Drag Racing Discussions > Front Engine Dragsters

new fed to me questions

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probird:
a few pics now that I have the body and wheels off.
Thoughts?

rooman:
I would like to see a photo showing the mid plate area before commenting but strictly speaking the forward bay may be non compliant as it appears that the long diagonal is not within 3 tubing diameters of the junction between the intermediate upright and the lower rail which is the normal criteria for a diagonal within a bay. The rear bay is OK because the upper tube makes the configuration a "K" in that bay. The fact that the bend in the upper rail is well behind the forward upright is also a bit of a worry (feel free to jump in here Bruce.  :) ) but that could be obviated somewhat by adding a diagonal from the top of the intermediate upright to the bottom of the motor upright (one of the reasons that I would like to see that part of the frame) to make an X in that bay. Alternatively that bay could also be converted to a "K" configuration although the lower part of the "K" would be a little shallow.

Roo

probird:
went out and took a couple mid plate area pics. thanks roo.
Im guessing it was a home built kit as the previous owner didn't know who built it.
looking for 7.50.

rooman:
Yep!  Just what I thought I would see. Typical of most cars that have had the motor moved forward, the mid plate is out in space (and so are the front motor mounts). Any flex in this area will cause coupler alignment problems. Also the mid plate is no longer acting as a firewall. I can't see from the photos but is the mid plate tabbed to the lower rails?
   When the mid plate is at the motor uprights (as the SFI spec intends) any torque is carried through those uprights to the diagonals/X's/K's in the side bays. As the motor torques up under load it tries to lift the left side and push the right down. In this case the only resistance is provided by the tube diameter and wall thickness rather than the "beam" provided by the braced side bay. Having the front mounts similarly out in space just adds to the problem.
  Worm's Cen-Pen cars seem to get by because the rails are .095 wall but it is not unusual to have problems with a .058 rail chassis if the engine makes plenty of power/torque (ask hotrod316 about that :) ). The ideal fix is to add an upright at the motor mount but even a diagonal from the original motor upright to the new mid plate location will help (although not with the firewall issue). Also I see that the stepdown in the top rail is behind the mid plate since the change in engine location and even the rule book spec for 10 second and slower calls for it to be at least 2" ahead of the motor upright.

Roo

probird:
ok. I will bring it back to where it was originally and set the engine high enough for the oil pan on both engine and trans so I can put a catch pan under the engine and seal the driver area with a nice belly pan. its tabbed on the bottom but will be cutting them off anyways. And will add 4 bolt hole mount to the rear end.

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