Scott Costanzo's 1968 MGB with GM LS4 V8
Owner: Scott Costanzo
BritishV8 UserID: Scott68B
City: Dublin, OH
Model: 1968 MGB
Engine: GM 5.3L LS4 (FWD) V8
Conversion by: Owner
| Engine: | All aluminum GM 5.3L FWD LS4 V8 (from a 2006 Chevorlet Impala SS donor car), updated with a block mounted starter (It came from the factory with a transmission mounted starter). The engine is mostly stock except for the addition of an LS6 intake manifold, a stock 87 MM DBC (drive by cable) throttle body and a GEN 4 timing cover. The engine is run by a GM OBD2 "0411" factory fuel injection system. Fuel is supplied to the engine by a 2004 Pontiac GTO in-tank fuel module. |
| Cooling: | An aluminum early Mustang style radiator, 180 degree thermostat, 16" Volvo puller fan, controlled by engine ECM. |
| Exhaust: | Custom 1 5/8" headers into 2 inch pipe which is merged into a single 2.25 inch pipe which flows into a
single cherry bomb muffler and then a resonator at the end of the exhaust pipe. |
| Transmission: | Borg Warner T5 from a 1987 Ford Mustang. Spec Clutch stage 3 1995 S-10 2.2L clutch/pressure plate.
External 1" diameter slave and stock clutch master cylinder. Fastshafts drive shaft. |
| Rear Axle: | GM 7.625 10 bolt (3.23:1 gear and limited slip differential (LSD)) |
| Front Suspension: | stock, upgraded with polyurethane bushings and MGB GT springs. 3/4 inch sway bar. |
| Rear Suspension: | stock, upgraded with polyurethane bushings, tube shocks and custom panhard bar. |
| Wheels/Tires: | 2010 Nissan Sentra alloy wheels, 205/45/16 Dunlop Direzza DZ102 tires. |
| Brakes: | Front: Vented rear rotors from a 2006 Nissan Frontier and front calipers from a 1997 Nissan
Sentra. Rear: Rear rotors from a 1994 Honda Accord, rear calipers from a 2006 Honda Civic. Stock MGB 3/4" brake master cylinder. |
Electrical: | Stock MGB gauges. The tachometer has been rebuilt with a Theo Smit circuit board
to suit the V8 engine. |
| Interior: | 77 to 80 MGB interior. Custom gauge cluster. Fiero NA seats. |
| Other: | "Special Tuning" spoiler (from Moss). Electric Power Steering from a 2008 Toyota Yaris |
| Weight: | 2483 lbs. (measured with a full 16 gallon tank of fuel and full trunk.) |
| Completed: | On the road since May 2015. Driven about 27,000 miles
as of November 2025. |
| Comments: | I originally converted my car to a V6, but hanging around the V8 crowd caused an attitude adjustment!
Seriously, I wanted more power and the V6 platform wasn't going to get me where I wanted to be without
using a blower/turbo, which was not what I wanted to do. I considered all of the common V8 engines used in LBCs and decided on the LS engine for a variety of reasons. The main reasons are; it is very well supported by the aftermarket and it was different (at the time)! I selected the FWD version of the LS engine because it is the shortest, lengthwise, of all the LS variants and I felt that I could more easily accomplish my goals with this engine. My main goals for this build were: 1. Steering rack must remain in the stock location 2. The stock bonnet must not be modified 3. Minimize modifications to the structure of the car One of the issues with selecting this FWD engine was the lack of a starter mount on the block. From the factory, the starter was mounted on the transmission belhousing. I fabricated a steel plate that mounted on the block, selected a common Small Block Chevy mini starter and was able to get the starter mounted to the block. It's been working well for 27K miles. You can read about the process of fabricating and installing the starter here. The LS has been on the road for 10 years as of June 2025. During this past year, 2025, most of the "sorting out" of the changes made to convert to the LS have been completed. Yes, it took me a while. The remaining tasks include adding air conditioning and installing a new cam. The LS has transformed the car for the better over both the original 4 cylinder and the V6 previously installed! I have a basically stock suspension under it so it still retains the stock handling that drew me to the car so many years ago. I now have the power to go with the classic handling! It puts a smile on my face everytime I drive it! I LOVE it!! |
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Engine Conversion History
GM LS4 5.3 V8 as currently installed
GM 3100 SFI (sequential fuel injection) V6 as previously installed
GM 3.1L "Multi Port" V6 as initally installed.
Construction Photos
The following are some constuction photos showing Scott's approach at a high-level.
Completed starter modification. The FWD block had no starter mounting point on the block.
The starter was mounted on the transmission bellhousing when used as FWD.
Mocking up the steering shaft after lowering the front of the
steering column for header clearance.
Motor mounts welded in. Gussets were added subsequent to this photo.
Firewall reconstructed after modifictations for the LS.
Completed driver side motor mount with engine in place.
Steering rack to harmonic balancer clearance. The steering rack is in the stock position.
Steering column/shaft clearance to rear exhaust port.
Mocked up lefthand header tacked together.
Left side header under construction.
Right side header under construction.
Modification/Additions
The following show some of the additions and modifications post engine conversion.
Electric power steering from a 2008 Yaris non-ABS model.
Vented rotors from a 2006 Nissan Frontier and front calipers from a 1997 Nissan Sentra.
Vented front disc brakes rear view.
Panhard bar mount under constuction.
Panhard bar mount test fitting to car.
Panhard bar mounting to unit body under construction.
Panhard bar installed in the car.
Panhard bar intallation details.
General Photos
76 to 80 MGB dash with custom gauge cluster. Miata NA Seats.
2010 Nissan Sentra alloy wheels, 205/45/16 Dunlop Direzza DZ102 tires.
Previously Published Information
The original "How It Was Done" article was originally published in BritishV8 Magazine, Volume XVII Issue 1, July 2009.
It can be viewed here to illustrate how almost all of the specifications have changed.
