That's how I bought it...
They're still better than a TW head or RPM head that I see alot of people running..
They are better than a T.W. head. Better at what? Take a look at this.
TREMEC TRANSMISSIONS - PURE STREET
NMRA SERIES 2008 RULES
Pure Street is designed for naturally aspirated small block 1979 and newer Ford Fox Chassis and 2005 to present Mustang bodied and Ford powered vehicles. Pure Street entries are limited to 302, and 2V/3V/4V 4.6L Modular engine types. 5.0L engines are permitted a maximum of 313 cubic inches. 4.6L engines are permitted a maximum of 291 cubic inches.
Qualifying Information, Ladder Type, & Tree
All Run, NHRA Sportsman Ladder, Pro .400 tree, Heads-Up.
Accepted Products Deadline: NMRA will accept requests from manufacturers to have new products considered for addition to 2008 accepted lists only up until January 1, 2008. After this date, NMRA will consider manufacturer requests for new products for the 2009 season.
Maximum Cubic Inch â 313 ci
AOD combinations may deduct 100 lbs.
Carburetor applications â add 75 lbs. to base weight. See section 1.19
TFS Twisted Wedge cylinder heads â add 50 lbs. to base weight. See section 1.17
Sullivan 4V manifolds â add 75lbs. to base weight. See section 1.21
Note: 15 lbs/cu in penalty applies for cubic inches over base weight break.
Note: All weights are with driver at conclusion of run at scale area.
CLASS RULES, PURE STREET
1.1 COOLING SYSTEM
RADIATOR: OEM production-style or aftermarket radiator is required and must be mounted in stock location. Stock core support is required.
WATER PUMP: Any aftermarket (belt drive or electric drive) pump permitted.
COOLING FANS: Any permitted.
ENGINE: Engine limited to 302W (5.0) and 4.6L Modular engine types. 302 Windsor type engines and 4.6L engines may be used in any 1979 and newer Fox based chassis. Engine swapping permitted during event.
1.2a) ENGINE DRIVE BELT SYSTEM: Factory style 6 rib drive belt system required. 6-rib belt required. Minimum crankshaft pulley diameter â 3-inch.
EXHAUST: All entries allowed to use tubular headers. Adapter plates to bolt headers to cylinder head permitted, maximum thickness .500-inch. Exhaust must be directed out of car body, away from driver and fuel tank. All exhaust gases released from engine must pass through entire exhaust system.
1.3a) HEADERS & COLLECTORS: All entries allowed to use tubular headers, maximum tubing size 1.75â.
1.3b) EXHAUST TUBING/SIZE: Maximum exhaust pipe diameter â 2.5-inch up to gas tank, 3-inch from gas tank rearward (tailpipe).
1.3c) TAILPIPE & EXHAUST RULES: Full exhaust system required. Tailpipes must exit within 12-inch of rearend centerline housing.
1.3d) MUFFLER REQUIREMENTS: Commercially available (generally available through retail locations) mufflers required.
A maximum of two (2) mufflers is allowed. A maximum of one (1) inlet and one (1) outlet is permitted. Mufflers may have a maximum of 2.5-inch inlet & outlet.
1.5 FUEL DELIVERY SYSTEM
FUEL DELIVERY SYSTEM: Electric or mechanical fuel pumps permitted. Pressure regulators, and any line size permitted. All fuel lines must originate and return to a single, non-segmented, fuel cell or OEM fuel tank. Fuel pump must shut off with a master electrical switch. Any method of artificially heating or cooling fuel prohibited (cool cans, ice, wet rags, Freon, etc.). A valve for removal of fuel (gasoline) during technical inspections is mandatory. Valve must be installed between carburetor/injection and regulator, and should be installed in such a manner that allows a cup to be placed to catch fuel removed from the line. Exit of valve should be capped or plugged in addition to being closed for added safety.
Aftermarket/fabricated fuel tank or cell permitted. Must be located in trunk area. If tank or fuel filler is inside trunk, a bulkhead of minimum .032â aluminum or .024â steel must be used between trunk and driver compartment, and tank must be vented to outside of car. When used, fuel cells must have a metal box protecting the part of the fuel cell that is outside the trunk floor. Non-metallic fuel cells or tanks must be grounded to frame. See NHRA General Regulations Section 1.5.
GASOLINE: Gasoline as outlined here is the only acceptable fuel for use in this eliminator for the specified combinations (See Section 13). The NMRA Racing Association reserves the right to check gasoline at any time during competition. Gasoline, as defined by the NHRA rulebook, is a mixture of hydrocarbons only. The average dielectric constant (D.C.) for the hydrocarbons that compromises gasoline is 2.025. This is defined as a reading of â0â on the fuel-check meter.
1.6a) SPEC FUEL: NMRA requires the use of one of the allowable NMRA spec fuels in this class. Mixing of fuels prohibited. Failure to pass fuel check is grounds for disallowance of the run during qualifying and disqualification from the event during eliminations. Fuel must pass color, fuel meter, specific gravity, chemical testing, and/or any other check as required by NMRA Technical Department.
1.6b) SPEC FUEL ACCEPTED LIST:
Manufacturer Fuel Type
VP Racing Fuels
1.6)c NITROUS OXIDE
NITROUS OXIDE: Prohibited.
