Injector question

[Subie addict]

What is the cc of the stock injectors, and also is there popular direct fit upgrade, and for a single turbo setup where 5-10 psi is about the range I want to use what is a good safe injector size to use where I wont risk surpassing their capabilities. I'm not looking to build a race car just some boost to play with at the strip every now and then. Thanks.

-Zak

[Earthworm]

I might be wrong but I think they were somewhere around 270cc

[Cam]

I cannot tell you exactly what the OEM flowrating is for the injectors (the previous post is very close, if not exactly correct), but you can install 370cc injectors from a nissan 300zx. They are blue/purple and there is engine management software for them available through ECUtune.com. This also requires the Z32 MAF for the software.

[Subie addict]

Ya I've looked a lot into ecutune and the stage 2 chip is about the one thing I actually have nailed down (next to some ecutune cams) on the parts list I'm making to turbo my svx, I want to follow phast's setup and run it on stock interals as he did and ill build my spare engine to 8.5cr while I play with the setup and learn tuning tricks and familiarize myself with turbo setups. Ive owned turbo vehicles but never made an n/a a turbo or modded a turbo vehicle. I was just wondering how big of a jump the injectors were making to go boosted. Thanks for the info:D

[Cam]

The other option is to use nismo 550cc injectors. You may be able to have mike from ecutune make you a one off chip for your ecu to support this, or you could go with a standalone ems (hydra).

[XT6Wagon]

Nismo 550's are awesome injectors... beware modded STi injectors or other larger injectors. Been too long since I knew all the lovely little facts, but the space above the 550's is ripe with injectors that are nearly impossible to control at low duty cycle or have serious linearity issues where a tiny change in duty cycle can have huge effect, and a large one nearly none at all.

Shouldn't matter as 550's are a ton of injector for most STi's, and having 50% more of them....

For modest improvements in fuel system capacity, you can allways just use a fuel pressure regulator and a good fuel pump. FPR's work by increasing the pressure differential across the injector which increases the flow. Puts more stress on the fuel pump though and the higher the fuel pressure, the lower the flow the pump can put out. While I'd advise proper injectors over making major increases in the fuel pressure, people have used FPRs for decades. Once opon a dark time they would even tune the engine with selecting a proper rate in a rising rate FPR as they were turbocharging a normaly non-turbo motor with EFI and no fuel tables for positive pressure.

[Subie addict]

Any idea where the 370cc nissan injectors run out of gas (pun intended) as far as boosting ? Would they easily cover 5psi or is that pushing it?

Or an easier question, how would I calculate the right size injector for my given application?

[XT6Wagon]

honestly there is no good way to tell when your going to run out of injector as some cars make alot more hp on a given amount of fuel than others.

I don't recall any handy places to find out generic injector forumulas, but perhaps its easiest to look up STi info and figure you have 50% more fuel flow for given injectors.

The Stock STi sidefeed injectors are 480cc/min and will be sufficent for 300whp with 4 of them. So 450whp could be achieved if you used these on your SVX. I don't know how cheap the STi sidefeeds are anymore though.