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View Full Version : DIY: Modifying stock injectors (increasing flow rate)



jimmyjames
04-21-2008, 10:22 AM
Chunky deserves all the credit on this but unless/until he reposts his old thread, I'll post my experience. (A copy of that thread is found here: http://www.k20a.org/forum/showthread.php?t=31752 )
Based on his figures, you should expect roughly:
270cc -> 480cc
310cc -> 520cc
Very inexpensive alternative for those of you looking for larger injectors (i.e. upgrading JRSC street to race). Best part is no resoldering clips. Stock injectors, stock clips.

Before anyone asks, there is no advantage to installing larger injectors in a stock/near stock car. This is used primarily for built N/A or boosted applications

1. Get stock injector

http://i30.photobucket.com/albums/c335/jjgarris7/car%20stuff/IMG_3852.jpg

2. Remove O-ring

http://i30.photobucket.com/albums/c335/jjgarris7/car%20stuff/IMG_3854.jpg

3. Pry off nozzle as carefully as possible. It does not HAVE to be reused but I am not a fan of breaking things or throwing parts away.

http://i30.photobucket.com/albums/c335/jjgarris7/car%20stuff/IMG_3855.jpg

4. Use a dremel / rotary tool and grind the nozzle to remove the screen. What you'll want to do is work your way around the edge until it looks like there is a crack emerging. Once the "crack" makes its way around, it'll fall off.

Before, during, after
http://i30.photobucket.com/albums/c335/jjgarris7/car%20stuff/IMG_3849.jpg

5. Send the injectors for cleaning and flow testing.
It will cost about $100 and is available at RC or Marren (among others):
http://www.rceng.com/Fuel-Injector-Cleaning-P43C0.aspx
http://www.injector.com/injectorservice.php?PHPSESSID=44f66c9c3fbd44c18699 1a0e8c838c7a

You will receive cleaned injectors as well as a flow testing sheet that will give you the precise figure for the new modified injector. Use this number in your kpro settings.

davisj3537
04-21-2008, 12:34 PM
The 270cc injectors mod out to around 485-490 and the 310cc injectors mod out to around 520-525. Or atleast that is from the flow charts I saw. It is a good idea to get them flow tested anyway...

Ba82Ep3
05-01-2008, 07:06 AM
Just got my 270's back from RC. They modded within 1.7% of each other and are 480's. Excellent spray pattern as well. I no longer have the plastic piece on the end you have to remove, and i DIDNT have to break them to get them off. Using red rubber covers for your slip joint pliers (found at Sears) makes for slow easy removal with no breakage/damage.

2-k-4blksi
05-02-2008, 11:13 AM
how do ya figure this out......always thought you had to buy bigger injectors no matter what.

Ba82Ep3
05-02-2008, 02:05 PM
Installed my modded 270's today and have been working on cleaning up the fuel maps. BIG difference. Injector duty went from high 80's and occasional low 90's to 46% duty cycle MAX!!! MAJOR improvement. The fuel maps are all jacked up... but im working on getting them straight. A/F in 4th is now flat as hell (pulls hard as shit now!!!)... but still spiky (rich) 6k rpm up to redline in both 2nd and 3rd. I had to bump my idle up to 900rpm. Ill have to clean up idle fuel % and then im sure it will be ok.

Since my injectors werent all 480's...

474cc
476cc
480cc
482cc

... i split the difference and put them in KPro as 478's. Sounds logical? Or should i send out my other four with these again (8 total), get them to match them up and install the closest four? Is the 1.7% difference going to make that big of a deal? Also... my injectors came back w/o the filter that is inserted in the top of the injector... looks like a round black plastic ring that drops into the injector tip. I tried removing the filters off of the other 270's but they didnt wanna seem to budge, and i didnt wanna break em. Anyone know where i can purchase these for reinstallation time? I couldnt find anything OEM but a whole injector...

jimmyjames
05-02-2008, 02:18 PM
Since my injectors werent all 480's...

