I followed a suggestion from this board and sent 4 2.0 injectors out to these guys. Excellent turn around time. He emailed me with the results and return tracking number today. I never considered installing these without a cleaning, but it sure is a great idea that i had them cleaned. Could have caused major problems!

http://www.cruzinperformance.com/fuelinj.html

$12 per injector. Two thumbs up!!

This resolves a question I've wondered about for some time. Brad Ander's site shows the 2.0 injectors as rated for 275-ish cc/min, but he doesn't state at what PRESSURE. D-Jet injectors operate at 2-bar (29psi), where most other injectors operate at 3-bar (43psi). The chart shows 42lbs/hour, which is 440cc/min, at 3bar.

So, Ander's number is at a 2-bar rated pressure, meaning 2.0 injectors really ARE gigantic. Injectors half that size run at 3 bar would be more than adequate for even a nice 2270 (150hp). 2.0 injectors at 3 bar would handle a 300hp 4-cylinder. Even V8 guys don't use injectors that big unless they're looking to break 600hp. Even at 2 bar, 275cc/min is enough for over 200hp.

Perhaps I should send out a set of 1.7 injectors I have on the shelf not only to be cleaned, but just to find out how big they really are. They'll do flow testing only for only $5/injector. If they're 85% of the size, then they're about 375cc/min at 3bar, or 230cc/min at 2 bar, which is still enough for over 150hp.

QUOTE (yarin @ Feb 15 2006, 11:19 AM)

but it sure is a great idea that i had them cleaned. Could have caused major problems!

Let me tell, you THEY DID cause major problems!! That is why you now have them!

QUOTE (dinomium @ Feb 15 2006, 11:10 AM)

QUOTE (yarin @ Feb 15 2006, 11:19 AM) but it sure is a great idea that i had them cleaned.  Could have caused major problems! Let me tell, you THEY DID cause major problems!! That is why you now have them!

Yea i bet they did. Especially when one injector doesn't flow ANY fuel

I just confirmed, they test injectors at 3 BAR.

The machine that does the job cost about $8000 a couple years back...don't know what it is now.

$12 is really inexpensive....most want $25 - $30+ dollars per.

I had 4 2.0 injectors tested here locally. Cost was $15.00 per injector, 2 of them turned out to be leakers the other 2 tested just fine. I thought 15 per was a good price, 12 bucks per. tough to beat.

Just because an injector will flow at a higher rate with higher pressure, doesn't mean that the service pressure should be maintained at that pressure. We do not know what service pressure the injectors were designed to sustain, or their pressure safety factor. The integrity of the whole fuel supply system relies on not only the fuel hose, but on the fuel hose clamps...

All together, the components of this system must be capable of sustaining the in-service pressures witha nice safety factor, and there are several issues:

Ever seen a torque value for the fuel hose clamps? Ever torque them to a known value? I retighten my hose clamps at every oil change (3000 miles) and they regularly loosen up in that period of time. It can be a pretty scary situation really. I wish this was a better more reliable connection, I think its a major weakness with the early FI systems.

While running the injectors at a higher pressure can be done, the safety margin decreases and the likelihood for leaks greatly increases.

I used these guys also. They found 1 leaker. They also replaced the screen in the fuel line and the plastic cover over the needle (pintle?). My injectors returned looking like new. He didn't have the bent hoses. I am using longer straight hoses without problems.

Mark

QUOTE (Bartlett 914 @ Feb 15 2006, 12:52 PM)

I used these guys also. They found 1 leaker. They also replaced the screen in the fuel line and the plastic cover over the needle (pintle?). My injectors returned looking like new. He didn't have the bent hoses. I am using longer straight hoses without problems. Mark

Bartlett 914 - What diameter hose are you using?

bowlsby - What is the torque spec for the fuel clamps?

I wasn't advocating running D-Jet injectors at 3 bar. These numbers merely confirm what's been said for some time: D-Jet injectors are way oversized for their application, even if run at 2 bar. 1.7 injectors at 2 bar are (most likely) about 2x bigger than they need to be for a 1.7, and would feed a hot 2270 just fine. Running them at 3 bar, if you decide to take that risk, would be enough for any Type IV, no matter how hot.

I sent my 3.6 engine injectors to RC engineering who cleans, calibrates and match flow balances original-equipment injectors. Money well spent!

QUOTE

Bartlett 914 - What diameter hose are you using?

I am using the forbidden 5/16 non fuel injection hose. My rational was the hose is good for 50 LBS. We use 29 to 30 in the 914. 5/16 is damn near 8mm. I read here that we are supposed to use 7.5mm hose. Anyway my car hasn't burned up yet.

