GTR Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
However it does not involve a GTR nor RB26 tech-talk I was wondering if you guys could help me out.

I'm currently swapping an RB25 into my Silvia. The main goal for the car would be to have fun with it - while doing both track days as drifting - while I do want to do things right from the beginning, creating the opportunity to go further later on.

I decided on sticking with the stock turbo for now, while I did upgrade a lot of other (external) parts such as Greddy intake, HKS cam gears, SSQV, Type-R IC, timing Belt, N1 pumps, Koyo rad., Apexi PowerFC and so on.

I keep having questions about which injectors I should go for. Since the RB25 has side feeds from factory and need High indep. injectors, I was wondering if I could tackle this issue by going for a HKS top feed fuel rail and SARD 700cc RB26 injectors. Since those are low indep. I keep wondering whether this should work fine on my RB25 - or not.

Also, since the HKS adjust. cam gears will only fit aftermarket cams, I'm not quite sure yet where to go for. Tons of HP is not my main goal, but getting higher torque would be a nice advantage.

Any help from you guys is appreciated :)

Thanks, Marco
 

·
Banned
Joined
·
11,494 Posts
Not sure why you are saying you want top feed injectors. If you're sticking with the stock turbo, 700cc injectors are overkill in the extreme. Stick with the stock injectors. If you upgrade your turbo, then decide what injectors you need. In general if you're aiming for Xhp, you need at least 6 x Xcc injectors. Unless you're going nuts, 6 x 555cc HKS side-feed yellow injectors should be adequate (for up to 555hp).
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #3 ·
Thanks for your reply. I figured that already, although I noticed a line that oversized injectors wouldn't harm.

I can't use the stock rail on the Greddy intake, so I have to go for upgraded fuel rail anyway. That's why i prefer the HKS top feed rails
 

·
Banned
Joined
·
11,494 Posts
Thanks for your reply. I figured that already, although I noticed a line that oversized injectors wouldn't harm.

I can't use the stock rail on the Greddy intake, so I have to go for upgraded fuel rail anyway. That's why i prefer the HKS top feed rails
Okay, not sure if the top feeds would work, need to ask someone else that. Too big won't harm but I think fuel economy may suffer. Ideally you should aim for a 60-85% duty cycle, with around 72% being optimum. 85% occurs roughly when bhp = injector cc in 6 cyl engines.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #5 ·
Thanks!

I'll overthink this and might decide to go for a bit smaller injectors then - since I have no need in getting 450+HP at all.
 

·
Registered
Joined
·
325 Posts
For any injector there is a minimum opening time (dictated by the parts and the laws of physics) and a maximum flow rate. The larger the maximum flow rate, the larger the minimum opening time. Consequently smaller injectors give more fine control, larger injectors higher peak fuel delivery at WOT.

For any single injector/cylinder injection system injector sizing is therefore a compromise between these two factors. This begs the question: Has anyone tried a staged dual injector setup on an RB engine?
 
1 - 6 of 6 Posts
Top