable that it makes no difference, unlike diesel, which would suffer badly i guess, and with durations over 30% you,re spraying petrol onto a closed inlet valve anyway eh (no atomisation if you,re sucking it back off the inlet mani wall !)
the key to getting a bigger t/b to work, is to increase the fuel ONLY at wider throttle openings eh, and i think most ecu,s only have a fueltrim that extends to 25%, so once you excede that it will start throwing wobblies
Ok. How I am trying to get it working is by changing MAF at the same time with injectors so that the signal will be having the same proportions as with stock injectors and MAF.
As an example:
Stock MAF signal 20% air going in, and injector duty cycle 20%.
If have changed the injectors to GA16 injectors meaning that with 20% duty cycle engine would be getting 30% too much fuel (injector capacities roughly 200cc compared to 150cc). Now if I change/mod the MAF so that is gives an 15% signal at the same airflow as stock MAF would give 20%, then the duty cycle with GA16 injector would be decreased to 15%.
I have understood that in open loop the ECU is using only MAF signal to determine the correct injector time. And it seems that my Micra is using open loop with first and second gear. Third and above the lambda is correcting the proportions to correct value.
I bought a VAG 1.9l TDI MAF (code 0281 002 531) which I assume is having airflow capacity of 850kg/h. Of course if the MAF capacity is too high, it gives lower signal than expected and I would need to make an electronics amplifier to make the signal correct. But I hope that it is not too high and small differences I can correct using increased fuel pressure.
As an example:
Stock MAF signal 20% air going in, and injector duty cycle 20%.
If have changed the injectors to GA16 injectors meaning that with 20% duty cycle engine would be getting 30% too much fuel (injector capacities roughly 200cc compared to 150cc). Now if I change/mod the MAF so that is gives an 15% signal at the same airflow as stock MAF would give 20%, then the duty cycle with GA16 injector would be decreased to 15%.
I have understood that in open loop the ECU is using only MAF signal to determine the correct injector time. And it seems that my Micra is using open loop with first and second gear. Third and above the lambda is correcting the proportions to correct value.
I bought a VAG 1.9l TDI MAF (code 0281 002 531) which I assume is having airflow capacity of 850kg/h. Of course if the MAF capacity is too high, it gives lower signal than expected and I would need to make an electronics amplifier to make the signal correct. But I hope that it is not too high and small differences I can correct using increased fuel pressure.
In case of someone using a stock ECU like me...
Before putting in the Bosch MAF, I fooled the stock MAF just for testing purposes. Using changeable voltage divider in the MAF signal and lowering the signal by roughly 5%, it was having close to 13:1 AFR throughout the second gear (WOT). This setup was working up to stock rev limit, but after that I assume it will be going towards lean as the stock MAF signal saturates.
My setup was having GA16DE injectors and 3.5 bar fuel pressure.
Before putting in the Bosch MAF, I fooled the stock MAF just for testing purposes. Using changeable voltage divider in the MAF signal and lowering the signal by roughly 5%, it was having close to 13:1 AFR throughout the second gear (WOT). This setup was working up to stock rev limit, but after that I assume it will be going towards lean as the stock MAF signal saturates.
My setup was having GA16DE injectors and 3.5 bar fuel pressure.
frank
Club Member
i think the closed loop perameters are pretty limited tho, when i had the QG injectors and stock fuel pressure the a/f/r needle was bouncing slowly during cruise (1 or 2 per sec) like as if the ecu was struggling to keep it @ stoich, but with the current SR injectors on low pressure during vacuum, the needle is bouncing a lot more regular (3 ish per sec).
and i,m getting some very good fuel milage atm (70 miles per £10 driven quite hard !)
and i,m getting some very good fuel milage atm (70 miles per £10 driven quite hard !)
