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

 

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

 

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

 

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]

 

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]

 

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]

 

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

 

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.

 

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]

 

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 ?

 

Yes.

 

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

 

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