cretinx

I've noticed when people run basic all motor builds (p73s with some cams, valvetrain and hondata) they frequently upgrade the injectors/fuel rail

is this really necessary ? is the factory fuel system really that restrictive that it can't pump enough fuel for ~200 whp ?

I realize you're bumping compression but does it really need to run so rich that you have to upgrade your injectors?

EKB18BPR3

it is better to run bigger injectors for few reasons. one is becuase its better to run at 50 percent on a bigger injector versus 90 percent on stock injector...exaggerated figure but u get the idea. it is easy on the injectors therefore the life span increases. also i dont believe we have anybody here on ht.com that is done with their project cars. what i mean is; people will always strive for more hp and so at some point u would have to upgrade. why not upgrade the fuel system before or at the same time u up the compression. i'd rather pay 200 to 500 to buy bigger injectors and know it'll be good for addtional upgrades and for the peace of mind that ur not maxing out the stock injectors causing u to blow ur $5000 motor.

allm0torGSR

Upgrading the fuel rail is completely unnecessary from a performance standpoint for all motor setups, I guess people do it because it looks pretty, or because some random boob online said to do it dawg. But it is very necessary to upgrade the injectors when your pushing up on 200whp. The rest of the OEM fuel delivery system is fine, though some people do upgrade the fuel pump to play it safe, which I can't argue with. Higher compression + bigger cams = more fuel required. You don't want your injectors running at more than 80% duty cycle for legnthy periods of time, they won't last long working that hard.

cretinx

Aha . . . well thanks for the advice

So if one hypothetically had a b18c1 in their civic, and were planning to bump compression to maybe 11.37 (p73s) and run a street cam, and rev within factory specified fuel cuts, would fuel system upgrades be necessary ?

also would it be necessary to pick up hondata or is that only if you plan to run a more aggressive cam or rev to 9500 rpm ?

ef9_b16a1

some people do it for safety, some because they cant find or afford someone to tune,so theu tweak fuel inj size and pressure..

my experience

in b16a n/a builds
basically u can get away with almost anything on stock injectors
compression, cams,exaust ,u name it
YES u might have about 85% duty cycle at some point, but nothing major

in a b18c , i/h/e , bolt on cams... and u r almost DONE with stock injectors..
most b18c are obd2 , and those run significantly higher fuel pressure so that helps

in anything more that the above setups, u d better AT LEAST buy a walbro pump.. and bigger injectors..
just dont overdo it if u cant TUNE the maps for the bigger injectors..
e.g stock 240
u install 310cc. ok u might geta away with no tuning
u ll be rich at tip in
at cranking etc

but of u go ahead and put 440 without recalibrating the maps..
it wont work

00Red_SiR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cretinx &raquo;</TD></TR><TR><TD CLASS="quote">Aha . . . well thanks for the advice

So if one hypothetically had a b18c1 in their civic, and were planning to bump compression to maybe 11.37 (p73s) and run a street cam, and rev within factory specified fuel cuts, would fuel system upgrades be necessary ?

also would it be necessary to pick up hondata or is that only if you plan to run a more aggressive cam or rev to 9500 rpm ?</TD></TR></TABLE>

If you want the best performance out of your cams and other bolt on parts, you buy a Hondata type tuning system, plain and simple. You buy bigger injectors ONLY when your tuning system says that your current injectors are maxed out and you will need bigger ones to make more power reliably. The only time you might upgrade in advance is if it's part of a PLANNED build that will REQUIRE bigger injectors. Fuel rails are for nothing more than looks and maybe the ability to run extra fuel taps off of them for things like nitrous or fuel pressure guages.

You buy fuel pumps when your stock fuel pump is fairly old or marginal for your intended setup. GSR/Type R/Si b-series fuel pumps will easily supply enough fuel for any all motor setup.

Put simply, you get what you need WHEN you need it, not because everyone else is buying them.

ef9_b16a1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00Red_SiR &raquo;</TD></TR><TR><TD CLASS="quote">


You buy fuel pumps when your stock fuel pump is fairly old or marginal for your intended setup. GSR/Type R/Si b-series fuel pumps will easily supply enough fuel for any all motor setup.

