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GM LS Asymmetrical FSR Dome

GM LS Dome - 15° Head Our brand new Asymmetrical FSR (Forged Side Relief) forging design allows for the use of the most popular stroke and rod combinations while eliminating reluctor wheel clearance problems. Asymmetrical forging design maintains a larger skirt on the heavily stressed major thrust side, while reducing friction with a smaller skirt on the minor thrust side. The result is a high strength, lightweight piston that significantly reduces friction in your engine. Lightweight and extremely durable, these pistons are machined for 1.2mm, 1.5mm, 3.0mm rings.

Designed for 15° Valve Pockets Only

Features:
Accumulator Grooves
Double Pin Oilers
Offset Wrist Pin
Includes:
Pin #945-2250-15-51C (105g) For use with 6.098” Rod Length
Pin #927-2250-15-51C (106g) For use with 6.125” Rod Length
Round Wire Locks # 927-073-MW
New for 2013!
GM LS Asymmetrical FSR Dome
STD Bore: 4.000" LS2 / 4.065" LS3 / 4.125" LSX
Ring Packaged Designed for 1.2mm, 1.5mm, and 3.0mm Rings
Note: 1.340 Compression Height Pistons utilize .945" Pin Diameter and 6.098" Rod Length.
*** LSA & LS9 Engines require oil squirter location modification for clearance. ***

Click here to see matching JE Pro Seal Head Gaskets!

