Hilborn Mechanical Injection
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Hilborn Mechanical Injection

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    Default Hilborn Mechanical Injection

    Im thinking of running some mechanical hilborn fuel injection on my new motor that im going to build for my daytona. I have a few questions and hopefully i asked them correctly so i can get some good feed back. The motor i plan on building is a 468 low compression with a mild cam, built more for reliability than HP. I have a good line from a friend on some 325 AFR heads and hilborn injection that i plan on running. I want ot run the injection mainly because it looks bad ass. here are my questions
    1. Do i need to run the mechanical fuel pump? Can i use a large electric fuel pump? say a 250gph
    2. How much of a pain in the ass is tuning?

    I also saw at the pirates cove deal a few weeks ago a bad ass flatty with some stack injection and i loved the angled velocity stacks. Can that be done on any injection set up?

    thats about it. any Pro's or Con's are greatly appreciated

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    Quote Originally Posted by SofaKingFast View Post
    Im thinking of running some mechanical hilborn fuel injection on my new motor that im going to build for my daytona. I have a few questions and hopefully i asked them correctly so i can get some good feed back. The motor i plan on building is a 468 low compression with a mild cam, built more for reliability than HP. I have a good line from a friend on some 325 AFR heads and hilborn injection that i plan on running. I want ot run the injection mainly because it looks bad ass. here are my questions
    1. Do i need to run the mechanical fuel pump? Can i use a large electric fuel pump? say a 250gph
    2. How much of a pain in the ass is tuning?

    I also saw at the pirates cove deal a few weeks ago a bad ass flatty with some stack injection and i loved the angled velocity stacks. Can that be done on any injection set up?

    thats about it. any Pro's or Con's are greatly appreciated
    Unless you go with an EFI (electronic fuel injection), you will need to run the matching mechanical fuel injection pump.

    1. A mechanical fuel injection unit is a "constant flow" fuel injection unit where the nozzle sizes, buypass jet and fuel pump are all matched for a fuel curve for your engine size, rpm, etc. Thus requiring the proper size mechanical pump.

    2. It is possible to run a constant flow injector on gasoline, but in my opinion they are sensitive and picky and a pain in the butt. However, an alky version (methanol) is realtively forgiving and not much a pain at all other than the maintenance. It is my opinion that each week when you come in from the lake that you need to flush and lube the pump, injector lines, barrell valve, etc.

    If one is going to run an mechanical alky injection unit, the performance will be much better with some cylinder pressure, so go ahead and run some compression.

    I think there is some similar threads on this site discussing this same subject.

    I hope this helps.

    Gear

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    Does the fuel tanks need to be higher, like above the pump, in order for it to work? I was told that the mechanical pump was gravity fed. If that's the case how did old school gassers run injection with tanks in the trunk or on the bumper? If my fuel pump will have constant fuel pressure at the valve and bypass back to the tank when not used, wouldn't that be the same thing the mechanical pump would do?

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    If your running (tanks) as in 2 saddle tanks you will need to run a sump tank that is fed with a separate pump and you will have to plumb in a return line off the sump and back to the saddle tanks. So there is a little bit of plumbing that will need to be worked out. not a big deal but a deal non the less. and it has to be done RIGHT. remember the more fuel lines you have the more risk of potential LEAKS. and we all know what fuel leaks on a boat can do! ruin your day in a second. I think if you look on hillborns sight they have alot of good info there

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    Question #1 yes. Question #2 easy to tune when you get the theory of how they work! Good luck and for what its worth you don't have enough compression to run alcohol effectively. MDAO.

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    Check Hilborn's website for stack injection with efi, good looks with great drivability.

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    Quote Originally Posted by ol guy View Post
    Question #1 yes. Question #2 easy to tune when you get the theory of how they work! Good luck and for what its worth you don't have enough compression to run alcohol effectively. MDAO.
    I understand how the system works, but my questions was really only with the fuel pump. I still do not understand why i need to run a mechanical fuel pump and why i cant run an electric fuel pump. I understand that there needs to be a return line back to the tank, since its a constant fuel set up. If the fuel tank can be mounted below the fuel up, and they are not gravity fed, then im good with that. I heard of guys using a little faucet pump to prime the injectors. Someone sugested running alcohol, but i never said that, nor do i really want to yet. I still want to use the boat and play. I dont want to have to drain oil all the time, and all the other stuff that comes with running alcohol.

