SS Road Racer

Phase 1 - Short Block Components

We were contacted last fall by a very special customer to build an LT1 based engine for her 96 Impala SS that would produce close to 1000HP.  A lofty goal I would say, but one that I think is achievable.  For those of you unfamiliar with her car you can check it out at www.hirevchevy.com.  This will be a serious ground pounder that handles the road with ease thanks to Hotchkiss' suspension upgrades.

When we were initially approached we had no idea the support she had already received from throughout the industry on this project.  Sponsors such as Air Flow Research, Lunati, Nitrous Express, Holley, Moroso, Weld Racing Wheels, TTC transmissions, Currie Enterprises, and the list goes on.  After reviewing her project and goals we decided to jump on board and provide the machine block, machine work and head porting.

We started out with a stock 1996 LT1 block and installed splayed main caps and ARP studs to handle the power and rpm.  ProGram supplied the caps which included custom 4 bolt front and rear caps in addition to the splayed center 3 caps.  Using our vertical mill makes the job relatively easy and very accurate.  We detailed the oil system as we do on all of our crate engines by rounding all of the sharp edges where the oil path turns.  Just like porting a cylinder head, we try to make all of the turns the oil has to make as rounded as possible and reduce sharp 90 degree turns.  This plays a significant role in maintaining consistent oil pressure throughout the system, not just at the at the sending unit location.

Once the block was prepped, Lunati provided a set of custom forged pistons that would attach to their Pro Mod rods and 4340 forged crankshaft.  We requested that the pistons had lateral gas ports machined into the top ring land to aid in sealing the piston rings.  We then coated the tops of the pistons with a Tech Line themal barrier specifically designed for high horsepower nitrous or forced induction applications.  This should reduce the chance of detonation and make additional horsepower by keeping the heat in the chamber and not transferring as much through the piston head.  We also used Clevite H series rod and main bearings and ACL cam bearings all coated by Calico Coatings.  At this point we were ready to bore and torque plate hone the block to 4.030" and mock up the assembly to see exactly how much to deck the block.  It tuned out that the Lunati assembly had a zero deck height at 9.000" so we took .025" off the deck to achieve this.  We are using a Felpro Performance head gasket  and our quench will be very good at the .041" thickness of the gasket.

Phase 2 - Short Block Assembly

We spent significant time chasing all the threads and cleaning the block, then installed the Calico coated ACL cam bearings and all of the freeze and oil galley plugs.  Assuming a big nitrous hit, the Mahle piston rings we used were file fitted to .030" for both top and second rings and then we deburred them and lapped them perfectly flat.  Lapping the rings is a process that is not commonly used but reduces friction on the rings by microscopically polishing them.  We use a piece of wet/dry 1000 grit sandpaper on top of a piece on glass with water on it and slowly swirl the ring around on it.  We actually hold the ring with a piece of phenolic that we cut a groove into but you can do it by hand if you are careful.  Professional race teams have used this technique for years and have found greater ring seal and faster ring sealing action.

After the rings were finished, we fit the pistons and rods to the wrist pins on our rod hone.  We set the piston to pin clearance at .0008" and the rod to pin clearance at .001".  During this 'blueprinting' process we also checked out the main and rod bore sizes which were both spot on in the middle of the specs.  We installed the coated main bearings and torqued the mains to find .0024-.0025" clearance which was perfect.  We used a stretch gauge on the rod bolts to get our measurements correct and found .0026-.0030" clearance which was a little higher than we wanted.  Time to make a call to Calico again and get a set of CB663H1 bearings.  The '1' bearings as they are known are .001" undersize and will take up some of that clearance.  We mixed and matched bearings to get the .0022-.0025 we were shooting for.  Now that all metal removal is finalized we set out to balance the crankshaft.  We chose to internally balance the crank as this reduces crank flexing and is easier on the bearings.  We will be using an ATI harmonic damper and an aluminum flywheel that are both neutral balanced with this combination. 

Crank balanced - check.  Rod and main bearing clearance set - check.  Rings filed and lapped - check.  Let's put together the short block.  Using our custom mixture of 2 parts Clevite 77 assembly lube, 1 part GM EOS assembly lube, 1 part 10w30 motor oil we slather up the bearings and lay the crank.  Endplay checks at .005" - great.  Rings on the pistons and coat the cylinder walls with ATF and we install the rods and pistons.  Smooth.  In goes the custom solid roller cam with 254/268 @ .050 on a 115 LSA.  Oh yeah, it only has .672/.688 lift.  The trick billet double roller timing chain is fantastic and the 9 way crank gear helped us dial the cam in at 113 ICL.

Phase 3 - Cylinder Heads

Air Flow Research provided a beautiful set of their LT1 203cc castings for this project that had great flow numbers out of the box.  Of course, being hot rodders, we had to go in and do some more porting on the intake side to boost the power potential.  You can see the comparison of the out of the box CNC ported heads vs. our additional porting.

Those heads are being paired with a set of Ferrea titanium intake and Competition Plus stainless steel exhaust valves, Ferrea springs, locks and titanium retainers.  The rest of the valvetrain includes Comp Cams Endure-X solid roller lifters, Comp High Tech pushrods and a Comp solid roller cam. 

We will be using Lunati 1.6 ratio roller rockers on the engine and the super-duper ultra cool ported Holley Stealth Ram intake manifold and throttle body.  Nitrous Express plumbed a row of nitrous and fuel squirters inside the manifold making a clean installation.  We will see if we can add a second stage without disrupting the flow of the fuel injectors.  Below is a picture of the Stealth Ram on a mock up engine.

To make the intake work with the LT4 style heads, we had to do a little work with the bolt pattern. We installed a set of aluminum bolts in the original bolt holes and welded them in place then milled the face flat again.  Using a Felpro 1206 gasket as a template, we then located, drilled and tapped holes to fit the 'old' style intake pattern.  Instead of just using the tapped holes to hold it in place we preferred to use Time-Sert thread inserts.  They are a steel insert with much greater resistance to coming out or pulling the threads than just using the tapped aluminum or a traditional helicoil insert.  In these pictures you can see the bolt hole discrepancy before and after the Time-Serts have been installed.

Phase 4 - Installation

After final assembly, we ran the engine in with and LT1 carburated intake and carburator to check for leaks and good oil pressure then switched over to the Holley Stealth Ram with the Holley 58mm throttle body. 

We also took the time to install a Nitrous Express fogger system in the lower intake manifold.  We were really guessing as to whether or not the Stealth Ram intake would fit under the stock Impala cowl, but miraculously it did!  Though a tight fit, it does fit, as does the oil pan with a significant kickout.  The exhaust system was already made on the car so we know that it will clear the car and it looks like it will clear the pan as well.

Check out the custom cross member for the TTC competition built T56 6 speed.  Below, you can see the custom Currie 9 inch rear end with Stainless Steel Brake Components custom disc brakes and the inside of the Weld forged Evo wheels.  You can also check out the Hotchkiss suspension that is set up all around the car.

The next step in this project is to install the custom fuel cell, dual Aeromotive A1000 pumps and the rest of the fuel system.  This will coincide with installation of the Accel DFI 7 fuel management system.  We are looking forward to dissecting the wiring harness to figure out which wires we will use from the oem harness and which ones to replace.

After all of the mockup was completed we have finally installed the engine for good.  Nitrous Express intalled a small single fogger system inside the plenum of the Stealth Ram and plumbed the nozzles we had installed for the big secondary nitrous system.

You can just see the two spray bars inside the plenum.

The big fogger kit installed and plumbed.

In the middle of the wiring harness installation and conversion.

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This site was last updated 12/26/07