Discussion and questions related to the course Diesel Tuning Fundamentals
Maybe best place to put on the diesel side of this forum as it’s all diesel.
This is one of the project where we can show some of what the diesel industry is able to produce as on this engine lots of special parts are needed and must say for me it a love & hate it engine with it’s good and bad things. Fact is it’s an old so we need to crank it up with loads of latest generation stuff and production techniques to get max engine performance.
First is what I do not like on this engine.
Fuel system. Lost of internal leaking costing engine power as more fuel needs to be pumped to the hi pressure side of the fuel system. (common rail). More later on during the build how and why.
Things in general we like about this engine.
Low in weight around 900Kg in total. Not bad for a 12.4L Semi truck engine.
Small and compact build. More a bout this later on.
Some of the numbers on performance. Engine power. Fuel system can handle over 1500Hp. Fit a bigger turbo and get more power.
Torque. Close to 6000Nm. Why is this important? Well this engine going to run FIA European truck race championship with a 63mm inlet restriction size limiting the airflow to the engine so massive low end power or Torque will give you a wider RPM range with max engine power.
Small youtube movie on what is coming and what the engine looks like.
Looks like a cool project. Will follow this as your progress.
D26E6 Truck Race engine Piston and injector explained
We get the engine striped down to what we call a small block. Rotating assembly engine block liners and connecting rods & pistons still in place so next week will disassemble these as well.
Cylinder head will be cleaned over the weekend to get all the soot out if the intake system as this engine runs EGR and inlet manifold is part of the cylinder head.
Valves are removed from the cylinder head and will be machines to specification. Some small changes to the meeting face of the valve and valve seat will improve heat transfer.
The rest of the cylinder head job is boring as no need to the in/exhaust porting is needed.
The rest of the job is inspect for cracks but we know the head has been replaced before so it should be fine. Must say due to the very hi combustion pressure on these race engines a cylinder head will last about 1,5 years racing and if the head creaks chance is the vale seats will fall out. Last thing is the clearance of the valve guides. Make them to small and the valve will stick. Make it to big and chance is on the exhaust valve is that burned oil will stick to the valve stem and make it stick as well. Get the clearance correct and all will work fine also providing max cooling to the valve as well as the valve stem will transfer heat to the cylinder head by a small layer of oil. Oil dos a loads more than only lubrication.
Oil, top piston ring sealing and cooling the top of the outer piston. What did you say? Did you know that 90% of heat transfer or the outside of the piston top takes place by the top piston ring? Just have a look @ a piston on that part and you notice the material thickness is the most on that part so it dos not only want to expand more but its also harder the transfer heat to the inside of the piston. So if your top piston ring dos not seal very well oil will be pushed down or out of the piston grove creating not only a load of blow down of combustion gasses but reducing piston cooling or heat transfer to the cylinder liner as well. An alloy piston will expand to a point all clearance is gone and it will leave alloy on the liner as well due to overheating and this stuff is very abrasive. A steel piston will expand a lot less but chance is the piston it self will get that hot that the piston pin will expand unable to rotate in the small end of the connection rod and things like friction welding the piston pin to the piston will lake place as it’s steel on steel and later on I will show you how small the services are on a steel piston and what can happen if it all dos not work out.
Engine is now completely striped and all parts are inspected for size and damage and cracks so yes very happy as all is still within factory specifications. Engine block is in the machine shop for some modifications needed to fit some special parts.
We also have an engine test system. You can call it a universal ECU system for diesel engines so we are able to test customers engines after they done there overhaul or repairs so they know all is OK before they sent it out to there customers.
I do not put a lot of effort in connection all sensors. Cam sensor is not needed as I programmed a auto sync on 720 crank or 4 stroke cycle detecting engine acceleration @ start-up.
