When you walk through the pits of any autocross event these days you’ll find the engine of choice is the Chevrolet Gen IV platform. Hardly a surprise when you consider the ease of power, compact package, and availability of the engines and performance parts.
When it comes to autocrossing, overall power might not be the first major consideration when it comes to building a car. Handling, braking, and driver skill can make up for lesser horsepower and torque—to an extent. And that is exactly where Dick Eytchison found himself at the end of last season.
Dick has been running his well-prepared 1965 Chevelle, named Edith, at autocross events around the country for several years. The “more-door” A-body has been refined over time, and as budget allowed, with bigger brakes, 17-inch wheels, and a complete Hotchkis Total Vehicle Suspension system. The Chevelle’s handling was pretty well dialed-in but Dick was finding it harder to get a podium finish even though he was making clean, cone-smashing-free laps. It was time to look at the drivetrain.
Dick has been running his more-door ’65 Chevelle with a ZZ383 small-block backed by a reworked Muncie trans. A Holley carb was used to regulate fuel, and Dick kept things simple with a standard HEI ignition. Everything worked well, but overall, the power was lacking.
As luck would have it, Russ O’Blenes, senior manager of the Chevrolet Performance Racing Team, also happens to have a ’65 Chevelle. In fact, it’s a low-mile, four-door dubbed Esther, and even the same color as Dick’s. Russ had seen it on YouTube and in magazine coverage before and was a fan. One day, Russ was talking to John Hotchkis of Hotchkis Sport Suspension about the car and John put Russ and Dick together.
Once the two ’65 Chevelle owners got on the phone together to discuss their cars, the seed was planted. Russ mentioned to Dick about a new crate engine they were coming out with based on the LT1 6.2L platform used in the Corvette Stingray and Camaro SS: the LT376/535. Dick was intrigued by the power and the package, but also a little intimidated about moving from a carb-fed small-block to a direct-port injection modern engine.
he LT376/535 engine is architecturally similar to the Gen IV/V family of small-block engines, but with a unique block casting, cylinder head design, oiling system, and more. It retains the advanced technologies of the LT1, including Direct Injection, to support an advanced combustion system to create a more-than-capable engine for your project. By adding CNC-ported heads and their high-lift LT1 Hot Cam, the LT376/535 delivers more naturally aspirated horsepower than its predecessors.
After years of keeping things simple with a mechanical fuel pump, carb, and vintage four-speed complete with state-of-art (for the ’60s) Z-bar linkage, Dick made the decision to move to modern performance with the LT376/535 crate engine.
To complete the update, Dick selected a T56 Super Magnum transmission package from Chevrolet Performance that includes a spec Quick Time bellhousing and heavy-duty clutch system. Since the complete drivetrain assembly is geared toward performance racing applications, the supplied ECU and harnesses are calibrated as a stand-alone system and require a minimum of power and ground connections.
The learning curve for the upgrade was nowhere near as steep as Dick feared it would be thanks to Chevrolet Performance making things as easy as possible. The ECU that is supplied with the engine is programmed as a stand-alone unit so the only inputs and info come from the engine and transmission. The harness is also as stripped down as much as possible, clearly labeled, and designed to be a direct plug-in assembly.
As far as fitment, the modifications were minimal with the heavy work taking place in the trans tunnel to make room for the larger T56 Super Magnum. The accessory drive, primarily the power steering system, required some fabrication, but we’re sure there’s going to be more LT1-based brackets and drive assemblies available soon.
We were able to follow the complete transformation from small-block Chevy to LT1 as Dick and the team at Hotchkis performed the swap. For a project of this scope, the engine install was fairly straightforward, and many of the hurdles were similar to any trans or engine swap. Things like shortening the driveshaft, moving the trans mount, modifying the tunnel, exhaust mods, and working out the radiator connections all were expected—and handled.
As for the newfound performance and power, not to mention a couple more gears, Dick has had to learn how to drive his Chevelle all over again. With a few events under his belt now, he’s feeling confident and has gained a lot of ground on the competition. Now with the added power, he’s reviewing his brake system, gearing, and tire fitment. It’s always something.
Special Thanks: Dick and Karyn would like to thank John Hotchkis and the team at Hotchkis Sport Suspension for their invaluable help and support with the drivetrain swap. Also, huge thanks to Russ O’Blenes for his recommendations, direction, technical knowledge, and, of course, for his taste in Chevelles (specifically 1965, four-door, teal models). CHP
Top Five Challenges and Areas to Plan Ahead
If you’re making the move from a standard small- or big-block Chevy to an LT1 there are a number of items you’re going to have to prepare for when you make the move. None of these areas are cause for alarm thanks to an innovative aftermarket and the availability of OEM components, but you’ll need to factor in some advanced planning and modifications to keep your engine swap rolling.
Power Steering and Pulleys: All of the new vehicles fitting the LT1 platform use electric power steering, which means there are no brackets for a hydraulic pump. Aftermarket companies are working on, with some already offering, solutions at this point but it’s something important to consider. It’s the same with the rest of the accessory drive components and their fit in your application.
Hydraulic Clutch: With no Z-bar ball-stud provision for a mechanical clutch linkage, you’ll need to upgrade to a hydraulic clutch. Thanks to several transmission specialists out there, making the swap to a hydraulic clutch system isn’t a major deal and chances are that you’ll be pleased with its operation and pedal feel.
