14.10 Engine and Drive Train
A. Engines must retain standard type lubricating system, but may have any oil pan (Accusump-type systems allowed), oil pump and pickup, oil coolers, oil or fuel filters. Fuel filters must be of automotive type and serve no other purpose. A permitted oil cooler may be positioned in an opening in an allowed spoiler, provided no unauthorized modifications are made in order to perform the installation.
B. Heat shields may be added.
C. Carburetors, fuel injection, intercoolers and intake manifolds are unrestricted. Alternate throttle linkage and connections to facilitate installation of allowed induction systems are permitted, but may serve no other purpose. As utilized only on engines originally equipped with forced induction, air-to-air heat exchangers (known as "intecoolers"), and radiators which are part of air-to-liquid charge coolers, must be cooled only by the atmosphere.

The use of chilled liquids, ice, dry ice, refrigeration systems, vaporized compressed gases, etc. is prohibited. If an induction system item is allowed to be removed and its original mounting bracket can be removed simply by unbolting it, the bracket may be removed as well. Turbochargers may not be added, changed or modified. Turbocharger and supercharger systems may only be updated/backdated with the accompanying engine unit. No changes are allowed to waste gates, pressure sensors or their location, and to other turbocharger or supercharger boost limiting systems. This allowance does not permit changes to blow-off (pop-off) valves. Devices known as "fuel cut defensers", and any modifications which alter or defeat the fuel cutoff when it is activated by boost level, are not permitted.
D. Air cleaner(s) may be changed or removed, velocity stacks may be added.
E. Emission control devices may be modified or removed. This permits the oil filler cap to be modified or substituted, but does not allow valve covers or cam covers to be altered to install a breather or for any other purpose.
F. Intake water injection systems are allowed.
G. Fuel lines and pumps are unrestricted except as specified herein as long as they do not pose a safety hazard. Fuel lines may be no larger than 1/2" i.d. and may only connect to the original fuel tank or allowed fuel cell. They may be no longer than necessary for reasonable and safe installation, and may serve no other purpose. A single fuel feed line may be used. A single fuel return line may be used, and a fitting for connecting it may be added at or near the top of the fuel tank. This does not authorize "cool-cans".
H. Exhaust manifolds and muffler systems are free, except that they must be quiet and terminate behind the driver. Exhaust heat shields may be removed. Rear- and mid-engined cars without exhaust headers/manifold systems may use any exhaust system that meets the requirements of 3.5. This permits the removal of "heater boxes" in order to install headers on such cars.
I. One bolt-on torque suppression device may be used. A torque suppression device attaches from the engine to the body, frame, or subframe in one location, and controls engine movement at that location along a single axis only. It may serve no other purpose.
Examples of permitted devices:
1. ) a chain
2. ) a rod with spherical bearings at each end.
Examples of devices not permitted:
3. ) one or more solid motor mounts
4. ) any link which confines movement along more than one axis
5. ) an engine mounting plate, or one or more plates rigidly bolted between the engine and the frame.
Holes may be drilled to mount a torque suppression device. The installation may not include the welding of any plate(s) to the motor mount(s) or bodywork (7/2002), nor may it include multiple non-parallel links.
This does not allow motor mount changes other than those which are update/backdates of factory components.
J. The engine fan and fan shroud (unless it serves another purpose, e.g. as an alternator/generator mount) may be removed, modified or replaced. Electrically driven fans are allowed.
K. On two-cycle engines, the ports must be of standard heights, size and configuration; crankcase volume and reed plates must not be altered.
L. Any metal clutch assembly, metal flywheel or metal torque converter that uses the standard attachment to the crankshaft may be used. Non-metallic friction surfaces (e.g. clutch disks) may be used. Dowel pins may be added. Minor repositioning of the clutch slave cylinder is allowed to accommodate the alternate clutch, but the unit may not be relocated and the repositioning may serve no other purpose. This allowance does not permit the substitution of slave cylinders or the use of non-original methods of clutch actuation (e.g. pull type vs. push type).
M. Any mechanical shift linkage may be used.
N. Limited slip differentials are permitted. This permits locked differentials, either by design, welding, or mechanical means. Differential cases, internal differential parts, and axle stubs may be machined as required for clearance and installation to the extent that material may only be removed, not added, and the exterior of the case may not be altered in any way. This machining may serve no other purpose.
O. Cylinders may be rebored to .0472 in. over standard bore and the appropriate standard oversize piston may be substituted. Cast or forged, non-stock pistons of the same dimensions and configuration as original equipment pistons may be used. Additionally the replacement pistons must be of the same weight or greater as the original equipment pistons. The .0472 in. limit is absolute, no additional tolerance is permitted to accommodate wear. This allowance does not permit alternative ring configurations. (3/2002)
P. Rotating and reciprocating parts may be balanced but not lightened.
Q. Intake and exhaust ports and manifold openings may be matched provided no change is made more than one inch from the port/manifold interface. Material may be removed to facilitate port matching, but no material may be added. (3/2002)
R. Any transmission oil cooler may be used.
S. The engine cylinder head(s) may be milled only to that amount specified in the manufacturer's workshop manual. If no amount is specified than a maximum of 0.010 in. may be milled.
T. Axle/halfshaft and driveshaft retention/location devices may be installed for safety reasons to control the motion of attached shafts upon the failure of a coupling or universal joint. They may serve no other purpose.
U. Any accessory pulleys and belts of the same type (e.g., V-belt, serpentine) as standard may be used. This allowance applies to accessory pulleys only (e.g., alternator, water pump, power steering pump, and crankshaft drive pulleys). It does not allow replacement, modification, or substitution of pulleys, cogs, gears, or belts which are part of cam, layshaft, or ignition drive or timing systems, etc. Supercharged cars are excluded from this allowance. This does not permit replacement of integral pulley-damper/balancer assemblies. Alternate pulley materials may be used. Idler pulleys may be used for belt routing in place of items which the rules specifically allow to be removed, such as smog pumps and air conditioning compressors. They may serve no other purpose. Supercharged cars may not change the effective diameter of any pulley which drives the supercharger.