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Injectors Recommendations

CeJay

By CeJay,
in Engines & Forced Induction

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CeJay Grand Master

CeJay

Posted
Posted

Ok I did a bit of a search. couldn't find anything. I'm looking at doing some work on my car, has an r32 spec rb25de-t in it.

Looking at putting in an aftermarket ecu and injectors. Wanted to know if anyone had any recommendations on injectors? Brands and size. Currently the car is putting out about 215kw at 18psi on stock injectors, with supporting mods to get it to this stage.

At this stage I don't think I'd want to go past 250-260kw. So would some 550cc or so injectors suffice? If so any good or bad experiences with different brands? Bit of a noob when it comes to injectors.

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https://www.sau.com.au/forums/topic/243032-injectors-recommendations/
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discopotato03 Grand Master

discopotato03

Posted
Posted

Do the R32 RB25DE's use top feed injectors ? Someone did tell me that the top and R33 side feed rails are interchangable with the top feed ones .

I think the Nismo SF 555's or 740's are high resistance saturated injectors so not sure what you'd do with an R32 .

A .

W0rp3D Grand Master

W0rp3D

Posted
Posted
Nismo 555's or 550's (cant remember the size fo RB25's)

They are bigger than you need.

You could get away with GTR 440's adapted to fit and they would be fine. (bit of dicking around)

I believe s15's are 440 and a straight fit, they pop up in a set of 6 from time to time.

W0rp3D Grand Master

W0rp3D

Posted
Posted (edited)

After the research i have done a good guide is that whatever horsepower your looking for thats the cc of the injectors you want plus a little more for headroom, the horsepower your after is 350, standards are 370cc so it does not leave you with much head room, next size up would be the S15 440cc, another thing you also need to take into account is once you have 260rwkw will you want more?

Not so long ago i would have been more than happy with the 220rwkw i have now, but things have changed, if you can see this being the case it might be worthwhile going 550cc so you dont have to do another change when your pushing for 300-350rwkw.

Edited by W0rp3D
Kranker Collaborator

Kranker

Posted
Posted

rule ive heard for minimum injector size is:

divide engine hp (rough figure) by no. of cylinders to get hp per cyl, and you need 5-6 cc fuel per hp

so for you say you want about 400bhp

400hp/6 = 6.667 x 6 = 400cc, plus fudge factor = 500cc injectors

but most of the stuff ive read says its better to go bigger, a good tune should iron out the problem of using oversize injectors, plus it gives u room to make more power with out buying another set of injectors

W0rp3D Grand Master

W0rp3D

Posted
Posted
rule ive heard for minimum injector size is:

divide engine hp (rough figure) by no. of cylinders to get hp per cyl, and you need 5-6 cc fuel per hp

so for you say you want about 400bhp

400hp/6 = 6.667 x 6 = 400cc, plus fudge factor = 500cc injectors

but most of the stuff ive read says its better to go bigger, a good tune should iron out the problem of using oversize injectors, plus it gives u room to make more power with out buying another set of injectors

LOL thats a lot of maths to agree with the theory that if you want 400rwhp that you should go 400cc injectors plus a bit more for head room.

Kranker Collaborator

Kranker

Posted
Posted (edited)

yeh i know, just illustrating the point that its a 6 cyl car, and u need 6 cc per hp

just happend to turn out that way, the rule works for V8 and 4s aswell, then you would be dividing by 8 or 4, then mult by 6

Edited by Kranker
W0rp3D Grand Master

W0rp3D

Posted
Posted
Anybody seen what they can get out of GTR 440cc injs on 4bar base pressure? By my calcs you would be able to see almost 350rwkw.

But gtr injectors are top feed and this application requires side feed.

  • 1 month later...
daisu Mentor

daisu

Posted
Posted
LOL thats a lot of maths to agree with the theory that if you want 400rwhp that you should go 400cc injectors plus a bit more for head room.

Yes, but your method doesn't take into account the number of cylinders. Which is predominantly fine considering this is a skylines forum, but you get my point.

If you had a 4cylinder engine and you wanted 400rwhp, you'd have to multiply by 1.5 to get an injector size (600cc) plus a bit more for head room.

Krankers method,

400hp/4cyl = 100hp/cyl

100hp/cyl * 6cc/hp = 600cc/cyl (plus fudge factor)

Same sh*t, different smell.

I wouldn't bother trying to retrofit GTR injectors when the S15 injectors are rated the same (if not higher, depends who you talk to) and are sidefeed.

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