Michael1

Whoa! Lotus, let's not get carried away here!

Yes, the supercharger may boost the intake charge pressure, but there is still the throttle in the system, which is cutting back manifold pressure. The engine only cares about two things with regard to the intake track: manifold pressure and manifold air temperature. When you are idling or cruising, you still have the same low manifold pressure as a non-supercharged car (except for a very slight increase to compensate for parasitic losses from the supercharger). Manifold air temperature may be slightly higher, but very little at low engine speeds.

OEM Eaton superchargers have a bypass valve, so there is no boosting at low power settings. Some OEM superchargers have a electric clutch to disengage the supercharger at low power settings (Toyota MR2 was an example of this). Both of these cutout methods were implemented to reduce parasitic losses, which would reduce fuel economy. Centrifugal superchargers favored by the aftermarket don't produce much boost at low engine speeds. In fact, boost is directly related to engine speed.

The bottom line is, if you never put you foot in the throttle, never raising the manifold pressure above ambient, the reduction in engine life would be EXTREMELY small, and only related to the parasitic drag of the supercharger, and slight charge temperature increase. In other words, I wouldn't worry about it. If you are running above ambient pressures, that's a different story.

Michael

TT Surgeon

I think the bottom line is that a sc is do-able in a 996/7, however, there will be more wear/tear on your motor, assuming you run your car hard, all that extra hp isn't free.
99-911 is a smart guy whose gotten good results with his car, however the few I've seen seem to be plagued with constant problems (oil leaks , etc) and run horribly at the track.
The warranty issue on a 100k car is no small one, I wouldn't do it, least not until my warranty expires then who knows.

1AS

PTEC"s comment interests me. The part about "if you were going 60, now you are going 75".
Has anyone with an sc noted the difference in track speed pre and post installation?
After many years of racing cars, I am impressed by the small difference in trap speed from power enhancement versus the much larger difference from tires, suspension, gearing and driving skill. This is particularly true for engines which make their power at the top of the rev range (which is definitely the case for the 997 sc described in Excellence). The exception of course is the long straight course like Elkhart Lake, where the straight is a mile long and uphill. But there the difference is 140 to 150, not 60 to 75. (and that is for a substantial hp boost)
I have seen expert drivers shift 2000 rpm short of the redline (thereby giving up 100 or more horsepower) and beat the lap times of guys wringing every rev out of the engine.
Torque out of a corner is a big help, but exit speed matters a lot more. I personally think you could exceed the track performance of an sc just by regearing the transmission. Of course a sticky set of tires would do the same, and both together would be far better. Making first a little longer, and 2-5 much shorter would be a huge boost. AS

TT Surgeon

Roger that, AS. My car with minor engine mods, X73 suspension and R compound tires will spank most stock turbos( and one sc'd 3.4 car in particular) around Watkin's Glen without too much trouble.. Driver skill, suspension and tires will overcome raw, untamed hp most of the time.

Michael1

Road racing is a combination of factors. It is very hard to predict whether one factor will overcome the other. There is a matter of degree, and how the factors relate to the track. Of course, some improvements cost more than others. It is pretty much, "try it and find out."

Michael

Itzkirb

I have a SC'd 996 and am considering taking it out due to minor issues.

pedsurg

Guys: I thought the most interesting part in the recent Excellence 997 SC article was that Evo opted to not SC the 997S due to concerns that the drivetrain could not withstand the increased power.

Jack

sticky

They did supercharger the carrera S but they run less boost due to the higher compression. There is a guy on 6speed with a supercharged 997 S.