Explain how Hilborn fuel inj regulates?

I understand the basics, but what continually regulates the fuel at let's say 10% throttle and WOT? What keeps it from just dumping the same amount of fuel in at 1/2 throttle as full power? Thanks guys!!

 

The barrel valve. It opens with the air plates.

 

The barrel valve that feeds the individual nozzles opens as the throttle is opened allowing more fuel to the nozzels. The more the ****erflys are opened, the more fuel the barrel valve p***es. At best, the bottom end is marginal. A hilborn set up is happiest at WOT.

 

As the fuel enters the p***age of the barrel valve, it meets the cylinder (barrel) that has a tapered slot. So as the throttle is opened, it rotates, allowing more fuel through to the hoses and nozzles.

 

The short answer to a pretty complicated question is increased system pressure due to increasing fuel pump speed. Gene Adams (I'm pretty sure....darn, my memory is getting bad!) used to have a real good manual out, but I haven't seen one for sale in a quite a while.

 

Correct. Don't forget the pump is turning at half crank speed and is a positive displacement pump. So it pumps twice the amount of fuel at 6000 rpm as at 3000 rpm.. The barrel valve will be wide open at about half throttle anyway regardless of the rpm. Since the pump efficiency doesn't fall off and the engine volumetric efficiency will fall off at higher rpm you have your high speed byp*** to drain a little pressure at higher rpm. And you have the secondary byp*** for idle speeds.

 

in circle track racing we call that part a spool.........lot of custom made spools around

 

Yeah, the system keeps returning more and more fuel to the tank as the rpm increases. How big the byp***es are and when they open (pressure) are major tuning changes for the mechanical system.

 

Ok, makes perfect sense. Where is this said spool/barrel located? Is it tied into the bellcrank system on the actual intake? Thanks guys.

 

Why are there a ramp on both sides of the slot on the spool?


..............................
Taildragger&fenderless

 

99.9% of everything and anything you would ever want to know Hilborn, www.hilborninjection.com, /tech-support, sections for both mechanical and electronic, books as well, TR

 

This is a little to close up. But the block with the two hoses coming out of it is the metering block. the spool is inside of it. This is a injection manifold I made for my Plymouth banger. You can see that there is a master rod connected to the throttle pedal. and it is connected to both throttle bodies and the metering block. So they all open together. Setting the spool is something that i have seen many people get in a bind over. You can use a leak down tester to set it for idle. I just look in and set it just barely open. The slot should be open toward the thicker side of the block. Rotates to open with the throttle plates.

 

I have been trying to decide on a fuel system for my Nos.drag car. 289 with dual carbs or run a Hilborn inj. I have no experience with inj. Is it difficult to set up and tune.??

 

I don't think it's more difficult than duel quads. Less difficult after a short learning curve.

 

For drag racing I would agree 100%. Terry, if you plan to cruise the car as well, injection isn't so friendly unless you really put your heart into tuning it for part throttle operation.

 

Just remember.....Fuel Injection looks sooooo cool. You can do it!

 

Granted. in fact I was thinking of the salt mostly. You don't even need any lower end power. The street would be a different deal.

 

Exactly.

As Dean said in post #3, mechanical injection is made for WOT.

Part throttle and idle are a compromise.

Gasoline more touchy than alcohol which is very forgiving when over rich.

 

http://www.alkydigger.net/technicalinfo.php

 

Basics of fuel injection are easier than multiple carbs in my opinion. I have a couple of Enderle setups. When you get in over your head, they're just a phone call away.

 

Here it is in a nutshell.


The metering valve is what we are referring to as a "barrel" valve in this thread.
Look carefully at the direction of flow. For all the byp***es, bigger jets mean a LEANER mixture. I've seen that screw a lot of guys up when they first switch from carbs. The other thing to always keep in the back of your head is the fuel pump is providing a variable amount of flow and pressure, so it must be matched to the needs of the engine. I believe a lot of problems come from people bolting on any old pump and either having way too much or way too little fuel flow at a particular pressure.

 

That's a lot of great help fast......Thanks guys.. Now,Gas or alcohol .MMMMMMMM ?

 

That's easy - alcohol.

 

Bull ****!

 

Nitro is way more fun, Dave!!!

 

Ha Jim...I'm sure it is but I can't afford that much fun. Maybe some day.

 

I agree. Porsche, BMW, etc all had mechanical FI for years until they had it very refined. Perhaps their rotor cap style injection was more user friendly..?

 

http://www.youtube.com/watch?v=**JD5StLDH0&feature=plcp

Electronic Hilborns are the ****!

 

Till the al***ude and air density changes.

 

With METERED air...try that with stacks and ITBs.