So, the LA Auto Show was about five months ago, but better late than never. Cars are becoming more defined by their software than powertrains, but there are still some fun cars that make an appearance. The horsepower wars are still going even with stricter emissions, and Chevy brought out a monster.
Powering the new ZR1 is a 5.5L twin-turbo V8 with port and direct injection. A pump-gas friendly 9.8:1 compression ratio allows this engine to make 828 lb-ft of torque and 1,064 hp through catalytic converters.
A pair of Borg Warner ball-bearing turbochargers have Mar alloy turbine wheels. This alloy allows for higher exhaust gas temperatures required to make power. The grey plug with aqua colored wire coming out is the turbo speed sensor; it allows the ECU to make maximum power under allowed conditions without overspinning the turbo. If you look carefully, the three buttresses in the ported shroud are not evenly spaced. If they were evenly spaced, they would excite the blades at a specific resonant frequency and cause early failure. Look up blade pass frequency if you want to geek out.
All of the modern high-performance gas turbo cars come with this heat shielding from the factory. It looks like this setup uses an integrated exhaust manifold and turbine housing. OEMs like this because it eliminates gaskets, fasteners, and the failure mode of a blown-out gasket. The compressor outlet tube is silicone instead of the more typical rubber. It’s been a while since I’ve looked at many engines, but I think this is a first from the factory. Rubber balloons a lot, which impacts transient response a fraction of a second, and silicone should be more durable. I believe the two hardlines coming out of the side of the center housing are the coolant lines. You always want one of the coolant lines above the other to allow for auto-siphoning of coolant through the center housing after the engine is shut down. A manufacturing aid is the white block and line on the silicone hose; the block is the range of where to install the clamp and the line aligns with the cast-in line on the compressor housing.
The two lines going to the bottom of the turbo center housing should be the oil feed and return. The smaller diameter tube should be the high-pressure oil line, which looks to get oil from the oil cooler. The bigger line should be the oil drain line; you want a fatter drain line to prevent oil from backing up into the turbo which can cause oil to get into the compressor and turbine housings.
This cooler is on the other side of the engine. The oil filter cartridge looks easy enough to get to.
3 comments
Great article. I´ve used to them being a lot longer though.
Silicone compressor outlet hoses are sometimes used on high boost diesel engines.
E.g. VW CUAA, a 2litre biturbo diesel with 236hp and 369 lbf⋅ft from 2015.
Makes sense on the higher boost diesels. More boost, higher temps.
There’s just not as many interesting cars that the LA Auto Show as there use to be unfortunately. None of the German makes show up anymore, so no Audi, BMW, Mercedes, or Porsche.
Most car shows in recent years have been snooze fests, especially the ones in Europe, just a whole bunch of soulless, political correctness on wheels on display.
The only car show in recent years that I find even mildly interesting is the 2023 Japan Mobility Show, but it was mostly a bunch of cool looking concept cars instead of cool production cars though.