Load testing a Liebherr D936 commonrail engine
This MAN has a compound turbo set-up. Small turbo for low end performance and the bigger one for mid and hi end power. compound turbo set-up is very basic as they use the wastegate on the smaller turbo to bypass exhaust gasses to the bigger turbo but still all intake air will pass over the smaller turbo so it always remain in operation as on some engine the smaller turbo will be bypassed with some vale system as well.
Also note the air to water after cooler system on this engine and the EGR coolers as well. This D3676 is the bigger 16L brother of the D2676 race engine we build.
Load testing a MAN D3676LA01.D engine
Also part of my daily work is engine diagnostics. What to make from this one? Engine gets above 60 degrees C coolant temp and starts smoking white out of the exhaust coming out of idle RPM un till getting into some boost. First thing that comes to mind EGR valve open to far? Nope and EGR + cooler already replaced as this things went on for some time now even the dealer diagnostics expert is out of option on what it can be.
So what’s next? Get a diagnostic tool and start looking for strange things on sensor readings.
OK notice that AFR was 16.8 on idle EGR valve closed!? DPF sensor reads only 2Kpa but lines to DPF sensor can be blocked so crawl under this very low city bus undo the pressure lines on the DPF sensor. Nope all are open and not blowing very hard so no backpressure on DPF and so on. OK next step. Take the MAP sensor out, yes blows air out of the hole on the inlet manifold. Looks OK. Next thing look @ the AFR reading getting out of idle soft and hard pressing the accelerator peddle. Go slow up in RPM all is OK. Go hard and AFR jumps below 14.2AFR. Engine has the same compound turbo set-up as the MAN D3676LA01 so some exhaust pressure on low end is normal but should not give massive EGR working on the engine unless the wrong camshaft is fitted. OK here is where you jump back to the engine build manual and if you know camshaft timing and valve open/close diagrams on diesel engine you know what will happen if you have to big numbers on valve chance over duration and exhaust gas pressure will do more than even keeping some exhaust gas in the combustion chamber. Exhaustgas will enter the inlet manifold as well.
So in this case there is a camshaft for internal and external EGR controlled engines.
This makes for some very interesting reading. The diesel piston was also quiet new to me so thanks for sharing.
The Dakar Rally Game is on. Shake down special stage 5e place and best private team only 8 seconds behind Nr1. Ideal for starting day one.
Scania 12.7L Commonrail 1130Hp over 5000Nm
Day 2 of the Dakar Rally is already underway. Have daily contact with the Dakar Speed Rally team. Everything under control, make no mistake much is new about the new Scania or is it now an International. There has been some testing but this is THE rally of rallies so I see it as a test year.
Preserved and still sticking to it, 11th place is good for me, it’s a long rally.
Scania engine technology. Apart from a few minor things, it is actually the same as all race and rally bikes. What is new is the automatic gearbox. This was a point of discussion because many Rally teams drive this set-up with more engine revs and the Scania engine that we build like a torque machine, a lot of pulling power underneath which also saves fuel, etc. and also make this engine a has a higher average power, comment of 1 of the Dakar Speed team members, they can't keep up with us out of corner, the power delivery impresses other teams.
What can I say! Game over for 2021 Dakar Rally. Big crash Dakar Speed Rally Team Scania International Dakar Rally 2021 stage 3
Just shows how fast things can go. Also shows how easy this truck takes the dunes up shifting to 4e gear. They were running around 6e place keeping up with the top 6 easy but yes motorsport can have it’s bad days.
I think we can all agree this. It’s the most epic looking Rally Truck Around. A head turner.
Such a shame. That truck looks awesome.
Flat out on work so not a lot of time to post things. And yes load of new things coming for 2021.
As for the future of commercial transport we hope to start load testing our https://smesh-e-axle.com next week. Please have a look at our website for more information.
Work in progress D26E race engine(s) 2021 spec. As always it’s the combination of man and machine that’s make the difference on overall performance. We can make massive toque and power numbers from our engine but what good will it be if its hard to control. Some things are not for sale or rent you just get them along with our products only and it’s called know how.