Engine Conversions


Lovely though the standard 2 litre six cylinder engine is, a number of GT6s (and Spitfires) have had other engines installed. Details of a few I have found are below:

Triumph 2.5 Ltr 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!


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.

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.