Hilborn Type MFI

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frnkeore
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Hilborn Type MFI

Post by frnkeore »

There is not much talked about, regarding setting up these old school MFI systems. I'm sure there must be a lot of people on this forum, that have experience with them though and I'm sure there will be those that say "Why bother" go EFI but, that's not what I want to do.

I have a 412 ci, Ford FE engine, with TFS heads, that flow 330 x 240 cfm @.600. Steel FT crank, offset ground to 3.81, with 6.560 LS rods and 4.150 Ross pistons.

It will be a Dyno Mule and I have a intake adapter, that allows me to use any 351c 4v manifold and I have a Weiand 5994 TR on it. The first cam that will go in it is, a SFT, 260 x 270 @.050, with a net lift of .632

The first MFI will utilized this 5994 manifold lower manifold.

I don't think much of that matters, other than the 412 ci but, it's there for back ground.

I know a little bit about this type FI, as I installed one on my Cosworth engine, in 1974 (yes, I'm a old guy). I set it up, in the car and then, later dynoed it.

As I remember, the jetting was done by ci, only. The pump was selected by different ranges of ci (i.e. 150, 175) and then the "pill" was "maybe" selected by HP? If not, it was also selected by ci.

I had to run 3 lines, in to the pump, out to the barrel value, a pill return line and a separate pressure by pass, for high rpm, closed throttle.

Now to the questions:
1. What size 90° nozzles do I want?
2. What pill size, to start with?
3. What barrel valve?
4. How much tuning can be done with the barrel valve?
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Re: Hilborn Type MFI

Post by Racer71 »

I would call Tim Engler, he or kinsler should be of good guidance. We used to mechanical on the midget engines, the sprint cars all still do.
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Re: Hilborn Type MFI

Post by gordon »

What type of MFI are you asking about constant flow or the Lucas timed variety ? If it is the constant flow style used on most modern sprint cars and many drag race cars then Enderle, Kinsler , and such are good sources for hardware and info. If you want to educate yourself to get the most out of this set up , then Google Racecarbook Bob. He has a series of books that cuts through the BS and shows you how this style system really works and how to tune it yourself instead of relying on others .
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Re: Hilborn Type MFI

Post by frnkeore »

Hilborn was the originator of the constant flow (or lawn sprinkler, as it is affectionately know) MFI system, like everyone has copied.
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Re: Hilborn Type MFI

Post by In-Tech »

lol, it's like Pink Panther movies, nobody talks =D>

Super simple to tune as long as you have enough injector, then just log wide band and fuel pressure. Add blow off valves accordingly and hand shape the barrel valve as needed for part throttle.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: Hilborn Type MFI

Post by rebelrouser »

You did not say what kind of racing you were doing. Constant flow mechanical injection works well at WOT, but slow speed driveability and starting not so much. I have messed with the old Hilborn stack style and the flying toilet style injection systems.
Especially if you are buying a used system send in the pump and get it flowed, after they have those numbers, and you give some specs on your engine they will give you a set up on nozzle size and starting pill size for return flow. I have seen guys chase their tails for a long time without doing this. And as the pump wears it will lean the engine, so normal Maintenace is to have the pump flowed and if needed rebuilt. Also you need a cylinder leak tester to set the idle of the barrel valve, and if more than a couple rounds on the idle adjustment is needed, see step one, something is wrong. And casnnot stress enough keeping the system clean. And if you are burning alcohol, I recommend draining the system and filling with gasoline, start at idle until it blubbers a little, anytime it is going to sit for a while, and for winter storage drain system and lube the pump, years ago Hilborn told me to use castor oil. Picture of my old Cuda altered wheelbase injected hemi, not very fast but it sure looked neat.
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Re: Hilborn Type MFI

Post by Mummert »

A secondary low speed bypass (which is just a a low pressure bypass) can help with low speed driving. A low speed bypass will become a part of the to total hi speed bypassing fuel so it will alter the size of the high speed bypass pill. The bypass valves can be pressure adjusted with different springs as well as pill size.
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Re: Hilborn Type MFI

Post by frnkeore »

rebelrouser wrote: Mon Jan 10, 2022 12:33 am You did not say what kind of racing you were doing. Constant flow mechanical injection works well at WOT, but slow speed driveability and starting not so much.
In the third paragraph, of my first post, I said it will be a Dyno Mule, at least for now. So, WOT is the application. I did leave out that it will be for AvGas. I'm not looking for steetabilty, just a good initial setup, such as what nozzles to use and pill size, with a 175 pump (I have that) or should I be using a 150 pump. I would also like to know what/whose barrel valve would be a good starting point.

