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 Post subject: Fuel Injector flow test
PostPosted: Sun May 31, 2020 6:59 pm 
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Supercharged

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a question for the folks running MPFI.

Do any of you have experience with or can recommend a shop for injector flow testing?
I don't currently know that I have a fuel delivery issue, but the next motor will be tuned a
lot tighter and have more output. So I am looking to eliminate a potential issue.

Running a single O2 sensor the system will basically average out the injectors fuel delivery.
Corrections made to get to a target is applied to all the injectors, not selectively to the one that
is a bit low on delivery or tends to the high side.

Looking at plugs means one really needs to tax the motor, then review the sparkplugs to see what can be gleaned.
I am wanting to shortcut that process and have some assurance that variation seen is not due to the injectors.

There are links to a few of the companies that provide injector flow testing that I have reviewed.
so if anyone can recommend a shop, I am interested.

https://highperformanceinjectors.com/

http://www.proflowtech.com/


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PostPosted: Mon Jun 01, 2020 4:13 am 
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My understanding is that flow variations are very small if you have injectors from the same batch. Maybe see if Will can pipe up on this as he works (or has worked) in an injector factory.

Lou

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PostPosted: Mon Jun 01, 2020 4:54 am 
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Quote:
are very small


Each injector manufacture will have their own specifications however generally injectors of the same type, regardless of batch are with in 5% on flow,, when new.

However things change,, nothing stays as when first built forever. That is what I am looking into.


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PostPosted: Mon Jun 01, 2020 6:49 am 
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Wasn't/isn't a member on here that did injector cleaning and matching?

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PostPosted: Fri Jun 05, 2020 4:03 am 
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Having helped a lot of people with fuel systems, the injectors are almost never the issue.
That being said.
Cleveland injector hospital.
I can do it as well but the turn around time would be at least a week.
Shoot me a pm and we will set up a time for a call,

Will


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PostPosted: Fri Jun 05, 2020 5:23 am 
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Thanks for chiming in, Will! Sounds good to me.

Lou

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PostPosted: Fri Jun 05, 2020 7:42 pm 
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Will and I have exchanged phone numbers and will talk sometime over the weekend.

Getting ready to pull the existing motor from the 68 Barracuda to be able to install the newer-better next motor.
Noticed at the header flange the inside of the header tubes for cylinders 1,2,3,4,5 had bright white - clean carbon.
The header tube for #6 cylinder had a much different appearance, the first couple of inches in it was black and sooty.


Attachments:
File comment: header cylinders 1 2 3
header 1 2 3.jpg
header 1 2 3.jpg [ 42.4 KiB | Viewed 1255 times ]
File comment: header cylinders 4 5 6
header 4 5 6.jpg
header 4 5 6.jpg [ 41.06 KiB | Viewed 1255 times ]
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PostPosted: Mon Jun 22, 2020 12:08 am 
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I have my own injector test setup build from dental chair clear water bottle system. In the
bottle I have "fuel". I most used diesel or ethanol as I dont like spray gasoline on the air
because high flammability. The system has air regulator and pressure gauge. At first I fill
the bottle, adjust the air pressure and made test shots to check that the air pressure will
stay constant.

For simple flow test I need just a 12 volt source, clock and a container with scale. I took
for example 30 sec constant flow for each indicator and for each read the scale. It is not
a surprice that one of 8 used injector is a little stuck and gives less flow than others.

No problem because the V8 set has eight of them. I just choose 6 equal and be happy with them.

More interesting test is run a test flow with short injection pulses (for example 2.5ms).
Different type of injectors can have same max flow but because of internal delays they
can be really different in the "low end" with short pulses. For that pulsing system I have
built my own contoller. It is very simple analog pcb I adjust with an oscilloscope.

Of course the spray angle can be seen during the test spraying. Usually if there is
difference with the angle also the capasity of flow has been changed.

Example. I was choosing a step larger injectors for my turbo bike. New ones came
from late model Corvette. In the test drive I had lot of problems with light throttle
ride but the full throttle and idle were fine. All Corvette injectors were "the same", not
bad but not fitting in to my application.

During the test I found that Corvette injectors does have angled spray to the side of
center of the injector. These also had really different (strange) habit with short pulses.
I crab those injectors, put the old onesback to manifold, raised fuel pressure from 3 bar
to 4 bar and the problem was solved.

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PostPosted: Mon Jun 22, 2020 4:22 am 
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Sounds like a great test system. Lots of food for thought there.

Lou

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PostPosted: Fri Jun 26, 2020 8:04 am 
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I received the injectors and test data back from Will. Thanks Lou, that was a good tip.
Will was great to work with. This forum has superb support.
It appears that the injectors are fine, although the #6 injector was the richest in the group.
Below is a table with averages and percent of average.

At idle the injectors were all within 3.4% of the average
At full open the injectors were within 4.8% of the average

No test data to support this, but it seems that cylinders 1 and 6 would tend to get less air flow due to the longer intake path,
and cylinders 3 and 4 would breath the easiest, due to the short runners.

I will put the injectors that flow the most in cylinders 3 and 4 and the ones that flow the least in 1 and 6.


Attachments:
injector flow.jpg
injector flow.jpg [ 39.83 KiB | Viewed 916 times ]
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PostPosted: Fri Jun 26, 2020 9:09 am 
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Hi Dadtruck,

Thanks for the data - very helpful. Note that cylinder 1 usually runs hotter, and so it might be good (if pushing the engine hard) to add fuel there. If it were me, I would probably put a higher flow injector in #1 cylinder. I have noticed, especially after road race events or in a car where I do more of those things, that #1 rockers/valves have more wear. If detonation is going to happen, my guess is it happens more in #1. I cannot recall if I have seen more plug speckling (boiled aluminum) on #1, but I feel like I have.

For economy, I imagine you might want less fuel to #1 to give the best mixture matching, but I need to think about that further...

Lou

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PostPosted: Sat Jun 27, 2020 9:07 am 
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Quote:
cylinder 1 usually runs hotter,


I can see that as the water to the radiator exits the head past #1 cylinder, so #1 combustion chamber never gets the coolest water as it gets the water that flows by everything else.
Interesting that #1 cylinder bore does get the water entering the block from the radiator, but the heat is in the head.


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PostPosted: Sun Jun 28, 2020 3:24 am 
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I think that most of the heat generated and then absorbed by the engine will be through the combustion chamber on the head. Only the top of the block gets much heat.

Lou

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PostPosted: Tue Aug 25, 2020 6:31 am 
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Supercharged

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something that I noticed after having the injectors cleaned and tested.
I have a gauge mounted on the regulator after the fuel rail to be able to monitor fuel pressure.
Prior to having the injectors cleaned, after the engine was shut down the pressure gauge show that
the operating pressure was maintained for approximately 20 minutes and then pressure would slowly drop to zero.
Since the injectors have been cleaned the pressure stays up on the gauge for at least 30 minutes. I have not actually timed it, maybe longer.
I'll plan to time it and make a note in my log book, that way I have a way to check to see how well the injectors hold
pressure over time and use. The injectors certainly hold fuel pressure longer now than they did before.


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PostPosted: Thu Oct 08, 2020 7:58 pm 
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Great discussion here for injector flow test.


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