Does somebody use twin injectors settings?

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
Gigievo
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Joined: Sun Jan 20, 2013 1:59 pm
ECU Model: S80 Pro
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Does somebody use twin injectors settings?

Post by Gigievo »

Hello,

I'm interested in understanding twin injector function of my S80.
I would know if in my 4 cylinder engine I have to buy 4 bigger injectors to have a commutation by the blend map.
Or, as I preferred, if I can install 4 more injectors of the same size that will work together. In this case, how I have to set DTA software? Does blend map only allow a percentual commutation? Using same size injectors I should'n have a flow change, I'm I wrong?
Is opening of outer due only by the injection time in main injection map and self managed from ecu?

Thank you for your help!
stevieturbo
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Re: Does somebody use twin injectors settings?

Post by stevieturbo »

Read the manual, but DTA must have both sets of injectors the same size. It cannot work with different sized injectors.

the blend map is purely to help make the transition between the two sets coming on smoother.

0% in the blend map would be all fuel coming from the primary injectors*
50% in the blend map would be fuel equally split between both sets
100% would be the secondary's providing all fuel and the primarys none.

*note. Pretty sure that if you leave it at zero, once a predetermined duty cycle is reached, DTA will start to bring the second set online regardless of the other settings. At least that's how it used to work before the blend map appeared.
Gigievo
Posts: 11
Joined: Sun Jan 20, 2013 1:59 pm
ECU Model: S80 Pro
Firmware Version: 65

Re: Does somebody use twin injectors settings?

Post by Gigievo »

Ok, but if injectors are of same size, how is possible fuel flow change? 0% all fuel from inner, 50% half from inner and half from outer (no difference) and 100% only from outer (no change, they give the same fuel of inner)... This is the reason because I thought it needed bigger outers...I'm confused
lumley32
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Joined: Mon May 10, 2010 5:09 pm
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Re: Does somebody use twin injectors settings?

Post by lumley32 »

you can use different injectors sizes, its just unlikely that the injector dead time will be the same for each set. this isent a massive problem but it would be better if there was a dead time table on each set of injectors
Gigievo
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Joined: Sun Jan 20, 2013 1:59 pm
ECU Model: S80 Pro
Firmware Version: 65

Re: Does somebody use twin injectors settings?

Post by Gigievo »

I would use 8 injectors of same size. 4 of them always active, the other only in some conditions (RPM/load) together main. Is it possible?
lumley32
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Re: Does somebody use twin injectors settings?

Post by lumley32 »

why do you want to? what are you trying to do?
Rob Stevens
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Re: Does somebody use twin injectors settings?

Post by Rob Stevens »

IF you use twin injectors it works like this if you don't enable the blend map.
if the ecu needs to inject say 20ms of fuel and there is 30ms of time available in the engine cycle to do this it will use only the 1st set, if you double the rpm but the injector still needs 20ms of fuel there is only 15ms of time to do this. Now the ecu will split the 20ms into 10ms on the first set and 10ms on the 2nd set. The actuial split point is 80% duty on the 1st set. Like this its just automatic.

You also have a way to force the change over point (to 100% 2nd set) on throttle and/or RPM.
There is also the blend map where you can tell the engine to use say 30% of fuel on 1st set and 70% on 2nd set
Blend map is for Throttle/RPM only
You have an option to use MAP as a hard changeover control also.
Injectors should be the same size and the pressure referenced from the same place, this is a bit tricky if one set is in the boost and the others are not. Just need to keep the fuel to engine pressure, therefore flow the same.
stevieturbo
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Re: Does somebody use twin injectors settings?

Post by stevieturbo »

lumley32 wrote:you can use different injectors sizes
I'm 99% sure you cannot. DTA offers no provision for independant scaling of injector flow. As far as I am aware and DTA has always been like this, both sets must be the same size.

As for the blend map. I use this as mine....MAP vs RPM of course ;)

Reasoning. When on load, ie full power I want fuel split equally between injectors, ie 50/50
Ive scaled the 0-50 loads to try and bring the second set on line progressively with no big duty changes. And at low loads but higher rpm's I still want the second set being triggered occasionally just so they arent sitting closed all the time. During a period of non-use I have seen injectors lock up before. And on my car, I could drive for a year very quickly and never need to go over 2000rpm lol.

If you want to test the second set, just change the map to 100% and the engine will run off them only.


Image
Rob Stevens
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Re: Does somebody use twin injectors settings?

Post by Rob Stevens »

Ahh you can use Map/rpm only if you have your main fuel map set to this also.
Gigievo
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Joined: Sun Jan 20, 2013 1:59 pm
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Re: Does somebody use twin injectors settings?

Post by Gigievo »

Ok, I think I understood....
I can use 8 same size injectors and when setted twin injectors, in main fuel map there will be a bigger opening time (more ms respect single injectors).
By blend map I will change % of main and remote injectors. 50% will be half time inj1 and half time inj2. But with twin injectors total time will be bigger of single injector case. Right?

Thank you again
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