mechanical constant flow injection



mechanical constant flow injection

Postby grumpyvette » January 25th, 2011, 2:37 pm

I was at a local guys house recently and he was discussing the fact that hes always loved how the older STACK injection systems, looked but he had heard they were miserable to tune and not nearly as precise as the newer EFI systems.
well I guess if your totally non- experienced with something anything you don,t fully understand is intimidating, but honestly, having grown up using that type of injection I really prefer them, as they really are fairly simple to tune once you understand the basic concepts.
with experience you can exactly match the engines air flow and fuel needs and INTAKE RUNNER LENGTH to PRODUCE RAM TUNED PULSE STRENGTH to maximize power
, its the ability to change intake runner stack length and exactly ram tune the intake to maximize power under a specific set of conditions that gives stack injection a pronounced advantage in torque curve produced.


theres several basic components, the most obvious is the manifold with the individual stacks feeding each individual runner, each has a throttle butterfly that needs to be adjusted so it exactly duplicates the other 7 angle and degree of opening, these butterfly or throttle plates restrict air flow into the engine just as the similar ones in a carburetor do. this is frequently done with a vacuum gauge but experience is required to get it tuned correctly

below the butterfly throttle plate is an injector,the injector size can be changed,like carb jets, this this injector sprays fuel in a fan or or fogger type pattern,
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similar to a nitrous system, but the amount of fuel depends on the fuel pressure and volume of fuel reaching it produced by the mechanical fuel pump, the injector size and the pill or return jet that cycles excess fuel to the fuel cell, some systems have a high and low speed return jet system, most have a barrel valve and adjustable ratio linkage

theres an adjustable mechanical linkage connecting all 8 throttle plates thats also linked to a linkage controlling a valve that controls how much fuel enters the common distribution manifold that all 8 fuel injector lines feed from that is adjustable, as to when and how rapidly it opens, this can be but is not necessarily directly proportional to the throttle plate position

theres a mechanically driven fuel pump,ImageImage

that pumps fuel at volume rates approximately similar to the engine rpm, I.E at 1000rpm if it pumps X amount of fuel, at 7000rpm its pumping approximately 7x times the fuel, this fuel flow feeds the valve that feeds the common distribution manifold that all 8 fuel injector lines feed from

theres a bye-pass jet (PILL) thats used to bleed off a controlled amount of the fuel pressure and volume that feeds the common distribution manifold that all 8 fuel injector lines feed from,
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http://hilborninjection.com/tech-support.asp

thru lines from the common manifold to the individual injectors
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the LARGER the opening in that jet or (PILL) the LESS the fuel pressure and flow volume that reaches the common distribution manifold that all 8 fuel injector lines feed from, and the leaner the jets feeding the individual injectors in each stack flow.
theres a quick access pill holder
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you will occasionally find older CROWER, HILBORN, ENDRL injection intakes and components for sales, these can be either a huge bargain or a bottomless money pit depending on condition and what parts are needed to rebuild them, so before jumping into a "bargain' be aware of the limited part support, limited parts, few skilled repair or tuners and the fact its part art and part science,and that it takes some experience to tune one correctly, and it won,t be cheap...you can make excellent peak power over a fairly limited power band, but unlike the current electronic control mpfi injection that uses sensors to measure and control air and fuel metering,constant flow mechanical injection is very unlikely to run well at both low and peak power levels
and the PILLS or JETS
on some systems theres also a vacuum controlled bye-pass circuit that makes fine adjustments to the bye-pass flow of fuel.

basic operation means selecting the injector nozzles that flow the correct amount of fuel for Wide Open Throttle operation, as the rpms increase the fuel pump rate of flow increases fuel flow supplying the flow necessary to compensate for the increased air flow as the engine rpms, increase
selecting the correct pill to get the correct fuel pressure for mid and upper rpm fuel curve, allows you to customize the effective flow feeding the valve that feeds the common manifold and further adjusting the throttle linkage to provide a smooth transition,allows some more control on the rate of fuel sprayed into the stacks,in most cases low or at idle operation tends to be a bit lean, or richer than ideal, based on the choices made in linkage adjustments or bye-pass pill size,but these systems can meter fuel very well in the mid to upper rpm ranges, once you learn how to tweak the system to get the fuel flow you want, at the rpm ranges you want. its certainly easier than most carbs once you get a good feel for how it works, but your efficiency is concentrated near W.O.T and your fuel air ratio will not be precise at part throttle or under low loads.
if you want to pass emission testing, or get better mileage, the newer electronic controls with the oxygen and map,temp sensors will prove to be superior,but if raw peak hp is your goal the constant flow systems cam provide that.