Tech and Installation Tips
Valve Relief Diagram
Part # CID Bore Stroke Rod
Lgth.
Block
Ht.
Comp.
Ht.
Head Cubic Centimeters
64cc 68cc 70cc
Compression Ratio
Dome
Vol.
Gram
Wt.
Footnote Oversize Recom.
Ring Set
312120 413 4.000 4.100 6.125 9.240 1.065 13.2 12.5 12.2 3.4 Call B, M STD LS2 JG3108-4000-7
312121 413 4.005 4.100 6.125 9.240 1.065 13.2 12.5 12.2 3.3 Call B, M .005 LS2 JG3108-4000-7
312122 414 4.010 4.100 6.125 9.240 1.065 13.2 12.5 12.2 3.1 Call B, M .010 LS2 JG3108-4010-4
312123 418 4.030 4.100 6.125 9.240 1.065 13.2 12.5 12.2 2.5 Call B, M .030 LS2 JG31F8-4030-2
312124 426 4.065 4.100 6.125 9.240 1.065 13.2 12.5 12.2 1.3 Call B, M STD LS3 JG31F8-4070-0
312125 427 4.070 4.100 6.125 9.240 1.065 13.2 12.5 12.2 1.1 Call B, M .005 LS3 JG31F8-4070-0
312126 428 4.075 4.100 6.125 9.240 1.065 13.2 12.5 12.2 1.0 Call B, M .010 LS3 JG31F8-4075-5
312127 429 4.080 4.100 6.125 9.240 1.065 13.2 12.5 12.2 .8 Call B, M .015 LS3 JG31F8-4075-5
312128 438 4.125 4.100 6.125 9.240 1.065 13.2 12.5 12.2 -.7 Call B, M STD LSX JG31F8-4125-2
312129 439 4.130 4.100 6.125 9.240 1.065 13.2 12.5 12.2 -.8 Call B, M .005 LSX JG31F8-4135-2
312130 440 4.135 4.100 6.125 9.240 1.065 13.2 12.5 12.2 -1.0 Call B, M .010 LSX JG31F8-4135-2
312131 445 4.155 4.100 6.125 9.240 1.065 13.2 12.5 12.2 -1.7 Call B, M .030 LSX JG31F8-4155-3
312132 451 4.185 4.100 6.125 9.240 1.065 13.2 12.5 12.2 -2.7 Call B, M .060 LSX JG3108-4185-3
312105 402 4.000 4.000 6.125 9.240 1.115 13.2 12.5 12.2 5.2 Call B, M STD LS2 JG3108-4000-7
312106 403 4.005 4.000 6.125 9.240 1.115 13.2 12.5 12.2 5.0 Call B, M .005 LS2 JG3108-4000-7
312107 404 4.010 4.000 6.125 9.240 1.115 13.2 12.5 12.2 4.9 Call B, M .010 LS2 JG3108-4010-4
312108 408 4.030 4.000 6.125 9.240 1.115 13.2 12.5 12.2 4.3 Call B, M .030 LS2 JG31F8-4030-2
312109 415 4.065 4.000 6.125 9.240 1.115 13.2 12.5 12.2 3.1 Call B, M STD LS3 JG31F8-4070-0
312110 416 4.070 4.000 6.125 9.240 1.115 13.2 12.5 12.2 3.0 Call B, M .005 LS3 JG31F8-4070-0
312111 417 4.075 4.000 6.125 9.240 1.115 13.2 12.5 12.2 2.8 Call B, M .010 LS3 JG31F8-4075-5
312112 418 4.080 4.000 6.125 9.240 1.115 13.2 12.5 12.2 2.7 Call B, M .015 LS3 JG31F8-4075-5
312113 427 4.125 4.000 6.125 9.240 1.115 13.2 12.5 12.2 1.2 Call B, M STD LSX JG31F8-4125-2
312114 429 4.130 4.000 6.125 9.240 1.115 13.2 12.5 12.2 1.0 Call B, M .005 LSX JG31F8-4135-2
312115 430 4.135 4.000 6.125 9.240 1.115 13.2 12.5 12.2 .9 Call B, M .010 LSX JG31F8-4135-2
312116 434 4.155 4.000 6.125 9.240 1.115 13.2 12.5 12.2 .2 Call B, M .030 LSX JG31F8-4155-3
312117 440 4.185 4.000 6.125 9.240 1.115 13.2 12.5 12.2 -.8 Call B, M .060 LSX JG3108-4185-3
324009 392 4.000 3.900 6.125 9.240 1.165 13.2 12.5 12.2 9.4 424 M STD LS2 JG3108-4000-7
324010 393 4.005 3.900 6.125 9.240 1.165 13.2 12.5 12.2 9.3 425 M .005 LS2 JG3108-4000-7
324011 394 4.010 3.900 6.125 9.240 1.165 13.2 12.5 12.2 9.2 426 M .010 LS2 JG3108-4010-4
324012 398 4.030 3.900 6.125 9.240 1.165 13.2 12.5 12.2 8.6 428 M .030 LS2 JG31F8-4030-2
324013 405 4.065 3.900 6.125 9.240 1.165 13.2 12.5 12.2 7.5 428 M STD LS3 JG31F8-4070-0
324014 406 4.070 3.900 6.125 9.240 1.165 13.2 12.5 12.2 7.4 429 M .005 LS3 JG31F8-4070-0
324015 407 4.075 3.900 6.125 9.240 1.165 13.2 12.5 12.2 7.2 431 M .010 LS3 JG3108-4075-5
324016 408 4.080 3.900 6.125 9.240 1.165 13.2 12.5 12.2 7.1 433 M .015 LS3 JG3108-4075-5
324017 417 4.125 3.900 6.125 9.240 1.165 13.2 12.5 12.2 5.7 440 M STD LSX JG31F8-4125-2
324018 418 4.130 3.900 6.125 9.240 1.165 13.2 12.5 12.2 5.6 441 M .005 LSX JG31F8-4135-2
324019 419 4.135 3.900 6.125 9.240 1.165 13.2 12.5 12.2 5.4 442 M .010 LSX JG31F8-4135-2
324020 423 4.155 3.900 6.125 9.240 1.165 13.2 12.5 12.2 4.8 450 M .030 LSX JG31F8-4155-3
324021 429 4.185 3.900 6.125 9.240 1.165 13.2 12.5 12.2 3.9 465 M .060 LSX JG3108-4185-3
312092 364 4.000 3.622 6.125 9.240 1.304 13.2 12.5 12.2 12.0 Call M STD LS2 JG3108-4000-7
312086 364 4.000 3.622 6.098 9.240 1.340 13.2 12.5 12.2 12.0 Call K, M STD LS2 JG3108-4000-7
312087 365 4.005 3.622 6.098 9.240 1.340 13.2 12.5 12.2 11.8 Call K, M .005 LS2 JG3108-4000-7
312093 365 4.005 3.622 6.125 9.240 1.304 13.2 12.5 12.2 11.8 Call M .005 LS2 JG3108-4000-7
312094 366 4.010 3.622 6.125 9.240 1.304 13.2 12.5 12.2 11.7 Call M .010 LS2 JG3108-4010-4
312088 366 4.010 3.622 6.098 9.240 1.340 13.2 12.5 12.2 11.7 Call K, M .010 LS2 JG3108-4010-4
312089 370 4.030 3.622 6.098 9.240 1.340 13.2 12.5 12.2 11.1 Call K, M .030 LS2 JG31F8-4030-2
312095 370 4.030 3.622 6.125 9.240 1.304 13.2 12.5 12.2 11.1 Call M .030 LS2 JG31F8-4030-2
312090 376 4.065 3.622 6.098 9.240 1.340 13.2 12.5 12.2 10.0 Call K, M STD LS3 JG31F8-4070-0
312096 376 4.065 3.622 6.125 9.240 1.304 13.2 12.5 12.2 10.1 Call M STD LS3 JG31F8-4070-0
312091 377 4.070 3.622 6.098 9.240 1.340 13.2 12.5 12.2 9.9 Call K, M .005 LS3 JG31F8-4070-0
312097 377 4.070 3.622 6.125 9.240 1.304 13.2 12.5 12.2 10.0 Call M .005 LS3 JG31F8-4070-0
312098 378 4.075 3.622 6.125 9.240 1.304 13.2 12.5 12.2 9.9 Call M .010 LS3 JG31F8-4075-5
312099 378 4.080 3.622 6.125 9.240 1.304 13.2 12.5 12.2 9.7 Call M .015 LS3 JG31F8-4075-5
312100 387 4.125 3.622 6.125 9.240 1.304 13.2 12.5 12.2 8.4 Call M STD LSX JG31F8-4125-2
312101 388 4.130 3.622 6.125 9.240 1.304 13.2 12.5 12.2 8.3 Call M .005 LSX JG31F8-4135-2
312102 389 4.135 3.622 6.125 9.240 1.304 13.2 12.5 12.2 8.1 Call M .010 LSX JG31F8-4135-2
312103 393 4.155 3.622 6.125 9.240 1.304 13.2 12.5 12.2 7.5 Call M .030 LSX JG31F8-4155-3
312104 399 4.185 3.622 6.125 9.240 1.304 13.2 12.5 12.2 6.7 Call M .060 LSX JG3108-4185-3

- Denotes part # has been issued a new part #. A list referencing old part #s to their new counterparts will be available shortly.


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