Injector Size

[fbssub1]

Hi have a 2.5 forged block with a TD67 25g turbo, will be limeted to hp as running a possumn link that came off a unrestricted rally car with antilag, WHAT I need to know is what size injectors should I run, it is still side feed rails but running split fuel system with after market reg,

So what size they say bigger the better but the link will limit hp so no need to be silly

[rex-leggy]

i was going to run big injectors on a possum link . but a few people have told me that once you get bigger in size it gets harder to control.

efficiency will end up going down the drain and you'll use s***loads of gas along with a not so flash idle .

also heard that around 240kw is around as far as you'll want to go with the possum link , in which case the 440cc yellows should get you there (especially with your nice block ;D) if you hook a good 12v feed to your fuel pump with a relay to get some more fueling.

this is why i upgraded to g3 (which you should do and get 800cc injectors and then shell haul!)

[fbssub1]

was looking at some 565s that i have will get them flow tested first, the walbro goes well, should be no need of a surge tank?

[wrx_lou]

What version yellows? have you though about getting them re-capped?

[fbssub1]

 wrx_lou said:

What version yellows? have you though about getting them re-capped?

I have some de capped yellows will flow test them too, but if the 565 are close to the mark will just use them

[rex-leggy]

what are you doing with the car ? if its just a road car you shouldn't need a surge tank.

if the pump is on the standard wiring then it will only be getting around 10 volts so it wont be flowing what the box says. if you put a relay in you'll get 12 volts and more flow.

just a cheep mod which could mean some significant power/more head room compared to alot of other more expensive mods

[fbssub1]

so run a seperate power feed to the fuel pump and use factory feed to trip the relay

[Pappu1]

 fbssub1 said:

so run a seperate power feed to the fuel pump and use factory feed to trip the relay

Exactly !!

That's how I had it in my gc8 Wrx and link

[rex-leggy]

 fbssub1 said:

so run a seperate power feed to the fuel pump and use factory feed to trip the relay

yep and then boom more fuel

[Koom]

I ran 740cc side feeds on an early Possumlink. It ran pretty well when using the factory MAP sensor but then you're limited to about 18-19psi (In which case my turbo was barely doing anything on my 2.0L).

Once I swapped to a GM 3 Bar MAP sensor, the idle went out the window, cruise cells were impossible to tune nicely but I could run 25+ psi. But it is very much like doing accounting with an Abacus.

So I'd say that the MAP sensor on a Possumlink has a bigger effect on un-tuneability.

[marc]

Convert to top feed rails and run the 565cc's if you want the best out of a possum link drivability and power wise at the same time.

The 440cc's will run out of fuel at 210wkw ish if you plan to keep the AFR's safe. 565cc's should do you about 230-235 safely.

As pretty much mentioned by Koom, I ran HKS 740cc on a possum link and it was ok too. However my idle was a tad average but still went ok. Stopped at 230wkw as my tuner said it wasnt happy nor safe on any more boost/power due to the ECU's resolution nd no proper IAT sensor. Thats why I say 565's as youl still have good drivability etc and reach the safty limit of a possum link. All day people push more with possum links but I wouldnt want to be the one frying an expensive motor by pusing an ecu past what it was really intended for. Well thats just my input

[fbssub1]

will stay with the 565 but flow test both sets of injectors, after spending close to 10k on motor and heads the last thing I want to do is blow it up on dyno, but it does happen when you push it to the limit, reliability as a daily is my main concern. Cheers a bit to think ova