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    Quote Originally Posted by SofaKingFast View Post
    I understand how the system works, but my questions was really only with the fuel pump. I still do not understand why i need to run a mechanical fuel pump and why i cant run an electric fuel pump. I understand that there needs to be a return line back to the tank, since its a constant fuel set up. If the fuel tank can be mounted below the fuel up, and they are not gravity fed, then im good with that. I heard of guys using a little faucet pump to prime the injectors. Someone sugested running alcohol, but i never said that, nor do i really want to yet. I still want to use the boat and play. I dont want to have to drain oil all the time, and all the other stuff that comes with running alcohol.
    SKF, you don't seem to REALLY understand how the system works. I'll be harsh, if you did, you wouldn't be asking the questions you are.

    The system is 100% dependent on a given flow thru a MATCHED fuel pump for EVERY revolution it makes, It is a positive displacement pump that moves a precise amount of fuel every time it rotates one revolution. The ENTIRE system is built around the volume the pump delivers. Electric pumps with a return pump the same amount of fuel regardless the speed of the engine. MFI REQUIRES a variable fuel volume that raises with the engine speed.

    MFI is tricky enough to learn running on alky. Running on gas requires you to be more than a little knowledgable. Also, the system is dumb with a capitol D. On gas you'll need to tune for virtually every weather condition. 8:00 am 75* requires a different tune than 110* at 2m. You'll be tuning for May and another tune for Aug. Specially if you run gas.
    I can assure you, based on your questions, you only THINK you know how the system works.
    Last edited by gn7; 10-08-2012 at 12:11 AM.
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    Quote Originally Posted by gn7 View Post
    SKF, you don't seem to REALLY understand how the system works. I'll be harsh, if you did, you wouldn't be asking the questions you are.

    The system is 100% dependent on a given flow thru a MATCHED fuel pump for EVERY revolution it makes, It is a positive displacement pump that moves a precise amount of fuel every time it rotates one revolution. The ENTIRE system is built around the volume the pump delivers. Electric pumps with a return pump the same amount of fuel regardless the speed of the engine. MFI REQUIRES a variable fuel volume that raises with the engine speed.

    MFI is tricky enough to learn running on alky. Running on gas requires you to be more than a little knowledgable. Also, the system is dumb with a capitol D. On gas you'll need to tune for virtually every weather condition. 8:00 am 75* requires a different tune than 110* at 2m. You'll be tuning for May and another tune for Aug. Specially if you run gas.
    I can assure you, based on your questions, you only THINK you know how the system works.
    I'm gonna look you up when I pull the trigger on my B/A deal!, I'll need an instructor.
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    Question

    I'll ask a question because I'm curious, so go easy on me...Bob

    I realize I'm talking two different fuel sources and two different ways of using them to produce power.
    One ignition and the other compression...but...in all types of weather (unless the fuel gels) the mechanical fuel pump on my 7.3 diesel is drama free. No computers, sensors bla-bla-bla and always consistent.
    Why wouldn't a mechanical IP for gas and pressured injectors be the same? Why is that set-up so finicky?

    Nervously waiting...maybe I have a drink or two, too
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    Quote Originally Posted by gn7 View Post
    SKF, you don't seem to REALLY understand how the system works. I'll be harsh, if you did, you wouldn't be asking the questions you are.

    The system is 100% dependent on a given flow thru a MATCHED fuel pump for EVERY revolution it makes, It is a positive displacement pump that moves a precise amount of fuel every time it rotates one revolution. The ENTIRE system is built around the volume the pump delivers. Electric pumps with a return pump the same amount of fuel regardless the speed of the engine. MFI REQUIRES a variable fuel volume that raises with the engine speed.

    MFI is tricky enough to learn running on alky. Running on gas requires you to be more than a little knowledgable. Also, the system is dumb with a capitol D. On gas you'll need to tune for virtually every weather condition. 8:00 am 75* requires a different tune than 110* at 2m. You'll be tuning for May and another tune for Aug. Specially if you run gas.
    I can assure you, based on your questions, you only THINK you know how the system works.

    OK, thank you for the info.

    one more thing that i need education on then is the pump. When you buy injection do you need to match the pump with the manifold or injection set up? also one last question for you, are the pump gravity fed? I was told that they were and if that was the case then the pump could never build any pressure, and the pressure that the gravity feed would provide would vary depending on the fuel amount corect?

