Joe_Dezod

Anyone know what the stock fuel injector cc rating is? I really don't want to send one out to be flow tested but I'm curious as to what it actually is. If anyone knows drop me some info if not I'll send it out a little later...

Thanks in advance guys

jmiller20874

Here are the volume specs from the tC repair manual.

Injection Volume
76 to 92 cc (4.6 to 5.6 cu in.) per 15 sec

Defference between each fuel injector
16 cc(1 cu in.) or less

Hope this might help

matty-tC

lol that's not right.
we'd be running uber lean if that were true

joe for some reason 260 or 220 comes to mind... but don't take my word for it. i'll see if i can find anything

jmiller20874

See for yourself.



Which is 304cc to 368cc as an acceptable range. How would this be lean?

lo_bux_racer

According to RC Engineering, this is what you need to support 200 hp in a NA application:


Looks a lot like what we have, doesn't it? Wasn't it nice of Toyco to give us much more injector than we need? (BTW, this is typical Toyco over-engineering, the 2JZ-GTE came with 550cc injectors for only 320 hp).

matty-tC

we're at 160 though so 260 or 280 makes sense

jmiller20874

Based on the above formula, it looks like Toyota figured on a 60% duty cycle. Gotta love that Toyota quality.

Joe_Dezod

So I should assume we're running with a 260CC injector then... I'll accept that. Thanks guys.

lo_bux_racer

If Toyco designed things that way. They don't. 550cc injectors on the 2JZ are good to a little over 500 crank hp. This has been proven time after time. While it is true this measurement is made at 50 psi, the standard pressure for returnless systems, it still means in service the injector will deliver, at a minumum specification, 304cc at 0 psig. If it can't do that, it doesn't meet minimum Toyco spec.

The real problem is, as you add boost, flow decreases. Under vacuum, with a fixed fuel pressure, flow increases. We can fix that with the values in the fuel map as long as our injectors will respond to short durations.

On the other end of the scale, when you apply boost, say 10 psi, your effective fuel pressure is now 40 psi, and your maximum flow is now 20% less than what you had at ambient pressure with 50 psi of fuel pressure, because flow depends on the pressure drop across the pintle, not the pressure in the fuel system, unless, like all the return style systems, rail pressure is indexed to manifold pressure. That's where the problems start. Not to mention, at 40 psi, atomization is getting worse, and if you try to run something like 15 psi, you are now at 35 psi across the pintle and flow is 30% less than what you had at 50 psi. Really not good. When you really need more rail pressure to counteract the boost and flow more fuel, you get just the opposite. Diminishing flow and poorer atomization lead to fuel starvation, detonation, and engine destruction. Where that actually starts to be a problem is only known by a few people right now, but as more people try to push higher boost with their turbo kits, we'll all be finding out fairly soon.

TurboCustomz

They are 370cc injectors.

-Keith-

I got a question..... do we need to get adaptors for the aftermarket injecotrs or are ours just like the honda injector plug?

And I guess I could go look but we dont have a injector resister box right

TurboCustomz

You need tails for the RC injectors.

-Keith-

aight cool thanks

Joe_Dezod

Yeah the MSD injector clips fit the MSD injectors, Accel injectors, and the RC engineering injectors.

Thanks for the number man (turbocustomz)

hahaitzskippy

thank you for breaking it down for me :D

matty-tC

good god thats huge. i wonder how big the ones with the s/c kit are.

hahaitzskippy

isnt it 420cc?

lo_bux_racer

Sure. At 64.4 psi, they'll flow that.

You guys do understand injectors are rated at a specific pressure? And if you change the rail pressure the injector flows either more or less depending on whether the pressure increased or decreased?

matty-tC

what fuel pressure is the car running stock?

lo_bux_racer

50 psi. It's controlled by a regulator in the tank and the pressure is fixed.