QUOTE (Bartlett 914 @ Feb 15 2006, 02:11 PM)

QUOTE Bartlett 914 - What diameter hose are you using? I am using the forbidden 5/16 non fuel injection hose. My rational was the hose is good for 50 LBS. We use 29 to 30 in the 914. 5/16 is damn near 8mm. I read here that we are supposed to use 7.5mm hose. Anyway my car hasn't burned up yet.

You used 5/16" on the pressure side (to the injectors, fuel rail, etc) ?

I used RC Engineering once before. Great service, but double the price. Their basic injector service doesn't "match flow balance". All of these guys just flow test, clean, flow test.

$12 is a good deal if they have flow matched/cleaned/blueprinted the injectors

Ive used Marren In the past, but they are 2x as expensive as cruzin...

Ill give cruzin a try for the injectors for our GT3RS

These guys will replace parts and include return shipping for $3 more per injector if you service a set of 4.

http://www.injectorservices.com/injectship.htm

-Rob

Brad Ander's site lists the flow of 2.0 injectors as 380 cc/min not 275-ish as James stated. No matter, his point is well taken. The 2.0L injectors, Bosch 280 150 019 or 280 150 038, are way big for the application. As I am in the process of building and soon to be installing Megasquirt on my 2.0L liter motor I am concerned about the excessive flow of the 2.0L injectors. I'd gladly trade some for those from a 1.7 as these would still be large for the horsepower that I anticipate but more appropriate than the larger ones. It sure makes me wonder what the Porsche or Bosch engineers were thinking when they selected the injectors. From what I've gathered the 1.8 injectors (Ljet) are much smaller and in line with the requirements for that application.

I found a formula in "Four Stroke Performance Tuning" by A. Graham Bell for estimating the injector flow at a pressure different from used for the rated flow.

revised static flow=SFxsqrt(RP/OP)

where SF=injector static flow at standard pressure,
RP=revised pressure and OP=standard pressure

The formula applies for pressures below 4 bar.

As given in the book it assumes that one wants to determine the flow due to an increase in pressure though I see no reason why it shouldn't work for a decrease in pressure. For the 440 cc/min at 3 bar quoted in this thread that would give 359 cc/min at 2 bar which is about 5.5% below the 380 cc/min per Anders. So the prediction is pretty good.

It's been stated in the past, and it sounds right, that in the early days, Bosch only had a couple of injector sizes they applied to everything under the sun. Remember that D-Jet was the very first use of EFI, at least in production engines, so they were still learning how to make all of this work. The engines it was used on ranged from the VW 1.6 fours (400cc/cylinder) up to the Mercedes 4.5 eights (560cc/cylinder), with most engines falling close those two extremes in terms of cylinder size. With all-analog ECUs, they could also run injectors right down to their physical limits on minimum pulsewidth w/o worrying about aliasing errrors caused by digital clocks.

Given the measurement techonologies of the day, getting really accurate mixtures was also going to be much more challenging than it is now, and it's possible they were simply erring on the side of richness. The fact that the early D-Jet cars actually work show these injectors aren't unusably big, just lots bigger than necessary to do the job on 80-90hp air-cooled fours, and certainly big enough to cause some headaches for a digital ECU with a low resolution.

Anyone have any flow specs for the 1.8 L-Jet injectors? I'd always assumed these were really just 1.7 D-Jet injectors, but never looked for part numbers.

The 1.8 injectors flow 185 cc/min according to this site: http://www.ratwell.com/technical/Injectors.html

I don't know at what pressure this is specified. Ljet does run higher pressure than Djet. I considered these injectors for my application as they take the nicer Ljet connector but the flow seemed marginal.

That IS marginal. According to SDS' tech section, a common rule of thumb is 0.55 * lbs/hr * (cylinder count) * 0.85 will give the max crank HP injectors can support. cc/min / 10.5 = lbs/hr, so 185cc/min = 17.6lbs/hr, which gives 108hp at 85% duty cycle with a 4 cylinder. Should work on most stock 1.7s and 1.8s, but would be tight for a 2.0.

I don't know of any other cars that use hose-barb L-Jet injectors that would use larger injectors. The Alfa V6 uses these, but with 6 cylinders, these injectors would support a bit over 160hp, which is right where that engine peaks. The late FIAT Spiders also used these injectors, but they're 85-90hp engines, tops. I'll bet that's a really common injector on European cars from the 70s and 80s.