Can I run a mechanical fuel injector on a street car?

A mechanical injector is classified as a constant flow system and was designed to operate at WOT under load. As a constant flow system, yes properly set up and tuned correctly mechanical injection can both look great and produce excellent power and torque over several thousand rpms , but it must be exactly matched to the application.
fuel pressure is controlled by the fuel pump which increases the volume of fuel as the rpms increase and fuel volume being delivered to the injectors is controlled by the main jet,which you can change that allows a semi predictable percentage of fuel to flow back to the fuel cell and not to the injectors , known as a pill, along with pump speed (engine rpm) and nozzle size. The barrel valve, also controls fuel reaching the injectors ,which controls idle fuel and transitional fuel from idle to WOT, can be compared to a ball valve much like the one that turns off the water in your house.
The basic design and lack of fuel control of a barrel valve does not allow us to precisely control the fuel at part throttle,as well as an oxygen sensor and injector pulse changes on modern EFI, but properly set up it can do a remarkably good job, especially on lower load part throttle, or peak power at wide open throttle under load. If you consider the fact that an engine's fuel requirements are based directly set on max power at full load, and that we can have many different loads at different rpms all at the same throttle angle, the lack of fuel control for street applications becomes apparent. A mechanical system does not employ enough fuel control in the operating range where you drive your street car and, therefore, is not recommended for street use.

Of course we have all heard the stories of mechanical system working on the street but few if any actually worked correctly. The use of a dial-a-jet, additional bypass valves, and home center ball valves have all been used to provide fuel control for adequate street use, but fall far short of the fuel control required as part throttle load is constantly changing. The constant manual adjustments needed, as one guesses the current fuel requirements of the engine, leaves very little time to actually drive the car and, at best, is incredibly inaccurate. Blown applications appear not to be as affected by the lack of fuel control of mechanical injection, possibly due to the load placed on the engine to drive the blower, but is still not recommended for those looking for the best all around drivability.

The use of alcohol helps because of it's large tune-up window, but fails to provide drivability due to loading up, mileage (in gallons to the mile) and severe oil dilution. Claims from those that run injected engines on stands or dyno's stating they can make mechanical injection streetable, are unable to simulate a fraction of the different part throttle load scenarios your engine will see, nor provide the required fuel control. Interestingly enough, engineers have devised a way to electrically control these valves and bypasses...it's called electronic fuel injection.

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intake runner stack length changes, and to some extent cam timing can be used to tune the torque peaks, but cross sectional area of the runners and head ports will dictate a great deal of the air flow speed and where the restriction to flow occurs


on the better 23 degree SMALL BLOCK AFTERMARKET HEADS THERE'S ABOUT 5.5 INCHES OF INTAKE PORT LENGTH ON AVERAGE FROM INTAKE GASKET TO THE BACK OF THE INTAKE VALVE AT THE FAR EDGE
READ THESE LINKS


you should read this related info also

http://www.vetteweb.com/tech/vemp_1303_ ... n_systems/

http://www.hilborninjection.com/PDF/installation.pdf

http://www.kinsler.com/page--Constant-Flow--14.html

viewtopic.php?f=55&t=10909

http://www.morrisonoz.com/ChevManifolds.html

viewtopic.php?f=55&t=6841

http://www.hilborninjection.com/tech_mech_overview.asp

viewtopic.php?f=56&t=789&p=1143#p1143

http://www.pelicanparts.com/techarticle ... TipMFI.htm

http://www.hilborninjection.com/category.asp?Id=187
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: mechanical constant flow injection

Postby grumpyvette » March 30th, 2012, 12:58 pm

http://www.hotrod.com/techarticles/engi ... ewall.html
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http://www.kinsler.com/hand31.html

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http://www.kinsler.com/072707/Cat56Pg_Whole_LR.pdf

http://stackinjection.com.au/

http://eightstack.com/

http://foxinjection.com/

http://www.force-efi.com/stacks.htm

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http://alkydigger.net/proddetail.php?prod=ENEFI427

