posted on April 25, 2011 22:16
Tuners: Test Your Injectors!
By Jim Wolf
Oh my God, what a mess this has become! As race engine development moves forward, aftermarket fuel injectors seem to be moving sideways. About ten years back a trend started to modify stock injectors for higher flow rates. This was done by either drilling out the spray orifices or removing the spray plate all together! While some of the companies attempting this seemed to be making a serious effort, actual flow testing in many cases would indicate otherwise. No doubt someone will eventually figure out how to do this accurately, but in the mean time, they at least need to be willing to do actual flow testing, static and dynamic on each injector (no duplicated flow sheets please). Add this twist to the already diverse methods used to state injector flow values and you have a bit of a mess to sort out.
Above, are various OEM manufacturers new multi-hole injectors. Spray patterns are well defined and flow rates are consistent and predictable over a wide range of pressures and pulse widths.
If you are a tuner, nothing can be more frustrating then turning out an otherwise perfect race engine, only to have it burned down by a set of crudely modified injectors! On the other hand, it is the tuner's responsibility to know, not assume, that injectors, MAF/MAP sensors, fuel pressure, etc. are beyond question before starting a tuning process. So, what to do?? If you tune professionally and have or are building a reputation as such, you must flow test every injector yourself or at least audit any flow reports you will be relying on. Very simply said, it’s your reputation at stake. Once you get into the habit of flow testing each set of injectors, you will find the good, bad and the ugly out there. Why would you build a perfectly balanced and blueprinted engine at great expense, only to subject it to an unqualified set of injectors?
More OEM injectors, clean and precise micro machining of the spray plate for accurate flow and spay patterns using high tech machining methods. Some of the holes are even vectored for better atomization.
So, how to do this testing as simply and accurately as possible? First, get yourself a copy of SAE J1832 for details on test rigs, best practices and testing. Also, pick up a copy of J2715 for quantifying spray patterns; both will give you the references to quantify your own test process. As to which fluid you use, there are 4 to choose from, Gasoline, N-Heptane, 40CFR86, or Mineral Spirits. Ok, Gasoline might seems like a winner here, but unless you’re suicidal, don’t do it! N-Heptane (also very flammable) and 40CFR86 are considered the better reference fluids, but may be harder to obtain in fresh lab quality for every day testing, however a gallon or so of N-Heptane should be obtained for comparative testing.
Tuesday, April 26, 2011 6:27 AM
Another fantastic MotoIQ article. Thanks!
Tuesday, April 26, 2011 7:09 AM
I understand the reason why, but I wish names were called in this article to protect us innocents.
Has JWT tested/examined the Injector Dynamics injectors which are supposed to be the ultimate after market injectors?
Tuesday, April 26, 2011 8:06 AM
None of us are going to get this equipment and do this ourselves. It seems very cost prohibitive. But who does quality testing for the public? I thought I remembered someone that would flow test your injectors for you for a small fee.
Tuesday, April 26, 2011 8:07 AM
WOW, quite the article!
I am currently running MSD 1000/cc min injectors, and their pintle/nozzles looks like this
I been eye'ing some injector dynamics injectors lately, theyre supposedly flow matched very well in sets, and have superb low pulse-width behavior, so idle/driveability/tuning is greatly improved on high flow, high hp applications.
Tuesday, April 26, 2011 9:14 AM
Thanks Moto IQ,
I have Pics of my XXX brand Inj. (we all know who) "popular in nissan and EVO tuning" on my 100X comparator, overlapping holes, burred edges (no obvious pintle damage though,
Some one buy a hole popper EDM and I'll show you how to do this properly,
Seriously I'd do it if I had any time left to do it myself.
MIKE buy a hole popper and I'll come set you up with tooling
Tuesday, April 26, 2011 10:52 AM
Enthusiasts: Buy from reputable vendors and manufacturers!
Thanks Jim for an up close look at how some of the most precise metering devices in our engine are being butchered.
Tuesday, April 26, 2011 12:28 PM
I'm pretty sure JWT tests injectors, as do many of the reputable companies (RC, for example).
Tuesday, April 26, 2011 12:28 PM
Too bad names can't be named here. I've heard of one brand that was like this, but didn't know it was such a common problem. Good to know. I always preferred to buy injectors that were made by a large injector company that supplies to OEMs though... then at least you know you're getting a precise product.
Tuesday, April 26, 2011 1:04 PM
Jim, excellent write up. I think my mind has been blown, in a good way. Could you possibly name rebutable injectors that you've flow tested where are dollars would be best spent?
Tuesday, April 26, 2011 1:41 PM
It's funny yall posted this. I just got a set of used injectors in the mail today. I was planning to send them off to get cleaned and balanced. Where does MotoIQ recommend I send them?
Tuesday, April 26, 2011 4:08 PM
I posted a pic earlier of an MSD-2015 96lb/hr 1000cc injector, wasn't very good so heres two fresh ones.
