RB20det Injectors

[MELLO*SOS]

Originally Posted by eh?

RB25's are side feed, RB20's are top feed. Not worth it to change fuel rail for just 100cc more. send them out to be cleaned and flow tested.

Listen to the man.

It doesn't sound like you've done nearly enough research on this important upgrade so I'll share some details with you that should help you make a more informed choice. Yeah if you can't tell I'm in the same boat as you.

RB20 = 270s Top feed high imp
RB25 = 370s side feed (w/e the exact #s are, they don't work)
RB26 = 444s Top feed low imp
KA24 = 270s side feed (w/e the exact #s are, they don't work)
SR20 = 370s side feed (w/e the exact #s are, they don't work)



You can see in that image ^^ the 2nd injector from the left in the top row is pretty similar to the top feed RB20 oem injectors. Top row #4 and bottom row #2 are side feed style, and as you can see there is no way you're going to make them work with your stock rail (top feed=fuel comes in from the top, side feed = comes in from the side). Disregard anyone who tells you to run the RB25s because they don't know what they're talking about (no offense LB). You'd have to swap the fuel rail from the RB25 which isn't worth it, considering your stock rail is fine with the right type of injectors.

To determine injector sizing for your power goal, you SHOULD KNOW by now how to do this math. If not, just know that on a 6 cyl gasoline motor you can achieve roughly 1bhp (@ crank) per CC of injector flow at 100% duty cycle. Running injectors at 100% of it's rated value will bring you problems in no time, so most places will advise you only run 80% to 85% max duty cycle. With this in mind:

270cc @ 80% = ~215 crank horsepower. ~190 wheel hp (@ 15% loss)
440cc @ 80% = ~350 crank horsepower. ~300 wheel hp (@ 15% loss)
550cc @ 80% = ~440 crank horsepower. ~374 wheel hp (@ 15% loss)
720cc @ 80% = ~575 crank horsepower. ~500 wheel hp (@ 15% loss)

Sure you'll see guys brag about hitting 300hp + at the wheels on their RB20 with stock injectors, but by using this new math you can see they're idiots and running their motor on borrowed time.

1) RB26's come with top feed 444cc's stock, but they have the wrong resistance, so you'll need to run a resistor pack if you go that way (to bring up the resistance to RB20 specs). This requires splicing some resistors into your injector harness, which is probably not something you want to do (considering you could just buy drop-in replacements with the same flow rating). They're still stock and most likely gunked up, they should be sent for rebuild

2) You can use some FC RX7 injectors, as they come with top feed 550s stock. IIRC they are even the right impedance, but you'll have to do your own research on the correct years you can rob from (and whether or not you'll need a resistor pack). The FC guys are constantly upgrading to much larger injectors so you can probably pick these up on the cheap... They're still stock and most likely gunked up, they should be sent for rebuild

3) Deatschwerks.com is a Zilvia sponsor and offers rebuilding services, where they ultrasonically clean your injectors and install new O-Rings and pintle caps then flow test the injectors. This service is like $15 to $20 each, depending on where you go and what you have done... $120 to $150 for the full set isn't bad.

4) Deatschwerks.com also offers brand new drop-in injectors in 400cc ~ 800cc range for about $300 to $350 for the set. For your power goals I'd suggest the 550s to be on the safe side and to allow for future upgrades. Plus they'll be easy to resell if you're unfortunate enough to grenade the motor in the future!

GL and please do your homework before you order or change anything! You SHOULD know that if you choose to run anything larger than 270s you are going to need a PowerFC or a custom rom tune or at very least an SAFC to fix the rich conditition you're gonna have otherwise. SAFC is the poor man's way out and I'd advise against it. Waiting for the day we have USB style injectors that tell the ECU what their flow rates are.. hehe

If anyone has corrections or additions please post them, there isn't enough injector info on Zilvia...