Lovely though the standard 2 litre six cylinder engine is, a number of GT6s (and Spitfires) have had other engines installed. This is helped by the fact that the engine bay is quite large, for such a small car (assuming the replacement engine is going into the front). Details of a few I have found are below:
Triumph 2.5 Litre Six
This by far the most popular conversion, as the engine block is identical, the only principle difference is the sump which is slightly deeper to accomodate the longer throw crankshaft. Also the front end is slightly different to accomodate the duplex timing chain. I don’t think my conversion, back in 1980-81, was the first but I think it must rank as an early conversion of this type. I used the original 2.5 sump and raised the engine slightly. Sources are from Triumphs TR5, TR6, 2.5PI or 2500, mine was a 1972 2.5PI. With the normal CD150 carburettors I expect the power to be in the region of 106bhp at 4700rpm compared to 104bhp at 5300rpm on the original 2 litre engine. However the torque should be in the region of 139 lb.ft at 3000rpm compared to117 lb.ft at 3000rpm, an increase of nearly 20% (figures from Motor tests on the Triumph 2500TC). This can of course be increased considerably by upgrading to Injection or Weber carburettors.
Rover 3.5 Ltr V8
I have found two examples of this conversion, one in Canada, where Al Gunnarson from Victoria, B.C. has fitted a Rover V8 engine into his 1972 Triumph Gt6 Mk3. He has cleverly overcome the height problem by slightly raising the body on the chassis frame, and minor notching for engine clearances at the firewall! His installation can be seen below. To see this car on YouTube click here.
Another conversion, by Terry Burgess in the UK (on a Spitfire MkIV), featured in the April/May 2018 issue of Triumph World. The installation can be seen below. In my view this was not as good as the Canada conversion as the air cleaner protrudes from the bonnet!
American Small Block V8 (Ford or GM)
This is a conversion more likely in the US due to the relative accessibility of these engines in that country. One I particularly like (because it is featured by a cool video on YouTube) is a Mk2 which belonged to Dan Burback. This featured a Ford 5 litre small-block V8 putting out 405 HP! Other modifications include a Ford T5 5-speed transmission, and Corvette rear suspension and brakes. To hear this on YouTube click here.
Another similar conversion, which I believe is ongoing, is the Project GT6 by Fanatik Builds in Canada. This features a Mk3, fitted with a GM LS4 small-block V8. This is a very impressively re-engineered car, to see this on YouTube clickhere. Below can be seen the new chassis.
Ford 2.8 Ltr V6 (Cologne)
I have discovered this conversion on the British V8 website, also to a Spitfire. Like the 2.5 Ltr the only modifications needed are to the sump to clear the steering rack. To find out more click here.
Rover K-Series 1.8 Ltr DOHC
This engine, which was built for Rover by Powertrain, is available in 1.1 to 1.8 litres with SOHC or DOHC. The best transplant is obviously the 1.8 DOHC, an installation of which can be seen below.
Honda S2000 VTEC
On the British V8 website there is a 1963 Triumph Spitfire fitted with the engine of the Honda S2000. As this engine puts out around 240bhp it should certainly be potent! Built by Joe Curry of Sahuarita, Arizona, USA full details can be found by clicking here.
5 Cylinder Volvo 2319cc 850 T5-R
This conversion was done by Mark (gt5r) whose blog can be found by clicking here.
Electric Vehicle Conversion
In this age of the EV you can now buy an electric GT6 Mk3, albeit for around £100k! Retro-EV will fully restore a GT6 Mk3 and install a 110 kW (145 hp) electric motor, together with a 19 kWh battery giving a range of around 75 miles. This can be in the form of either an E-GT6 Coupe or a Spitfire E-Roadster.
Their website can be visited by clicking their logo above, or here. Founded by Michael Richardson (seen below in one of their GT6s), they are located in Finland.
1.8 Litre VAG Engine (Mid-engined Spitfire)
Nick Truman has gone one better and installed his Audi engine behind the seats! The whole story can be found on his website thespitfire.uk. He also has a video on YouTube which can be seen by clicking here.
Mazda PB1.8 (BP-ZE)
This robust engine, originally from a 2000 NB Miata (MX-5), was installed into a GT6 Mk1 race car by Whack-A-Do Racing in California. Their YouTube video can be seen by clicking here. A superbly prepared car!
Other engine conversions done include the Ford Zetec; and a turbo-charged, intercooled Mitsubishi 2000cc.
If I was doing an engine conversion I would consider the last Triumph engine designed by Mike Loasby. According to AROnline “Although it has received a bit rap in the trade thanks to its well-documented problems, the SD1 Six is a very capable engine. However, it could have been so much more had it been given the start it so richly deserved.” In 2.6 litre form, it could have with only camshaft and manifold changes achieve an easy 150-160bhp. To find out more about this engine read Robert Leitch’s excellent article by clicking here.