Chevelle LS Engine Build Blog

Hmmm, what's in the crate?

It's a brand new GM LSA block!

I chose this block for my Chevelle engine project for several reasons. I'm pointing at one of them here. It's an oil squirter. It squirts oil up under the piston to help cool the piston crown and keep the pin well lubricated. Additional cooling is important on engines with power adders since the combustion temperatures can get way up there! Other reasons are the longer cylinder sleeves that increase piston stability in a stroked engine, the nodular iron main caps, and the stronger type of aluminum used in the LSA blocks.

Those are actually six bolt main caps; in addition to the four bolts you can see here, there are two more bolts in each main cap that bolt in from each side of the block. These main caps are nodular iron, an upgrade over the simple cast iron main caps used on most other LS blocks.

Closer view of the oil squirters. Their position will need to be tweaked a little to clear the pin bosses on the CP pistons. I'll be grinding off the sharp edges on the block that you can see in the middle of this picture later on when I clean up the block...

The displacement is 6.2L with the stock 3.622" stroke. My original plan was to build the engine out to 6.8L (416 ci) with a 4.0" stroke Callies crank. But there were interference issues between the connecting rods, piston skirt and pin boss, and the oil squirters so I ended up using a stock LSA crank. That's still a good piece since it's forged steel unlike the cast iron cranks used in most LS engines.

Looks straight but we'll align hone it after replacing the OEM main cap bolts with ARP studs to make sure it's straight.

You can see texture in the block; the aluminum LSx blocks are sand cast, not die cast.

The block doesn't need much cleanup, just a little grinding to remove some sharp edges.

Those "towers" in the valley are for the Active Fuel Management (AFM) feature used on some engines, like the L99, but not on the LSA.

Look at those 4.065" bores just begging for a set of forged CP pistons! The bores will get checked to make sure they're perfectly square with the crank and receive a final hone that the NPR rings will like.

Doing some final cleanup grinding...

Removing the OEM main cap bolts and replacing them with ARP studs.

The OEM bolts weren't too bad but they look like skinny weaklings compared with the ARP studs! Look how much larger the diameter of the ARP stud is. I know which fasteners I'm using from now on!

The ARP studs install just finger tight.

All torqued down. The outer studs are longer because the windage tray mounts on them. The block is just about ready to visit MadCap Racing Engines for its machine work. We'll align hone the main journals since I replaced the stock bolts with ARP studs.

Back from the machine shop. My friend Tom is helping me with it. The block was well within factory tolerances but now it's perfect! The bores were a little oval (maybe from the extra clamping force of the ARP main studs?) and the deck was around 0.003" tall. Now it's exactly on spec and the bores are round and honed out to 4.070".

Installed the Clevite HK series coated main bearings and now checking the final journal diameters so I can tell what the crankshaft main bearing clearances will be.

Until the rotating assembly is balanced, that's about all I can do on the block for now. So it's time to work on the LSA heads. The OEM LSA valve train can't keep up with the Lingenfelter GT9 cam I'm using so it's time for some significant upgrades.

The as-cast combustion chambers are pretty nice. The OEM LSA valves are okay for the mild OEM LSA cam but they are too heavy for the GT9 cam. The LSA intake valves will make way for LS3 hollow stem intakes. On the exhaust side I'll be using LY6 valves which are made from Inconel, an incredibly heat tolerant type of stainless steel.

The LS3 intake valve is on the right. Notice the better finish on it and that the head is thinner. Those LS3 valves are around 20g lighter than the LSA valves.

Another piece in the valvetrain puzzle -- Yella Terra Ultralight 1.7 ratio full roller rockers. They mount in pairs on a common shaft over two studs which greatly improves their stability over the OEM rockers which mount singly on just one stud.

This is a nice valve spring compressor from Crane Cams. With it you can easily remove valve springs even with the head still on the block.

One LSA head with a little cleanup, LS3 intake valves, and LPE dual springs with titanium retainers. The LPE springs give me about 160 lb on the seat and around 415 lb open at max lift. The LY6 exhaust valves come later...