OILING SYSTEM: Wet sump oiling system required. Dry sump oiling systems prohibited. External oil pumps prohibited. Oil lines run outside engine block to feed oil galleries prohibited. Vacuum pump and/or evacuator system (header, or otherwise) prohibited. Any oil pan permitted.
BLOCK: Any cast iron Ford type 302W permitted. Any cast iron or cast aluminum 4.6 based engine block permitted. Block must maintain Ford OEM bore spacing, deck heights, and crankshaft spacing for engine type used. Deck spacers (extensions) prohibited.
1.16 ENGINE LOCATION/MOUNTS
ENGINE LOCATION: Engine location may be altered from stock, however no part of engine or heads may contact firewall. Engine plates prohibited. Solid engine mounts permitted.
302W TYPE HEADS: Only commercially available cast aluminum or cast iron, two-valve per cylinder heads permitted. Billet, one-off, custom and/or fabricated heads prohibited. Cylinder heads must be overhead valve single spark plug per cylinder design.
4.6 TYPE HEADS: Only commercially available cast aluminum or cast iron, cylinder heads permitted. Billet, one-off, custom and/or fabricated heads prohibited. Cylinder head must be single spark plug per cylinder design.
1.17a) HEADS, PERMITTED: Only original manufacture, generally available heads, accepted by NMRA, permitted. External modifications prohibited in port area. Spark plug placement and depth must remain stock. Billet, one-off, custom and/or fabricated heads prohibited.
1.17b) HEADS, MASS PRODUCED: Only mass produced, commercially available, NMRA accepted, cast aluminum or cast iron Ford cylinder heads permitted. Low volume, one off, aluminum cylinder heads prohibited.
1.17c) HEADS, BOLT PATTERN: Class is permitted standard bolt-pattern only for cylinder heads.
Maximum of 10 head fasteners per side in Ford OEM location.
1.17d) HEADS, PORTING: Permitted.
1.17e) HEADS, WELDING/EPOXY: Prohibited.
1.17f) HEADS, VALVES: Maximum valve sizes for 302W heads is 2.025-inch Intake/1.605-inch Exhaust. Maximum valve sizes for 4.6L two valve heads are 1.850-inch Intake/1.452-inch Exhaust. Maximum valve sizes for 4.6L three-valve heads are 1.368-inch intake and 1.514-inch exhaust. Maximum valve sizes for 4.6L four valve heads are 1.487-inch Intake/1.211-inch Exhaust. Valve stem size in guide area must be 11/32-inch for 302W heads, Valve stem size in guide area must be 0.274-inch for 4.6L heads. Undercut stems permitted. Aftermarket steel valve permitted, titanium/exotic valves prohibited. Bronze lined or replacement guides permitted.
1.17g) HEADS, MILLING: Permitted. See combustion chamber volume. Cylinder heads must maintain original production valve angles + or â 2 degrees.
1.17h) HEADS, PUSHROD SLEEVES: Prohibited.
1.17i) HEADS, COMBUSTION CHAMBER VOLUME: The following cylinder heads are not restricted on combustion chamber volume: Ford OEM cast iron 289, 302, 351, FRPP GT-40, & GT-40P heads. Minimum combustion chamber volume for all other 302W heads is 58.0 ccâs. Minimum combustion chamber volume for 2V/3V/4V 4.6L heads is 42.0 ccâs.
1.17j) HEADS, PORT PLATES/ADAPTER PLATES: Intake port plates prohibited, exhaust port plates maximum thickness .500-inch permitted.
1.17k) VALVE JOB: Any valve job permitted.
1.17l) PERMITTED CYLINDER HEAD LIST, PARTS NUMBER: These are the only permitted cylinder heads and part numbers for competition in this category. If your cylinder head is not on this list, it is prohibited.
Stock Ford OEM 289/302/5.0 and 4.6L Cylinder Heads.
Ford GT-40 and GT-40P Cast Iron Cylinder Heads
FRPP GT-40 Aluminum Cylinder Heads, PN# M 6049 X303 & Y303
FRPP/SVO 4.6 2V Cylinder Heads
FRPP/SVO 4.6L 4-Valve Cylinder Head, M 6049 T46
Edelbrock Performer & Performer RPM Heads, PN# 60329, 60359, 60279, 60229, 60259, 60269
Trick Flow Twisted Wedge Aluminum Standard Version (Non-R) Cylinder Heads **
Brodix ST 5.0 & 5.0R Aluminum Cylinder Heads, PN# ST 5.0 & ST 5.0R
Holley 5.0 Aluminum Cylinder Heads, PN# 300-573, 574, 575, 576, 577, 578, 579
World Products Roush 180 & Windsor Jr, PN# 53030, 23030
Air Flow Research 165, PN# 1398, 1399, 1400, 1402, 1472
Air Flow Research 185, P/N# 1387, 1388, 1389, 1406
Dart Pro 1 170cc As-Cast Cylinder Heads, PN#13100080, 13111181, 13111182
Canfield 170cc Street #18-350
RHS 180cc (Iron & Aluminum)
** These heads permitted with a 50 lb. weight adder to base weight
Note: Stock factory OEM heads are those cylinder heads that are factory production line installed on production vehicles as recognized by NHRA.
Not according to the NMRA Pure Street rules. Perhaps they just add weight to T.W. cylinder headed vehicles for ####s and giggles, not because they make exceptional power.