I have never herd of anyone replacing the camshaft on these engines to gain HP. You can do a lot of damage to the engine if the timing is messed up. Besides, you can always change the ignition timing by tuning the ECU.
Have read some bad reviews about the 3.91 diff as well.
Totally the opposite my good friend Hasan.
Both myself and Bavarian Beast ( John ) have installed Schrick ( Kelleners simply sells them under his brand name ) cams.
It is a myth that damage can occur or that there is no gain in power.
Let me inform you firsthand.
Schrick cams for the S85 cost 2800$ and can be found at Turner Motorsport for 2250$.
Their duration is 292 degrees and the valve lift is 12.2 mm.
The gain is +18 hp at 7800rpm and -1hp at 4500rpm. This means that the engine becomes somewhat peakier.
What is the problem then ???
Two problems.
1) Find a REAL EXPERT with true knowledge to do the installation.
2) Find a software tuner with bal*s to tune the engine accordingly ...cough... cough ESS.
So the total cost of cams, installation and tune is approximately 4500$.
Not cheap by any means. But from personal experience worth every penny.
Especially if someone has already installed all the bolt-on goodies. Headers, exhaust, ram-air induction, pulley and the final tune
for all of these plus cams.
I got 605 hp crank at 8150 rpm with the limiter raised to 8450rpm, while before installing the cams I could barely reach 580.
And all that on a Maha dyno which is very-very conservative and the most accurate dyno in the world.
Now regarding 3.91 diff.
I do not see what the problem may be. No, I do not have it.
Shorter final drive will reduce top speed and improve acceleration. Further than that what is the problem ???
Best regards,
George:cheers:
P.S.
The cams have nothing to do with ignition timing. They simply allow a larger air-fuel quantity to pass through the valves and be compressed in the chambers.