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Project C7 Corvette Stingray: Introduction Part 2, A Closer Look at the LT1 Engine

by Mike Kojima

 

In the last edition of Project C7 Corvette Stingray, we were doing an overall look at the car including it's mostly all new LT1 engine. As we were saying, although the LT and LS share the same architecture, they are indeed very different engines. They are so different that they only share a handful of parts. 

The LT1 is a vastly different engine that has a lot of development differences over the already excellent LS3 engine and deserves a closer look at some of its unique internals. Most of the differences are to improve fuel economy, emissions, torque and powerband width, but there are are some tweaks to make more power overall as well.

Of course, you are probably interested in more than what the typical press release info about the LT1, so let's take a look inside of it!

 

First, let's talk about the part of the older LS engines that drove us nuts- the oiling system! If you have had much experience trying to race or drift an older LS, you know that oil starvation can be a bitch on these engines under extreme cornering loads. Aftermarket baffled pans, windage trays, and Accusumps were needed if your LS was to see hard use on the track.

The engineers at Chevrolet have been hard at work to improve this system much to our joy, and the LT1 has a bunch of things to address this issue. The first change is a greatly improved oil pan with extensive baffling and a sump designed to keep oil around the pump pickup. 

 

The next thing that the LT1 has added is this windage tray, which is designed to strip oil off of the rotating crank and return it to the sump quickly. This reduces drag losses and oil temperature as the crank has less of a churning cloud of oil to cut through as it spins around. 
 
The standard LT1 uses a pretty sophisticated variable volume oil pump. It pumps a lower volume at light throttle loads to reduce the engine's frictional pumping losses, but it ramps up volume and pressure at high rpm and high loads.
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Comments
Dan DeRosia
Dan DeRosialink
Monday, August 07, 2017 5:58 AM
I can't help but find it interesting that after this many years they're still finding fairly fundamental changes to make to this platform. "Oh, the ports work better if we reverse the intake/exhaust order" is kind of a big thing; ignoring the obvious addition of direct injection. Splayed valves on a production engine again too?
stuntman
stuntmanlink
Monday, August 07, 2017 11:04 AM
"Even with "old fashioned" 2 valves per cylinder and pushrods, you would be hard pressed to find a naturally aspirated engine with much better power density and efficiency than the LT1. "

-unless you look at Ford V8s ;)
I wonder how long the LT and pushrods will last until GM gives up and goes to DOHC motors.
Mike Kojima
Mike Kojimalink
Monday, August 07, 2017 11:35 AM
Fords are much bigger and heavier, 80 lbs to be exact and about 5-6" wider and 3-4" taller. The Fords have better power to displacement but the Chevy has better power density which means for the size and weight.
Mike Kojima
Mike Kojimalink
Monday, August 07, 2017 11:50 AM
There are rumors that GM is working on a 6.2 liter DOHC V8 which will be called an LT5 for the proposed mid engine Corvette.
ThisGuy
ThisGuylink
Monday, August 07, 2017 12:47 PM
They love their pushrods and mono leafs as much as they love their engine codes. The base C4 had LT1 and an LT5 in the ZR-1. Those LT5s were, you guessed it, dual over head cam 32valve. Whats next, paint the C7 LT1 intake red and call it an LT4?
warmmilk
warmmilklink
Monday, August 07, 2017 2:04 PM
is it just me or are the valve heads welded to the valve stem?

also, did you guys check the part numbers on the T1 dampers? I'm pretty sure they're the same as the standard Z51 shocks. At least they were on my buddy's Z51.
stuntman
stuntmanlink
Monday, August 07, 2017 5:01 PM
@Mike Kojima -

I guess if you define "density" as engine dimensional volume rather than engine displacement. But:

Ford 5.0-liter DOHC V8:
Length: 26.08 inches
Height: 28.89 inches
Width: 29.05 inches
Weight: 430 pounds (with accessories)

GM 6.2-liter LS3 V8:
Length: 28.75 inches
Height: 28.25 inches
Width: 24.75 inches
Weight: 418 pounds (with accessories)

= Coyote is 2.67" shorter, 0.64" taller, and 4.3" wider than an LS3, while only being 12LBS HEAVIER (not 80lbs). I assume an LT is dimensionally similar to the LS (and probably heavier with all the DI).

http://www.chevyhardcore.com/tech-stories/engine/ls3-vs-coyote-budget-shootout-results-the-winner-is/

This link says the LS is 27.0" tall:

https://ls1tech.com/forums/conversions-hybrids/1416332-ls1-vs-smallblock-dimensions.html#&gid=1&pid=1
Mike Kojima
Mike Kojimalink
Monday, August 07, 2017 5:38 PM
We weighed the difference at 80 lbs fully dressed when we were trying to figure different engines that we could use for FD. It was one of the main reasons why we didn't run Ford engines.
Mike Kojima
Mike Kojimalink
Monday, August 07, 2017 5:40 PM
The LT1 engine code goes back to 1970 as a Gen I small block.
warmmilk
warmmilklink
Monday, August 07, 2017 5:45 PM
my brain is having a hard time registering the Coyote is only 4" wider. its always looked huge under the hood of my Mustang and the LS has always looked a decent bit smaller. But then again I've never seen the 2 side by side in person
Mike Kojima
Mike Kojimalink
Monday, August 07, 2017 5:50 PM
We weighed our old LS2/LS3/LS7 hybrid race motor at 395 lbs. The Ford motor was 475 or so with all the stuff on it on our scale. Our current RHS engine weighs 440 lbs with dry sump. It is heavier due to a tall deck block with more beef around the deck and mains and heads with a thicker deck. The taller figure was from the large plenum manifold that was on the Ford engine.
stuntman
stuntmanlink
Monday, August 07, 2017 6:44 PM
Gotcha. Apples: bananas

Vorshlag weighed a fully dressed 5.7L LS1 (with no headers) & T56 at 609lbs. The T56 at 126lbs, putting the dressed LS1 at 483lbs.

http://www.vorshlag.com/forums/showthread.php?t=8142

Dry sumps lower motors A LOT. But yes it's hard to package the wide DOHC coyote within an FDs frame rails.

Mike Kojima
Mike Kojimalink
Monday, August 07, 2017 9:52 PM
Our T1 shocks are adjustable
engineered
engineeredlink
Thursday, August 10, 2017 10:09 PM
Enjoying this build so far.
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