Fuel System 101 The Barrel Valve

all right on this week's parts plus motorsports moment i'm here with the man that calls the shots my long time friend long time crew chief and a lot of you folks have been asking what are the guys doing up on the starting line when i back up from the burnouts and mike is going to kind of go into some of the details of pardo a lot of you've been asking about a fuel system so we're going to go into part of it exactly what are we going to tell everybody about today we're going to tell everybody what the barrel valve is and what it does perfect all right folks this is the barrel valve and this is what mike's going to tell us about today so mike what is it what does it do well the barrel valve is the engine's fuel metering valve the primary use of the barrel valve is to give us our idle circuit and give us our wide open circuit we're lucky and that we don't get to drive this thing around so all we have to worry about is doing a burnout and going wide open so the barrel valve consists of inlet fuel lines which are these two fuel lines we're going to remove these two fuel lines the other fuel lines on the barrel valve are are idle returns these have fuel in them they're coming out of the barrel valve and back to the fuel pump while we're idling because the engine cannot use all of the fuel that the fuel pump makes while we're idling so the idle returns run through these check valves these check valves are set to a magical pressure which we cannot tell you so what what does the check valve do so the check valve um it gives us our high side it tells us tells the engine how how much fuel we want at at launch um on the main circuit now there's a secondary idle circuit that we control for control for launch which will show you that that's that's called the idle screw we're going to show you that in a minute so you mentioned the high side so i guess we probably need to explain kind of what the fuel system is doing for startup burnout well when we start the engine we only need a small amount of fuel like i mentioned before to idle and to do the burnout and that's controlled by the driver he sets it to a predetermined idle fuel flow and pump pressure so the handle in the cockpit that the driver controls will set the fuel pressure and the dashboard tells the driver what the fuel pressure and idle fuel flow is one of the things that's that's very unique and different about a barrel valve the metering valve on a top fuel dragster is that it's it's basically intended to be either at idle or wide open it's is much like an electric switch as we can make it without it being being electric um the engine idles on a really small hole that none of you can see on tv and play you'll bring the camera around to the back so we're idling on a small amount of fuel in this hole that you can see and you can see that this hole quickly goes away as we open the barrel valve now you'll see that there's nothing in the way of the fuel it goes straight into the engine so that's what you mean by saying it's basically a light switch it's basically back up a little bit it's basically a light switch over here on this side you can see the idle returns and as soon as the idle returns are blocked off then all the fuel has to go in the engine even though it's not wide open and as you can see right there all the fuels going in the engine and you can look at the butterflies and see the butterflies are really not open that far so at that point at this point right here all all of the fuel is going in the engine even though the butterflies are open a small amount that's so cool we're trying to get the fuel to beat the air that is really cool so at this point where i'm looking i can see the small hole and then i can see the slot so at this point the i the checks that you showed us are uh the checks will work checks are working and and only during the idle portion um when when these when these ports are open to the check valves uh they're allowed to set the fuel pressure of the of the idle circuit and then wide open those check valves don't come into play they're not part of the wide open circuit in any way all right so when this thing goes wide open you can see that it is that light switch that mike's talking about hit the throttle there mike and you can see that hole open up as soon as that throttle blade opens the light switch effect now one of the most obvious things that you see all the crew chiefs do is we'll generally have an idle fuel flow that keeps the engine at just the right temperature not too cold and not too hot but when we go up to launch we like to make the engine a little bit richer it's something that we want to have some additional control over the idle screw on the back of the barrel valve allows us to richen the engine by turning the screw out or to lean the engine a little bit by turning the screw in and you can see i have some color-coded marks for different days and different idle flows um maybe even a different car we might be racing might get a different uh different idle setting and that idle setting the crew chiefs you and basically everybody else out there is there something you see something that makes you decide if you're riching or leaning the engine at the last moment i mean kind of what's your train of thought at the point when when we are like literally about ready to stage the cars typically when that happens well