Here is some more 1.8 injector info.
Bosch part numbers:
280-150-105
280-150-112
280-150-114
280-150-116
These are supposed to be interchangable according to the table at http://www.ratwell.com/technical/Injectors.html

The flow is 187cc/min at 43psi for the -105 according to http://www.telusplanet.net/%7Echichm/tech/...h/injectors.pdf

These might actually be a reasonable choice for mild 2.0L <110HP or so. There sure is a big difference between these and the 1.7 and 2.0 injectors. The pressure range would be compatable with the rated range (36-45psi) of the MSD manifold pressure referenced FPR although I'm told that those will work fine at 30psi.

By the way, there is a fair bit of good info at www.ratwell.com that applies to the 914 although the site is focused on baywindow vans. Lots of good links.

Rich Atwell is a great guy and a casual friend of mine. Anyone here in the bay area would do well to get to know him, he is very personable, I recall he lives on the peninsula - Sunnyvale or is it San Carlos maybe?. He is mildly interested in 914s too becasue of the similarites with his bus, but I have not persuaded him to bite.

Another variable to consider, is not only the flow rates and service pressures, but also pulse width and there is another variable but I cannot recall it off hand (dwell time?). I understand that aftermarket EFI systems calculate fuel requirements and control AFR by pulse width modulation (PWM), eliminating things like the CSV as a positve benefit. So really there should be several suitable injectors to select from if committed to a swap.

Mac at Emerald Perfomance also knows of other injectors that work, look him up and see what he has found. I recall a conversation with him recently that indicated he knew of inexpensive injectors that would fit our cars.

QUOTE (bowlsby @ Feb 16 2006, 06:22 PM)

Rich Atwell is a great guy and a casual friend of mine. Anyone here in the bay area would do well to get to know him, he is very personable, I recall he lives on the peninsula - Sunnyvale or is it San Carlos maybe?. He is mildly interested in 914s too becasue of the similarites with his bus, but I have not persuaded him to bite. Another variable to consider, is not only the flow rates and service pressures, but also pulse width and there is another variable but I cannot recall it off hand (dwell time?). I understand that aftermarket EFI systems calculate fuel requirements and control AFR by pulse width modulation (PWM), eliminating things like the CSV as a positve benefit. So really there should be several suitable injectors to select from if committed to a swap. Mac at Emerald Perfomance also knows of other injectors that work, look him up and see what he has found. I recall a conversation with him recently that indicated he knew of inexpensive injectors that would fit our cars.

Injectors inject using a pulsewidth, which is not, strictly speaking PWM. PWM is used on some ECUs for current limiting.

Basically, the injectors are on or off, and the time they're on is the pulsewidth. The length of time they're on, their flow rate, and the pressure across the injector (fuel rail pressure - manifold pressure) is what determines how much fuel is injected. Pulsewidth goes up with airflow into the engine to maintain the desired mixture ratio.

Duty cycle is the other commonly seen term, and is simply the percentage of time the injector is open. The maximum is obviously 100%, in which the injector never closes, but is injecting continuously. This will overheat most injectors, and to allow enough cool-off time, injectors are typically limited to a duty cycle of 80-85%. This effectively sets the maximum amount of fuel the injector can flow under normal use: 85% of the flow rate at the rated pressure differential.

There is also a minimum injection time set by the physical properties of the injector, which normally takes about 0.8-0.9ms to open and 0.8-0.9ms to close. So, if you define the pulsewidth as the time from when you signal the injector to open and when it actually closes, you have a minimum pulsewidth about 1.6-1.8ms. The injector can't flow any less than this other than to flow nothing at all.

This is why injector sizing matters, as you may not be able to flow little enough fuel at idle with an injector that's too big, or you may not be able to flow enough fuel with the injector open 85% of the for full load.

The PWM is used with low-impedence injectors to limit the amount of current flowing through the injector. PWM snaps the voltage off and on faster than the injector coil can react to it, lowing the average voltage seen by the injector, and thus limiting the current. This is strictly a trick for digital ECUs, which can't easily control voltage beyond "it's on" or "it's off". This PWM doesn't actually have anything to do with the pulsewidth that controls the open time, and thus the fuel flow.

So, pulsewidth and duty cycle aren't really variables to consider when selecting injectors, other than observing the 85% duty cycle limit. This is the reason for the 0.85 term in the fuel flow v HP calculation I gave above. Max pressure ability, fuel connection type (hose-barb, O-ring, or side feed), and flow rating are the important variables. Most injectors have the same size nozzles (so they fit into all injector spigots), though not all of them have the same size coil section, which can matter with some spigots. There's also pintle type (pull back or push forward), though this is pretty esoteric.