Factory K-series Injector Sizes

K20A3
US 02-06 RSX Base, 02-05 Civic Si EP3

K20A4
Euro CR-V

K20A6
Euro Accord

K20Z2
Canadian 05-11 FD5 Civic CSX; eco engine with a detuned RBC head. A unique engine but still eco based lol.

 JDM K20A – ECO variant
ECO variant K20A engine PNL/PNC;  JDM version of the K20A3.

JDM K24A RAA/PPA – ECO variant
ECO variant K24A engine found in JDM Accord/Step wagon/and Odyssey lower grade model vehicles.

K24A1
US 02-06 CRV

K24Z1
US 07-09 CRV; not a single exhaust port K24Z engine!

K24A4
US 03-05 Accord, US 03-06 Element

K24A8
US 06-07 Accord, US 07-11 Element

K20A2
US 02-04 RSX Type-S, UK 01-05 EP3 Civic Type-R

K20Z1
US 05-06 RSX Type-S

K20Z3
US 06-11 Civic Si, 06-11 Canadian CSX Type-S

K20Z4
UK/AUS/NZ 03-10 FN2 Civic Type-R

JDM K20A Type R – Performance variant
Performance JDM variant K20A Type-R engine family found in EP3-R/DC5-R/FN2-R/CL7-R/FD2-R vehicles.

JDM K24A RBB
Performance JDM variant K24A engine found in the 03-08 CL9 Accord, RB2/3/4 Odyssey vehicles.

K24A2
US 04-08 TSX

K24A3
UK/AUS 03-10 CL9 Accord Type-S

Notes
Unless you surely know what engine you pulled a set of 270cc or 310cc injectors from, there is no easy way to visually discern factory black bodied 270cc injectors from 310cc injectors. From my experience, the etched alphanumeric numbers printed on the body of these oem injectors do not help indicate their CC size or which vehicle they originated from. Performing an injector flow test is a sure way to identify an injector’s flow rate and CC size.

The RDX 410cc injectors are easily identifiable by their iconic royal blue body color. But take heed, there are many fake RDX injectors on the market these days. So make sure you only purchase these from a reputable seller or directly from the dealership. There are many articles + videos if you google this topic to help discern fake from real RDX injectors.

Decapping Injectors (budget racer DIY hack)
This old thread on K20A.org exploits a hack known as decapping for the factory eco and performance K-series injectors. Decapping significantly bumps up the CC size for free by simply and carefully removing the laser welded screen from the tip of the injector after carefully removing the pintle cap.

Member Chunky’ found the following information out after sending decapped 270cc & 310cc injectors over to RC Engineering for flow and spray pattern testing:
Modded 270cc injectors are bumped to 490cc, and are rated as an “excellent” spray pattern post-mod.
Modded 310cc injectors are bumped to 520cc, and are rated as a “good” spray pattern post-mod, excellent rate pre-mod.

He did not get around to decapping RDX 410cc injectors, but it’s assumed that their already excellent spray pattern would be ruined if decapped.

If you decide to give this a shot here’s a few extra important details:

• Use factory dead times for 270cc or 310cc injectors.
  Tip: you can find factory dead times in Hondata’s Kmanager software when loading a 270cc or 310cc respective startup map
• Any injector change requires a FULL RETUNE.

From what I’ve gathered and what some have reported on the k20a.org forum , this is a pretty reliable mod when done right.

Decapping tutorial videos: