Everything We Know About the 2024 Duramax L5P 6.6L Engine
this is our current Duramax l5p and this is the 2024 gen 2. what makes this one different well I'm Gale Banks and we're going to tear it down and show you [Music] right away I can see we've got a new turbocharger here the bolt up is completely different new turbine housing new compressor housing a new high-speed variable geometry controller and probably a new compressor and turbine so we'll get this puppy off we'll break it down measure all the critical dimensions on the compressor wheel turbine wheel inducer diameter on the compressor cover and I'm really curious about this new VG controller I'm told it's Ultra quick it's time to get this thing over to Mike in the engine room and he'll get it torn down all right Mike here he comes [Music] this 2024 l5p is a pre-production gamma engine it's what you'll find in the new 2024 GM pickup trucks Mike Keegan our engine builder has partially disassembled both the 2024 and the 2023 engines so we can compare the parts side by side let's start with the bottom end crankshaft rods Pistons it's basically the same but the l5p bottom end is pretty damn Bulletproof we have tried to blow up a Duramax there's a series called killing a Duramax that we've done we got to over a thousand horsepower with a stock bottom end we did make a cam change because we also over revved it a bit but yet we've never broken this bottom end we're good to go there but what has changed is on the other end of the conn-rod the piston is all new [Music] this is really different I think what you're looking for here is two things combustion efficiency and diminished emissions if you can cut emissions in the engine the emission system has less work to do and will live longer or maybe even could be redesigned to be less restrictive the piston comes within about 30 or 40 thousandths of touching the head it actually protrudes slightly out of the deck of the block on these l5ps as you start injecting before top dead center the piston comes up within about a millimeter of the head pushes air back into the fuel there's a huge clockwise rotation of the air in cylinder it's called swirl it's part of what makes the combustion more uniform air fuel ratio but suffice it to say the air fuel ratio in the combustion process on a diesel engine is not uniform you have richer areas and you have leaner areas you don't want to have too rich of an area or you might produce soot that's one of the pollutants that might be cut with this new design so that's been kind of stated in our in our in our racing pistons about five years ago we made the section in the center this dome more pointed what I was trying to do was take a lean section which is right at the center of the combustion chamber and fill it with piston to push that air outward the guys at GM have done the same thing we've been doing in the racing engines uh but they've taken a one huge step further with ebola diameter they put in what we might call a shelf around the perimeter of the combustion chamber and the squish area is quite a bit narrower let me retrieve a nozzle here the spray angle out of the nozzle it was a very small Outlet holes for the fuel and the fuel pressure into this thing on this new engine is 2200 bar shooting the hell out of 30,000 pounds at the peak injection pressure it doesn't come straight in comes out at 155 degree angle on this new engine 158 degree angle on the older version of the l5p I'm estimating the included angle of the plume at about 16 degrees it might be more it might be less it might vary with pressure and flow which I'm sure it does the black line here is the included angle that's the aiming angle of the injector tip so mult there are multiple holes around the perimeter of that tip that spray into this combustion chamber so what might have been impinging here is now spraying into this area so the mix of air and fuel at that point way the hell different I think this might be a power enhancement as well at the same fuel rate in other words if you make the engine more efficient at the same fuel rate it makes more power or you can make the same power with less fuel that's what this is all about and if you burn less fuel you're probably going to make less emissions there's a real enemy in diesel emissions other than a smoke or the soot and it's Knox nox that has to do with peak temperature in the combustion process if this has anything to do with diminishing the peak temperature whoa you're going to reduce knocks next thing we want to look at here is the head gaskets here's the 23 head gasket 23 and earlier here's the 24. they're both multi-layer gaskets so the layers are uniform in thickness and there's four of them on the early one on the later one we have three uniform layers and one thicker one there's different ways of getting high unit loading around the cylinders the guys at GM have come up with a new improved head gasket design that will seal better and last longer there's some oil drain back passages there's water and overlaying them they're identical in size and placement which they'd have to be backward compatible so we have a new improved gasket on the 24.
