Updated 11/29/06 11:25 AM

IHRA Horsepower Adjustments
(see also: IHRA Accepted "Crate" Motor List)

11/29/06

Stock Eliminator horsepower adjustments:

1967 Ford Shelby 428/ small valve/aluminum head/automatic was 358 + 5 to363 HP 1967 Ford Shelby 428/small valve/aluminum head/standard was 355 +3 to 358 HP All Chevrolet Crate 350/355/365 + 10 to 375 HP 1973 Ford and Mercury 351-246/253/291+3 to 294HP 1990 Chevrolet Corvette 350-247/250 was 260+5 to 265HP 1969 Chevrolet Corvette 427-430(L-88) was 440-5 to 435HP(cam lift 560/580) 1969 Chevrolet Camaro 427-430(ZL-1) was 440-10 to 430HP All Ford Crate 302/285/265-10 to 255HP

Super Stock Eliminator horsepower adjustments:

1971 Ford Mustang 429-375/380-30 to 350HP

4/28/06

Stock Eliminator horsepower adjustments:

● 1973 Ford and Mercury 351-246/253/285+6 to 291 in all Stock GT applications
● All Ford 302/320/300 Aluminum Head Crate Engine / Y 302 Al Head-10 to 290 HP
● All Ford 302/320 Aluminum Head Crate Engine/ X 303 Al Head -20 to 300 HP
● All 1966 Chevrolet 283/220/210 + 5 to 215 HP in Full Size Wagons

12/23/05

Pure Stock horsepower adjustments:

• 1979 Chevrolet 305-160/235/245 – 15 to 230 HP
• 1968 Pontiac Firebird Ram 1 400/335/340/355/360 +5 to 365 HP

Stock Eliminator horsepower adjustments:

• 1969 Mercury Cougar 428-335/375 non ram air -5 to 365 HP
• 1969 Pontiac 350-325 and 330, -10 and -15 to 315 HP
• 1971 Chrysler, Dodge, Plymouth 318-230/195 -10 to 185 HP
• 1972 Chrysler, Dodge, Plymouth 318-150/195 -10 to 185 HP
• All Mopar 360/360 Crate Engines -15 to 345 HP
• All Mopar 360/380/370 Cast Iron Head Crate Engines -15 to 355 HP
• All Mopar 360/380/380 Aluminum Head Crate Engines -15 to 365 HP
• All Chevrolet 454/425 Cast Iron Head Crate Engine / Accepted Aluminum Head
12363392 +15 HP to 440HP
• All Ford 302/320/300 Aluminum Head Crate Engine / Accepted Aluminum Head
X 303 + 20HP to 320HP

9/29/05

● 1968 Pontiac Firebird Ram Air 1 400/335/340/355 to +5 to 360 HP

8/31/05
Pure Stock horsepower adjustments:

● 1972 Plymouth Barracuda 340/240/285 +5 to 290 HP

TOP STOCK: (effective 8/4/05)

• 514 Ford CM @ 430 HP - 5 HP to 410 HP
• 360 / 340 CM Mopar - 5 HP to 335 HP (aluminum head version only)
• 360 / 345 CM Mopar -5 to 340 HP
• Fastburn 350/340/355 - 5 HP to 350 HP
● GM LS-1 (alum) 355 HP - 10 HP to 345 HP

• 1966-1970 CHEV 396/375/370 HP + 15 hp to 385 HP
● 502/502 / 435 HP + 5 hp to 443 HP
• 500 / 445 Mopar (Wedge) CM + 5 HP to 443 HP

6/1/05 (effective 6/6/05)

Pure Stock horsepower adjustments:

• 1972 Buick GS 455/250/345 +10 to 355 HP
• 1968 Pontiac Firebird Ram Air 1 400/335/340 +15 to 355 HP
  
  Stock Eliminator horsepower adjustments:
• 1987 Pontiac Formula 305/185/238 +3 to 241 HP
• 1986 Chevrolet Camaro 305/165 / 253 and 305/190 / 253 + 10 to 263 HP

Super Stock horsepower adjustment:

• 1986 Ford and Mercury 302/200/240 -20 to 220 HP
  

2/4/05

1964-66 Chevy 283 / 220 HP increased to 215 (automatic combos only)