there's a wide variety of things that can happen up on the starting line it can your opponent might be taking a little bit longer than normal and so rather than letting your engine run a little longer and build a little more heat you might turn your idle screw up a little bit to help keep the engine at the same temperature rather than allowing your opponent to control the temperature of your engine so if someone takes a little longer i can turn it up if our engine looks a little cold after it comes back from the burnout and it sounds a little sounds a little cold i can lean it down if it sounds a little hot i can turn it up and and help to cool the cylinders a little bit it's a fine tuning tool it can't make or break you but it can help a situation uh you can it can prove the performance of your race car it's it's about 10 of the idle circuit is the idle screw so there's not a tremendous amount of adjustment but the last 10 is controlled by the screw so i always tell people that uh it's kind of like that screw is kind of like the squirter on a holley carburetor would that be a true statement i've said that forever because it definitely is because on uh on a on a cold day we're gonna turn it down we don't need as much fuel on a hot day we're gonna turn it up because we need more fuel that might not be the same that would happen in a holley but it's it definitely can rich in the engine and give you a little extra power uh like a squirter like a power valve and a carburetor so one other thing that that is on here that i want to ask about is i see this little fitting right here exactly what does this do we'll talk about all the other lines well the this is our this is our fuel pressure line this is a quick disconnect line that line now can handle the 750 pounds of pressure that the fuel pump makes when we go down the race track um and then to take to take it apart quickly now we've got the line off and the guys wish they had these on all of the lines but no such fitting exists that can uh give us the flow that we need and not be egregiously heavy so essentially that is a data gathering port it's this this well it goes to the dash also it tells the driver what's happening it goes to a pressure channel transducer that's displayed on the dash so where did the barrel valve originate kind of where where did that that piece that we're looking at i mean it's going way back what did the top fuel cars use compared to what we have right now well they they've used a much smaller device that essentially does the same thing without some of the wonderful features this has used to be one idle check return one fuel line going in no thumb screw to adjust the idle you had to have more check valves if you had a high and low system on your on your your in your race car you would have to have four checked valves instead of the two check valves that we have right now you would have low side check valves high side check valves and a and a spool valve that allowed you to be on one or the other so the a lot of the fuel system is mechanically simpler than it used to be this barrel valve was designed originally by pete jackson in burbank california pete was a a longtime drag racer pete also did some racing on the dry lake beds pete was a real live rocket scientist he worked at the jet propulsion laboratory in pasadena so he did that in the slide rule days pete's pete's passed several years ago pete and i were very good friends this current barrel valve was really the product of all the things that we did in development when i was with dawn perdom in the late 80s we wanted a idle screw like a motorcycle had so that we could easily richen the engine up so that every time you wanted to rich in the engine that idle you had to change a check valve so we wanted a screw so we could stop fooling around with the idle checks all the time and that's where the screw came from pete's idea to have the balanced idle return ports allowed the driver to have better reaction times the barrel valve became much easier to open because we were putting too much pressure on the barrel valve with a single idle return so p jackson fixed a lot of the problems that the old original enderly barrel valve had so he made his own and this is what everybody uses this is the same exact barrel valve that's on all the rest of the race cars that run on top fuel and funny car so one other quick question is this basically is goes all the way through the barrel valve and so the connection from here to the injector has got to be pretty critical i would think well it it is um [Music] there's a spool inside the barrel valve and we've shown you how the spool rotates inside and there are some critical timing elements of the spool to the butterflies and that's controlled with the with the barrel valve linkage so we'll use some feeler gauges to put the spool in us in a certain place and turn the butterflies up to a 4000 sphere legs that we use in the idle slot so we make sure that the idle slot is is completely closed and we use a feeler gauge to set that so that's that's what this is for connects the barrel valve to the to the butterflies which is connected to the gas pedal and that's what we like to do stomp on that loud pedal [Music] you

Channel: Clay Millican

Views: 36,967

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Id: wbk2ig2Cn78

Length: 12min 48sec (768 seconds)

Published: Fri Sep 25 2020