A dyno sheet that came with our car indicated that the engine produced 120.3 horsepower at 6700 rpm, along with 98.1 ft.-lbs. of torque at 5800 rpm. Reality reared its ugly head regarding an ideal apples-to-apples comparison, though: The dyno figures for the original configuration were taken on an engine dyno, while we tested and set up the new one on a Dynojet chassis dyno, meaning that the new horsepower numbers include some driveline loss. How much loss? Most experts say 15 to 20 percent.

Our new engine’s best run showed a max of 119.7 horsepower and 98.1 ft.-lbs. of torque. If we factor in a 15-percent driveline loss, that equates to about 137 horsepower at the flywheel. In other words, we more than achieved our goal of increasing output by 10 to 12 percent.



Then there was the real test: how the car performs on track. At a subsequent outing at VARA’s Big Bore Bash at Willow Springs International Raceway, our Sprite passed cars it couldn’t before. We’re going to call this build a success.

LOOKING GOOD UNDER THE HOOD

We wanted to improve more than just our engine’s performance with our rebuild. We wanted it to look better, too. First we repainted the block and head, trading the original Austin-Healey dark green for POR-15 Engine Enamel in MG Maroon. The dark red is a better match for our engine’s host vehicle. Next we plated the oil pan, mounts and pulleys in gold iridite. And for a finishing touch, we used ARP polished stainless-steel fasteners wherever possible.

SOURCES

Advanced Performance Technology
(951) 686-0260
aptfast.com
Camshaft, lifters

Automotive Racing Products
(800) 826-3045
arp-bolts.com
Engine fasteners

BHJ Dynamics
(510) 797-6780
harmonicdampers.com
Harmonic damper

De Groff’s Mark Cylinder Head Service
(81 701-5274
Cylinder head work

JE Pistons
(714) 898-9764
jepistons.com
Pistons and rings

Manley Performance
(732) 905-3366
manleyperformance.com
Valves, springs, retainers

Moroso Performance Products
(203) 453-6571
moroso.com
Oil accumulator

Moss Motors
(800) 667-7872
mossmotors.com
Rear oil seal kit

Penta Motorsports
(747) 888-9800
pentamotorsports.com
Engine assembly, dyno test

Pierce Manifolds
(40 842-6667
piercemanifolds.com
Weber carburator, intake

POR-15
(800) 726-0459
por15.com
Engine paint