I'm gearing up to do a DIY tune with NepTune on my GS-R. I've done a lot of research on injectors and found a lot of conflicting information.

Common injector calculators indicate that 240cc is safe only for close-to-stock power output, but anectodally many say that they can handle 190-200 whp on stock fuel pressure. On the other hand I've heard that even on ITR fuel pressure 240cc injectors see close to 95% duty cycle at peak HP on stock ITRs.

My question is, will I be safe sticking with the stock injectors and seeing what my duty cycles look like, or should I just spring for larger injectors now (probably RDX)? Saving money would help me a lot, but I don't want to cut corners I shouldn't cut and put my engine in danger. I will not be running an aftermarket FPR.

Here's my current engine setup:

Stock GS-R block
AEM CAI
Blox A cams
Apexi WS2 catback
GS-R cat and header

 

you will be fine Blox A's are not much bigger then plan ITR cams and the WS2 isn't much better then a ITR exhaust, so you will prob. make ITR power

 

Stock would be fine but with bigger injectors you have more room to grow.

 

I've gotten the impression that ITRs have higher fuel pressures than GS-Rs. On GS-R fuel pressure I still won't hit 100% duty cycle on 170-180 whp?

 

what fuel are you going to run?

 

Stock 240cc injectors can handle 190 whp on 91-93 octane fuel without an issue.
If your fuel pump is old & stock, replace it with a walbro.

Your not in any "danger" unless the car is running extremely lean...
Install a wideband, tune the car, have fun :-)

 

@ Mr.johnson -- I'll be running 91 octane (it's the best I have access to)

Thanks for the replies. It confirms a lot of what I've read but it's nice to have the info firsthand.

I have to admit I'm a bit relieved that I'll be OK with stock injectors -- the cost of all the hardware plus injectors was starting to look scary esp. with a baby on the way, but I want to make sure I do this right.

I'll monitor my A/F and duty cycle with a TunerView and update with duty cycle info for future forum searchers.