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    your pump should be matched to the injection and the fuel level should be above the pump or it wont work for long

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    Quote Originally Posted by SofaKingFast View Post
    OK, thank you for the info.

    one more thing that i need education on then is the pump. When you buy injection do you need to match the pump with the manifold or injection set up? also one last question for you, are the pump gravity fed? I was told that they were and if that was the case then the pump could never build any pressure, and the pressure that the gravity feed would provide would vary depending on the fuel amount corect?
    The pump is sized/matched flowed with the "injection" setup. This consist of nozzle sizes, bypass or bypasses and barrel valve, etc, all matched to the engine cubic inch, operating rpm range and fuel. In a mechanical "constant flow" injection, the pump flow increases with the rpm of the engine to provide the fuel requirements of the engine.

    Mechanical FI pumps make good pressure on the output side, but are not good suction pumps. folks have limped them along a lot of ways, but the best placement of the pump is at or below the lowest fuel level. The mechanical injection pump is generally run at 1/2 crankshaft speed and cam driven and mounted off the front of the cam or belt driven at 50% of crankshaft speed. One can belt drive off the crank and have the pump mounted at a low point of the engine similar to where a power steering pump sits.

    As was mentioned earlier, a "surge" tank can be used. This is where a smaller tank is mounted above and close to the pump and then you feed this smaller tank with say an electric pump from your larger side tanks. Your return lines from your injection would then return to the surge tank. The one thing you have to watch here is your mechanical FI pump may pull a larger demand on the surge tank than your side tank pump can refill. This will then cause aeration,cavitation and starvation and lean out your engine.

    After you gain the base information you are seeking, then give Hillborn, Enderle, Kinsler or others a call and they can lead you right through it. It is a very good idea to have the entire unit flowed and calibrated prior to ever placing it on the engine, especially if you are not experienced in setting bypass poppet pressures, barrel valve leakdown, throttle blade settings, main and possibly high speed bypasses. Kinsler and others can set you up with a near bolt on and run system. Again though you would rather not hear it..... the methanol based FI unit is much easier to live with and adjust than a gasoline in a mechanical FI.

    Although a carb can be setup to run methanol decently, my preference in racing is Gasoline is for carburetors, and Injection is for Methanol and Nitro.

    Gear

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    Quote Originally Posted by Gearhead View Post
    The pump is sized/matched flowed with the "injection" setup. This consist of nozzle sizes, bypass or bypasses and barrel valve, etc, all matched to the engine cubic inch, operating rpm range and fuel. In a mechanical "constant flow" injection, the pump flow increases with the rpm of the engine to provide the fuel requirements of the engine.

    Mechanical FI pumps make good pressure on the output side, but are not good suction pumps. folks have limped them along a lot of ways, but the best placement of the pump is at or below the lowest fuel level. The mechanical injection pump is generally run at 1/2 crankshaft speed and cam driven and mounted off the front of the cam or belt driven at 50% of crankshaft speed. One can belt drive off the crank and have the pump mounted at a low point of the engine similar to where a power steering pump sits.

    As was mentioned earlier, a "surge" tank can be used. This is where a smaller tank is mounted above and close to the pump and then you feed this smaller tank with say an electric pump from your larger side tanks. Your return lines from your injection would then return to the surge tank. The one thing you have to watch here is your mechanical FI pump may pull a larger demand on the surge tank than your side tank pump can refill. This will then cause aeration,cavitation and starvation and lean out your engine.

    After you gain the base information you are seeking, then give Hillborn, Enderle, Kinsler or others a call and they can lead you right through it. It is a very good idea to have the entire unit flowed and calibrated prior to ever placing it on the engine, especially if you are not experienced in setting bypass poppet pressures, barrel valve leakdown, throttle blade settings, main and possibly high speed bypasses. Kinsler and others can set you up with a near bolt on and run system. Again though you would rather not hear it..... the methanol based FI unit is much easier to live with and adjust than a gasoline in a mechanical FI.

    Although a carb can be setup to run methanol decently, my preference in racing is Gasoline is for carburetors, and Injection is for Methanol and Nitro.

    Gear
    Thats great info, thank you. Thats more or less what i was looking for. The guy im getting everything from has it running currently on a boat and it works pretty damn good. They run stack tanks in front of the motor, thats something that i can not do in my daytona.


    Does anyone have any pictures of the "surge tank" ? or maybe a whole set up that i can use for comparison?

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