so this is the 23 nozzle this is the 24 nozzle similar shape different manufacturing process the outlet of both nozzles and these spray up into a gallery in the piston to cool the Piston they're both about two millimeter a little over two millimeter then you have the retaining bolts and they have gotten different as well I really like the retaining bolt on the 24. it is a lot sexier looking thing that being this one here in my right hand it's just fully machined this one isn't but both of them serve the same purpose when you come back down to idle and you don't need all that cooling nozzle capacity there's a little call it a pressure relief valve inside it's like a ball check a spring-loaded ball check the oil enters the bolt idle that ball check forces all the oil flow to go to the crank to the rest of the engine you don't need the Piston cooling but you want the idle oil pressure that's what you're looking for then we move to the oil cooler foreign [Music] got here is the LBZ as this is typical of the earlier Duramaxes with lower power outputs then we move into the 17 to 19 l5p and then we move to the 2020 and the 2020 they did a lot of other things they put put a far more powerful cooling fan for the radiator a hell of a lot more engine coolant radiator they upped the towing capacity so lots of other stuff in the truck having to do with suspension etc Ram Ford and GM I understand they're getting near 40,000 pounds towing capacity now which to me is obscene absolutely obscene whatever weighs 40,000 pounds it's going to dwarf the truck unless it's just a big meteorite on a trailer or something so when we saw this 2020 cooler we realized everybody with 19 all the way back to '01 needs this thing if you do anything with your truck that's aggressive including tuning so we put a kit together that allows you to do this all the parts all the hard to find items are in the box and you you can heavy duty oil cool all the way back to o1 you can find that kit on bankspower.com [Music] the next change in the 24 Duramax is a high pressure fuel pump which we've got right here kind of a like a little V8 engine one of the cylinder heads off inside the pump there's a cam ring which is flat so as you rotate that cam the surface of the cam ring the cam being inside of the cam ring is rising and falling as the camshaft rotates within the ring you have a kind of a superior situation in an engine you have a lifter or cam follower and it rubs against a camshaft rubbing surface would never cover the entire surface of the lifter but by doing this it does cover the entire surface of the lifter so you've got a uniform pressure profile across the face of this plunger you still have rubbing or sliding friction also uniformly loaded I'm surmising that in addition to other improvements they've applied a diamond-like coating otherwise known as DLC to all the critical load-bearing friction surfaces so this gives it extended life I think this pump has a pumping capacity of 2200 bar that's 32,000 pounds per square inch the 23 is 2000 bar so that's 2900 pounds less or nominally 29 000 pounds peak pressure what is this other three thousand pounds or so give you it gives you the ability to put the fuel amount desired through smaller holes atomizing it to a more refined State improving the combustion process and the completeness of combustion when the fuel is injected you have droplets the compressed air compressed with by the Piston rising in the cylinder is hot enough that those droplets start burning but they they don't necessarily explode they're not as volatile as gasoline they burn from the surface in peeling layers of molecules off the surface of this droplet until it's completely combusted it's moving through the air seeking oxygen to get enough momentum for it to burn completely if it just stops it's going to burn the oxygen around it and starve so it has to have enough momentum to keep moving through the available oxygen until it's gone and that higher pressure gives you that but if you're going to put three thousand pounds more pressure into the fuel rails you got to change the fuel rail [Music] the fuel rail diameter on the 23 which is this fuel rail is nominally because these aren't perfectly round nominally 24 and a half millimeters and on the 24 26.3 millimeters I guarantee you that's all additional metal wall the 24 has a safety margin just like the 23 to get that safety margin you have to thicken the walls of the fuel rail which they have done you know I want you to think about 32 000 pounds of pressure anybody's ever seen a water jet cutter it's up there that pressure number is way up there the other thing that's different about the fuel rail other than the thickness is the length of the fuel rail the length of the 23 is about 359 millimeters the length of the 24 is about 343 millimeters and one last thing they the fuel rail pressure sensor has changed although it appears that the plug to the wire loom is identical but this guy has to go another 3000 psi all right we're moving on to the cylinder heads 23 24 externally they look virtually identical the 24 is more durable they've revised the structure call it the water jacket area of the head that's all I know short cutting one up which I'll do eventually anyway but what's really apparent is the free length of the exhaust valve spring free length on the 24 is greater than the free length on the 23. what's going on here well in order to have more exhaust break action