1/12/05

TOP STOCK HP ADJUSTMENTS (effective 1/12/05 )

1966-1969 CHEV 427/ 425 / 400 HP - 5 HP to 395 HP

514 Ford CM @ 430 HP - 5 HP to 415 HP

500 / 445 Mopar (Wedge) CM - 7 HP to 438

360 / 345 CM Mopar - 5 HP to 340 HP (aluminum head version only)

360 / 350 CM Mopar -5 to 345 HP

6/2/04

1965 Ford 289 / 271 reduced to 245 hp (pure stock only)

12/19/03

1994 Camaro LT-1 350 275 / 325 reduced to 315 hp (pure stock only)

8/13/03

TOP STOCK HP ADJUSTMENTS (effective 8/13/03)

Fastburn 350/340/365 - 10 HP to 355 HP

1966-1970 CHEV 396/375/385 HP - 15 hp to 370 HP

GM LS-1 (alum) 365 HP - 10 HP to 355 HP

Camaro / Firebird LT-4 350 / 345 - 10 HP to 335 HP

1970 Stage 2 Buick - 5 HP to 385 HP

1966-1969 CHEV 427/ 425 / 405 HP - 5 HP to 405 HP

427/470/ 430 (ZL-1) - 15 to 415 HP

514 Ford CM @ 430 HP - 10 HP to 420 HP

428/335/385 CJ (F5 Head) - 10 hp to 375 HP

500 / 430 Mopar (Wedge) CM + 15 HP to 445 HP

472/525/415 crate hemi - 5 HP to 410 HP

440/six pack - 10 hp to 375 HP

67-71 426 / 410 Street Hemi - 5 HP to 405 HP

360 / 350 CM Mopar - 5 HP to 345 HP (aluminum head version only)

1963-64 Mopar 426/425/415 hp HI Comp. Max Wedge -5 to 410 HP

6/11/03

TOP STOCK and Pure Stock HP ADJUSTMENTS

360/340 CM Mopar +10 to 350 HP (top stock only)

502/502 / 435HP +3HP to 438HP (top stock only)

67-71 426/415HP Street Hemi -5HP to 410HP(top stock only)

1987- 89 Ford 302 / 225 / 215 + 8 HP to 223 (stick combos only)

5/13/03

PURE STOCK HP ADJUSTMENTS

1972 Buick GS 455/250/330 +15HP to 345

1964-66 Chevy 283/220/210 +5HP to 215 (automatic combos only)

1987-89 Ford 302/225/210 +5HP to 215 (stick combos only)

1/13/03

STOCK HP ADJUSTMENTS (effective 1/14/03)

·1964-66 283 / 220 HP reduced to 210 (automatic combos only)

1/6/03

TOP STOCK HP ADJUSTMENTS (effective 1/6/03)

· Fastburn 350/340/355 +10hp to 365 HP
· 514 Ford CM @ 430 HP
· 500 Mopar (Wedge) CM @ 430 HP
· 360/335 CM Mopar +5 to 340 HP 
· 351/335 CM Ford + 5 to 340 HP

8/28/02

TOP STOCK HP ADJUSTMENTS (effective 8/29/02)

Fastburn 350/340/365 -10hp to 355 HP

1966-1970 CHEV 396/375/390 HP -5 hp to 385 HP

1966-1969 CHEV 427/425/410 HP -5 hp to 400 HP

428/335/390 CJ (F5 Head) -5 hp to 385 HP

7/31/02

Super Stock

1965 Chevrolet 327 / 250 / 260 HP reduced to 255

Stock

1965 Chevrolet 283 / 220 HP reduced to 210 (automatic combos only)

6/19/02

TOP STOCK HP ADJUSTMENTS (effective 6/24/02)

Fastburn 350/340/360 + 5hp to 365 HP

GM LS-1(alum) 355 HP +10 hp to 365 HP

502/502/423 HP +12 hp to 435 HP

428/335/385 CJ (F5 Head) +5 hp to 390 HP

5/28/02

STOCK HP ADJUSTMENTS (Crate Motors - effective 5/28/02)

350/345/355 @ 360 HP (dish version)

350/345/355 @ 365 HP (flat top version)

350/355/365 HP

360 / 300 / 315 hp (Commando) increased to 320 hp.