474cc
476cc
480cc
482cc

... i split the difference and put them in KPro as 478's. Sounds logical? Or should i send out my other four with these again (8 total), get them to match them up and install the closest four? Is the 1.7% difference going to make that big of a deal? Also... my injectors came back w/o the filter that is inserted in the top of the injector... looks like a round black plastic ring that drops into the injector tip. I tried removing the filters off of the other 270's but they didnt wanna seem to budge, and i didnt wanna break em. Anyone know where i can purchase these for reinstallation time? I couldnt find anything OEM but a whole injector...

Not sure what you mean by filters, please post a picture.
As for the difference in the injector size across all of them, you can split the difference as you mentioned or to be very accurate, click on fuel trim in kpro and add/subtract fuel percentage for each cylinder.
using 478cc as the injector size:
474 = +.83%
476 = +.42%
480 = -.42%
482 = -.83%

Ba82Ep3
05-02-2008, 07:53 PM
http://i30.photobucket.com/albums/c335/jjgarris7/car%20stuff/IMG_3854.jpg

For lack of a better pic... its the thin black plastic washer looking thing at the top of the injector above the black o-ring. If you look down into the injector... there is a small arrow shaped fine screen filter that is part of that thin black plastic thing at the top. It basically looks like a black auto-x corner cone pressed into the end of the injector. It used to be a part of fuel system maintenance on older Prelude and Accord engines (2.0L) to take the injectors out/apart and back wash these filters out... then reinstalling them. These however didnt seem to want to budge... and the injectors i got back from RC didnt have the filters in them. Im a little concerned about it... although there probably isnt anything in the fuel system big enough to cause any issue over a short period of time...


... by the way... is it common for the larger injectors to be somewhat of a pain to get tuned correctly w/o the fuel maps looking like total dog shit? My 2D maps look like a 3yr old went nuts with a fat crayon... but damn if it doesnt run good!

Yeah if they had marked which injector was which according to the printout (i assumed left to right as i opened the box and i used what i thought was the 482 on cylinder 3 - its a stab in the dark tho) i could have individually matched them in KPro. I guess i need to use the service thats the next up to get them to match them up for me... and send them a larger quantity of 270's to get a nice matched set of 4. :mfrown:

We should do a group shipment... and see if they would give us a break on the price too...

jimmyjames
05-03-2008, 07:06 AM
Ok, i get it now.
If they have excellent spray, that should be all that matters.
I would call/email RC and ask what the deal is though. If they're disassembling something and not putting them back together right, that is a problem.
PM chunky and ask if his black auto-X cone was removed from his when he sent them in. :mwink:

As for the tuning, I have no idea, aside from modifying the injectors, i've never tested them or ran them.

Marc-111
05-03-2008, 07:41 AM
nice DIY bro...thanks!

LAvtec818
05-03-2008, 10:44 AM
wow never saw this one coming thumbs up

Ba82Ep3
05-03-2008, 02:10 PM
PM chunky and ask if his black auto-X cone was removed from his when he sent them in. :mwink:

:lol:

Sorry, it was the best comparison i could come up with. Thanks for your info and help thus far though.

:thumb:

I picked up an inline fuel filter im going to install before the rail to be sure i get no crap in the injectors. Its Purolator F21124. Its clear and fairly small. Il hit a pic of it once its installed for anyone elses future reference.

parkjehhyun
05-30-2008, 06:29 PM
dang, i seriously didnt see this coming. how did you figure this out? ephatch has some real geniuses up in here.

talonXracer
05-30-2008, 07:07 PM
:lol:

Sorry, it was the best comparison i could come up with. Thanks for your info and help thus far though.

:thumb:

I picked up an inline fuel filter im going to install before the rail to be sure i get no crap in the injectors. Its Purolator F21124. Its clear and fairly small. Il hit a pic of it once its installed for anyone elses future reference.


That may cause a drop in fuel pressure and can cause the fuel pump to overheat. If it is a clear plastic I dont think it will handle the fuel pressure,,,,wouldnt that be spectacular,,a burst fuel filter just dumping massive amounts of fuel on a hot engine....................

