TVR T350
TVR T350
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FORMULA
2000
HOTROD
FORMULA
2000
HOTROD
I was asked to build this vehicle from a box of bits. Well not exactly a box, but the engine was incomplete and the chassis was without an engine. The chap who owns this hotrod bought it without an engine as the previous owner kept the original for another race project.
I was given the majority of the engine as an assembled item, plus a load of parts from various other donor vehicles.
The block is a 2 litre Cosworth item as fitted to the Ford RS Cosworth Escort. The race specifications for this race series are very specific. They are are very precise with regard to which parts can be used and what modifications you are allowed to do to the various components. To start with, the block (the stronger 205 Cosworth one) was rebored to maximum oversize of +80 thou to obtain the largest capacity and power from this engine. The crankshaft has to sourced from a Cortina or Sierra, the conrods and pistons, Mondeo and the cylinder head a Pinto engine (Cortina or Sierra) The exhaust can be fabricated from scratch, whilst the inlet manifold and carburettor must be Pinto.
The block needed to have a decking plate bolted to it for the boring process. This is a huge block of metal that takes the place of the cylinder head when it is being machined and stresses the block straight as if the head was bolted to it. It has four holes in it to allow for the work to be carried out on the cyliners, and once the machine work has been completed, the block is cleaned and decking plate removed. New core plugs are fitted and the casting then stove enamelled. When the head is bolted on the built egine, it all pulls the block square again and the engine hopefully should run true. Well that’s the theory.
The reciprocating parts (Crankshaft, pistons, rods, flywheel and clutch) are then balanced to help the engine run as smoothly as possible at all rev ranges.
The cylinder head was fitted with new hardened valve seats, bronze valve guides along with a set of new valves.
The mating face of the cylinder head was machined to raise the compression ratio to around 11.5:1 which will maximise the power output, although great care is needed setting up the engine as the valve to piston clearances are at the minimum because of the metal removed from the head.
The camshaft is a specific profile for the series and is 305 degree in duration, which is designed to produce maximum power but at a narrow rev range. The engine is run at almost maximum speed whist racing, between 5000 to 8000 rpm, which allows this type of cam to be used to maximum effect.
The pictures shown below, detail the build stage by stage with explanatory notes for each photo.
The block has been securely anchored to the bed of the boring machine. The decking plate is bolted and torqued to the block ready for the boring process to start.
The boring process underway with a constant supply of cutting oil to reduce heat and tool wear. Each of the cylinders is machined identically to the same size and tolerances.
A close up view of the process. You can see the holes in the decking plate just slightly larger then the size of the cylinder bore.
The crankshaft and pistons fitted, the front pulley is temporarily bolted on to enable the crankshaft to be turned over during assembly.
The crankshaft and pistons fitted, the front pulley is temporarily bolted on to enable the crankshaft to be turned over during assembly.
Here you can see the pistons fitted in the newly machined cylinders and the hi-tensile crankshaft bolts. Also the top of the block has been lightly machined to ensure it is exactly square to the bores.
The cylinder head assembled with new valves and stronger springs. The spring bases had to be modified to stop coil binding at maximum lift. The lift of the cam is the most you can get away with on this engine and springs are compressed to the maximum. The coils can touch at high RPM which will damage the cam and followers.
The underside of the head. The inlet manifold has been ported and matched to the head.
The cylinder head bolted to the block, the blue camshaft pulley is an adjustable one so the timing can be precisely set up.
A new water pump fitted along with a new cooling fan.
Spark plugs fitted, cam cover is just placed on the engine until the cam belt is installed and timing completed.
The chassis prior to engine installation.
The engine installed with the radiator and the exhaust system. There is still some wiring modifications and some new instruments to fit.
All the wiring completed, fuel system connected and the new instrumentation fitted. The engine is ready to run now, and will need some running in before being set up on a rolling road and dyno.
Unfortunately the exhaust note from this vehicle was so loud, I was unable to run it very much in the workshop, so it went back to the owner for further running.
The following pictures are of the finished vehicle. It went off for a respray after the rolling road session, and continued to do very well in the national series.