5/23/02

TOP STOCK HP ADJUSTMENTS (effective 5/31/02)

Fastburn 350/340/355 + 5hp to 360 HP

GM LS-1(alum) 350 HP +5 hp to 355 HP

502/502/420 HP +3 hp to 423 HP

1963 426/415/410 (low comp) Max Wedge –5hp to 405 HP

1967-69 Corvette 427/400/385 (oval port, 3 X 2) –10 to 375 HP.

Note: Mopar Performance Cylinder head # 4876311 is an approved part on 440 6-pack combinations. (In. 2.140 Ex. 1.810)

5/7/02

TOP STOCK HP ADJUSTMENTS (effective 5/7/02)

• Fastburn 350/340/345 + 10hp to 355 HP
• GM LS-1(alum) 345 HP +5 hp to 350 HP
• 1966-1970 CHEV 396/375/385 HP +5 hp to 390 HP
• 502/502/415 HP +5 hp to 420 HP

4/25/02

TOP STOCK HP ADJUSTMENTS

• Fastburn 350/335 +10hp to 345 HP

4/3/02

STOCK and SUPER STOCK HP ADJUSTMENTS (effective 4/15/02)

Ford  (Stock)

• 1962-64 260 / 164 HP reduced to 145
• 1965-67 289 / 225 HP reduced to 203
• 1970-71 429 / 375 HP reduced to 355
• 1962-63 406 / 405 HP reduced to 365
• 1963 427 / 425 HP reduced to 385

Ford   (Super Stock)

• 1970-71 429 / 415 HP reduced to 385

Olds / Pontiac

• 1966 67 (Olds 442’s) 400 / 360 HP reduced to 330
• 1970 455 / 365 / 370 HP reduced 350
• 1967-68 Ram Air 1- 400 / 360 and 370 HP reduced to 342
• 1964 389 / 348 HP reduced to 325
• 1965-66 389 / 360 reduced to 335

Chevrolet

• 1961 409 / 360 HP reduced to 325
• 1962 409 / 380 HP reduced to 340
• 1962 409 / 409 HP reduced to 365
• 1963 409 / 340 HP reduced to 306
• 1963-64 409 / 400 HP reduced to 360
• 1963-64 409 / 425 HP reduced to 375

Chevrolet (Super Stock)

• 1965 327 / 250 / 265 HP reduced to 260

1/25/02

TOP STOCK HP ADJUSTMENTS (effective 1/25/02)

· 1966-1970 CHEV 396/375/380 HP +5 hp to 385 HP
· GM LS-1(alum) 340 HP +5 hp to 345 HP
· Camaro / Firebird LT-4 350 at 345 HP

· Fastburn 350/340 -5hp to 335 HP

· 502/502/420 HP -5 hp to 415 HP

· 1967-70 Ram Air 4 Pontiac (1970 engine spec) 400/350 HP

· 360/340 crate -5 hp to 335HP

· 472/525/420 crate hemi – 5 hp to 415 HP

· 351/340 crate –5 hp to 335 HP

· 460/535/420 crate –5 hp to 415 HP

· 428/335/370 CJ (Steel Standard OEM CJ Head) +5 hp to 375 HP

· 428/335/380 CJ (F5 Head) +5 hp to 385 HP
· 1966-67 Fairlane 427/410/415 (med rise) 410 HP

· 1966-67 Fairlane 427/425/440 (med rise - 2 /4 bbl) 420 HP

9/25/01

TOP STOCK HP ADJUSTMENTS (effective 9/25/01)

• 1966-1970 CHEV 396/375/390 HP -10 hp to 38O HP
• 1966-1969 CHEV 427/425/420 HP –10 hp to 410 HP
• 350 GM Fast Burn 350/385/355/345 hp -5 to 340 HP
• GM LS-1(alum) 345 HP -5 hp to 34O HP
• 350 GM LT-1 hp to 340 HP
• 502/502/430 HP –10 hp to 420 HP
• 454/425 (LS6) –10 hp to 410 HP
• 427/470 (ZL-1) to 430 HP
  