Fuel System: With the direct port injection of the LT1 platform requiring extreme fuel pressure of up to 2,175 psi, we were concerned with this part of the swap. However, an in-tank electric fuel pump capable of about 80 psi will do the trick to feed the secondary mechanical pump located at the rear of the lifter gallery. Whew!
Wiring: As with any late-model engine upgrade, the wiring can be a daunting task. However, when you get an engine package from Chevrolet Performance, the harness, ECU, and wiring are ready. We’re talking direct connections, factory locking and sealed connectors, and an ECU programmed for the engine. Be prepared to embrace a throttle-by-wire system, as well.
Trans Swap: The level of challenge here depends on what kind of trans you decide to run. If you’re planning to step up to an electronic overdrive, such as a 4L85E, you’ll need to make a little more room in the tunnel. This is also the case in going with a T-56 six-speed, which is a pretty hefty and large trans, but well worth the effort.
The LT376/535 (PN 19355378) is based on the 6.2L LT1 platform, but with a specific block and head design. The total displacement comes from a 4.062x3.622-inch bore and stroke. The forged steel crank is held in place with six-bolt, cross-bolted main caps with forged powdered metal rods and hypereutectic aluminum pistons.
As far as the valvetrain, the billet-steel cam specs out with a lift of 0.577-inch on both the intake and exhaust side with a duration of 228-degrees intake/248-degrees exhaust (@ 0.050 in.). The cast-aluminum heads receive extensive CNC porting and are fit with 2.13-inch intake and 1.59-inch exhaust valves. With the 58cc chambers, compression comes out to be 11.5:1. The combination is rated at 535 hp at 6,300 rpm and 470 lb-ft of torque at 4,600 rpm.
At the same time as the engine swap, Dick decided to update the transmission with a close-ratio T56 Super Magnum from Chevrolet Performance. The package comes with a race spec bellhousing and clutch assembly.
Since an LT1, not to mention any Gen III/IV/V engine, doesn’t have a provision for a mechanical clutch, Dick had to step up to a hydraulic clutch. He chose a purpose-built assembly from American Powertrain, which bolted right in place. A small bracket was made to accommodate the fluid reservoir to the firewall near the steering column.
A set of adjustable adapters from Dirty Dingo allowed Dick to position the engine as far back as possible. The adapters work with the original SBC mounts and have four positions to locate the engine. The third farthest back worked best for positioning the LT1 in the Chevelle.
CNC-ported heads are part of the reason for the added horsepower when combined with the high-lift LT1 Hot Cam (0.577-inch intake/exhaust lift, 228-degree intake and 248-degree exhaust duration).
Dick was running an old-school mechanical fuel pump so the fuel system required an overhaul. He upgraded to a new RestoMod tank from Rick’s Tanks with a factory GM Pump Module. The OEM fuel pump is pulse width modulated by the factory ECU so no return line is necessary. The pump is regulated to about 80 psi to feed the high-pressure mechanical pump on the engine.
Muscle Rods had just finished developing several Chevelle/LT1 swap components, including these headers. Not only do they look great but they fit perfectly and tuck up nicely for ground clearance.
The Connect & Cruise system is supplied with the close-ratio T56 Super Magnum transmission. The trans is much beefier and heavier than the original M22 Dick was running. This resulted in substantial tunnel reworking, as you can see.
While the trans was fit, the supplied throttle by wire pedal assembly was installed on the floor. The pedal assembly was included in the Connect & Cruise package and was easily bolted in place.
The new tunnel, complete with two cup holders, was crafted by Fast Eddie’s (Orange, California) to cover the larger T56 Super Magnum six-speed trans.
The ECU was designed to be mounted in the engine compartment, and the harness has enough length to put it just about anywhere. Dick chose the front of the passenger wheelwell near the main power distribution block.
Just like a new car, the OBD-II connector was mounted below the dash for easy access to tune or check out the inner workings of the programming.
The driveshaft was shortened by Denny’s Driveshafts, plus the yoke needed to be changed to connect to the 31-spline output shaft of the T56 Super Magnum.
All factory LT1 car applications use electric-assist power steering so it was a pleasant surprise to find threaded bolt holes on the heads for a power steering pump. (A testament to Chevrolet Performance understanding where these engines will be used.) Aaron Agawa, one of the lead fabricators at Hotchkis, crafted a handy little power steering pump bracket. Note the dual-belt balancer.
Dick was able to retain the Mattson’s radiator he ran previously. He used a pair of silicone adapters to downsize the inlet and outlet to fit the smaller LT1 necks. A little custom tubing work, helped by a friendly hand at the Muffler Man (Placentia, California), was needed to complete the path for the coolant.
After getting the car running and driving, Dick took the Chevelle to Westech Performance in Mira Loma, California, to run it on the chassis dyno to check for updates, go over the calibration, and touch up a few areas for driveability and off-corner acceleration. Wide open is easy, it’s everything in between that really counts. Special thanks to Eric Rhee for reviewing and tweaking a few things
“The performance difference is substantial,” Dick told us. “The power is phenomenal and after about three events, I’m feeling much better behind the wheel. The car comes out of the corners much harder, and the torque always seems to be there.”
Dick and Karyn Eytchison
Photos by Todd Ryden and Drew Oliver