Performance Increase?

The testing of the ESC and it's ability to communicate with the Bosch ECU is solved without having to piggyback the ECU. The theory of "piggybacking" was and has been tested by another vendor only to find that it failed miserably after selling several $7000 plus centrifugal belt driven super charger units to customers. That supercharger is no longer available for sale from that vendor.

The ability of the OEM CTS factory 3.6 engine with it's factory forged internal combustion chamber has never been an issue, nor has the compression and it will easily support the required boost to bring another 100 horsepower to the flywheel.

There are no required modifications to the dual air intake plenum as the air, fuel volumetric efficiency was and has been tested, tested and retested on the bench very early on when we considered either a turbocharger, or centrifugal or Eaton roots style supercharger.

The current Cadillac CTS 3.6 6 speed manual and automatic transmission engineering has NEVER revealed any mechanical problems in close to 8 months of actual road-testing of the electric supercharger.

Where our concern is in releasing this supercharger for installation is in what we suspect may be the engineering integrity of the Cadillac CTS 3.6 aluminum rear differential case due in part to what we suspect may either be deflection in the current driveshaft or the "ugly deal-breaking possibility" that the current OEM rear end differential is simply under-engineered to support an additional 80RWHP.

Through road testing of the ESC; on several occassions we have had the rear end differential case literally crack in half, the ring and pinion gears chewed and have even had the rear drive shaft twist.

This issue is obviously of paramount importance because when you add another 80 RWHP to this vehicle platform, the rear-end differential has to be able to support it.

So we are currently working via "outsourcing" with a specialty engineering firm on the "possibility" of a cradle system that will lock down the rear differential assuming that drive-shaft deflection is the source of the rear differential failure. We are hoping that this is the case!

We are "hoping" that it is not the case that the rear-end differential is underengineered to support the additional 80RWHP as that could be the "deal breaker".

We suspect that it is drive-shaft deflection due to "wheel-hop" and remain hopeful that a cradle system can be engineered that will lock down the differential and prevent what we suspect is deflection that may have caused the rear-end differential failure.

If the above proves to be true; it should be a relatively inexpensive engineering solution to lock down the differential.

If it proves that the differential simply cannot support the additional 80 RWHP; than the entire landscape changes as we would be looking at a price that would more than double the manufacturing costs as you would literally be rebuilding the rear-end differential.

And unfortunately, we can't simply sell this supercharger unit until we are 100% sure that it operates 100% of the time without failure to any of the drive-train components.

The very moment we/you install this supercharger unit; if your differential was to fail; that failure would NOT be covered under your factory warranty. And out of pocket costs on a new installed CTS rear-end differential is about $3000.00

We wouldn't have too many friends left in the Cadillac community if we started blowing out there differentials and then those customers find out that the repair is not covered under there warranty.

So we're not just out to make a "buck" as some may think in some cases. We have to be 100% sure that it operates flawlessly 100% of the time.

We'll keep you posted as more unfolds from the outsource engineering company regarding this final obstacle.

Cadillac MotorSports, Limited
[email protected]***********************

I don't know about a retrofittable fix for the differential itself, but GM released a TSB for new (stiffer) cradle bushings that are said to eliminate much of the 'hop', and increasing harshness only slightly. V owners can get them for free if the complain, but I'm pretty sure that they can be purchased also. I suspect many of the failures, especially twisted axles are a result of wheel hop, and not just max HP. The Getrag 645 differential is supposedly rated for 310 lb-ft (420N) of engine torque. Marginal for a built 3.6, and downright unacceptable for a 400 lb-ft LS6 in the V.

The V has the same diff, but with 3.73:1 gearing and limited slip. They also have a shorter one piece driveshaft (the regular CTS has a two piece driveshaft) and slightly beefier axles. While it will physically bolt into the chassis, I'm not sure about the mounting for the driveshaft or axles, since they carry different part numbers.

Remember too that gearing essentially multiplies the torque. If your engine puts out 250 lb-ft at the crank, then at the differential (ignoring drivetrain losses) it will put out that amount in fourth gear (1:1), but much more than that in first gear (3.5:1 first gear will put out 875 lb-ft at the diff). In off-road four wheeling, more axles get broken in 4-Low and granny gear when a wheel spins and then grips, than anything else. Even with little four cylinder engines!