• 1970 Stage 2 Buick 395 HP -5 hp to 390 HP
  
• 1963-64 Mopar 426/425/415 hp HI Comp. Max Wedge -5 to 415 HP
• 1966 Mopar 426/425/420 Street Hemi -10hp to 410 HP
• 1967-71 Mopar 426/425/420 Street Hemi -5hp to 415
• 426/415 Max Wedge –5hp to 410HP
• 440/six pack –10 hp to 385 HP
• 472/525 crate hemi – 10 hp to 420 HP
• 360/385/350 crate –10 hp to 340 HP
• 64-65 426 race hemi to 430 hp
  
• 351/385/350 crate –10 hp to 340 HP
• 460/535/430 crate –10 hp to 420 HP
• 428/335/375 CJ (Steel Standard OEM CJ Head) –5 hp to 370 HP
• 428/335/375 CJ (F5 Head) +5 hp to 380 HP

8/28/01

TOP STOCK HP REDUCTIONS (effective 8/28/01)

• 1966-1970 CHEV 396/375/390 HP -5 hp to 385 HP
• 1966-1969 CHEV 427/425 HP -5 hp to 420 HP
• 350 GM Fast Burn 350/385/355 hp -10 to 345 HP
• GM LS-1(alum) -5 hp to 345 HP
• 350 GM Fast Burn 350/385/355 hp -10 to 345 HP
• 1970 Stage 2 Buick -5 HP to 395 HP
• 1963-64 Mopar 426/425 hp HI Comp. Max Wedge -5 to 420 HP
• 1966 Mopar Street Hemi -5hp to 420 HP
• 1966-67 Ford (4V)427/410/415 hp -5 to 410 HP
• 1966-67 Ford (2X4V)427/425/440 hp -15 to 425 HP

6/27/01

Stock HP Adjustments (effective 7/12/01)
("Crate Motor" HP changes)

Chevrolet

• 350 / 300 / 310 hp reduced to 305 hp.
• 350 / 335 hp increased to 340 hp.
• 350 / 355 / 360 hp increased to 365 hp.
• 350 / 385 hp increased to 395 hp.

Mopar

• 360 / 300 / 315 hp (Magnum) increased to 325 hp.
• 360 / 300 / 305 hp (Commando) increased to 315 hp.
• 360 / 360 hp reduced to 350 hp.
• 440 / 410 hp reduced to 405 hp.

6/6/01

Super Stock HP Adjustments
1972 Buick 455 / 315 hp reduced to 300.

Stock HP Adjustments
1970 Olds 455 / 375 hp reduced to 365.

4/26/01

Stock and Top Stock HP Adjustments

Pontiac Firebirds (Ram Air 1,2,3&4)

• '67 400 / 360 reduced to 342
• '68 400 / 370 reduced to 352
• '69 400 / 375 reduced to 356
• '70 400 / 380 reduced to 361

Top Stock HP Adjustments

• Reduce accepted Big Block crate combinations to 430 HP.
• Reduce accepted Small Block Chevrolet and Mopar combinations to 355 hp.
• Reduce accepted Small Block Ford crate combo to 350 hp.

2/26/01

Chevrolet Crate Motor
350/345 should read 355 hp for factored horsepower

6/27/00

HP Adjustments (adjustments are for Stock and Super Stock)

• 1970 Chevrolet 350 / 370 hp reduced to 351.
• 1966-69 AMC 290 / 225 hp reduced to 214.
• 1973-74 Pontiac 455 / 290/350 hp reduced to 332.
• 1972 Pontiac 455 / 300/350 hp reduced to 332.

5/1/00

Stock Eliminator HP Adjustments

( "Crate Motor" HP changes)
Chevrolet

• 350 / 330 hp increased to 340 hp.

Mopar

• 360 / 300/310 hp (Magnum) increased to 315 hp.
• 360 / 300 hp (Commando) increased to 305 hp.
• 360 / 380 hp reduced to 370 hp.

(Stock Eliminator)
Ford

• 1986 302 / 200/210 hp reduced to 205.

The minimum cylinder head volume for the 360 / 300 Commando combination has been reduced from 70.2 to 64.7 cc. Based upon this change the hp has been increased from 300 to 305.

1/25/00

Stock Eliminator HP Adjustments

Ford "Crate Motor" HP Reductions

• 302 / 270 hp reduced to 250 hp.
• 302 / 285 hp reduced to 265 hp.
• 302 / 320 hp reduced to 300 hp.
• 351 / 385 hp reduced to 375 hp.
• 351 / 362 hp reduced to 352 hp.