.</TD></TR></TABLE>

Agree, i just mentioned that , to help someone that just might not be able to buy injectors or a tuning system , as a band aid..

e.g
u have the built b18c
stock pump etch
u see u run 14/1 , thats lean...

and u cant afford to tune..
ok with an fpr or a walbro pump U REMEDY ,QUICK FIX.. the problem...
ITS NOT RIGHT..
but a lot better than running lean

cretinx

thanks a ton everybody

I'll stick with bolt ons for now and see where it takes me - gotta research cams as well

scmil95eg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allm0torGSR &raquo;</TD></TR><TR><TD CLASS="quote">Upgrading the fuel rail is completely unnecessary from a performance standpoint for all motor setups</TD></TR></TABLE>

Not true. Especially when running larger injectors (560's, 720's, etc.). Because:
Every time an injector fires, there's a pressure drop in the rail. The larger the injector, the larger the pressure drop. The higher the duty cycle, the larger the pressure drop. It's quickly compensated for by the pressure relief valve and replenished by the pump, however, these pressure drops create a frequency in the rail. So, you can have (and typically do have) a situation where at higher RPM, #1 injector fires, pressure drop in rail, #3 injectors fires before the rail is completely replenished (on the low cycle of the frequency), #3 mixture is leaner than desired. The best way to remedy this is by having as much volume in the rail as possible because then, each injector duty uses less percentage of the available volume. The more volume you have, the easier the job is for the P.R. and pump, pressures are more stable, fuel delivery is more accurate, engine runs more effeciently. I have had 1 customer do back to back tests using our -8 fuel rail and -12 fuel rail on a 1000 HP small block - changing nothing but the rails they gained 60 HP with the -12 rail. I can't say the gain was 100% due to the rail volume, there are many other dynamics going on at that level, but it did prove that more rail volume has a positive effect.

typer ej

im running a b18c5 intake jdm 4-1 header exhaust no cat cam gears street tuned on crome and at 8600rpm my injector duty cycle is at 96% and at 9200rpm were the revlimit is its at 102%...

im thinking about putting my 440cc dsm injectors from my turbo car on this car just so it will only be at 30-50% duty cycle...

ive heard of having such a high duty cycle on the injectors is bad for them and could screw them up.. correct me if im wrong but thats what i heard

DonF

There is no such thing as 102%. Honda gets by with 90+ % because most street cars are not above 8500 RPM allday. Maybe a few seconds.

allm0torGSR

I said all motor setups, scott@kinsler. When the hell does an all motor setup require 540cc+ injectors? And I'm asking that question living in the real world....I'm talking about a streetable setup that regular guys like us would put together.... not Eric Aguilar.
Fuel rails are only required for boosted engine, highly boosted engines, that require lots of fuel and the huge injectors you brought up to try and prove me wrong.

drift4jesus

There are guys running that big of an injector on built K series and even some H series motors on the street.

Plus more and more people are trying different fuels like e85 for the street. Those motors tend to need about 35-45% more fuel than a similar gasoline powered engine.

scmil95eg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allm0torGSR &raquo;</TD></TR><TR><TD CLASS="quote">I said all motor setups, scott@kinsler. When the hell does an all motor setup require 540cc+ injectors? And I'm asking that question living in the real world....I'm talking about a streetable setup that regular guys like us would put together.... not Eric Aguilar.
Fuel rails are only required for boosted engine, highly boosted engines, that require lots of fuel and the huge injectors you brought up to try and prove me wrong.</TD></TR></TABLE>

Why do OEM rail's use dampers?


Modified by scott@kinsler at 10:06 AM 7/27/2007

00Red_SiR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by scott@kinsler &raquo;</TD></TR><TR><TD CLASS="quote">

Why do OEM rail's use dampers?


Modified by scott@kinsler at 10:06 AM 7/27/2007</TD></TR></TABLE>

To stabilize the amount of fuel delivered through the injectors by absorbing the injector pulses that kick back into the fuel rail like a reverse pressure wave.