Differential bracket issues Superformance early Mod. 100's

[eschaider]

Lets give the OP the benefit of the doubt an assume he actually did buy two (!!) Roush Yates FR9 NASCAR engines. If we use the claimed 900 HP target which is in the ball park for an FR9 engine and accept the engine produces the power in the neighborhood of 7500 rpm then that only requires 630 ft/lbs of torque. There are many large displacement engines in cars on the site here, that produce that level of torque and more at decidedly lower engine speeds that do not seem to experience the mechanical failure the OP has experienced.

Even if he actually does use an FR9 engine, 639 ft/lbs torque is nothing particularly remarkable and certainly not adequate to do that level of damage out of the box so to speak. I am still of the opinion the car was abused, not maintained and eventually failed most likely because it was not maintained.

The OP's representation of 900 FWHP and 875 RWHP is a significantly different FWHP to RWHP loss than any replica owner on the site that has ever posted. The OP's claim to have measured his RWHP at 875 would imply a chassis dyno session and obviously documentation from the shop that did the pull. He could easily put the doubts to rest by producing a copy of that pull.

As olddog has already pointed out, the side pipes alone cost two bushel baskets of TQ and HP. Ignoring side pipes it is not uncommon to see powertrain losses approximating 15% if not more. That means the 630 ft/lb torque number would drop to a 530-ish number at the wheel in a best case scenario. My guess is likely lower. This brings us back to abusive operation and inadequate maintenance or perhaps no maintenance at all, as the culprit.

I am obviously still suspicious. To the OP, I am sure we all would like to see a picture of the engine in your car and some supporting dyno pulls to validate the RWHP differential you reported. Additionally the PM you sent me claiming a 208 MPH top speed for your Cobra seems, like a number of your other claims, a bit optimistic. If we ignore the fact that a 208 mph top speed would put you among the one or two fastest Cobra's ever (and likely the fastest in that elite group), I find it more than a little interesting that the mechanical failure did not happen at 208 mph !?!?!

Bottom line though, the failure comes back to minimally a maintenance issue and probably an abuse issue also. If it was the previous owner that abused the car then the pregnant question becomes, after putting an engine that is that powerful into the car why did you not do a thorough vehicle and in particular powertrain inspection before putting yourself and potentially others at risk and certainly before driving the car 208 mph.

As olddog observed and I think the OP had indicated, some of the damage may have predated his ownership of the car. Certainly he had to see the diff mounting issues when he installed the driveshaft and once again before driving the car 208 MPH — right?

I am still smelling a rat and it is not a Chevrolet ...


Ed