They say a picture is worth a thousand words...
This is a solid mount from my car when it was running mid 11's. We have found that with a solid mount, there is not much ability to flex. With the motor torquing over, something has to give. LUCKILY, it was the solid mount and not the block. That is one of the reasons we designed a mount with polyurethane bushings built into them. Poly has more desirable characteristics than the stock rubber, without the problems associated with solid mounts.
Stock motor mounts with a tie-down
When we ran the stock mounts with a tie-down
strap, we broke an alternator housing, broke the main bracket for the
accessories, and ruined several serpentine belts. That doesn't
include all the hassle and wasted money and time wrenching, fixing,
welding, and missed races that a stock mount/tie-down combination caused
Other problems that tie-downs could cause
When we blow head gaskets, it is usually worse on the side with the tie-down. The stress is transferring to the head, and separating the head from the manifold as the motor torques over. Slightly slower 60 ft. times will be had from the power being transmitted slower because the stock mounts and tie-down absorb some of the power. Unexplained knock retard is usually coming from the stock mounts hitting their limiter and/or flexing to allow something to contact metal-to-metal. Extensive testing on the street as well as the track has proven to reduce and/or eliminate the above negative effects with the new Poly motor mounts. We do NOT recommend any type of tie-down or engine restraint at any HP level when using our Poly motor mounts.