they're beefing up the 24 valve spring so you can get more exhaust back pressure created by the geometry and the turbocharger turbine housing the variable geometry is used for exhaust braking purposes as well you could float the exhaust valves if you got the pressure too high so you need more seeding pressure essentially that's what GM is doing here to get that braking pressure to a higher value and not float the valves off the seats and if they don't see they smack the pistons or the pistons smacks a valve you don't want that to happen I've heard guys say I can't feel the the exhaust brake on these things they're answering that uh by changing the spring rate and basically you can see the free length of the spring is higher you know it's almost a quarter of an inch more the wire diameter is a bit smaller 152 thousandths versus 156 to 158 thousandths the outer diameter is also about 30,000 smaller thinner wire but more turns the installed height is the same an inch 690 the seat pressure is what where you see the difference we get a an average of about 80 pounds Seat pressure on the stock Springs up up through 23. these little babies give you about 95 pounds of Seat pressure so you're picking up 15 pounds of Seat pressure over the nose is about the same at an inch 330 in other words 360 thousandths valve lift is where we're measuring open we've got about 154 versus 155 coil bind I think you can go a little higher valve lift with this spring than with the earlier but when I say over the nose that's a peak lift going over the nose on the camshaft so that's a good thing if you're hooking up to your 36 38 40 000 pound trailer you might want a little more exhaust braking so what makes the exhaust back pressure the variable geometry in the turbo so let's have a look at the turbo [Music] now I give you the turbos this is the 24 23 and earlier Inlet diameter about an inch and three quarters I'm told there's some durability Improvement in the up pipes that feed this turbine mount casting but the turbine mount casting is quite a bit different we had one conventional perpendicular bolt and one angled bolt on either side of this earlier style l5p setup here it's conventional flat I this might have had to do with manufacturing but I don't think so these bolts appear to be somewhat symmetrical I think I'm getting it now in terms of wrenching pressure you know the old school deal is the bolts are symmetrical around the flange for a uniform wrenching pressure etc if you have automated bolt driving equipment you had to clear the v-band clamp where the turbine housing attaches to the center bearing housing so they angled both of the upper bolts they went conventional here everything's perpendicular bolt and they moved the bolt on this side so that you could still hit it but it's not a symmetrical bolt pattern I think what they found was the loaded distribution Works through the rest of the casting and makes the wrenching pressure adequately uniform as far as the turbine housing itself and the turbine wheel the outlet or ex-ducer bore on the 24 is about 40 thousandths or one millimeter bigger than 23 and earlier and the blade count on the turbine wheel goes from 11 to 10 so how how is that a benefit well bigger Outlet and less turbine blades means more mass flow area for the exhaust as long as you can get the the necessary horsepower to drive this whole thing because the turbine has to produce enough horsepower to overcome its own inefficiency the drag of the bearing system and the load of the compressor and we're going for 25 more horsepower we went from 445 to 470. now let me show you something that's more visibly different and that would be on the compressor side or cold side of the setup to run the variable geometry mechanism you've got to have a calibration controlled actuator these are both Borg Warner pieces but the 24 is a enhanced mechanism it's quicker it's more powerful and as a result you can change the speed of the turbocharger more quickly so that kind of reduces turbo lag if you want to call it that it also allows you to control the air but you can't change the air that fast this helps you get closer to changing the air mass flow and pressure ratio more quickly throttle response that's fuel efficiency that's reduced emissions all of the above the inducer bores are both the same the blade counts are both the same this is a turbo speed sensor it will not be on the production trucks this is a Turbocharger off of one of our pre-production gamma engines and all the gamma engines for engineering purposes and calibration purposes come with a speed transistor but in production there'll be a different casting and this won't be there so up through 23 the center bearing housing which is water cooled it's kind of a one-piece thing here with a compressor back plate integral and in cast iron on the 24 we've gone back to an aluminum back plate that bolts on it to the center bearing housing in the center of the back plate which is quite conventional the back plate in this case also mounts the actuator assembly and here the compressor cover has the mount for the actuator assembly so overall a more robust unit it's exactly what they need on the 24. we made over a thousand horsepower with a gen 1 l5p Duramax what do you think we're going to do with a Gen 2 I aim to find out [Music]
2022-11-27 16:33
