Engine1

Turbo & Intercooler
Group A competition regulations prohibit modification of certain engine components. The GT-R design team have included the following performance boosting parts and modifications in the stock engine. The GT-R's turbo-charger exhaust and compressor rotors have been increased from 52.5mm to 62mm and the A/R ration has risen from 15 to 16. The design team selected these specifications after thorough testing, in line with the basic engineering policy of maximizing boost pressure at the top end, while minimizing turbo-lag. Low-friction ball bearings replace the GTX,s floating-metal bearings in the water-cooled turbo-charger journal. Components are made from new heat-resistant materials to withstand rigorous rally conditions 1	Anew larger-diameter duty valve at the waste gate is under microcomputer control. The same microcomputer regulates the intercept point and maximum boost pressure settings
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	The intercooler core size is 70% larger, up from 125mm x 247mm in the GTX, to 225mm x 234.6mm for the GT-R. Performance has soared 37% from 4.500 kcal/h to 6.150 kcal/h. The cooling fins are arranged in zigzag pattern which increases cooling efficiency. The intercooler is mounted in front of the radiator to catch the cool air stream, lowering the intake gas temperature to prevent engine knocking, The intercooler's square shape and tube layout minimizes pressure loss

1. Turbo-chargers: GT-R (right) and GTX (left)

2. Intercoolers: GTX (upper) and GT-R (lower)

	The surge tank wall baffles equalize intake air pressure, reducing cylinder overload and improving performance and reliability. This design was pioneer by Mazda engineers and developed following extensive testing. The technology is a world first and Mazda holds the patent The exhaust manifold is made of lightweight, heatresistant ferrite steel. Lost-foam casting gives the manifold its smooth inner surface which reduce gas flow resistance. The con-rods are made of a tougher alloy and their "I"-shaped cross-sections rigidity and strength The stock GT-R engine contains numerous modified parts over the GTX that increase the car's potential for Group N competition. The capacity of the air flow meter, fuel pump, and fuel injection system have increased for higher power output. The exhaust valve stems are hollow and partially filled with sodium. As the valves heat up, the sodium melts and is agitated violently as the valves move. Heat is absorbed from the valve neck by the liquid metal and conducted to the valve stem where it dissipates.
	3	The cooler exhaust valves prevent predetonation, increasing engine reliability. The forged aluminum pistons with cooling channels, resemble Formula One engine pistons. The piston crowns are tin plated. There are two compression rings and one oil ring. Nickel cement is fuse-bonded to the groove area of the top ring to enhance wear resistance. The well-lubricated kelmet metal con-rod big-end bearings are the same as those fitted in Group A competition motors. The new five-stage water-cooled oil cooler has a greater capacity over the GTX's old two-stage unit. Oil jets spray oil up into the cooling channels in the underside of the pistons, cooling the piston crowns Exhaust temperature and pressure is reduced by minimizing the number of cells in the catalytic converter and by straightening the silencer's internal construction.
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3. The GT-R intake manifold

4. A GT-R sodium cooled exhaust valve

5. Diagram of oil flow from oil jet to piston cooling channel

6. The GT-R piston crown