I think they remove the filters in the injectors to get the flow consistent.

pynikal
09-13-2008, 04:42 PM
good stuff!!!

Onasty
08-23-2010, 12:23 PM
have to bump this if i modify my injectors get them flow tested and cleaned. install them and fix kpro setting for injectors should i get a retune also is it worth a retune??

Ba82Ep3
08-23-2010, 02:58 PM
Man this thread is old. lol

I DEFINITELY had to adjust the tune, even with KPro set to the 'proper' flow of the injectors. Since this thread, i sent a batch (12 or 16 of them, cant remember) of modded 270's in to be tested/cleaned and MATCHED. That way i KNEW each injectors flow rate, and i had a greater chance of getting 4 injectors that were close to each other.

When you send them in just for testing and cleaning, you get a sheet that tells you flow rate and such, but nothing tells you which one is which (as in, they werent marked). I dont remember my exact flow rate differences from the first batch i sent in so long ago... but i think the lowest was close to 475cc and the highest was almost 485cc.

While that isnt a large variation, i didnt want to run the risk of putting the lowest of them on the hottest cylinder (#3) and creating issues the more i tuned the engine. Its only natural to push the performance envelope the more we mod our cars... and i wanted to be certain that the values i adjusted in KPro were as accurate as possible, since i was boostin the k24.

Plus im just an anal muhfukkah. lol

Do you datalog your car at all?

jimmyjames
08-24-2010, 09:50 AM
You should retune your car ideally but I would say it's not essential.
What I would do if I were you is to just enter the new numbers from the flow test into kpro.
Use the lowest of the 4 to insure you don't run lean.
Do some datalogging and check out how things are working; I would bet it should be good to go.
The spray pattern will be affected and this does affect the effective output but you could be fine waiting until a future major mod to spend the money on a retune.

Onasty
08-25-2010, 08:30 AM
yea i datalog im at high 80's low 90's but i want to put a 3" intake and velocity just dont want to max out my injectors

Ba82Ep3
12-21-2012, 04:29 PM
Bump this thread UP!

tinman5
03-11-2013, 06:02 PM
For the sake of bumping and genuine need for an answer I ask this:
Are the hard plastic grommets/nozzle extensions neccesary for install and proper function?
If so, can these pieces be sourced at all? No auto parts retailer nor dealership parts look up shows availability or even a part number.
How can you identify the 270's from the 310's (or any other K variant)?
There is a guy selling a couple sets of injectors from both a base and Type S and I want to make certain I get the correct (270's).
I am looking at a black body injector with...SE12
ABG on the body just below the connector and the letter G just to the left.

And a couple of the plastic grommets have a fine crack going around and a third is straight up broken in half. Input please...

Jpax
03-11-2013, 10:42 PM
Are the hard plastic grommets/nozzle extensions neccesary for install and proper function?

No - The Hard plastic is a shroud that also limited the amount of fuel flow. they are not necessary but if removed they will make your injector flow MORE fuel. the injector it self will flow properly, Vrs stock it will only flow more fuel.

If so, can these pieces be sourced at all? No auto parts retailer nor dealership parts look up shows availability or even a part number.

For the hard plastic pieces, they come with the stock injectors - they don't sell them separately only the o rings that seal the injector to the manifold are sold, and the filters If i remember right.

How can you identify the 270's from the 310's (or any other K variant)?

these are 310s
http://i21.photobucket.com/albums/b274/Stubby3si/inject3.jpg

these are 270s
http://i21.photobucket.com/albums/b274/Stubby3si/inject.jpg
http://jacksonracing.com/shop/fuel-injectors/honda-270cc-fuel-injectors/



There is a guy selling a couple sets of injectors from both a base and Type S and I want to make certain I get the correct (270's).
I am looking at a black body injector with...SE12
ABG on the body just below the connector and the letter G just to the left.

And a couple of the plastic grommets have a fine crack going around and a third is straight up broken in half. Input please...

if the hard piece is broken in 1/2 then don't buy them. unless you have a spare injector you can replace it with that has is not broken.