Stock FC turbo + 1680CC injectors?

[m1tch]

Hi guys just wondering about this, I have a stock turbo on my FC3S that is running the stock 550s primary and secondary. Its mapped to 0.9 bar and all the cooling and intercooler is sorted to run this safely, its got a chipped Knightsport ECU and I also have an E-manage ultimate that will piggyback my system soon.

I will be uprating the turbo for a much larger one in the future, but I want to get everything bolted in and sorted so its ready to accept it when the time comes.

I am just wondering if I am able to run the stock 550 primarys - this part is fine, and then install the HUGE 1680cc injectors in the secondaries and get the E-manage to cut the fueling to run as per the 550s or maybe act like 800ccs for safety.

I am just wondering if this will be ok as the 1680s won\'t be running a very high duty cycle when the fueling switches to the secondaries. I believe the knightsport ECU runs the primaries higher than stock to allow for the higher boost - perhaps this could be overridden with the e-manage changing the fueling signal to change this back to stock and increase the duty cycle on the secondaries so that if the 1680s were fitted, they would be running at a higher duty cycle.

I am just asking as I know that large injectors don\'t really like low duty cycles due to the large amount of fuel the injector injects each cycle.

Thanks in advance

[Prof]

The problem with larger injectors and low duty cycles is twofold:
 
1) The injector has a \'lag\' and this is often larger for larger capacity injectors.  If you like this is the \'turn on\' time - the stock injectors are 0.73ms, from memory I think the Bosch units are about 1.6ms.
 
2) The resolution of the ECU that drives the injector - the old 8 bit ECU\'s probably only used 8 bit or maybe a 16 bit timer - whereas modern ECU\'s have 32bit timers or better - this means the minimum change in pulse time is a lot smaller - giving finer control.
 
I think the emanage has quite accurate timers - compared to the stock ECU - which as 16 bit timers.
 
However, there is a plus side - when the secondaries come on, they come on at boost and start at about 20% - going up to whatever the ecu demands.  So with the emanage, you can either set the injectors as 840\'s and then half the resulting value to get the correct amount, or just leave them as 550\'s and calculate the difference as a percentage or fraction and set the time accordingly.  What I would say is that because the secondaries are only there to provide the additional fuel for the boost part of the map - it should be easy to configure this.
 
The change in turbo\'s is nothing to worry about, you can simply use the emanage to correct the injector times for the current turbo and chipped ecu (with 1680\'s), and when you have the bigger turbo - use the emange maps to set the fuelling correctly at the higher boost levels.

[m1tch]

So I guess it would be possible if the different lag times were taken into account, the e-manage has an option for lag time doesn\'t it?

[Prof]

So I guess it would be possible if the different lag times were taken into account, the e-manage has an option for lag time doesn\'t it?

It does :yes

[m1tch]

Awesome lol I just checked the software and it showed the lag times for the injectors I was worrying that it might go like this:

Boosting up to 5psi on primarys....secondaries kick in *FLOOD* lol

[Prof]

Awesome lol I just checked the software and it showed the lag times for the injectors I was worrying that it might go like this:
 
Boosting up to 5psi on primarys....secondaries kick in *FLOOD* lol

All it will do is just \'bog\' horribly and when you lift off it will sort itself - until you next hit about 5psi that is. :Giggle
 
I actually used that at the top of my injector table whilst mapping - just to avoid a boost spike causing any likelyhood of leaning out. Although it did catch me out during an overtake manouvere. If you do set things up like that, it\'s best to drive the car at different conditions to make sure you know where the outer envelope is. :yes
 
Obviously to tune the tables properley you are going to need the wideband in.
 
It\'s worth noting as well, that the stock ECU has a much larger transition between primary and secondary injectors compared to the chipped ECU - on the stocker, the primaries fall to 40%, on my chipped ECU they go from about 90% down to 60-70%, and therefore the secondaries come on more softly.  I think that was done to reduce the harsh transition that exists in the stock ECU maps, as well as allowing more fuelling at higher than stock boost limits.