In the mid 80's, I consulted Hilborn about a 350, SBC, gas setup and told them, I had a 175 pump and they said that a 150 was the std pump but, that I could use the 175 with a larger pill and that it would run higher line pressure with it, as I remember. I didn't get into what difference the pressure curve might make. This is a larger engine so, I figured the 175 would also work ok.

Thank you, Mummert, I may need that after initially getting a setup.
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Re: Hilborn Type MFI

Post by bill jones »

---this link should get you to pdf file that has Hilborn nozzles all laid out on a grid to show you how much they flow at various pressures etc

http://www.ryanbrownracing.com/pdf/flow1.pdf

---looking at running gas you need about 1/2 a pound of fuel for each hp as a starting point

---might help you in some way
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Re: Hilborn Type MFI

Post by frnkeore »

Thanks, Bill.

I expect this engine to produce ~600 hp. Am I correct in selecting the nozzles, underlined in red, as a starting point, based on the given line pressures?

At the top of the page, it says the the chart is for methanol:

HILBORN NOZZLE FLOW CHART, at 30psi and .792sg (methanol).

So, if I've chosen correctly, will those be correct, only for meth and not gas?

I did some research tonight and found that the specific gravity for gas, is:

Pump gas can vary between 0.71 and 0.77. Avgas 100LL, 0.68-0.74

So lets call it .73, or 92% of meth. Also, I have found that the basic, high hp, AFR is approx 4.9 meth & 12.65 for gas so, it takes about 2.58 less gas than meth.

So, now my next question is, if the chart is indeed for meth, how do I translate that to gas nozzle sizes?
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Re: Hilborn Type MFI

Post by bill jones »

---the fluid I used when doing my wet flowtesting was a .792 SG stoddard cleaning fluid---same as what I use in my parts washing tub

---so that made dealing with methanol easy
---I was dealing a lot with methanol sprint cars so that is why that chart exists
---I chose 1 to 1----1 pound of fuel per horsepower per hour for my methanol engines just as a nice quick easy way to use my wet flow bench results

---and then gasoline engines use closer to 1/2 a pound of fuel per hour per horsepower
---------------------------------
---if you expect to make like 750 hp in a sprint car engine you'd start out with 750 PPH of fuel at your maximum rpm
---or if you expected to make 750 hp using gas then you'd only need to be dealing with around 375 PPH
-----------------------------------
---I feel it's extremely important to have an easy to read pressure gauge

---I also set up like 4 pressure sensors to measure the fuel pressure like in 30/40/50/60 psi increments
---connected them to four different colored lights---and installed a small 12v battery to operate this system in the sprint cars
---this way at night races I could visibly see when the fuel pressure gets to these points from the pits
---so that helped me get stuff sorted out
-----------------------------------------
---basically I'd probably start with #8 nozzle size for 600hp or so on gas

---I've never used anything other than a PG150 dash zero Hilborn pump
---run that same pump on serious sprint car engines and methanol---used it on our 2000 Pinto at Bonneville with gas and with methanol
---I'd probably start with a number 8 nozzle on gas and a #17 or #18 nozzle for methanol
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Re: Hilborn Type MFI

Post by stealth »

This book might be helpful. The 56 Chevy on the cover is a picture of a good friend of mines. He passed away a few years ago, but he and I spent quite a bit of time sorting out the stack injection on his car..

Ran pretty well on the street, but 5MPG was about the best it got. Was really cool though!!

My friend spent quite a bit of time with the author providing him details of the trials and tribulations to make this work.
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Re: Hilborn Type MFI

Post by frnkeore »

Thank you, Bill. That helps a lot.

Did you ever run pressures much over 60?
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