Anyhow, my understanding is they're made by same OE supplier who does GM and others injectors; they're of a ball type, but look disc to me... I haven't had complaints but I been meaning to get them flowed since new. Close looks a little better than the one at the front of this article.
Injector-dynamics injectors as i described earlier, supposedly represent a damn tight injector set, but I'm sure theres other cutting-edge offerings also offering this level of injector.
Tuesday, April 26, 2011 4:58 PM
Although it's not as convenient as a clip-on inductive current probe, a simple current shunt made from a low value resistor (there are resistors made for this specific purpose) works just as well and is much cheaper if you're already making an injector board too. The only downside is that you will have to do some simple math. That just means using Ohm's Law (V=I*R) instead of telling the oscilloscope that you have a current probe with whatever standard current ratio. You have a known resistance, and the voltage across the resistor is proportional to the current passing through the resistor.
You could also use a circuit board mounted DC loop transformer, which is the active heart of a DC current probe without all of the extra stuff you don't need. It's just a cheaper means to the same end.
The cost of an accelerometer is a much trickier problem to solve.
I know the total cost of the setup in the article is pretty high, but it's an investment for a professional tuner and not really necessary for the DIY home mechanic. If you need a set of injectors tested, find a tuner or shop who has already made the equipment investment and can do the testing for you.
Tuesday, April 26, 2011 5:30 PM
I was discussing who to send injectors to to test today with my inspector, problem I see is the only companies i know that test injectors also make injectors (ie re-drill stock injectors) so if I send brand x to brand Y hq to get tested what kind of results do you think I'll get?
Tuesday, April 26, 2011 10:22 PM
I have no personal experience, but RC Engineering has been dealing with fuel injectors forever and provide a cleaning service. Part of the cleaning service is measuring the flow rate of course.
Tuesday, April 26, 2011 10:53 PM
Do your homework. Then you will see that Injector Dynamics is the best choice. Thank you JWT and MotoIQ for putting the truth out there.
Tuesday, April 26, 2011 11:39 PM
I wanted to say this last night, but some of those drilled injectors are just janky! Good god.
Wednesday, April 27, 2011 12:01 AM
RC engineering has a cleaning and testing program. Stick with new injectors from OEM sources and you will be fine for most use. Like Steve said Injector Dynamics are the best.
Wednesday, April 27, 2011 2:32 PM
Thanks for this awesome article!!! Wished I saw it a month ago. I'm currently working on getting some ITBs on my K20 and was researching what injectors to use (and what will fit) on my ITBs. I'm glad I didn't go with drilled injectors but with OEM AP1 S2000 injectors (conservative but I figure you can't go wrong with OEM).
Wednesday, April 27, 2011 4:21 PM
This is a shop in Indianapolis that specializes in Injectors
They seem pretty reputable and I believe i have heard positive things about them
Thursday, April 28, 2011 2:50 PM
IDs may be good, but there's absolutely nothing wrong with OEM injectors or off the shelf Bosch, Denso, or JECs injectors either. In fact, many of the legit aftermarket companies' injectors are exactly that: off the shelf Bosch, Denso, or JECs injectors which is why they are considered so good.
Thursday, April 28, 2011 3:03 PM
That's exactly right, the only problem is finding the OEM injectors in BIG flow rates without going outside of the off-the-shelf product lines. I'm sure you're aware of the amount of private labeled Bosch, Siemens, Denso injector products that are on the market for the standard injector flow rates.
Thursday, April 28, 2011 3:16 PM
Is there any truth that newer injectors with better atomization can result in more power?
In my case (Honda K-Series), a lot of people are throwing in RDX injectors and saying it produces more power.
Friday, April 29, 2011 6:04 PM
Fabrik8: Its actually the same deal with the big flow rate injectors. They are also just off the shelf OEM injectors. The only difference is that those companies did their research, know which part numbers to order, and have a channel to purchase them through. The nature of the injector manufacturers is that they do not share flow data and specifications because they were only ever designed to be used in their intended application.
Eric L: That's a case by case situation. Every engine has different port shapes, valve angles, inlet manifold designs, and injector locations that can affect what the optimum atomization might be. Then of course there's also the injection timing (when the ECU fires the injector) that can further affect things. I don't know jack about NA K20s so I can't help you there.
Saturday, April 30, 2011 9:10 AM
A lot of the big injectors are simply natural gas injectors. There is a 2000cc natural gas Bosch injector for example that are relatively inexpensive. You have to machine top hats for them to work on most cars though...
I have a set of ID1000s and honestly, the flow sheet that came with them wasn't a custom sheet and matched what they had up on their web site. If the injector is within 0.5% it really doesn't matter if it is a custom sheet, but I was kind of disappointed it was just a copied sheet.
Saturday, April 30, 2011 2:29 PM
Yep, that's correct. Just Google "Bosch NGIS" and you've found the source for 2000cc Bosch injectors.
The only thing that sucks is that they are not compatible with alcohol based fuels which means no E85 or Methanol. Of course neither are the IDs since I'm guessing they are one and the same.
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