g5x3 question
no notch, on either LSA with stock heads.
We dont reccommend the 918s. I know Unaffiateds situation but we float new 918s at 6700 at the stock installed height.
We reccommend the 921s.
We dont reccommend the 918s. I know Unaffiateds situation but we float new 918s at 6700 at the stock installed height.
We reccommend the 921s.
TECH Resident
Joined: Dec 2004
Posts: 881
Likes: 1
At 1.75 the 918 and 921 have the same seat pressure (146 vs 143, respectively, with spring to spring variation). At 1.8 the 918 is stiffer.
Over the nose at .600 the 921 is stiffer, about 17% (333 vs 388). and the 921 has a lower coil bind so it could be installed with more preload. At a 1.7 installed height, the 921 would be 154 and 408. However, then you get into the questions of how long the spring will last.
I think the Tony from AFR summed it up in one of his posts. With a stock valvetrain, the 918 works well. With heavier pieces (valves, pushrods, rockers, etc), you need a bigger spring.
Over the nose at .600 the 921 is stiffer, about 17% (333 vs 388). and the 921 has a lower coil bind so it could be installed with more preload. At a 1.7 installed height, the 921 would be 154 and 408. However, then you get into the questions of how long the spring will last.
I think the Tony from AFR summed it up in one of his posts. With a stock valvetrain, the 918 works well. With heavier pieces (valves, pushrods, rockers, etc), you need a bigger spring.
