Injectors too big??

[sky_high_psi]

Hey all

Basically i bolted all my aftermarket stuff to my silvia (motor is rb25) myself including some sard 850cc injectors and now my car is currently at a workshop which are trying to get it wired up, running smoothly and dyno tuned.

Now the workshop has contacted me and they cant seem to get it running right and think it might have to do with the injectors being to big.I bought the injectors second hand and the previous owner said they ran on his rb25 fine. I had the injectors cleaned and flow tested and all was good.

So pretty much what im wondering is are 850cc injectors actually too large for an rb25?

Trent.

[mitchy]

it might be certain brand injectors.. my old (possbly nismo?) 740's used to idle a bit rough, but that could have been that one was about to die..

replaced them with another set of powerflow 740's and it idles perfectly

[Tocchi]

yeh size doesnt matter if the tune is good.
chucking in larger injectors on a stock tune wont work well, if at all. the engine will get flooded.

its either the tuner or the injectors

[Alt_F4]

What ECU?
Could be incorrect injector/injector latency correction settings?
Or it could be just a shitty injector harness :(

Injector sizing is relative to the power your chasing, but generally anything under 1000cc shouldn't have any dramas with running correctly if set up/tuned properly imo

[sky_high_psi]

yeh size doesnt matter if the tune is good.
chucking in larger injectors on a stock tune wont work well, if at all. the engine will get flooded.

its either the tuner or the injectors
yeh i cant see them being bad tuners because they specialize in my ecu but i cant see there being anything wrong with the injectors either because they've been tested.


What ECU?
Could be incorrect injector/injector latency correction settings?
Or it could be just a shitty injector harness :(

Injector sizing is relative to the power your chasing, but generally anything under 1000cc shouldn't have any dramas with running correctly if set up/tuned properly imo


Im using a microtech lt16 (the latest microtech)

Thats what i thought, i thought its not that huge of an injector really and that it would just have a smaller duty cycle (if thats how it works? im no mechanic)

[RRob]

Sard side feed suck wang hard. Check to make sure the lower orings arn't leaking fuel into the manifold. They are also hard to get a clean
AFR out of down low in the rev range with a premium ECU. And IMO the microtech can't control dirty injectors nicely on a piston engine.

[R3N]

i've heard some brands sort of "leak" and don't have a good spray pattern so will cause your car to run/idle like shit. how much power are you chasing anyway? checked fuel pressure? lines etc

[cactus]

take it to ovaboost

[sky_high_psi]

i've heard some brands sort of "leak" and don't have a good spray pattern so will cause your car to run/idle like shit. how much power are you chasing anyway? checked fuel pressure? lines etc

yeh ive heard of that too but they've been tested and were fine...

roughly 300-350bhp

[mitchy]

850's are massive overkill for 350hp.. even a set of 550's would shit it in.

[Joe]

Get rid of them.. Sard 850s are like garden hoses, they'll wash your bores nicely.

[DISTRBD]

850's are massive overkill for 350hp.. even a set of 550's would shit it in.

LOL my shitter has 650s n makes 280hp :lol:

[mitchy]

LOL my shitter has 650s n makes 280hp :lol:

good on ya.. everyone knows you can make 500 on stock 370's, just use that wolf you have

[sky_high_psi]

850's are massive overkill for 350hp.. even a set of 550's would shit it in.

I know but i got them at a reasonable price so i thought why fork out more for a smaller injector like 550's when i can use bigger ones for cheaper(thinking they would work fine).

All i really want to know is CAN they be used and if not why?

[RRob]

Yes you can use them with microtech.

Would I use them? No
Would I put a microtech on a rb25? No

[cplagz]

Swap the 750s for 550s if you're that worried about money, I'm sure someone wants to make more power, has small injectors and doesn't have coin to buy new ones. Everyone's happy then.