Raby Rebuild & S transmission
 

Just thinking about the potential options to freshen my 98, I was wondering if you
guys thought a six speed mated to the + 60 hp Raby rebuild motor would be a good place to waste hobby money.

The 6 speed would be a true waste of your hobby money. Spend it on something that would make a positive difference, like suspension, LSD and tires.

OK just looking for thoughts, I had intended on doing some work on the suspension but was told on another thread the LSD would be pointless on the street, although I tend to think it would be a good upgrade. You didn't really address whether any performance would be had from the 6 speed, I'm just curious about that.

The 6 speed may or may not be of benefit based on your application more than anything.. The fact is the 6 speed is a much stronger arrangement, able to take any amount of power we can throw at it. The gear ratios and spreads are great for some applications, and they suck for others.

The 6 speed is a heavier and longer tranny than the 5 speed.. That may or not be of concern for you. The 6 speed does have larger CVs and uses a heavier duty input shaft with more selections for clutch packages available.

I have a 5 speed in my Boxster and a 6 speed in my 911. The 6 speed was optimum for my Wife's Land Speed Racing last weekend, but it doesn't work very well for my DEs at Road Atlanta, where the 5 speed seems to be much more effective. She was at the top end of 5th gear at 149.280 MPH with 200 RPM of potential left... I seldom touch 5th at Road Atlanta except the back straight and I use 6th gear maybe once per week driving the car daily.

You should select the 6 speed based on what your application of the engine and car will be. We'll couple that with the engine package that I design for you, as some optimize the 6 speed much better than the 5 speed and vice versa.

The difference in my engine isn't really the HP, its what we do with the concentration of the engine's power and how much TORQUE we add to the combination.

That said, over this winter I am starting with a 3.2 core and building a Stage III 3.6 for my '98 Boxster. I will be coupling this to a 6 speed tranny for a dual purpose street/ DE much like my 911 and we'll be converting the 911 into a full blown LSR car for my Wife.

I am choosing the 6 speed due to the extreme torque the 3.6 engine in stage III tune will be producing along with it's 8,500 RPM rev range...

Its all up to YOUR application, I'll work with you to design a complimentary package; thats what I do.

I added an LSD on a 100 hp Rx-7. The cars are notorious for a "loose" rear end, Nevertheless, it made a noticeable difference in the way it put down power around a corner on the street. If you drive somewhat aggressively at times, I have to believe that you'd notice the improvement even if you've got the 2.5. Once you install a 300+ HP engine, you'll definitely notice it.

Having said that, I'd certainly attack suspension first, it's the most bang for the buck. M030 and some suspension bracing really make a car more fun to drive.

On the 6-speed, I'm not impressed with the extra gear. I've noted in a couple places on this board that the 5th ratio is more or less useless and 3rd is too tall. The narrower the car's power band, the more gears are needed, for the Boxster, a 6 speed is a marketing move, not a performance one.

Thanks for the info Jake, I should know about a full time position in the next few weeks, if that comes though we will be in touch.

With these cars the LSD is most desirable under heavy deceleration from high speeds... When adding a ton of power and a lot more speed capability this is much more beneficial than anything else. If you spend time at high speed and transitioning to braking the "wiggle" that can be so intimidating with an open diff is basically eliminated.

I agree that with the stock "S" that the 6 speed was a marketing ploy by Porsche.. With the stock 3.2 engine, 6th gear is virtually worthless and the engine doesn't make enough torque to "pull it".

You'd find this stabilizing behavior on a clutch type LSD, not a torque biasing type, correct?

Correct. TBD's don't offer any lockup on decel. In terms of gearboxes, I'd like to see a 6-speed re-geared with useful ratios.

$$$

I live near GBox and would love to change 3-5 to be closer, but on the street car, it's just not worth the price.

If I had a 5 speed, I'd stick with it for sure, the ratios are better for street driving and probably autocross too.

Oh I'm well aware..hence why my 6-speed is staying stock :)