Agree. Interesting we have shifted from high revving engine similar to a VTEC opening up over 4K to a very low end grunty powertrain
Exactly and that is what a truck needs, not crazy Tesla 0-60 stunts.
Agreed. People buy horsepower but they drive torque.
The center housing rotating assembly/CHRA has one intake impeller, and an exhaust impeller design that has two exhaust impellers that are the same CHRA center shaft. Each exhaust impeller set is to capture exhaust gas from the exhaust manifold by utilizing thermal, kinetic, and exhaust impulse energy. I do not know the firing order, but IF the engine had a firing order of 1-2-3-4, the isolated exhaust from cylinders 1 and 3 would spin up one exhaust side impeller, and exhaust gas 2 and 4 would spin up the remaining exhaust impeller. The exhaust manifold/header design is important for a twin scroll turbocharger to gain any benefit from the twin scroll turbocharger design. Each of those exhaust impellers are placed inside an isolated “snail” section for exhaust gases- the exhaust housings that isolate each set of exhaust impeller blades are dedicated for thr upstream exhaust gas- so exhaust gas from cyl 1 and 3 would be channeled to exhaust impeller “A” and cyl 2 and 4 would be channeled to exhaust impeller “B”
That is so cool and makes sense. I’d love to cut one open lol. Only confusing part is - does the exhaust gas that goes over impeller A keep going over impeller B as well or is it taken out of the system before that?
I am not certain, but I believe that camshaft timing is also adjusted on this engine, like a VTEC/VANOS.. almost every automotive manufacturer utilizes this on current engine platforms. Combined with direct injection fuel timing, this in itself, creates more power and efficiency. I don’t even see indicated boost in lower gears when driving.. but I keep the truck in ECO mode and for the most part, drive mellow.
You have answered your own question, perfectly! It is an isolated circuit that hinders the turbo charger design at high rpm but makes much more power in it’s “sweet spot”
I enjoy nerding out on this shit.
The smaller isolated ports that utilize exhaust gases from two of the four cylinders are smaller and don’t flow as well at high rpm, volume restriction… but if the system is designed properly, it will make significantly more power between 4k to 5.5k rpm…. Having a single exhaust scroll turbo set up to capture more power at redline may not make up
And that combined with a well programmed transmission and the hybrid is why this powertrain is never caught flat footed. No matter what the situation is I find my truck is always responsive and strong and it feels better than the old V6 engines that people were freaked out about losing. The turbo four alone feels so much better than my Taco with a 4L V6 ever did.
