engine mount / torque strap

[Pete Sprenger]

I tried to post this a few minutes ago, but my computer wigged out and I don't think it went through.

 

I took my 240Z to its first track day with its 3.1L stroker installed back in October. The engine had 670 miles on it before I took it to the track day and when I installed it, I threw in a brand new set of genuine Nissan engine mounts. I have taken the car to numerous track days with the same style mounts with no problems on the stock L24. Due to the torque of this engine (the N-42 head received over-sized valves and was ported and polished, all head work was done by Rebello racing) the rubber was plulled away from the metal on the sides of the engine mounts. This allowed for so much engine movement that my throttle linkage was pulled apart at one of the ball and socket joints. I have all the parts to convert it to a throttle cable, but is there a different option for engine mounts that would hold up better? I was thinking of fabricating a torque strap for the engine to limit movement and still use the stock style mounts. Does anyone have pictures of a torque strap they have used? Are there better engine mounts that would eliminate the need for a torquestrap?

 

By the way, My Z is primarily a street and autocross car, but I have built it pretty much as a race car that still has an interior.

 

Pete

1972 240Z

[Tony D]

Plenty of engine strut ties you can use.

MONZTER made a nice set of engine mounts using Moustache Bar urethane mountings.

 

Many use a tie to the upper starter bolt and make a reinforcement to the fram rail where you place the bracket.

 

Others simply put a lock-bolt through the engine mount so it can not fail and catastrophically separate.

 

The tie bars link the engine's torque to the chassis so your throttle inputs are more immediate from what I have felt. On and off throttle response becomes more pronounced so a smooth driving style is rewarded.

 

I have even seen heim jointed linkages to the K-Member (crossmember) from the engine mounting brackets, keeping the stock rubber mounts. This keeps the isolation and vibration down, and still ties the engine to the chassis more positively with no give/compliance windup on/off throttle.

 

Note on the ZX's they have 'snubbers' on the engine mounts as well? That engine moves axially within the chassis under some conditions...just something to keep in mind!

 

FWIW, if you aren't in it all that much, solid mounts do solve it. But you get a lot of vibration and bolt checking becomes critical from the increased vibration transferred to the chassis.