IF you know what your looking at and what parts are easily replaced youll find theres a few deals available on older constant flow injection intakes, many can be converted to EFI and MAP sensor control if your good at fabrication and welding aluminum, but keep in mind the main advantage of individual runner EFI conversions of older constant flow mechanical injection is the retention of the ability to change stacks and effective runner lengths the newer intakes with a common plenum and throttle body can,t be as flexible but they will be much easier and cheaper to work with, and while the mechanical injection can be tuned to make exceptional power over a narrow rpm band the newer EFI with computer controls and sensors will be much more efficient over a wider rpm band and fuel economy will tend to be better, as will be ease of low rpm operation and a computer control can be easier to tune for those guys UN-familiar with the art of jetting tuning and reading spark plugs

http://www.summitracing.com/parts/EDL-7136/?rtype=10
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I wish ID never sold my bbc crower injection when money got tight!
I loved the look and performance of those older mechanical FUEL injection stack systems and once converted to true EFI they are even better.
neither of these pictures above do the properly set up and maintained injection system any justice , both look like crap compared to a well cleaned intake with the optional stacks, (the top intake looks like has the cheaper non-chrome powder coat versions)

btw for those guys that don,t know a big block chevy has 4 intake runner ports that empty into the center of the cylinder and 4 that empty into the cylinder wall the different length stacks on the injectors change the charge inertia and enhance the volumetric efficiency, and yes IT DOES HELP, and YES changing the stack lengths can change the torque curve a bit


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picture blood red injector bells, chrome stacks and black powder coated intake base
thats what I had on my race 496 BBC for years
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: mechanical constant flow injection

Postby grumpyvette » April 4th, 2013, 9:40 am

keep in mind theres more intake manifold options available in MPFI intakes that the old single vertical stack designs, and many of the older constant low intake injection manifolds can be converted to the newer EFI design or are factory available as EFI now
some research and parts swapping can allow a self tuning MPFI config.
individual runner fuel injection has a rather unique feature in many intake designs not found in most intakes, and that the ability to easily change the runner length, changes in stack heights can noticeably change the engines torque curve , thru inertial ram tuning, its fairly easy to boost the ram effect on a single stack runner intake to produce over 100% cylinder fill efficiency, over a fairly narrow rpm band, but one you can tune for and predict, with experience,you can actually feel the change in the seat of your pants in many cases.


viewtopic.php?f=55&t=8957&p=31913&hilit=holley+control#p31913

http://www.kinsler.com/page--Manifolds--6.html

http://www.kinsler.com/page--EFI--4.html
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: mechanical constant flow injection

Postby bytor » April 4th, 2013, 12:25 pm

Good info, I have wondered how the mechanical injection setup worked. So there's no individual injector sequencing or timing, they are all always spraying fuel?
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Re: mechanical constant flow injection

Postby grumpyvette » April 4th, 2013, 2:03 pm

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yes constant flow injectors
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CONSTANTLY fog fuel into the intake runner , but the volume of that fuel flow changes and is controlled and adjustable, just like a carburetor allows fuel to flow out of the carburetors venturie boosters, air flow and differences in pressure drag fuel out of the carburetors, venturies where its atomized, at a rate controlled by the jets,selected and installed, in the carburetor plus further enriched,by the vacuum drop opening the secondary power valve enrichment etc.

viewtopic.php?f=55&t=5229

but like a carburetor. theres a rotary valve that controls the volume of fuel thats potentially flowing AND unlike current MPFI theres no constant fuel pressure, feeding the injector nozzles, as the rpms increase the fuel pump supplying the constant flow injector nozzles increases boosting the volume of fuel, thus theres three factors controlling the amount of fuel, a injector flow size, a sliding pressure curve and a return (PILL) or jet that allows fuel to return to the fuel tank supplying the mechanical fuel pump.

on the more modern EFI , multi port injection theres a constant supply of fuel and pressure at the fuel rail and the injector, if its properly sized can supply 100% of the engines fuel needs at a 70%-75% pulse duration,but that pulse timing and duration is controlled by sensors measuring unburnt fuel/oxygen ratios in the exhaust, air flow rates and temperatures, or put a different way, if the solenoid in the injectors getting power for 75%-80% of the time, because the sensors control the fuel/air ratio and check and correct that every fraction of a second it can potentially flow fuel as its needed,and it will more than adequately flow that level of fuel needed.

