One of the most basic rules in motorsport is that you should only ever change one thing at a time. This way you can nail down cause and effect, while avoiding confusion over which tweak has made what difference. Following the same rule when tuning a road car is also a smart thing to do.
The Diablo Mountains, east of San Jose, offer some of the best and most spectacular driving roads in Northern California. Bordering the local state park, Route 130 starts in the foothills by Highway 680, and winds its way up Mt. Hamilton towards Observatory Peak at 1,284m (4,213ft) above sea level, and down the other side.
Running across Mt. Hamilton for 22.5 miles, Route 130 has considerably more gradient than flat, a short few straights, many open, but even more numerous tight bends, with the occasional hairpin thrown in for good measure.
In all, there are 365 curves here, one for each day of the year, and all the tighter corners are cambered the right way. The backdrop to this sinuous piece of tarmac is a rock face on one side and a sheer drop on the other. This is a drivers’ road par excellence!
The last time I came here, the RS 3.8 had already acquired Shark Werks’ full suspension kit, but its motor was stock apart from their lightweight titanium/stainless steel hybrid sports exhaust and EVOMS ECU upgrade. A healthy 470bhp at the flywheel was the order of the day.
So what has changed? Outwardly almost nothing, apart from that big Baron RS rear wing that sits three inches higher up and offers eight degrees more angle of attack. A side benefit is better visibility in the rear view mirror!
The big news is that Shark Werks has leapfrogged their famous 3.9-litre conversion and morphed this GT3 RS 3.8 into a 4.1. Appropriate badges on the engine’s air box, doorsill entry plates, and the carpet behind the lightweight race seats constantly remind you of the fact.
On the face of it, Shark Werks 3.9 conversion was already a weapons grade conversion. To my surprise, it had more torque than the factory RS 4.0, so when Shark Werks’ boss, Alex Ross e-mailed me to say that the 4.1 litre upgrade was finally ready for testing, I could not wait to get behind the wheel.
From the word go, the 4.1 feels quite different from anything in the Porsche GT3 road car world that has gone before. Where the stock 3.8 with its single-mass flywheel revs quickly and smoothly to its redline, and the 4.0 is more of the same but with a bigger punch, the Shark Werks 4.1 feels like a 4.0 on steroids, coupled with some aspects of the new 991 GT3’s even higher-revving motor.
Revving fast and hard is not the only characteristic worthy of note here. While the 3.8 and 4.0 factory motors produce more and more power as they head for their respective red lines, the 4.1 feels like it is bursting with energy trying to force its way out of the motor as well. There is a fundamental difference in the way this motor answers the throttle, which makes this big engine all the more enticing.
The irony is that with 540bhp at 7,950rpm and 400 ft lb (542 Nm) of torque on normal 93 Octane pump gas, the naturally-aspirated flat-six is now so powerful and so responsive, I quickly realised that I could not use anything close to its full potential on this test road.