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What Size Injectors To Go For When Chasing 300kw ?

madaz R33

By madaz R33,
in Tasmania

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madaz R33 Proficient

madaz R33

Posted
Posted

hi all, well its ssems like it has been a long slog but almost finally there, (last of the mods) had the car dynoed a little while back, (safe tune only, little over 200rwkw) as at that time i had a stock turbo and was running premium not 98 octane fuel, I have since installed a Vg30 hi flow and just waiting on the tune to switch to 98 octane, I need to know which injectors to buy to help me achive my aim of 300kw!! will the 550 sard inj do the job nicely? my mods so far include: pwr fc, Vg30 hi flow turbo, fpr, jj intercooler, ebc, when the car goes in to have the tune, injectors as well as Z32 afm will go in, thing is i have heard conflicting stories about running overly large injectors in a car that doesnt have massive amounts of power/let me re phrase that, overly large injectors can cause idiling and fuel consumption problems. with the mods i have listed what size injectors would people reccomend for me to achive my aimed 300kw?? at $760 delivered i am looking at the sards, but for $860 Delivered i could also get TOMEI 555cc or TOMEI 6 Injectors for $875 Delivered or 6x Tomei 600cc injectors - $820 delivered so what does eveyone think? will i need anything larger than 600cc to achive 300kw with supporting mods or can this be achived easily with 550cc injectors help!

Al Grand Master

Al

Posted
Posted

550cc-600cc

But that turbo will not make 300rwkw :(

I made 277rwkw with my hi-flow rb25/VG30 combo. That included cams and extensive head porting; boost was 16psi, but higher boost settings did not make significant power increases (ie: past the efficiency range of the turbo).

I am now building up a completely new engine setup (including new turbo), which should make about 300-330rwkw; i still intend to use the 550cc injectors as my mechanic's calculations have indicated that the injectors should flow enough fuel.

Al Grand Master

Al

Posted
Posted

sorry was editing my first post while you replied, so please review it.

On a stock rb25 i think about 250-260rwkw.

I sold that turbo to a guy, that goes to the same w/shop; on an std rb25NEO it made 270rwkw. BUT rb25NEOs have larger cams, solid lifters and probably some more engineering/power benefits over the R33 rb25.

madaz R33 Proficient

madaz R33

Posted
  • Author
Posted
  guesty said:
You shouldn't have a problem running even bigger injectors because the computer is only ever going to let the injectors open up enough for the fuel it needs.

its just that i had heard running larger injectors than u need can cause problems with idleing issues

mass_iv Grand Master

mass_iv

Posted
Posted

that is correct, larger injectors may cause ideling issues, ur car will run a little rough, and sound like it has cams hahaha... i think ur best bet wud be to go the 555cc injectors and if they dont do the job throw in a FPR to keep the fuel pressure up.

madaz R33 Proficient

madaz R33

Posted
  • Author
Posted
  ardie said:
550's will do it without breaking a sweat, just grab a 2nd hand set and away you go, easy

^^ i wont get s/h ones, always brand new gear when it comes to my baby LOL! BTW i neglected to metion i also have a bosch040 fuel pump to go with my supporting mods

  • 2 weeks later...
Yawn Mentor

Yawn

Posted
Posted
  QWK32 said:
it roughly works out that 450cc will do the job so 550cc would be good.

So by your calculations, how much power will 600cc injectors flow at just under 100% injector duty cycle?

TAS_SINFUL Collaborator

TAS_SINFUL

Posted
Posted

personally i would never want my injectors running at, or near, 100% cycle..

the last thing you want to run out of is fuel. they do, and will go fkn bang if you keep running them like that.

injectors are not really that expensive between different sizes now, for 300kw @ wheels i would at a minimum be using 600cc - 720cc

using bigger injectors than needed is going to be better than running ones that are just big enough. if you have your car tuned properly

when they go in you will find that you will have very little problems at all..what fuel you dont need will be returned by the fuel preassue reg.

good luck with it.!

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