Engine Modifications (Tuning)


There are a  lot of opinions as how best to achieve this, depending on who is giving the advice! Basically to increase power in any internal combustion engine it is necessary to modify it to accept more air and fuel, and this is done by both increasing the airflow into the engine (via the carburettor or other device), and out of the engine (via the exhaust). Of course doing all this may make the engine more powerful, but it is important to make sure that this power is delivered reliably so any serious modifications need the engine to be strengthened so it doesn't break!

Common sense says that the best way to 'tune' an engine is to ensure that everything is as it should be! First, make sure that all the ignition components are in tip top condition and then ensure the ignition is timed correctly. Then adjust the carburettors to ensure the mixture is correct and also balancing them is beneficial. If you still want to modify your GT6 for more power, the books featured below may help!


The 'Guru' of Triumph engine modification is Kas Kastner, who single-handedly launched Triumphs’ very successful Competition Department and literally wrote the book on tuning Triumphs for higher performance, the 'Triumph Preparation Handbook' (see above). You can visit his website by clicking here, where you can download an e-book (PDF) for $17.95. His advice is quite detailed and follows a lot of actual experience on the track and he was very successful so his opinions should be respected.


Another 'Guru' is David Vizard whose book "Tuning Standard Triumphs Over 1300cc" was published by Triumph themselves. Ex-aerospace engineer David Vizard is one of the world's most widely published automotive writers. He holds numerous patents and is a winning engine/car builder so should know what he is doing! You can download a PDF of the Standard-Triumph version by clicking here.



Gareth Thomas is a bit of a maverick when it comes to Triumph tuning. According to his website, many of his ideas have been stolen.

According to Christian Marx on the Kas Kastner's Forum  "The book is different to the Kas Kastner books. The Kastner books are on the practical side, hard facts combined with well tested tuning ideas that are needed for winning races. The Thomas tuning manual is more of theoretical nature. He gives a good view on how combustion and gas flow works. It's a good help to get an idea of the engineering side of engine development. I would think....the Thomas book is a very good enhancement of the Kastner books. I recommend it". You may be able to get a copy of his Tuning Manual from his website http://www.jagclub.ru/triumph_tun.html but be warned, they are like hen's teeth!


Classic & Sports Car’s Features Editor Greg MacLeman owns a 1974 Triumph 2500TC which has a similar engine to the GT6, and he has taken it to 'Stage 2' (December 2019 issue) by doing the following:-

1. Camshaft - Took to Piper Cams who re-profiled it to 'yellow' specification - "a grind that majors on usable torque and came highly recommended by Matt George and Jason Wright at TRGB". To visit the appropriate TRGB page click here.

2. Fit vernier timing gear in place of the Duplex chains, so that the camshaft timing can be set more precisely. The main, if not only supplier of this, is Kent Cams who sell the S75 kit. Visit www.kentcams.com or their ebay page here.

3. The cylinder head was uprated by Peter Burgess - he opened up the inlet and exhaust ports, cut the inlet seats and reshaped the combustion chambers, finishing with a skim to raise the compression ratio from the factory 8.5:1. His website is here.

4. Fit a Chris Witor easy breathing 6-3-1 stainless steel tubular exhaust manifold. A version of this suitable for the GT6 can be seen by clicking here.

Mr MacLeman has a youtube channel, you can see the Triumph 2500TC Stage 2 first start up by clicking here.