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Old 05-30-2020, 07:24 AM   #1
AVANTI R5
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Default What Makes GMís Oversized 2.7-Liter Turbo Four-Cylinder Special?




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One of the most intriguing engines released by GM in recent years is its 2.7-liter four-cylinder known as the L3B. In this video, Jason from Engineering Explained talks about what makes this engine interesting.

The first thing is its displacement; 2.7-liters, making it the largest displacement four-cylinder currently on the market. In a press release announcing the L3B engine, which you can view here, Chevrolet continually referred to it as being a ďtruckĒ engine that was ďdeveloped from the outset as a truck engine.Ē

While calling the L3B a truck engine is all very well and good, the only issue is that it is also fitted beneath the hood of the Cadillac CT4-V, a sports sedan thatís about as far removed from a pickup truck as you can imagine. In CT4-V form, the engine pumps out 325 hp and 380 lb-ft (515 Nm) of torque and in the Chevrolet Silverado, the only truck that it is currently offered with, is rated at 310 hp and 350 lb-ft (475 Nm).

One of the most intriguing things about the L3B engine is that it features a dual volute turbocharger, meaning it has two volutes and operates in a similar fashion to a twin-scroll turbocharger. Jason says an advantage of a dual volute turbocharger is that it enables engineers to separate the exhaust pulses so they donít interfere with each other. This results in better response, improved low-end torque, and greater efficiency.
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Old 05-30-2020, 01:28 PM   #2
oichan
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Nice torque numbers for sure.
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Old 05-30-2020, 04:24 PM   #3
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So the difference between this turbo and a standard twin scroll is that the volutes are beside each other in a twin scroll, but with this one, there is an inner and an outer volute. I'm surprised this hasn't already been tried.
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Old 06-01-2020, 06:58 AM   #4
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Worse mileage than the v8. Because less is less...
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Old 06-01-2020, 09:28 AM   #5
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Worse mileage than the v8. Because less is less...
I havenít checked but is that true? That doesnít make a lot of sense especially when you consider this engine should make for a lighter truck.
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Old 06-01-2020, 09:37 AM   #6
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I havenít checked but is that true? That doesnít make a lot of sense especially when you consider this engine should make for a lighter truck.
The I4T is rated better around town but worse on the highway, the average for the I4T is slightly better than the V8, I'm talking 1 or 2 MPG IIRC.
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Old 06-01-2020, 10:50 AM   #7
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The I4T is rated better around town but worse on the highway, the average for the I4T is slightly better than the V8, I'm talking 1 or 2 MPG IIRC.
That's pretty mediocre efficiency IMO making this engine not so special after all. I suppose every MPG counts for manufacturers even if the reality is lipstick on a pig.
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Old 06-01-2020, 05:42 PM   #8
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I havenít checked but is that true? That doesnít make a lot of sense especially when you consider this engine should make for a lighter truck.
Maybe its running on 4 cylinders on the highway portion of the test?
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Old 06-01-2020, 06:16 PM   #9
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Maybe its running on 4 cylinders on the highway portion of the test?
I am guessing the 4 cylinder idea was just botched by bureaucracy that is GM. I am not sure that small of an engine could push a half ton around at 70MPH on two cylinders.

Should have kept the 4.3 and added the new transmission. But in general i am not in favor of smaller turbo gas engines on trucks.

If you really dont use the truck as a truck then a smaller gas turbo can be ok, but for fleet or heavier fleet use the turbo side can cause sooooo many issues.
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Old 06-01-2020, 08:14 PM   #10
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I am guessing the 4 cylinder idea was just botched by bureaucracy that is GM. I am not sure that small of an engine could push a half ton around at 70MPH on two cylinders.
If you really dont use the truck as a truck then a smaller gas turbo can be ok, but for fleet or heavier fleet use the turbo side can cause sooooo many issues.
Things are just become way to over-complicated v8s running as v4s, then v4s running as v2's
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Old 06-01-2020, 09:25 PM   #11
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Things are just become way to over-complicated v8s running as v4s, then v4s running as v2's
Or we could just have a couple drive motors and a battery pack
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Old 06-01-2020, 09:51 PM   #12
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Originally Posted by wrxsubaru View Post
.

If you really dont use the truck as a truck then a smaller gas turbo can be ok, but for fleet or heavier fleet use the turbo side can cause sooooo many issues.

I don't know man, I have 3 Ecoboost trucks/vans that haul/tow daily and the only mechanical issue I've had has been the driveshaft on the transit van. We have two 3.5's and one 2.7, the youngest has almost 200k and the oldest has about 400k. They are all less than 6 years old.
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