Ad Radar
Car Craft
Click here to find out more!

Inside the 2015 Supercharged, Direct-Injected LT4

Horsepower Escalation

By , Photography by General Motors

While 1970 was a great year for thumpin' engines and 11:1 compression – nobody was building supercharged engines for the street. In 2013, Chevrolet introduced the supercharged Corvette ZR1 making 638 hp. But that was no flash-in-the-pan event. This was followed by the 11:1 (yes, the compression is back!) LT1 - a direct-injected small-block. It seems fitting that Chevrolet's next step in performance would be to stuff a supercharger on top of that direct injected engine – and that's exactly what they did.

The LT4 (should we call it LT4-B?) is firmly rooted in the LT1 architecture and is basically a boosted version of the LT1 with only slightly reduce static compression (from 11:1 to 10:1) and a slightly smaller Eaton supercharger bolted on top. The engine will be released with the 2015 Corvette sometime later this year as the ZO6 and will also incorporate variable valve timing (VVT) as well as Active Fuel Management (AFM) which is the cylinder deactivation function. Because this information was released early, there are no set-in-stone numbers, but Chevy engineers promise no less than 625 hp (LS9 was 638 hp) and the LT4's torque will be at least 635 lb-ft, which looks to obliterate the LS9's 604 lb-ft achievement - and with less boost (9.5 vs 9.7 psi). The engineers also say that because this blower is shorter and smaller in displacement, it will spin up quicker and will benefit from a revised intercooler located below the blower that is also more efficient.

Interesting technical tidbits that have been released for the production LT4 include titanium intake valves, forged pistons, stainless steel exhaust manifolds, a revised dry sump system, machined connecting rods, and an aluminum balancer. Most of these revisions point to either increased durability or reducing reciprocating weight. All that means is the engine will rev accelerate that much quicker because by reducing the mass the engine has to accelerate, much more power can make it to the flywheel. And speaking of the drivetrain, Chevy will match this LT4 with brand new 7seven-speed manual and eight8-speed automatic transmissions.

Power density is a term used by engineers to encapsulate the effort of increasing power from a smaller package. The LT4's integrated supercharger is only 25mm (1 inch) taller in the rear than its normally-aspirated LT1 cousin. For perspective, it weighs 20 pounds less and it 85 mm (3.34 inches) shorter than the LS9 with nearly the same power – that's the definition of power density. The advantages are impressive for a production engine, but the future of this engine as swap potential will depend mainly on how easy it is to integrate this direct injection engine in an early chassis. Swaps that will use the engine in its stock configuration should not be difficult, but time will tell how this all plays out. We anticipate it won't take long for car crafters to figure out how to extract even more power from this combination. If anybody asks, this certainly must be the golden age of horsepower.

Corvette Power Curve 1953 to Present

YearEngineHP
1953 235ci Blue Flame 6 150
1957Fuel Injected 283ci283
1962Fuel Injected 327ci360
19673x2 Carbureted 427ci435
1970LT1 350ci370
1975Carbureted 350ci205
1985TPI 350230
1996 LT1 350300
1996 LT4 350330
2013 LS9 6.2L Supercharged638
2014LT1 6.2L 460

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
73 comments
Yuyew  Ryu
Yuyew Ryu

……my poor car .... also got 86HP. topspeed up toooooooooooooooo 160in 5min... .╭(╯ε╰)╮

Tommy Roberts
Tommy Roberts

How did a Ford Motor (gt500) get brought into this? Last checked the ls9 crushed those numbers and hell it's ls7 spanks it in real world performance

Bashar D. Saleh
Bashar D. Saleh

Cid size is irrelevant when labeling Big or Small blocks.

Michael Pizzulo
Michael Pizzulo

Now performance cars are making between 520 and 1000hp all day long.

Jon Houp
Jon Houp

depends on block... ls7, still a small block...

Vin O'Mara
Vin O'Mara

Awesome!!! Will it fit in an 88 Fiero?

Quenton Paul
Quenton Paul

Very nice engine not sure about the plastic coverings

John Booker
John Booker

What is so impressive about this particular platform of a SBC (LS) it has the DNA of a 1955 V8, (thank you Zora Duntov); the bore and stroke really hasn't change much along with the OHV configuration. The impressive part is the power with reliability and superb gas mileage. Yes, the internals have changed; oiling system, bottom end strength, etc etc., however, the neat thing is you can buy these engines at selected dealerships throughout the US of A. (with a warranty) Like Tom Igoe mentioned, let the engine swaps commence. Cam Beaton commented he hates when they call an LS a SBC, well, I can understand; but I am mystified why they resurrected the name "LT". Go figure...

Cam Beaton
Cam Beaton

I hate when they call an LS a Small Block Chevy! SMH.

Tom Igoe
Tom Igoe

let the red 69 camaro-next-generation-engine-swap cover stories begin!

Eduardo Llamas
Eduardo Llamas

pinches chevroleteros de por si se sienten soñados con sus LS

Robert Bob Hughes
Robert Bob Hughes

Woo inject's the air and fuel from opposite sides of the cylinder head and created an added 40 ft lbs of torque and 30 hp!!!

Johnny Watson
Johnny Watson

Yea you can just go ahead and drop that bad boy off at my house

Rod Launer
Rod Launer

written by Jeff Smith, dated April 1 ,2014. Glad to see he's still at Car Craft.

Hal Harvey
Hal Harvey

Nothing's out of the question Paul, but for FIG JAM I've now found what I'd like - still to find out if it can be done fast enough. The Trimatic's going to have to get ditched for a 2spd PowerGlide... At any rate I can't wait a year or two, it has to happen fast.

Chase Williams
Chase Williams

Before anybody says they physically change need to look at the exhaust manifold on an lt1 and then looking at LT 4 it's just an LS with an LT name

Chris Story
Chris Story

This "pushrod motor" will lay waste to many "high tech" sports cars when the Z06 comes out!

Dave Skinner
Dave Skinner

Thats true but, if the never change anything again the repairs will still keep going up..lol

Brown Hornet
Brown Hornet

not the same workers and bosses..the company is huge..Corvette has its own people just like the people that did the Z/28..

Ronnie Cordell
Ronnie Cordell

How bout the ZR1 LT5, no push rods,no distributor, 4 cams,32 valves, 16 injectors,,

Jim Jacobson
Jim Jacobson

Oh damn !!!! Ill give you my shipping address...overnight it !!

Benjamin Luke
Benjamin Luke

hommage a celui qui doit faire la courrois d'accessoire la dessus :)

Car Craft