on the older mechanical flow injection your balancing five owner adjustable controls, or flow curves,
(1)first the injector jet or nozzle in each intake runner which controls max fuel flow,
(2)next the rotary valve that controls fuel flow from the pump that can reach the injector nozzle from the fuel supply lines, was adjustable for both minimum and max flow
(3)next the pump volume is adjustable in some designs as the cog belt pulley diameter between the crank drive and the pump are selected to give a known
pressure curve and pressure,the diameter of these belt drive pulleys were something you select from a chart.
and
(4)volume reaching the nozzles is also controlled with the size of the return jet, that routed excess fuel back to the tank,
the larger the jet the more fuel bye-passes back to the tank .
(5)on most system there was an optional second return jet mounted near the rotary control valve.

this may sound complicated but with a good understanding of the process and how the parts interact tuning the system is remarkably fast, consistent ,repeatable and accurate, you just need to understand what your doing!
it took me several weeks to fully understand how and why I should make changes and what I was doing and you darn sure learn a great deal about reading spark plugs and how you need to understand ignition advance curves and how cylinder temps are used as an indicator of some of the burn conditions in the cylinders.
THERE WERE dial adjustable return jets that made changes to get close to ideal very fast and easy, fine tuning from that point involved secondary jet changes, changes to the injector stack length, and adjusting how far the barrel valve opened, timing advance changes and other minor tweaks you leaned over time, you also very quickly lean that METHANOL IS CORROSIVE on aluminum if not properly cleaned, and that you were better off running high octane race gas if you were not into constant cleaning.

BTW
with the properly matched cam timing, and a tuned set of headers with a low restriction exhaust the inertial ram tuning of a single runner per cylinder intake injection system and an anti reversion exhaust can frequently give very noticeable torque gains , Ive frequently seen guys who get everything tuned correctly see 40-70 ft lbs of torque at some point in the power band that a common plenum single carb intake manifold can,t duplicate because those intakes can,t provide the true inertial ram tuning that the combo of stack injection and a tuned anti reversion exhaust can produce.
if you think about it the TUNED PORT INJECTION (TPI) INTAKES

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used similar technology using long intake runners to boost low rpm torque with inertial ram tuning, but unfortunately they used about 1.5" diameter intake runner cross sectional areas designed to maximize torque under 4000rpm on a 305 displacement engine, if you do the calculations you quickly see thats going to be very restrictive on a 350-406 SBC at anything close to max potentially useable rpm levels, which could easily reach or exceed 6400rpm with PROPERLY SELECTED and matched, performance components


related info
http://www.kenlowe.com.au/LFS_book_intro.htm

http://www.hotrod.com/techarticles/engi ... to_03.html

http://www.kinsler.com/Cat_32_Pgs/Cat_32_4_09_Pg_72.pdf

http://www.hilborninjection.com/tech_mech_overview.asp

http://www.hotrod.com/techarticles/engi ... ewall.html
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: mechanical constant flow injection

Postby grumpyvette » May 13th, 2013, 8:56 am

1st to 4th Harmonic Intake Tracts CFD
"Here are two animations of intake tracts , I found posted else ware. showing the pressure and velocity dynamics and how it differs in various length tracts.

The lengths are: 26.5, 15, 10.4 and 8.2
The animation runs for 63 frames.
Each frame is 15 degrees of crank rotation
The 1st frame is the beginning of an intake stroke
Frames 48 to 62 would be a 2nd intake stroke but I intentionally left the velocity out so that the waves can be seen unaffected.
This is simulation of an engine running at 10,000 RPM
Each frame is at an interval of 0.0025 seconds.
The motion of the air is defined by velocity at the cylinder end and an opening to atmosphere on the runner opening.
1 degree taper per side was used.
The blend radius is 0.25"

Enjoy"
notice how the longer length runner has a more pronounced and stronger inertial pulse strength and duration
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: mechanical constant flow injection

Postby grumpyvette » April 6th, 2015, 4:03 pm

If youve ever wondered why I've repeatedly suggested individual runner fuel injection intakes have advantages look closely at the dyno chart I found and the two different torque curves, and why comparing only the peak horse power is so misleading on the true advantage of a significantly more robust torque curve of the stack injection, theres easily 60 plus foot lbs, of additional torque gained with the stack injection over a noticeable part of the rpm band
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http://www.hotrod.com/cars/project-vehi ... am-tuning/

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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: mechanical constant flow injection

Postby 87vette81big » April 6th, 2015, 8:39 pm

I would like to find IR Stack Injection for a Pontiac V8 Grumpy.
I would try it out.
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