Some test fitting with the heads sitting on the block, Holley valve covers, the timing cover and water pump temporarily hung on to make it look more like an engine.

Sort of a piston-eye view of the combustion chamber with a head on the block.

Anyone want to buy a set of new, unused LSA beehive springs and intake valves?

The jewel-like CP pistons; I specified coated skirts to help prevent scuffing. The specified 13cc dish, 70cc combustion chambers, and 0.045" thick head gasket will yield a 9.5:1 static compression ratio with a 0.040" quench. The pistons were spec-ed to end up 0.005" above the deck and after test fitting and measuring, they measured *exactly* 0.005" out. You gotta love the precision machining of the pistons, rods, and block!

Carrillo H-beam rods will keep the pistons connected at "elevated" RPM.

Installing the cam.

If a cam is the heart of an engine, then here's the brain of an LS series engine. This is an E67 ECM. HPTuners software will allow me to tweak the tune after getting it baselined on a chassis dyno.

And the nervous system that connects that brain to all of the sensors, injectors, and ignition coils. This wiring kit is from GMPP

Mocking up the coils and ignition wires.

And here is the main attraction! This supercharger will definitely wake up an engine and explains the "low" 9.5:1 compression ratio. My goal is at least 600 HP at the wheels with a mild tune.

The rotating assembly is back from balancing at MadCap Racing Engines. Time to install it!

The crank is in and and the main caps are all torqued down. The end play measured 0.003".

Test fitting the YellaTerra rockers.

Squaring the ring in the bore with the squaring tool so that I can measure the end gap.

Filing one of the rings to get to my desired end gap.

Fitting a pin to the rod and piston

After installing a half dozen of these Kramm-Lox retainers I finally got the hang of it.

Installing the oil rings.

One Carrillo rod, CP piston and ring pack ready to be installed in the block.

The flywheel in installed now. The LSA crank has an 8 bolt flywheel flange; most LS cranks use only 6 bolt flanges. A McLeod RSX twin disc clutch will find a home there later on.

Measuring the rod bearings to determine the rod bearing clearance.

That ARP tapered ring compressor made installing the pistons really easy on both the rings and me!

Carefully inserting the rod through the bore being very careful not to nick the cylinders or the crank journal

Almost home on the crank journal.

One bank with all of its pistons installed.

In this close-up you can see the tight clearance between the oil squirter and the piston. I was able to slightly bend the squirter from its stock location to get it to clear the piston pin boss and skirt.

View of the bottom end with all of the piston and rod assemblies in place. Now it's time to tighten all of the rod bolts.

The rods bolts are tightened to a given stretch, not just a torque value. That ensures a more accurate clamping strength. This rod bolt stretch gauge from Summit will do the trick.

I tightened the bolts a little bit at a time and measured their stretch until I got to the 0.0055" of stretch that I was looking for.

The windage tray and oil pickup tube installed after tightening the rod bolts.

Here's the completed short block

The Morel 5206 tie bar lifters finally arrived; they were back ordered for many months! They're soaking in oil for now. Once I have some free time I can check valve to piston clearance, cam timing, and measure and order the push rods.

Custom length Manton Series 5 pushrods. These are 11/32" diameter and 0.120" wall vs. the stock 5/16" diameter and 0.080" wall. According to Manton, their Series 5 "are the strongest most durable chromoly pushrods ever produced in the world."

Degreeing in the cam while waiting for a set of heavy duty, Inconel exhaust valves...

GM LY6 Inconel exhaust valves. They'll tolerate heat better than the stock LSA valves.

Tightening the head studs to final torque values.

The long block is completely assembled.

And complete wiring harness and serpentine belt.

Test fitting the headers.

Installing the McLeod RXT twin disk clutch. This is rated to hold up to a 1,000 HP.

QuickTime scattershield to couple the engine to the Tremec T56 Magnum 6-speed transmission.

Hydraulic clutch release bearing.

T56 Magnum on its way to mate with the engine.

All ready to go! Now I need to find the right '66 Chevelle to house this powertrain!