Looking over the Press release about CART's 2003 engine rules, the thing that stood out the most is the 12k rev-limit. This one difference in rules will make it very costly to switch an engine over from the IRL's 10,700 limit to the CART 12,000 limit. The valve train on the IRL engines will not turn 12,000, so you would have to make new cams and springs to run 12,000. If you designed the valvetrain for 12,000 and tried to run it @ 10,700 it wouldn't make as much torque and HP as the valvetrain designed for 10,700. At 12,000 the engines Intake system will be required to move 80 more CFM of air, that will require a different port and intake design to optimize power at each RPM limit. I don't know if CART is going to limit the bore size to 3.661" like the IRL, but either way there will be problems. If they don't limit bore size, than they will increase the bore and cut the stroke to get the piston speed below 5,000fpm. This will require almost everything being changed to make the engine optimum for 12,000.
If they go with a 3.661" max bore like the IRL, then the piston speed will be over 5,000fpm @ 12,000rpm and require stronger and more expensive cranks, rods, and pistons.
Besides all this the engines will be required to handle 70 more HP @ 12,000 than they will @ 10,700 so some parts for the 12,000 limit will be heavier than the same parts for the 10,700 limit.
So, from what I see, I don't see much that will be common between the CART and IRL engines in 2003.
If they go with a 3.661" max bore like the IRL, then the piston speed will be over 5,000fpm @ 12,000rpm and require stronger and more expensive cranks, rods, and pistons.
Besides all this the engines will be required to handle 70 more HP @ 12,000 than they will @ 10,700 so some parts for the 12,000 limit will be heavier than the same parts for the 10,700 limit.
So, from what I see, I don't see much that will be common between the CART and IRL engines in 2003.
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