gWRXm

What type of injectors should i be looking to upgrade to Side or top? And what would be gained by getting 850cc as opposed to 550cc

barge

I was just about to ask the same thing.

can you over inject a phase one engine ?

my simple brain says get the 850 injectors & that way they wont be working as hard, can someone confirm ?

cheers

john banks

How much power do you want (or rather how much will your turbo and breathing allow)? That answers the question.

RB5_245

depends on your're power requirements, for best power i beleve you should be running over 65% duty cycle although depending on the injector you shouldn't really be going over 85/90%

Flows are generally rated at 2.5bar, so at say 4bar(above manifold pressure) your 550 would flow closer to 680-700. (remeber to take your duty clycle off that).

to calculate the flow you need use

flow = HP x K
.......------
..........C

Hp= horsepower
K= constant for turbo engine = 5.6
C= number of cylinders

Hope this isn't a lesson in 'tell me somthing i don't know'

Dave (i'm not actually clever by the way, i was just reading this the other night )

edited to make my formula look nice

[Edited by RB5_245 - 11/19/2003 4:50:13 PM]

john banks

380, 440, 500(ish), 550, 660, 740 and 850 injectors commonly used on Scoobys are AFAIK quoted at 3.0 bar which is factory, so 4.0 bar only gives you 15% extra, and then only if your regulator and fuel pump will cope with it (e.g. 1.5 bar boost would give 5.5 bar fuel pressure, this is a too much for many aftermarket fuel pressure regs).

If you are using any factory turbo off a Subaru Impreza, then 550s will be more than adequate, and you can usually get away with 440s at higher fuel pressure for the largest factory turbo which is a TD05. Going too big results in problems opening the injector for a short enough time to accurately control idle mixture. This could affect smoothness and emissions compliance.

[Edited by john banks - 11/19/2003 5:00:03 PM]

RB5_245

Cheeky B******* This means my 440's are really only about 400's.... which in turn means i need new injectors. Best get saving

Edited to say, would anyone like to swap a set of 550's for a kidney, well used but still in working order....

[Edited by RB5_245 - 11/19/2003 5:17:32 PM]

john banks

Thought you didn't want massive power? Yesterday You are on the slippery slope

RB5_245

LOL, More slippery than you can imagine, I have an MR2 turbo in the garage... or more appropriatly spread around the garage

By my calculations for 340bhp i would need 440's running around 90% duty cycle at 4bar above manifold pressure. I think this is pushing it a bit.

RB5_245

Mind you, it would be a shame to let all that potential from the TD05/06 go to waste.......


[Edited by RB5_245 - 11/19/2003 6:03:46 PM]

barge

ok so my 93 wrx which at the moment just has HKS exhaust & induction kit but looking at LINK ECU would be fine onm the 550's ?

john banks

Yes.

Fatman

If it helps anyone, I may have a set of 550s (Denso purple top-side feeds) for sale in a week or two.

AlanG

I know someone else with 550's that drop in to phase II rails and connect with std plugs......
Could let them go for 300....

Alan